Magnesium Supplements Review (Including Calcium,
Vitamins D & K, and Boron)
Find the Best Magnesium
Supplement. Tests and Reviews of Popular Magnesium Supplements & CL's Top
Picks.
Medically reviewed and
edited by Tod Cooperman, M.D. 
Last Updated
: 12/09/2021 | Initially Posted:
11/23/2019Latest Update: Magnesium for Metabolic Syndrome?
Table of Contents
Summary
·
What is magnesium? Magnesium is an essential mineral for
proper metabolism and nervous system functioning, including helping to maintain
the electrical stability of the heart. Although magnesium can be easily
obtained through the diet and overt magnesium deficiency is not common, many
people do not get adequate amounts of magnesium and can benefit from increasing
magnesium intake from foods or supplementation. Conditions that may deplete
magnesium include alcohol abuse, diabetes, diseases of the digestive tract, and
use of medications such as Nexium and Prilosec.
·
What does magnesium do? Inadequate intake of magnesium may
modestly elevate blood pressure and increase the risk of osteoporosis and
fractures. In addition, supplementing with magnesium may be helpful for
conditions such as migraines and menstrual pain and it is an effective laxative
and antacid. It may also improve glucose status in people with prediabetes --
particularly if they are low in magnesium. It also helps control levels of
vitamin D and can boost low levels. Maintaining adequate magnesium intake also
has cardiovascular benefits, and maintaining a proper ratio of magnesium to calcium
intake may have cognitive benefits (See "What It Does").
·
How much magnesium do I need? If you are not getting at least 300
to 400 mg of magnesium from your diet, consider a supplement that will get you
to that level.
·
What did CL's tests of magnesium find? Among the products
ConsumerLab.com selected for testing, two magnesium-only supplements
failed review because they contained less magnesium than listed or
were contaminated with lead and two magnesium formulas failed for
incorrect amounts of vitamin D, vitamin K, and/or boron (See What CL Found).
·
Which magnesium is best? Among the products that passed testing
and were "Approved" for their quality, CL selected a Top Pick for magnesium that is low in price
(just 6 cents per pill), well-absorbed, and in a stable chemical form. CL also
selected Top Picks for
combination formulas that include magnesium, such as those
marketed for bone health that contain calcium, vitamin D, vitamin K, and/or
boron.
·
How do forms of magnesium differ? Magnesium comes in
many forms. Magnesium oxide tends to be less expensive than other forms but may
also be less well absorbed and more likely to cause diarrhea. Forms that are
more water soluble, such as magnesium chloride, citrate and many chelate forms
(e.g., bisglycinate), may be better absorbed. Magnesium chloride is less likely
to cause diarrhea and is recommended if you are taking a higher dose but is
best in liquid form rather than as a tablet. (Be aware that, because magnesium
chloride tends to attract and hold water, which can cause pills to
disintegrate, magnesium chloride pills should be stored in a sealed container,
away from other pills -- see Storage.) Some magnesium chelates are also
less likely to cause diarrhea but are bulky, requiring larger pills to get the
same amount of elemental magnesium. Labels are required to show the amount of
elemental magnesium in each serving, but you need to read labels carefully. See
"What to Consider When Buying" for more
about the different forms.
·
What's the right dose of magnesium? When used as a
treatment, magnesium is often recommended at doses of 250 to 600 mg daily
(which is similar to the daily intake requirement in adults of about 400 mg).
However, unless treating a deficiency, limit your daily intake of magnesium
from supplements and fortified foods to no more than 350 mg (the Upper
Tolerable Intake Level), to avoid side-effects. You can easily get the rest of
your required magnesium from your diet. (See "What to Consider When Using").
·
Safety and side effects of magnesium: Magnesium
supplements may cause upset stomach, nausea, or diarrhea in some people.
Although rare, excessive intake can cause thirst, low blood pressure,
drowsiness, muscle weakness and slowed breathing. Be aware that magnesium can
interact with certain supplements and drugs. (See "Concerns and Cautions").
Update
ReMag (5/19/21): We were contacted
last Friday by Virginia Sanders, the Chief Operating Officer of New Capstone,
the manufacturer of ReMag which, as noted in this Review, was
Not Approved because we found it contaminated with 0.58 mcg of lead per ½
teaspoon serving (1.2 mcg per two servings). These amounts exceeds
the California Prop 65 limit of 0.5 mcg of lead per daily serving, above which
a warning label regarding reproductive harm is required.
Ms. Sanders provided a letter which noted the following:
"When we understood the nature of the violation, we made an immediate and
swift adjustment. Not only did we become even more rigorous with our lead level
testing incorporating lead level testing at an earlier stage of manufacturing,
but we also changed our labeling to removing the recommendation for child's
dosing. All adjustments were completed by January 2020."
Ms. Sanders also suggested that newer bottles of ReMag look
different from the one that we tested (and is shown in our results table).
We have not tested the newer ReMag.
BulkSupplements.com Magnesium Citrate (11/5/19):
CL was contacted late yesterday by a representative of BulkSupplements.com
regarding our finding in this Review that its Magnesium Citrate powder
contained only 399 mg of the claimed 500 mg of magnesium per teaspoon (listed
as 3,325mg of powder). The representative claimed that our results were in
error because the product serving size is 4,400 mg. Early this morning, we sent
an image of the product we tested (Lot Number 1806206, Best Before June 30,
2021) that lists a serving size of 3,325 mg, as noted in our report, not 4.400
mg.
Eight hours later, the representative responded, "We are aware of the
misprinted labels and have recalled the bags. As stated before, our serving
size is 4,400mg." Attached was a photo of a more recent product (Lot
number 1905609, Best Before Sept. 30, 2022) showing a 4,400 mg serving size,
described as "Rounded 1 ½ tsp providing 500 mg of magnesium. He added,
"I again ask that you please remove your findings. If not, is there an
area where we can respond/explain? Or will you note that this is specific to
lot 1806206?" We responded that we would post an update about this
situation and asked if they would provide a link on their site with information
about the recall and instructions for affected consumers.
We have not yet received the link or additional information from BulkSupplements.com.
Disconcertingly, an image of the product found on Amazon.com today shows the
same serving size as the product we purchased, "3,325 mg." The lot
number is blank on the Amazon image. Unless, that photo happens to be of the
exact lot we had purchased, it seems possible that the label error may not be
limited to a single lot.
Should you have purchased this product and the serving size is 3,325 mg, be
aware that to get 500 mg of magnesium (which is above the upper tolerable
intake level for magnesium for adults), you will need to increase the serving
size from 1 teaspoon to 1 ½ rounded teaspoons.
What It Is:
Magnesium
is an essential mineral for the body. It comes in a variety of chemical forms,
including magnesium oxide, magnesium chloride, magnesium gluconate, magnesium
citrate, magnesium orotate and many others. (For information about how these
forms compare, see ConsumerTips™: What to Consider When Buying).
In addition to magnesium-only supplements, supplemental magnesium can be
obtained from laxatives, antacids, multivitamin/multimineral products
(see Multivitamin/Multimineral
Supplements Review) and calcium supplements containing magnesium
(see Calcium Supplements Review).
What It Does:
Magnesium deficiency and insufficiency:
Magnesium is needed for proper metabolism and nervous system functioning,
including helping to maintain the electrical stability of the heart. While
sufficient magnesium can be obtained easily from the diet, and few people have
overt magnesium deficiency, many people get insufficient amounts, particularly
men aged 71 and older and adolescent females (Moshfegh, NHANES 2005-2006)
(see ConsumerTips™: What to Consider When Using for
more information about daily requirements and how to get magnesium from foods).
Magnesium deficiency may increase the risk of osteoporosis (Castigliooni, Nutrients 2013).
Low and deficient levels of magnesium have also been associated
with elevated blood pressure (Wu, Nutr J 2017). A
study in Spain that followed 14,057 people (average age 35) for about 10 years
found that the risk of high blood pressure was 45% higher among those consuming
less than 200 mg of magnesium daily compared to those consuming 400 to 500 mg
daily, and this inverse association was strongest in people who were overweight
or obese. Getting more magnesium didn't help: Intakes of more than 500 mg daily
carried the same risk of high blood pressure as intakes below 200 mg daily (Dominguez, Nutrients 2021).
Although low intake of magnesium has been linked with elevated blood pressure,
magnesium supplementation appears to have only modest benefit in people with
high blood pressure and insufficient or deficient magnesium levels. An analysis
of 34 clinical studies among people with and without high blood pressure found
that those who took approximately 368 mg of magnesium per day for about three
months had overall reductions of just 2 mm Hg and 1.78 mm Hg, respectively, in
systolic and diastolic blood pressures. The study also found that magnesium
might only be effective among people with magnesium deficiency or insufficiency
(Zhang, Hypertension 2016). A
subsequent study among 59 healthy adults (average age 57) with elevated blood
pressure (averaging 133.4 mm Hg systolic and 82.6 mm Hg diastolic) and not taking
blood pressure-lowering medication, found that 480 mg of magnesium (as
magnesium glycinate) taken daily for three months modestly decreased systolic
and diastolic blood pressure by 4.5 mm Hg and 1.9 mm Hg, respectively, but the
decreases were not statistically significant compared to placebo. However, it
was not reported if participants were lacking in magnesium (Sesso, Hypertension 2020).
There is some evidence that magnesium supplementation may modestly decrease
blood pressure in people with metabolic syndrome, even if they have normal
blood levels of magnesium.
Several studies have shown a correlation between adequate
magnesium levels or magnesium intake and heart health. A study that followed
thousands of older men and women in the Netherlands for about 9 years found
that those with the lowest blood serum magnesium levels (0.8 mmol/L and below)
were 36% more likely to die from coronary heart disease and
54% more likely to experience sudden cardiac death over the
course of the study than those with moderate levels (0.81 and 0.88 mmol/L) (Kieboom, J Am Heart Assoc 2016). High levels
(above 0.89 mmol/L) were associated with a 6% lower risk of coronary heart
disease but a 35% greater risk of sudden cardiac death than moderate levels.
(Note: Normal magnesium levels range from 0.7 to 0.91 mmol/L or, using units
more common in the U.S., 1.7 to 2.2 mg/dL). A study of middle-aged
men in Finland followed for around 25 years also found lower serum magnesium to
be associated with greater risk of future heart failure (Kunutsor, Eur J Epidemiol 2016). Similarly,
a study in the U.S. that followed over 150,000 postmenopausal women (ages 50 to
79) for an average of ten years found that those with the lowest intakes of
dietary magnesium (about 189 mg per day) had a 19% higher risk of fatal
coronary heart disease that those with the highest intakes (about 330 mg per
day) (Li, J Womens Health (Larchmt) 2019).
Low tissue levels of magnesium may be a
contributing risk factor for the development of "torsades de pointes,"
an abnormal heart rhythm that can cause sudden death. Low blood levels of
magnesium have been associated with another type of abnormal heart rhythm known
as premature ventricular complexes (PVCs), which are sometimes also
referred to as "palpitations." In adults with low blood levels of
magnesium (< 0.70 mmol/L), the prevalence of PVCs was found to be twice that
of adults with sufficient blood levels of magnesium, according to a study in
Canada among obese men and women with type 2 diabetes (Gobbo, Cardiovasc Diabetol 2012). However, a
review of the evidence for treating abnormal heart rhythms with magnesium
concluded that more research is still needed to determine if correcting
magnesium levels improves clinical outcomes (Baker, Eur Heart J Cardiovasc Pharmacother 2017).
Early signs of magnesium deficiency include loss of appetite,
nausea, vomiting, fatigue, and weakness. Low serum magnesium levels can also
result in serious adverse events including muscle spasm (tetany), irregular
heartbeat (arrhythmias), and convulsions (seizures); however, patients do not
always have these symptoms. Severe magnesium deficiency is rare.
Conditions that may deplete magnesium include
alcohol abuse, diabetes, diseases of the digestive tract (such as ulcerative
colitis, Crohn's disease and celiac sprue), and use of medications such as
cisplatin, certain diuretics, and certain acid blocking drugs (e.g., proton
pump inhibitors). In people with Crohn's disease, magnesium supplementation
should be considered during bouts of severe diarrhea — the form of magnesium
should be one that is not likely to have a laxative effect and sipping an oral
rehydration formula containing magnesium throughout the day may be better
tolerated than taking a large dose of magnesium (Huang, Inflamm Bowel Dis 2021).
The FDA in 2011 warned that proton
pump inhibitor (PPI) medications (used to reduce stomach acid) may also cause
low serum magnesium levels if taken for prolonged periods of time (in most
cases, longer than one year). Examples of PPIs are Nexium, Dexilant, Prilosec, Prevacid,
Protonix, AcipHex, Vimovo, and Zegerid. Treatment of hypomagnesemia generally
requires magnesium supplements. However, in approximately one-quarter of the
cases reviewed, magnesium supplementation alone did not improve low serum
magnesium levels and the PPI had to be discontinued.
Dementia and cognition:
Adequate intake of magnesium (from the diet and/or supplements) may optimize
cognitive function and reduce the risk of developing dementia, as suggested by
several studies, although getting too much is not beneficial. There is no human
clinical evidence to suggest any particular form of magnesium is better than
others at crossing the human blood-brain barrier to enter brain (although some
forms of magnesium are better absorbed than others from the
gut).
Increasing magnesium intake for 12 weeks in a
placebo-controlled study involving 240 healthy individuals in Tennessee was
found to improve cognitive function by 9.1% among those aged 65 and older who
otherwise consumed high amounts of calcium relative to magnesium. For example,
if a person was consuming a total of 1,200 mg of calcium and 300 mg of
magnesium per day (a ratio of 4 to 1), that person was assigned a dose of
magnesium (as magnesium glycinate — as found in the KAL product in this Review) of 221.7 mg,
getting them to a calcium:magnesium ratio of 2.3 to 1. The daily dose ranged
from 77.25 mg to 389.55 mg, with the average being 216.5 mg. The magnesium
supplementation was found to affect activity at a gene (APOE) that plays a role
in calcium signaling in nerve cells and is associated with late-onset
Alzheimer's disease. The effects on this gene were associated with the
improvements in cognitive function. Magnesium did not have effects on people
younger than 65 years of age (Zhu, J Alz Dis 2020). ConsumerLab
Note: These findings suggest that supplementing with magnesium to
lower high calcium:magnesium ratios may be helpful, but be aware that excessive
magnesium intake can have negative effects on cognition and mortality (Dai, BMJ Open 2013) -- do not reduce
calcium:magnesium ratios to below 1.7.
A study in the U.S. that followed 6,473 women beginning around
70 years of age for an average of 20 years found that those who consumed
between 257 mg and 317 mg of magnesium per day from foods and supplements had a
37% lower risk of developing mild cognitive impairment compared
to those who consumed less than 197 mg per day, which is significantly below
adult RDAs for magnesium (Lo, BMJ Open 2019).
Somewhat similarly, a study that tracked over 9,500 adults in the Netherlands
for about eight years found that those who began the study with the lowest or
highest blood levels of magnesium (respectively, 0.79 mmol/L or less and 0.9
mmol/L or greater) were approximately 30% more likely to develop dementia (predominately
Alzheimer's disease) over the course of the study compared to those with
mid-range levels (0.84 to 0.85 mmol/L) after adjusting for factors such as age
and other diseases (Kieboom, Neurology 2017).
Although these types of studies do not prove cause-and-effect, getting
the daily requirement of magnesium from one's
diet and, if necessary, supplements, and avoiding excessive magnesium would
seem prudent.
Another study found the intake of magnesium laxatives to be
associated with reduced risk of dementia. The study, among over 6,000 men and
women in Taiwan age 50 and older, found that those who were prescribed oral
magnesium oxide for the treatment of constipation (average length of usage
about 5 months) at the beginning of the study were 48% less likely to develop
dementia over a 10 year follow-up period than those who had not taken magnesium
oxide, even after adjusting for factors such as age, gender, and other medical
conditions (Tzeng, Curr Med Res Opin 2017).
Those who took magnesium oxide for more than one year had an even lower risk —
they were 59% less likely to develop dementia. Unfortunately, the study did not
report the average daily dose of magnesium taken by participants or take into
account the amount of magnesium they were getting from their diets.
A small study funded by the makers of a magnesium-L-threonate
supplement called Magtein (also
sold as Clarimem from
Neurocentria, Inc.) found that men and women with self-reported memory and
concentration impairment, anxiety, and difficulty sleeping who received between
1.5 and 2 grams of magnesium-L-threonate daily for three months had a small
(10% on average) increase in the speed of performance on an executive function
task, while those who took a placebo showed even smaller improvement. There was
no improvement, however, in working memory, episodic memory, attention, anxiety
or sleep, relative to placebo. No serious adverse events were reported and
there were no significant changes in blood pressure or heart rate (Liu,
J Alzheimer's Dis 2016).
Another small study that sought to determine if taking
magnesium-L-threonate (600 mg in the morning and 1,200 mg two hours before bed
time) for two months improved learning and memory in 17 people with dementia
was conducted at Stanford University and was completed in mid-2016. Based on
results posted to ClinicalTrials.gov in February 2021 (but apparently not
published in a peer-reviewed journal), patients in this study showed no
clinically meaningful improvement in cognitive function, although, when
retested four months later, there was still no decline from baseline levels.
The lack of a placebo group and small study size limits the value of these
results (ClinicalTrials.gov,
accessed 7/20/21).
Animal studies of magnesium's effects on memory and cognition have been
conducted (Slutsky,
Neuron 2004; Hoane, Magnes Res
2008; Abumaria, J Neurosci
2011), including one funded by the makers of Magtein
that found that rats given magnesium-L-threonate performed significantly better
on tests of long and short term memory. Magnesium-L-threonate also enhanced
signaling of a specific part of brain receptors associated the ability to store
information. Other forms of magnesium tested, including magnesium chloride,
magnesium citrate, magnesium glycinate, and magnesium gluconate, were not as
efficient at raising magnesium levels in the central nervous system (as
measured by levels in cerebrospinal fluid) and did not improve memory as well
as magnesium-L-threonate (Slutsky,
Neuron 2010). It has been noted by other researchers that
the amount by which magnesium-L-threonate raised cerebrospinal fluid levels of
magnesium was only 7% to 15%, and the dose used in the animals (50 mg/kg/day)
would be equivalent to 7 grams (7,000 mg) per day in humans — 20 times the
tolerable upper intake level for adults (Bush, Neuron 2010).
Parkinson's disease:
Although there is preliminary evidence showing that magnesium levels are lower
in the brains and cerebrospinal fluid of people with Parkinson's disease
compared to healthy people, there is no clinical research showing that
magnesium prevents or slows the progression or improves symptoms of Parkinson's
disease. It has been reported that magnesium as magnesium-L-threonate increased
magnesium levels in the cerebrospinal fluid in a mouse model of Parkinson's
disease (Shen,
Neuropsychiatr Dis Treat 2019), but this has not yet been confirmed in
humans. Magnesium sulfate does not appear to enter the brain in an animal model
(Oyanagi, In:
Magnesium in the Central Nervous System [Internet] 2011),
although it has been shown to enter the cerebrospinal fluid in small amounts in
women with pre-eclampsia when administered intravenously (Thurnau, Am J Obstet
Gynecol 1987).
Be aware that a very high dose of magnesium oxide was shown to reduce
absorption of Parkinson's medications. At the same time, Parkinson's
medications may increase absorption of magnesium (See Concerns and
Cautions).
Type 2 diabetes, prediabetes and metabolic syndrome
Magnesium supplementation may modestly improve insulin sensitivity and some
markers of blood sugar control, as well as modestly decrease blood pressure in
people with type 2 diabetes and/or prediabetes or metabolic syndrome.
Magnesium supplements may increase insulin sensitivity in
people with type 2 diabetes, many of whom have hypomagnesemia (low
blood levels of magnesium). Increased intake of magnesium from the diet and
supplements has generally been associated with a decrease in the risk of
developing type 2 diabetes — particularly among people with magnesium intakes
below the Recommended Daily Allowance (RDA) (Larsson,
J Intern Med 2007).
A study among obese, insulin insensitive people with normal magnesium
plasma levels showed that daily magnesium supplementation improved insulin
sensitivity. A 7% improvement in fasting plasma glucose levels was observed
among those taking 365 mg of magnesium (as magnesium-aspartate-hydrochloride)
daily for 6 months -- a significant improvement compared those taking placebo (Mooren,
Diab Obes Metab 2010).
A study of people with hypomagnesemia and
prediabetes in Mexico found that after 4 months of taking 382 mg of magnesium
daily (as a magnesium chloride liquid supplement), 50.8% had improved glucose
status versus 7% of those receiving placebo. On average, those taking magnesium
had a 22% improvement in fasting glucose levels. During the study, both groups
were advised to follow a balanced diet and to engage in physical activity for
at least 30 minutes three times a week (Guerrero-Romero,
Diab & Metab 2015).
A subsequent study by the same researchers involved giving
the same dose and form of magnesium to people with low magnesium levels (below
1.8 mg/dL) and metabolic syndrome, which is a combination of high
blood pressure and blood sugar, excess body fat around the waist, and low
HDL-c. After four months, only 48% of those given magnesium had metabolic
syndrome compared to 77.5% of those given placebo. The treated group
experienced significantly greater improvements in blood pressure, fasting
glucose, and triglycerides (Rodriguez-Moran, Adv
Chronic Kidney Dis 2018).
A study in
Germany among 24 men and women (average age 67) with metabolic syndrome and
normal blood levels of magnesium found that 400 mg of magnesium (as magnesium
citrate) taken daily for three months modestly decreased average values of
HbA1c (a measure of blood sugar levels over time) from 6.43% to 6.15% (normal
range is 4.0% to 5.6%), while the placebo group had little change. Those who
took magnesium also experienced a large decrease in systolic blood pressure (-
24.2 mmHg) and a modest decrease in diastolic pressure (- 6.8 mmHg), compared
to little improvement in the placebo group. Be aware that the dose of magnesium
used in this study exceeds the daily Tolerable Upper Intake Level (UL) for
magnesium from supplements for adults (350 mg). One person in the magnesium
group reported having soft stool, but this was temporary and no other side
effects associated with magnesium supplementation were reported (Afitska, Magnes Res
2021).
Magnesium for other conditions
An analysis of several studies concluded that magnesium may
help reduce the risk of stroke. People who consumed 100 mg of
magnesium more per day than average (the average being about 300 mg) had an 8%
lower risk of strokes of any kind and a 9% lower risk of ischemic stroke (Larsson, Am J Clin
Nutr 2012). This finding is based on total magnesium in
the diet -- it does not mean that 100 mg of magnesium from a supplement will
necessarily have the same risk-lowering effect, but getting a total of at least
400 mg of magnesium from your diet per day may be beneficial. Similarly, an analysis of 40 observational studies ranging from 4
to 30 years in length and involving a total of 1 million participants found
that each 100 mg/day increase in dietary magnesium intake (up to about 500 mg
total daily intake) is associated with a 7% decrease in the risk of stroke, as
well as 22%, 19% and 10% decreases in the risks of heart failure, type 2
diabetes, and all-cause mortality, respectively (Fang,
BMC Medicine 2016).
Some observational studies have found that low blood
levels of magnesium and low magnesium intake from food are each associated with
an increased risk of depression (Islam, BMC
Psychiatry 2018; Cheungpasitporn,
Intern Med J 2015; Yary, Biol Trace
Elem Res 2013). Supplementing depressed individuals with
magnesium has shown some promise in preliminary studies, although none of the
studies were placebo-controlled making it impossible to determine true
efficacy. These studies, which lasted from 6 weeks to 3 months, involved daily
doses of 250 mg to 300 mg of magnesium (from magnesium citrate or chloride) (Barragán-Rodrí,
Magnes Res 2008; Bagis, Rheumatol Int
2013) to as much as 450 mg (from magnesium chloride
liquid) in a study involving people with low blood levels of magnesium (Tarleton, PLoS One
2017). The studies showed comparable results to
tricyclic antidepressants or improvements over no treatment (meaning the
subjects were aware of when they were given the treatment or not). A study in Iran among 60 young men and women (average age
20) with moderate depression and magnesium blood levels at the lower end of
normal found that 250 mg of magnesium (from magnesium oxide) taken twice daily
for two months modestly reduced symptoms of depression compared to placebo (an
average reduction of 16 points vs. 10 points on a scale of 0 - 63). In those
who took magnesium, blood levels increased from an average of 1.77 mg/dL to
2.08 mg/dL, while there was no change in magnesium levels in those who took the
placebo (Rajizadeh,
Nutrition 2017). If you have depression, it would seem prudent
to at least make sure you are getting adequate magnesium from your diet and/or
supplements.
In a study of elderly men and women aged 70-79 years, magnesium
intake from food and supplements was associated with a significant increase
in bone mineral density (BMD) in white men and women, but not
in black men and women. Most people in this study did not have adequate
magnesium intake. In white women, getting the recommended amount of 320 mg
daily of magnesium was associated with a 2% higher BMD compared to intakes 220
mg or lower. Similarly, in men, intake meeting the recommended amount of 420 mg
daily were associated with a 1% higher BMD compared intakes of 320 mg or lower
(Ryder, J Am Geriatr
Soc 2005). This does not, however, indicate that getting
more than the daily requirement is beneficial or that a supplement is necessary
if you get sufficient magnesium in your diet.
Higher intake of magnesium (from a combination of food
and, if used, supplements) was shown to reduce the risk of bone
fracture among older men and women (average age 61) in a study in the
U.S. Participants recorded their magnesium intakes and their outcomes were
followed for 8 years. Those who reported the highest intakes of magnesium
(averaging 491 mg/day for men and 454 mg/day for women) also reported the
fewest fractures over the follow-up period. The risk of fracture was 53% and
62% lower, respectively, among men and women with the highest intakes compared
to those with the lowest intakes (205 mg/day for men and 190 mg/day for women).
It was found that women meeting the RDA for magnesium (350 mg) had a 27% lower
risk of fracture than those not meeting the RDA, although no such association
was found for men (RDA of 420 mg). Interestingly, only one quarter of
participants met the RDA (Veronese, Br J Nutr
2017). This association between higher
magnesium intake and better bone health, however, was not seen in an analysis
of older people in Taiwan that focused exclusively on use of magnesium oxide
(typically taken as a laxative or antacid). It found that people who used
magnesium oxide supplements were 66% more likely over a 5-year period to suffer
a hip fracture than people who had not used magnesium oxide (Wu, Osteopor Int
2020).
Getting adequate magnesium has been shown to help maintain optimal blood levels
of the active form of vitamin D, boosting lower levels and, in some cases,
moderating high levels. For example, a study in Spain among postmenopausal
women, many of whom had low dietary intakes of magnesium and and/or low blood
or erythrocyte levels of magnesium, and most of whom had insufficient blood
levels of vitamin D (< 20 ng/mL) found that 500 mg of magnesium taken daily
for two months increased vitamin D levels by average increase 3 ng/mL (Vázquez-Lorente,
Nutrients 2020). (For more details see the Vitamin
D Review).
A study in healthy women older than 65 involved in
a mild, weekly exercise program found that physical performance improved
for those who were given a daily magnesium supplement (300 mg from magnesium
oxide) for 12 weeks, compared to those given placebo (Veronese, AJCN 2014).
Improvements were seen with activities such as the speed of walking and rising
from a chair. Although all the women had normal blood levels of magnesium,
improvements in physical performance were more evident in participants with magnesium
dietary intake lower than the RDA (320 mg for women 31 years and older), which
is common among older women, suggesting that some women may still be
"deficient" despite normal blood levels.
A small study among healthy male recreational endurance runners (average age
27) who consumed a diet low in magnesium (< 260 mg per day) found that
supplementing with magnesium (166.6 mg taken 3 times a day [500 mg total] from
magnesium oxide) for 7 days prior to a timed 10 kilometer downhill treadmill
run reduced muscle soreness by 32% in the first 24 hours after
the run and by 53% three days after the run in comparison to placebo. In
addition, blood levels of a marker of inflammation (IL-6) were lower 24 hours
after running when magnesium had been taken versus placebo. However,
supplementation did not improve running performance, decrease muscle damage, or
increase recovery of muscle strength. It should be noted that 500 mg of
magnesium is above the daily upper tolerable intake level for magnesium and can
cause a laxative effect. The published study failed to report on side effects (Steward, Eur J Appl
Physiol 2019).
A study among 22 healthy college students (average age 22)
found that 350 mg of magnesium glycinate (providing 50 mg of magnesium) taken
once daily for 8 days prior to a bench press test modestly reduced
self-reported delayed onset muscle soreness (DOMS) 48 hours
after the test compared to placebo (average reduction of about 2 points on a
6-point scale vs. no reduction in placebo). Exercise performance (i.e. the number of repetitions) was also slightly improved
in those who took magnesium, but this did not reach statistical significance.
Blood levels of magnesium were not measured, but a dietary assessment before
the study began showed that half of the participants were getting less than 50%
of the RDA for magnesium (from foods and supplements) and only two individuals
met or exceeded the RDA (Reno, J Strength
Cond Res 2020).
Magnesium supplements are sometimes promoted to help relieve
symptoms of restless leg syndrome (RLS) but this effect is not
well established. One study in 10 men and women with insomnia related to RLS
found a dose of 301.38 mg of magnesium (as magnesium oxide) taken in the
evening for 4-6 weeks significantly reduced leg movement associated with
waking, however, this study was not blinded or placebo-controlled (Hornyak, Sleep 1998).
Similarly, there is little evidence that magnesium
supplementation reduces leg cramps or nighttime leg
cramps in most people (Garrison, Cochrane
Database Syst Rev 2012; Sebo, Fam Pract 2014).
For example, a study among 88 older men and women (average age 64) in Israel
who regularly experienced nighttime leg cramps found that 520 mg of magnesium
(as magnesium oxide) taken at bedtime for one month did not decrease frequency,
severity or duration of the cramps compared to placebo (Maor, JAMA Intern
Med 2017).
Although a small study in Thailand among pregnant
women with leg cramps found that a daily dose of 300 mg of magnesium
(as magnesium bisglycinate chelate) reduced the intensity and frequency of leg
cramps compared to placebo (Supakatisant,
Matern Child Nutr 2012), other studies using similar doses of
magnesium (as magnesium lactate and/or magnesium citrate) have not found a
benefit (Nygaard, Eur J
Obstet Gynecol Reprod Biol 2008; Araujo, PLoS One 2020). An
analysis of data from four studies, including the three discussed above,
concluded that, overall, oral magnesium supplementation is not effective in the
treatment of leg cramps during pregnancy (Liu, Taiwan J Obstet Gynecol 2021).
Magnesium is one of several minerals (including calcium,
iron, zinc, sodium, and copper) that make up nails. Some research suggests that
people with "soft, flaky nails that are inclined to break or split"
may have significantly reduced levels of magnesium in the blood and nail plate
(Cashman, Clin
Dermatol 2010). However, there do not appear to be any
clinical studies on the effects of magnesium supplementation on nail health or
strength.
Magnesium supplements do not appear to help prevent kidney stones.
Use of magnesium supplements may help prevent a number of conditions
including: hearing loss from excessive noise (Sendowski, 2011.
Magnesium in the Central Nervous. System University of Adelaide Press), migraine headaches
(including menstrual migraines) (Yablon, 2011.
Magnesium in the Central Nervous. System University of Adelaide Press),
and menstrual pain and PMS (Parazzini, Magnes Res
2017). Magnesium is also an effective laxative and antacid (Dupont, Nutrients
2020; Swain, South Med J
1999). Intravenous magnesium (as opposed to oral
magnesium supplementation), is sometimes used in hospitals to treat acute
asthma, arrhythmias, overdoses of certain drugs, osmotic coma, diabetic
ketoacidosis, pancreatitis, hyperthyroidism, hepatitis, and other conditions.
Magnesium orotate
Magnesium orotate is a complex of magnesium plus orotic acid. Although it has
been promoted to improve athletic performance, there is no reliable evidence to
support this. However, a preliminary clinical study in people with heart
failure found that giving 6,000 mg of magnesium orotate daily for one month,
followed by 3,000 mg daily for 11 months reduced the risk of dying during the study
by about 25%. It also improved heart failure symptoms in about 40% of patients
(Stepura, Int J
Cardiol 2009). However, there are potential safety concerns
with magnesium orotate (see Concerns and
Cautions).
Magnesium Creams, Sprays and Oils
There is some evidence that magnesium may be absorbed through the skin, but the
amount absorbed may be minimal and topical magnesium products have not been
shown to be effective for any condition. Furthermore, they may cause
irritation. In one study, applying a cream containing magnesium (form not
identified) and MSM (MagPro) on the leg before stretching and exercise
had no effect on flexibility or endurance compared to a
placebo cream (Gulick,
J Strength Cond Res 2012). In a pilot study of a magnesium chloride
spray (Fibro Flex, Magnesium Direct, Inc. — 31% MgCl2) on the quality of
life in women with fibromyalgia, women reported modest improvements
cramps and fatigue but there was no placebo control and no statistically
significant improvement in quality of life. Participants were asked to apply
(and rub in) 4 sprays per limb 2 times daily for 4 weeks, showering it off
before bedtime to avoid transfer to bed sheets. Forty percent of participants
dropped out of the study, with 22.5% being due to skin irritation (Engen,
J Integr Med 2015). A small, placebo-controlled study in the UK
found no statistically significant increase in blood levels of magnesium from
applying a cream containing a low dose of magnesium chloride (56 mg) to the
stomach and legs daily for two weeks (Kass,
PLoS One 2017).
Magnesium "oil," which is technically not an oil but a solution of
magnesium (typically magnesium chloride) and water, is also promoted to
increase magnesium levels in the body and have other beneficial effects. A
study among nine men and women found that daily use of a magnesium oil spray
containing 31% magnesium chloride (BetterYou Magnesium Oil Original spray —
20 sprays per day anywhere on the body), plus a twice weekly magnesium foot
soak (BetterYou Magnesium Oil Original Soak —100 mL, 31% magnesium
chloride) for three months increased cellular magnesium levels (as measured by
hair samples) by an average of 59.7%. However, there was no placebo control,
the significance of magnesium in hair samples has not been established, and
blood/serum levels of magnesium were not measured (Watkins,
Eur J Nutr Res 2010). In a study conducted by Dr. Norman Shealy (Shealy Wellness Clinic,
Fair Grove, Missouri) in which participants performed a 20-minute foot-soak
with transdermal magnesium chloride bath flakes and sprayed their entire body
with magnesium oil once daily for one month, intercellular levels of magnesium
(as measured in skin cells swabbed from the mouth) were reported to increase
from 31.4 mEq/L to 41.2 mEq/L. However, this study does not appear to have been
placebo-controlled or published in a peer-reviewed journal.
Be aware that some companies selling topical magnesium products claim that the
skin irritation caused by these products is an indication of low magnesium
levels in the body. There does not appear to be evidence supporting this claim.
Epsom salt baths
Although no peer-reviewed studies have been published on the absorption of
magnesium from Epsom salt (magnesium sulfate) baths, a non-controlled and
undated study performed at the University of Birmingham (published by the Epsom
Salt Council) showed that soaking in a bath with Epsom salts
(flakes or granules of magnesium sulfate) increased concentrations of magnesium
in the blood and urine. In the study, 19 men and women (ages 19 to 64) soaked
for 12 minutes in a hot bath (122° to 131° F) in a standard bathtub with 400 mg
to 600 grams (0.9 to 1.3 lb) of Epsom salt added to 15 gallons of bath water (2
cups of Epsom salt is about 1lb). This was repeated daily for seven days. After
the first bath, levels of magnesium in the blood rose by an average of 9% and,
after seven days, by 35% (excluding two people with no significant increase),
and magnesium levels in the urine rose on average by 109% -- indicating that
magnesium was being absorbed as well as excreted. Sulfate levels in the blood
and urine also increased.
Quality
Concerns and Tests Performed:
Like other supplements, neither the FDA nor
any other federal or state agency routinely tests magnesium products for
quality prior to sale. However, quality issues for magnesium supplements can
include the following:
·
Labeled Amount — Does
the product really contain the labeled amount of magnesium and other key
ingredients such as vitamins D and K and calcium and boron? Too little
magnesium in a supplement is a problem if relying on it to prevent or correct a
deficiency. Excessive consumption of oral magnesium frequently causes diarrhea.
While it is unlikely that an individual with healthy kidneys can take enough
magnesium orally to elevate blood levels, if this does occur, potentially
dangerous heart and nerve-related symptoms may develop. (Individuals with
severe kidney disease should not take magnesium supplements.)
·
Purity — Many sources of
magnesium, like other minerals, may naturally contain amounts of toxic heavy
metals such as lead, cadmium or arsenic. In 2005 and 2009, for example,
ConsumerLab.com found magnesium supplements contaminated with lead, and, in
2012, found a combination product containing magnesium, calcium, vitamin D and
vitamin K to exceed limits for lead contamination.
·
Ability to Break Apart for Absorption — Will pills break apart properly so they can release their
ingredients in the body? For a tablet to be most useful, it must fully
disintegrate prior to leaving the stomach, delivering its contents for
absorption in the gut. Some tablets and caplets are not properly made and can
pass through your body completely or partially intact, depriving you of its
ingredients. Remnants of such products are sometimes found in the stool. This
happens, for example, when a tablet is too tightly compressed (too
"hard") or is too thickly coated.
·
Side Effects at Suggested Dosage — ConsumerLab.com reviewed the levels of magnesium to determine
if any product provided doses high enough so as to carry a risk of adverse side
effects. Those that exceeded upper tolerable limits (ULs — see discussion
below) are footnoted.
ConsumerLab.com, as part of its mission to independently
evaluate products that affect health, wellness, and nutrition, purchased many
leading magnesium-containing supplements sold in the U.S. and Canada and tested
them to determine whether they possessed the claimed amount of these
ingredients. Products sold as regular tablets were tested to determine whether
they could disintegrate properly. Products claiming to provide 250 mg or more
of minerals or listing whole herbs as ingredients were tested to determine
whether they were free of unacceptable levels of lead, cadmium, and arsenic
(see Testing Methods and Passing Score).
What CL
Found:
Magnesium-only
supplements:
Among the 12 magnesium-only supplements that ConsumerLab.com selected for testing,
10 passed testing, along with five products voluntarily tested in our Quality Certification Program.
The following are the two magnesium-only products that failed to meet CL's
quality criteria. These findings were confirmed in a second independent
laboratory. These products were "Not
Approved" for the reasons
described below:
·
BulkSupplements.com Magnesium Citrate did not contain its claimed amount of magnesium, providing
only 399 mg of the 500 mg of magnesium listed per teaspoon, i.e., only 79.8% of
the promised amount. (See Update)
·
ReMag was found to be
contaminated with a small amount of lead, containing 0.58 mcg per ½ teaspoon
and 1.2 mcg per two ½ teaspoons of liquid. This amount exceeds the California
Prop 65 limit of 0.5 mcg of lead per daily serving, above which a warning label
regarding reproductive harm is required. Although this amount of lead is
unlikely to cause harm to an adult, it is best to avoid unnecessary lead
exposure. (See Update)
Supplement formulas that include magnesium:
ConsumerLab also selected 9 products that include magnesium as part of
supplement formulas that include calcium, vitamin D, vitamin K, and/or boron
which are largely marketed for bone health. Among these, 7 passed testing,
along with 5 products voluntarily tested in our Quality Certification Program.
The following are the two magnesium-containing products that failed to meet
CL's quality criteria. These findings were confirmed in a second
independent laboratory. These products were "Not Approved" for the reasons
described below:
·
Natural Vitality Natural Calm Plus Calcium - Raspberry-Lemon
Flavor contained its
claimed amounts of calcium and magnesium, but contained a bit less vitamin D
than claimed (22.1 IU instead of 35 IU) and more than double its listed amount
of boron (198.5 mcg instead of 88.3 mcg) per teaspoon of powder. Although this
suggests a quality control problem, these discrepancies do not pose a safety
issue as the listed amounts are relatively small to start: The daily
requirement for vitamin D is 400 IU to 800 IU, and although there is no daily
requirement for boron -- because it is not essential -- most people get about
1,000 mcg to 10,0000 mcg from their diets and the daily upper tolerable intake
level for adults is even higher: 17,000 to 20,000 mcg (National Academies). (Note: In 2017 CL
tested a magnesium-only version of Natural Calm of the same
flavor and it passed testing.)
·
Thorne Basic Bone Nutrients contained its claimed amounts of calcium and magnesium,
but only 69.7% of its claimed vitamin D (348.5 IU vs. 500 IU) and just 2.2% of
its vitamin K (1 mcg versus 45 mcg). These are major discrepancies,
particularly for vitamin K, indicating that one should not rely on this product
for either of these nutrients.
Be aware that even among products that were Approved in testing,
several provide daily amounts of magnesium above the upper tolerable intake
level (UL) for magnesium (350 mg per day for an adult) if taken within their
listed suggested daily serving sizes. Each is identified with "UL" in
the second column of the Results table. This can be acceptable when magnesium is taken to treat
deficiency but is otherwise generally not advisable.
Magnesium per pill or teaspoon
Be aware that the amount of magnesium in a single pill, teaspoon of powder, or
liquid serving of a supplement varied tremendously across products. As shown
below, this ranged from 100 mg to 500 mg among magnesium-only products and from
just 8.3 mg to 250 mg in magnesium-containing formulas. Most magnesium-only
products provide 100 mg to 250 mg per unit, which is in line with safe and
effective doses to boost daily magnesium intake to recommended levels — 310 mg
to 420 mg for adults.
Cost
Magnesium can be a fairly inexpensive ingredient, with 200 mg costing as little
as 3 cents from some products, as calculated and shown in the graph below.
However, special formulations and extra ingredients can dramatically increase
the cost.
Among products Approved by CL for their quality and labeling, the cost to
obtain 200 mg of magnesium was as low as 3 cents from GNC Magnesium (from
magnesium oxide) and 6 cents from Vitacost Magnesium Citrate but
as high as 20 to 30 cents from some products. The most expensive source of
magnesium was ReMag, at 42 cents per 200 mg, and, as noted earlier,
it failed to pass testing for heavy metals.
Top
Picks:
Our Top Pick among
magnesium-only supplements is Vitacost
Magnesium Citrate (200 mg per tablet for 6.5 cents). Although it
costs a few cents more than GNC Magnesium, the magnesium oxide in
GNC product is not absorbed as well as the magnesium citrate and magnesium
bisglycinate in these products.
(Update 7/20/2020: Swanson
Chelated Magnesium had also been a Top Pick of ours
in this category, but it is no longer. Swanson claimed to
provide 133 mg of magnesium from "TRAACS magnesium bisglycinate chelate
buffered" per capsule for 5 cents — a little less expensive than the
magnesium from Vitacost. However, new labeling of this product
indicates that some of the magnesium is also from magnesium oxide, which is not
absorbed as well as the bisglycinate form. This change in labeling may have
been triggered by lawsuits over mislabeling. We
recently contacted Balchem, which, through its Albion subsidiary, manufacturers
the TRAACS ingredient in Swanson, and asked what percentage of
magnesium in the ingredient is actually from magnesium bisglycinate versus
magnesium oxide. They would not provide an answer, leaving us unsure of its
composition and, therefore, no longer comfortable with it as a Top Pick.)
Be aware that the magnesium citrate in Vitacost can have a
laxative effect if taken at high dosage (the bisglycinate form in Swanson is
less likely to have this effect). Also, citrate-containing supplements can
increase absorption of aluminum from other medications and foods (and aluminum
may be harmful in the body). This is not a problem for people with normal
kidney function. However, it would be best not to take magnesium citrate along
with aluminum-containing medications, such as Maalox. Also, be aware that Vitacost's label
recommends a daily serving of two tablets, which is somewhat higher than the
daily upper limit (UL) for intake of magnesium from a supplement. If you are
just trying to get some extra magnesium, take only one tablet daily.
If you need to take large doses of magnesium (more than 350 mg), consider
the chloride form of magnesium, as it is less likely to cause
diarrhea than magnesium oxide and magnesium citrate and is less bulky than
chelated forms, although it is more expensive. A drawback though, is that
magnesium chloride as a tablet can quickly attract water — in fact, after
leaving a magnesium chloride tablet out for less than a day during a photo
shoot for our last Magnesium Review (in 2017), droplets formed on its surface
(see photo) and this water caused adjacent pills to become wet as well.
|
|
If you're going to use magnesium chloride, it's best to get it in liquid form
to avoid this problem; in fact, we no longer select magnesium chloride tablets
for review. Unfortunately, the only liquid tested this year, ReMag,
failed our tests. If you want a liquid magnesium chloride, we suggest a product
that passed our last review, Nutricology Chloride Liquid,
which provides 200 mg of magnesium as magnesium chloride per 1 ½ teaspoons for
30 cents (it may cost a bit more now). This product is a good choice for people
who have trouble swallowing pills or otherwise prefer a liquid. (If you prefer
a liquid, 365 [Whole Foods] Magnesium Cherry Fizz,
a powder to be mixed with hot water and served warm or cold, was also Approved
in this review. It costs 15 cents per 200 mg of magnesium (a little more than
half a scoop of powder). However, it must always be mixed with hot water so
that its crystals properly dissolve. It can, however, be used as an antacid.)
Our Top Picks among formulas
that include magnesium are as follows:
Magnesium and Calcium: Puritan's Pride Chelated Calcium
Magnesium Zinc provides 333 mg of calcium (from calcium carbonate and
calcium gluconate) and 133 mg of magnesium (from magnesium oxide and magnesium
gluconate) per caplet for just 5 cents. Be aware that this product also
contains zinc (8 mg per caplet, which is about the adult daily requirement).
The Puritan's Pride product actually suggests taking 3 caplets
daily, but this would put you just over the upper tolerable intake level for
magnesium from supplements and probably give you a lot more zinc than you want.
Magnesium, Calcium, and Boron: Solgar Calcium Magnesium Plus
Boron provides 333 mg of calcium (from carbonate, gluconate, and
citrate forms), 133 mg of magnesium (oxide, citrate, and gluconate forms), and
1,000 mcg of boron (citrate form) per tablet for 7 cents. Note that taking the
suggested dose of 3 tablets daily would put you over the upper tolerable intake
level for magnesium from supplements. Be aware that when a product shows a
combination of forms for a mineral, the forms are listed in order of magnitude
and it's possible that the majority of the mineral is from the first form
which, in this case for calcium, is carbonate, and for magnesium is oxide —
both are forms that may not be absorbed as well as the citrate form of
each.
Magnesium, Calcium, and Vitamin D: All three of the products tested
in this category use calcium carbonate and magnesium oxide, which are less
bulky than other forms (keeping pill size down) but may not be absorbed as
well. Among the three, however, our Top Pick is Puritan's
Pride Calcium Magnesium Vitamin D3 as provides a lower dose of calcium
(333 mg) per pill, for 7 cents, allowing you to take more
if necessary, while the others provide 500 mg (in Rainbow Light) or
600 mg (in Caltrate) per pill.
Children's Products Containing Magnesium, Calcium and Vitamin D: Similar
to the adult products in this category, both of the products that we tested for
children primarily use calcium carbonate and magnesium oxide. Both provide the
same amounts of calcium (250 mg) and vitamin D (200 IU) and similar amounts of
magnesium per two chewable tablets. Our Top Pick is Pioneer
Children's Cal Mag & D as it is less expensive (15 cents)
than Bluebonnet Rainforest AnimalZ (23 cents). Pioneer is
vanilla flavored while Bluebonnet is cocoa flavored.
Magnesium, Calcium, Boron and Vitamin D: Vitalite Now! Calcium
& Magnesium Plus provides calcium (250 mg), magnesium (125 mg),
and boron (1,000 mcg) in each capsule, as well as a modest amount of vitamin D
(100 IU). Although the label suggests taking four capsules daily (for a
relatively high daily cost of 48 cents), fewer capsules would be sufficient for
most people with regard to the three minerals, although not necessarily for
vitamin D. The source of calcium is a list of nearly every form of calcium, but
carbonate is the first and may be the main form, so it is important to take
this product with a meal, which you should anyhow to maximize vitamin D
absorption.
Magnesium, Calcium, Vitamin D, and Vitamin K: Only one of two
products in this category passed our tests: New Chapter Bone Strength
Take Care. However, due to its high cost, it is not a Top Pick.
The suggested daily serving of 3 tablets provides 1,000 IU of vitamin D, 770 mg
of calcium, 80 mcg of vitamin K from K1 and K2, and a modest amount of
magnesium. It is best to break this into two or three servings to be taken with
meal during the day, as 770 mg of calcium is too much to take at one time. This
is a relatively expensive product at 96 cents per day and, considering that
there is no compelling research showing superiority of algae-based calcium or
magnesium, you can easily get these same ingredients for less by purchasing the
ingredients separately.
Magnesium, Calcium, Vitamin D, Vitamin K, and Boron: Both of the
products that we tested in this category, GNC Calcimate and Jarrow
Formulas Bone Up, provide significant amounts of calcium, vitamin K, and
boron. What sets them apart is the amount of magnesium they provide, with Jarrow providing
several times as much as GNC as well as a daily dose of
vitamin D (1,000 IU) that is closer to the adult requirement (600 IU to 800 IU)
than GNC's 2,000 IU. Although it costs more (51 cents daily for 6
pills versus 25 cents daily for 4 pills), Jarrow Formulas Bone Up is
our Top Pick for this category. With either product, consider
cutting the suggest dose in half if you are just trying to boost your intake of
these nutrients and not trying to fulfill the majority of the daily
requirements from a supplement. By the way, Jarrow Formulas Bone-Up provides
calcium as StimuCal microcrystalline hydroxyapatite —see What to Consider When Buying section of the
Calcium Supplements Review for more information about calcium hydroxyapatite.
Test
Results by Product:
Listed below are the test results for 31
supplements containing magnesium. Products are grouped by form — pills first,
then powders and liquids. Within each group, products are listed
alphabetically. ConsumerLab.com selected 21 of these products. Ten others (each
indicated with a CL flask) were tested at the request of their
manufacturers/distributors through CL's voluntary Quality Certification Program and are included for
having passed testing.
Shown for each product are the labeled amount and form of magnesium, the
serving size recommended on the label, and the unit (e.g., pill) size. Products
listed as "Approved" met their label claim and ConsumerLab.com's
quality criteria (see Passing Score). Those that did not are
listed as "Not Approved" with an explanation of the problem found.
Price comparisons are in the fourth column and the full list of ingredients is
in last column.
Results
of ConsumerLab.com Testing of MAGNESIUM SUPPLEMENTS
(INCLUDING COMBINATIONS
WITH CALCIUM, BORON, VITAMIN D AND/OR VITAMIN K)
(Click arrows or swipe
left or right to see all columns)
Approval Statusⓘ
Product Name
Claimed Amount and Form of
Magnesium, Calcium, Boron Vitamin D & K Per Servingⓘ
Heavy Metalsⓘ
Suggested Daily Serving on
Label
Pill Sizeⓘ
Cost for Suggested Serving
[Price per 200 mg
Magnesium]
Price
Notable Features
Full List of Ingredients
Per Serving
Magnesium Only: Pills
APPROVED
Carlson® Chelated Magnesium
Dist. by Carlson Division
of J.R. Carlson Laboratories, Inc.
1 tablet
200 mg
(magnesium glycinate chelate, magnesium oxide)
✔
Heavy metals: NA
Also tested for disintegrationⓘ
Adults: take one tablet
daily at mealtime.
Large tablet
1 tablet
$0.17
[$0.17]
$14.99/90 tablets
Gluten-free. No artificial
preservatives.
1 tablet
Magnesium (from magnesium glycinate chelate and magnesium oxide) 200 mg.
Other Ingredients: Microcrystalline cellulose, stearic acid, hydroxypropyl
cellulose, croscarmellose sodium, more...
APPROVED
Designs For Health®
Magnesium Malate
Mfd. by Designs for Health,
Inc.
2 capsules
360 mg>UL
(di-magnesium malate)
✔
Heavy metals: Pass
As a dietary supplement,
take two capsules per day with meals, or as directed by your health care
practitioner.
Large vegetarian capsule
2 capsules
$0.39
[$0.22]
$23.50/120 vegetarian capsules
Does not contain gluten.
2 capsules
Magnesium (as Di-Magnesium Malate) 360 mg.
Other Ingredients: Cellulose (capsule), vegetable stearate.
APPROVED
Doctor's Best® High
Absorption Magnesium
Dist. by Doctor's Best,
Inc.
2 tablets
200 mg>ULⓘ
(magnesium lysinate glycinate chelate)
✔
Heavy metals: Pass
Also tested for disintegrationⓘ
Take 2 tablets twice daily,
or as recommended by a nutritionally-informed physician.
Large tablet
2 tablets
$0.12
[$0.12]
$14.05/240 tablets
Non-GMO / Gluten free / Soy
free / Vegan.
2 tablets
Magnesium (from magnesium lysinate glycinate chelate) 200 mg.
Other Ingredients: Microcrystalline cellulose, croscarmellose sodium, more...
APPROVED
GNC Magnesium 500 mg
Dist. by General Nutrition
Corporation
1 capsule
500 mg>UL
(magnesium oxide)
✔
Heavy metals: Pass
As a dietary supplement,
take one capsule daily.
Large capsule
1 capsule
$0.08
[$0.03]
Lowest cost for magnesium oxide
$9.98/120 capsules
No sugar, no artificial
colors, no artificial flavors, sodium free, no wheat, gluten free, no corn, no
soy, no dairy, yeast free.
1 capsule
Magnesium (as Magnesium Oxide) 500 mg.
Other Ingredients: Cellulose, gelatin.
APPROVED
Jamieson™ Magnesium Ultra
Strength 250 mg
Dist. by Jamieson
Laboratories
1 caplet
250 mg>ULⓘ
(magnesium oxide, magnesium gluconate, magnesium lactate)
✔
Heavy metals: Pass
Also tested for disintegrationⓘ
Take 1 caplet 2 times
daily.
Medium/large caplet
1 caplet
$0.24
[$0.19]
$21.15/90 caplets
No sugar, starch, gluten,
lactose, artificial flavours or preservatives.
1 caplet
Elemental Magnesium (oxide, gluconate, lactate) 250 mg.
Also contains: Cellulose, vegetable stearic acid, modified cellulose gum,
water-soluble cellulose, more...
APPROVED
Jigsaw Health® MagSRT®
Dist. by Jigsaw Health, LLC
4 tablets
500 mg>UL
(dimagnesium malate)
✔
Heavy metals: Pass
Also tested for disintegrationⓘ
As a dietary supplement,
take 4 tablets per day with food. Divide doses if desired, or use as directed
by your health care provider.
Large tablet
4 tablets
$0.55
[$0.22]
$32.99/240 tablets
Vitamin B6 5 mg, Folate 200
mcg, Vitamin B12 6 mcg, Malic Acid 1,436 mg
ConsumerLab.com flask seal. Sustained release. Non-GMO. Vegan. Soy free.
Gluten free.
4 tablets
Vitamin B6 (as Pyridoxal 5-Phosphate Monohydrate) 5 mg, Folate (as Quatrefolic®
5-Methyl Tetrahydrofolic Acid Glucosamine Salt) 200 mcg, more...
APPROVED
KAL® Magnesium Glycinate
400
Dist. by Nutraceutical
Corp.
2 softgels
400 mg>UL
(magnesium glycinate)
✔
Heavy metals: Pass
Take 2 ActivGels™ softgels
daily with a meal or glass of water.
Very large ActivGels™ softgel
2 softgels
$0.38
[$0.19]
$22.93/120 softgels
None.
2 softgels
Calories 15, Calories from Fat 10, Total Fat 1.5 g, Saturated Fat 0 g, Protein
<1 g, Magnesium (from Magnesium Glycinate) 400 mg.
Other Ingredients: Rice bran oil, more...
APPROVED
Mag-Ox® 400
Dist. by Akorn Consumer
Health
2 tablets
483 mg>UL
(magnesium oxide)
✔
Heavy metals: Pass
Also tested for disintegrationⓘ
Take 2 tablets daily with
food or as directed by a healthcare professional.
Medium circular tablet
2 tablets
$0.18
[$0.08]
$21.98/2 bottles of 120 tablets (240 tablets total)
None.
2 tablets
Elemental Magnesium (as Magnesium Oxide) 483 mg.
Other Ingredients: Microcrystalline cellulose, hydroxypropyl cellulose, more...
APPROVED
Mag-Tab® SR
Dist. by Pharmaceuticals
Inc.
1 caplet
84 mg
(magnesium L-lactate dihydrate)
✔
Heavy metals: Pass
As a dietary supplement, take
1 or 2 caplets every 12 hours or as directed by a physician.
Large caplet
1 caplet
$0.33
[$0.78]
$19.53/60 caplets
Sustained release.
1 caplet
84 mg of Elemental Magnesium L-lactate dihydrate.
Other Ingredients: Polyethylene glycol, microcrystalline cellulose, carnauba
wax, stearic acid, calcium stearate, and color added.
APPROVED
NOW® Magnesium Citrate
Dist. by Now Foods
3 capsules
400 mg>UL
(magnesium citrate)
✔
Heavy metals: Pass
Take 3 capsules daily,
preferably in divided doses, with food.
Large veg capsule
3 capsules
$0.22
[$0.11]
$8.72/120 veg capsules
Kosher. Non-GMO. Not
manufactured with wheat, gluten, soy, milk, egg, fish, shellfish or tree nut
ingredients.
3 capsules
Magnesium (from Magnesium Citrate) 400 mg.
Other Ingredients: Cellulose (capsule), magnesium stearate (vegetable source)
and silica.
APPROVED
Pure Encapsulations®
UltraMag Magnesium
Mfd. by Pure Encapsulations
1 capsule
225 mg
(Sucrosomial® magnesium)
✔
Heavy metals: NA
As a dietary supplement,
take 1 capsule daily, with or between meals.
Large capsule
1 capsule
$0.30
[$0.27]
$36.30/120 capsules
Gluten-free, non-GMO &
hypoallergenic.
1 capsule
Magnesium (as Sucrosomial® magnesium) 225 mg.
Other Ingredients: Sucrosomial magnesium (magnesium oxide, pregelatinized rice
starch, more...
APPROVED
Solgar® Chelated Magnesium
Mfd. by Solgar, Inc.
4 tablets
400 mg>UL
(magnesium glycinate chelate, magnesium oxide)
✔
Heavy metals: Pass
Also tested for disintegrationⓘ
As a dietary supplement for
adults, take four (4) tablets daily, preferably with a meal or as directed by a
healthcare practitioner.
Medium/large tablet
4 tablets
$0.52
[$0.26]
$12.99/100 tablets
Kosher. Non-GMO. Suitable
for vegans. Gluten, wheat & dairy free. Free of: gluten, wheat, dairy, soy,
yeast, sugar, sodium, artificial flavor, sweetener and preservatives.
4 tablets
Magnesium (as magnesium glycinate chelate, magnesium oxide) 400 mg.
Other Ingredients: Microcrystalline cellulose, vegetable cellulose, more...
APPROVED
Swanson® Chelated Magnesium
Dist. by Swanson Health
Products
1 capsule
133 mg>ULⓘ
(TRAACS® magnesium bisglycinate chelate buffered)
(See Update)
✔
Heavy metals: Pass
As a dietary supplement,
take one capsule three times per day with water.
Large capsule
1 capsule
$0.05
[$0.08]
Lowest cost for magnesium bisglycinate
$4.55/90 capsules
None.
1 capsule
Magnesium (TRAACS® magnesium bisglycinate chelate buffered) 133 mg.
Other Ingredients: Magnesium oxide, gelatin, citric acid, silica, maltodextrin, more...
APPROVED
Top
Pick
for magnesium only
Vitacost® Magnesium Citrate
Dist. by Vitacost.com Inc.
2 tablets
400 mg>UL
(magnesium citrate)
✔
Heavy metals: Pass
Also tested for disintegrationⓘ
As a dietary supplement for
adults 18 years of age and over, take 2 tablets daily with food or as directed
by a healthcare professional.
Large tablet
2 tablets
$0.13
[$0.06]
Lowest cost for Approved magnesium citrate
$7.79/120 tablets
None.
2 tablets
Magnesium (as magnesium citrate) 400 mg.
Other Ingredients: Vegetable stearic acid, hydroxypropyl methylcellulose,
microcrystalline cellulose, croscarmellose sodium, more...
Magnesium Only:
Powders/Liquids
APPROVED
365® [Whole Foods]
Magnesium Cherry Fizz
Dist. by Whole Foods Market
1 scoop [4 g]
350 mg=UL
(magnesium carbonate)
✔
Heavy metals: Pass
Place 1 scoop (included) in
a cup and add 2-3 oz hot water. Let it fizz. Stir until dissolved. Fill cup
with additional warm or cold water, depending on taste preference.
Powder in container
1 scoop
$0.26
[$0.15]
$14.99/8 oz [227 g] container (approx. 57 servings)
Vegan.
Precaution: Produced in a facility that processes tree nuts, milk,
eggs, shellfish, fish, wheat and soy.
1 scoop
Magnesium (as Magnesium Carbonate) 350 mg.
Ingredients: Ionic magnesium (blend of citric acid and magnesium carbonate),
natural flavor, organic stevia leaf extract (Stevia rebaudiana).
NOT APPROVED
Bulk-
Supplements.com Magnesium Citrate
Dist. by Bulk-
Supplements.com
1 teaspoon [3.325 g]
500 mg>UL
(magnesium citrate)
Found 399 mg per teaspoon (79.8% of listed amount)
(See Update)
Heavy metals: Pass
As a dietary supplement,
take 1,662 mg (1/2 tsp) to 3,325 mg (1 tsp) daily in liquid, or as directed by
a physician.
Powder in container
1 teaspoon
$0.06
[$0.02 based on amount listed]
[$0.03 based on amount found]
$17.96/35.27 oz [1,000 g] container (approx. 300 servings)
Free of: Sugar, soy, diary,
yeast, gluten or additives.
1 teaspoon
Magnesium (from Magnesium Citrate) 500 mg.
Other Ingredients: None.
NOT APPROVED
ReMag®
Dist. by New Capstone
1/2 teaspoon [2.5 ml]
150 mgⓘ
(magnesium chloride)
✔
Heavy metals: Found 0.58 mcg lead per 1/2
teaspoon; 1.2 mcg per two 1/2 teaspoons (0.23 mcg per gram)
(See Update)
Adults: place up to 1/2
teaspoon (2.5 ml) serving in water, and consume in one sitting or throughout
the day. For optimum results, up to two (1/2 teaspoon) servings may be consumed
daily, either independently or added to a liter of water and sipped throughout
the day. Children 4 - 12: Take 1/4 - 1/2 teaspoon daily.
Liquid from bottle
1/2 teaspoon
$0.31
[$0.42]
$29.99/8.1 fl oz [240 ml] container (approx. 96 servings)
ReMag® is vegan, gluten
free (<20 ppm), and contains no yeast, dairy, egg, soy, wheat, sugar,
starch, artificial flavors, artificial colors, artificial preservatives or
animal byproducts.
1/2 teaspoon
Magnesium (from Magnesium Chloride) 150 mg.
Other Ingredients: Reverse osmosis water (Met™ water) and sorbic acid (to
protect freshness).
Magnesium & Calcium:
APPROVED
Top
Pick
for magnesium & calcium
Puritan's Pride® Chelated
Calcium Magnesium Zinc
Mfd. by Puritan's Pride,
Inc.
3 caplets
400 mg>UL
(magnesium oxide, gluconate)
✔
1,000 mg
(calcium carbonate, gluconate)
✔
Heavy metals: Pass
Also tested for disintegrationⓘ
For adults, take three (3)
caplets daily, preferably with a meal.
Large coated caplet
3 caplets
$0.15
[$0.07]
$4.99/100 coated caplets
Zinc 25 mg
No artificial color, flavor or sweetener, no preservatives, no sugar, no milk,
no lactose, no soy, no gluten, no wheat, no yeast, no fish. Sodium free.
3 caplets
Total Carbohydrate <1 g, Calcium (as Calcium Carbonate and Calcium
Gluconate) 1,000 mg, Magnesium (as Magnesium Oxide and Magnesium Gluconate) 400
mg, Zinc (as Zinc Oxide and Zinc Citrate) 25 mg.
Other Ingredients: Vegetable cellulose, more...
APPROVED
Standard Process® Calcium
Lactate
Dist. by Standard Process
Inc.
6 tablets
50 mg
(magnesium citrate)
✔
250 mg
(calcium lactate)
✔
Heavy metals: Pass
Also tested for disintegrationⓘ
Six tablets per day, or as
directed.
Medium circular tablet
6 tablets
$0.56
[$2.23]
$30.60/330 tablets
Gluten-free.
Precaution: Caution: This product is processed in a facility that
manufactures other products containing soy, milk, egg, wheat, peanut, tree
nuts, fish and shellfish.
6 tablets
Calories 5, Total Carbohydrate 1 g, Calcium 250 mg, Magnesium 50 mg.
Ingredients: Calcium lactate, magnesium citrate, and calcium stearate.
Magnesium, Calcium &
Boron:
APPROVED
Top
Pick
for magnesium, calcium
& boron
Solgar® Calcium Magnesium
Plus Boron
Mfd. by Solgar, Inc.
3 tablets
400 mg>UL
(magnesium oxide, citrate, gluconate)
✔
1,000 mg
(calcium carbonate, gluconate, citrate)
✔
3,000 mcg
(boron citrate)
✔
Heavy metals: Pass
Also tested for disintegrationⓘ
As a dietary supplement for
adults, take three (3) tablets daily, preferably with a meal, or as directed by
a healthcare practitioner.
Medium/large tablet
3 tablets
$0.22
[$0.11]
$17.99/250 tablets
Kosher. Non-GMO. Suitable
for vegans. Free of: Gluten, wheat, dairy, soy, yeast, sugar, artificial
flavor, sweetener and preservatives.
3 tablets
Calcium (as calcium carbonate, calcium gluconate, calcium citrate) 1,000 mg,
Magnesium (as magnesium oxide, magnesium citrate, magnesium gluconate) 400 mg,
Sodium 10 mg, Boron (as boron citrate) 3 mg.
Other Ingredients: Microcrystalline cellulose, vegetable cellulose, citric acid, more...
Magnesium, Calcium &
Vitamin D:
APPROVED
Caltrate® Bone Health
Advanced
Dist. by Pfizer
1 tablet
40 mg
(magnesium oxide)
✔
600 mg
(calcium carbonate)
✔
800 IU (20 mcg)
(D3)
✔
Heavy metals: Pass
Take one (1) chewable
tablet up to two times daily with or without food or as directed by your
physician.
Medium/large circular chewable tablet
1 tablet
$0.10
[$0.48]
$14.97/155 chewable tablets
None.
1 tablet
Calories 0, Total Carbohydrates <1 g, Total Sugars [Includes 0 g Added
Sugars] 0 g, Sugar Alcohol <1 g, Vitamin D3 20 mcg (800 IU), Calcium 600 mg,
Magnesium 40 mg, Zinc 7.5 mg, Copper 0.25 mg, Manganese 1.8 mg, more...
APPROVED
Top
Pick
for magnesium, calcium
& vitamin D
Puritan's Pride® Calcium
Magnesium Vitamin D3
Dist. by Puritan's Pride,
Inc.
3 caplets
500 mg>UL
(magnesium oxide)
✔
1,000 mg
(calcium from oyster shell)
✔
400 IU (10 mcg)
(D3)
✔
Heavy metals: Pass
Also tested for disintegrationⓘ
For adults, take three (3)
caplets daily, preferably with meals.
Large coated caplet
3 caplets
$0.20
[$0.08]
$7.99/120 coated caplets
No artificial flavor, no
artificial sweetener, no preservatives, no sugar, no milk, no lactose, no soy,
no gluten, no wheat, no yeast. Sodium free.
3 caplets
Vitamin D (as D3 Cholecalciferol) 10 mcg (400 IU), Calcium (as Oyster Shell)
1,000 mg, Magnesium (as Magnesium Oxide) 500 mg.
Other Ingredients: Vegetable cellulose, contains <2% of: natural palm leaf
glaze, polydextrose, titanium dioxide color, triacetin, more...
APPROVED
Rainbow Light® Food-Based
Calcium™ With Magnesium & Vitamin D3
Dist. by Rainbow Light
Nutritional Systems®
1 tablet
250 mgⓘ
(magnesium oxide, aspartate)
✔
500 mg
(calcium carbonate, amino acid chelate, citrate-malate)
✔
500 IU (12.5 mcg)
(D3)
✔
Heavy metals: Pass
Also tested for disintegrationⓘ
For pure and potent
protection, take one tablet per day, with or between meals. May take 2 per day
in divided doses for advanced usage.
Large tablet
1 tablet
$0.10
[$0.08]
$17.99/180 tablets
Betaine HCl 20 mg, stinging
nettle [tops] 20 mg, horsetail [whole herb] 20 mg, organic spirulina 20 mg
Free of gluten, wheat, milk/dairy, nuts, soy, eggs, fish, shellfish, yeast,
sugar, artificial additives.
1 tablet
Calcium (as Carbonate, Amino Acid Chelate, Citrate-Malate) 500 mg, Magnesium
(as Oxide, Aspartate) 250 mg, Vitamin D (as D3 Cholecalciferol) 500 IU, Betaine
HCl 20 mg, Stinging Nettle [tops] 20 mg, Horsetail [whole herb] 20 mg, Organic
Spirulina 20 mg, more...
Children's Products
Containing Magnesium, Calcium & Vitamin D:
APPROVED
Bluebonnet Rainforest
AnimalZ® Calcium Magnesium & Vitamin D3 - Vanilla Frosting Flavor
Dist. by Bluebonnet
Nutrition Corporation
2 chewables
50 mg
(magnesium oxide, bisglycinate chelate)
✔
250 mg
(calcium carbonate, citrate, malate)
✔
200 IU (5 mcg)
(D3)
✔
Heavy metals: Pass
As a dietary supplement for
children three years of age or older, take two animal-shaped chewables once
daily or as directed by a healthcare practitioner.
Medium/large animal-shaped chewable tablet
2 chewables
$0.23
[$0.91]
$10.24/90 chewables
Super fruit and veggie
blend 30 mg
Kosher. Gluten free. Free of milk, egg, fish, crustacean shellfish, tree
nuts, peanuts, peanuts, wheat and soybeans. Also free of yeast, gluten, barley
and sodium.
2 chewables
Calories 6, Total Carbohydrate 1.5 g, Sugars [Includes 1.5 g added sugars] 1.5
g, Vitamin D3 (as 200 IU cholecalciferol) 5 mcg, Calcium (as carbonate,
citrate, malate) 250 mg, Magnesium (as oxide, bisglycinate chelate) 50 mg, more...
APPROVED
Top
Pick
for children magnesium,
calcium & vitamin D
Pioneer® Children's Cal Mag
& D - Cocoa
Mfd. by Healthway Corp.
2 tablets
85 mg
(magnesium oxide, citrate)
✔
250 mg
(calcium carbonate, citrate)
✔
200 IU (5 mcg)
(D3)
✔
Heavy metals: Pass
Children ages
4-8: Two chewables once daily. Children ages 9-13: Two
chewables two times daily.
Medium/large circular chewable tablet
2 tablets
$0.15
[$0.36]
$9.18/120 chewable tablets
Trace mineral complex 10 mg
Gluten free. Product contains no added artificial colors or flavors. Formulated
to be free of dairy.
2 chewables
Calories 5, Total Carbohydrate 2 g, Sugar Alcohol 1 g, Vitamin D-3 (from
cholecalciferol) 200 IU, Calcium (3:1 from carbonate: citrate) 250 mg,
Magnesium (2:1 from oxide: citrate) 85 mg, Trace Mineral Complex (from sea
vegetation: Lithothamnion spp.) 10 mg, more...
Magnesium, Calcium, Boron
& Vitamin D:
NOT APPROVED
Natural Vitality® Natural
Calm Plus Calcium - Raspberry-Lemon Flavor
Dist. by Natural Vitality
1 teaspoon [2.5 g]
106.7 mg
(magnesium citrate)
✔
70 mg
(calcium gluconate)
✔
88.3 mcg
(boron citrate)
Found 198.5 mcg boron per serving (224.7% of
listed amount)
35 IU (2.6 mcg)
(D3)
Found only 22.1 IU vitamin D per serving (63.1% of
listed amount)
Heavy metals: Pass
Take 1 - 1 1/2 rounded
teaspoons twice per day at any time, at least 5 hours apart.
Powder in container
1 teaspoon
$0.52
[$0.32]
$15.57/8 oz.[226 g] container (approx. 90 servings)
Vitamin C 88.3 mg, potassium
(elemental from potassium citrate) 35 mg
Vegetarian. Gluten-free. Non GMO Project Verified
seal. Contains no yeast, dairy, egg, gluten, soy, wheat, sugar, starch,
preservatives or artificial color or flavor.
1 teaspoon
Vitamin C (as ascorbic acid) 88.3 mg, Vitamin D3 (as cholecalciferol) 35 IU,
Calcium (elemental from calcium gluconate) 70 mg, Magnesium (elemental from
magnesium citrate) 106.7 mg, Potassium (elemental from potassium citrate) 35
mg, Boron (elemental from boron citrate) 88.3 mcg.
Ingredients: Calcium gluconate, more...
APPROVED
Top
Pick
for magnesium, calcium,
boron & vitamin D
Vitalite Now! Calcium &
Magnesium Plus
Dist. by Vitalite Now!
4 capsules
500 mg>UL
(magnesium oxide)
✔
1,000 mg
(calcium carbonate, dicalcium phosphate, citrate, amino acid chelate,
hydroxyapatite, gluconate, lactate, orotate, succinate and alpha ketoglutarate)
✔
4,000 mcg
(boron amino acid chelate)
✔
400 IU (10 mcg)
(D3)
✔
Heavy metals: Pass
4 capsules daily preferably
with meals or as directed by a healthcare professional.
Large capsule
4 capsules
$0.47
[$0.19]
$27.90/240 capsules
Phosphorus 77 mg
Precaution: This product is manufactured and packaged in a facility
which may also process milk, soy, wheat, egg, peanuts, tree nuts, fish and
crustacean shellfish.
4 capsules
Vitamin D-3 (cholecalciferol) 400 IU, Calcium (from carbonate, dicalcium
phosphate, citrate, amino acid chelate, hydroxyapatite, gluconate, lactate,
orotate, succinate and alpha ketoglutarate) 1,000 mg, Phosphorus (dicalcium
phosphate) 77 mg, Magnesium (from oxide) 500 mg, Boron (from amino acid
chelate) 4 mg.
Other Ingredients: Gelatin (bovine), vegetable magnesium stearate and rice
flour.
Magnesium, Calcium,
Vitamin D & Vitamin K:
APPROVED
New Chapter® Bone Strength
Take Care™
Dist. by New Chapter, Inc.
3 tablets
58 mg
(magnesium from algae Lithothamnion calcareum & corallioides)
✔
770 mg
(calcium from algae Lithothamnion calcareum & corallioides)
✔
1,000 IU (25 mcg)
(D3)
Found 1,968 IU vitamin D per serving (196.8% of listed amount)
35 mcg
(K1)
45 mcg
(MK-7 K2)
80 mcg
(total vitamin K)
✔
Heavy metals: Pass
Also tested for disintegrationⓘ
Three tablets daily with
food.
Large slim tablet
3 tablets
$0.96
[$3.31]
$38.37/120 slim tablets
Strontium 5 mg, silica 2
mg, vanadium 13 mcg
Kosher. Non GMO Project Verified seal. Gluten free;
100% vegetarian; no artificial flavors or colors.
Precaution: Contains: Fermented soy.
3 tablets
Vitamin D3 (as cholecalciferol from ferment media) 1,000 IU, Vitamin K1 (as
phylloquinone from ferment media) 35 mcg, Vitamin K2 (as menaquinone-7 from
natto) 45 mcg, Calcium (from algae Lithothamnion calcareum & corallioides)
770 mg, Magnesium (from algae Lithothamnion calcareum & corallioides)
58 mg, Strontium (from algae Lithothamnion calcareum & corallioides)
5 mg, Silica (from algae Lithothamnion calcareum & corallioides)
2 mg, Vanadium (from algae Lithothamnion calcareum & corallioides) 13 mcg, more...
NOT APPROVED
Thorne® Basic Bone
Nutrients
Mfd. by Thorne Research,
Inc.
1 capsule
50 mg
(Albion® DiMagnesium Malate)
✔
200 mg
(DimaCal® DiCalcium Malate)
✔
500 IU (12.5 mcg)
(D3)
Found only 348.5 IU vitamin D per serving (69.7%
of listed amount)
45 mcg
(MK-7 K2)
Found only 1 mcg vitamin K per serving (2.2% of
listed amount)
Heavy metals: Pass
Take 1 capsule one to four
times daily or as recommended by a health-care practitioner.
Large capsule
1 capsule
$0.32
[$1.27]
$38.00/120 capsules
Gluten Free.
1 capsule
Vitamin D (as Vitamin D3) (500 IU) 12.5 mcg, Vitamin K (as K2 (MK-7)) 45 mcg,
Calcium (as DimaCal® Dicalcium Malate) 200 mg, Magnesium (as Albion®
Dimagnesium Malate) 50 mg.
Other Ingredients: Hypromellose (derived from cellulose) capsule, calcium
laurate.
Magnesium, Calcium,
Boron, Vitamin D & Vitamin K:
APPROVED
GNC Calcimate Complete™
Dist. by General Nutrition
Corporation
4 caplets
100 mg
(magnesium oxide)
✔
800 mg
(calcium citrate malate)
✔
1,000 mcg
(boron hydrolyzed protein chelate)
✔
2,000 IU (50 mcg)
(D3)
✔
50 mcg
(K2)
✔
Heavy metals: Pass
Also tested for disintegrationⓘ
As a dietary supplement,
take two caplets at breakfast and two caplets at dinner for a total of four
caplets daily.
Large caplet
4 caplets
$0.25
[$0.50]
$14.99/240 caplets
Zinc 7.5 mg, copper 1 mg,
manganese 1 mg, MBP® 40 mg
No artificial colors, no artificial flavors, no wheat, gluten free, yeast
free.
Precaution: Contains: Milk and soybeans.
4 caplets
Vitamin D (as Cholecalciferol D-3) 2,000 IU, Vitamin K-2 (as Menaquinone) 50
mcg, Calcium (as Calcium Citrate Malate) 800 mg, Magnesium (as Magnesium Oxide)
100 mg, Zinc (as Zinc Oxide) 7.5 mg, Copper (as Copper Glycinate) 1 mg,
Manganese (as Manganese Gluconate) 1 mg, MBP® 40 mg, Boron (as Hydrolyzed
Protein Chelate) 1 mg.
Other Ingredients: Cellulose, titanium dioxide (natural mineral whitener),
vegetable acetoglycerides.
APPROVED
Top
Pick
for magnesium, calcium,
boron, vitamin D & vitamin K
Jarrow Formulas® Bone-Up®
Dist. by Jarrow Formulas®
6 capsules
500 mg>UL
(magnesium oxide)
✔
1,000 mg
(StimuCal™ microcrystalline hydroxyapatite)
✔
3,000 mcg
(boron citrate)
✔
1,000 IU (25 mcg)
(D3)
✔
45 mcg
(MK-7 K2)
✔
Heavy metals: Pass
Take 2 capsules 3 times per
day (for a total of 6) with meals to facilitate maximum absorption, or as
directed by your qualified healthcare professional.
Large capsule
6 capsules
$0.51
[$0.20]
$20.37/240 capsules
Vitamin C 200 mg, zinc 10
mg, copper 1 mg, manganese 1 mg, potassium 99 mg
No wheat, gluten, egg, fish/shellfish, or peanuts/tree nuts.
Precaution: Contains: Soy (in trace amounts).
6 capsules
Vitamin C (as Calcium Ascorbate) 200 mg, Vitamin D3 (Cholecalciferol) 25 mcg
(1,000 IU), Vitamin K2 (as Natural MK-7 [Menaquinone-7]) 45 mcg, Calcium
(Elemental) (from StimuCal™ Microcrystalline Hydroxyapatite) 1,000 mg, Magnesium
(as Magnesium Oxide) 500 mg, Zinc (L-OptiZinc®) (as Zinc L-Methionine Sulfate)
10 mg, Copper (as Copper Gluconate) 1 mg, more...
Unless otherwise noted,
information about the products listed above is based on the samples purchased
by ConsumerLab.com (CL) for this Product Review. Manufacturers may change
ingredients and label information at any time, so be sure to check labels
carefully when evaluating the products you use or buy.
If a product's ingredients differ from what is listed above, it may not
necessarily be of the same quality as what was tested.
The information contained
in this report is based on the compilation and review of information from
product labeling and analytic testing. CL applies what it believes to be the
most appropriate testing methods and standards. The information in this report
does not reflect the opinion or recommendation of CL, its officers or
employees. CL cannot assure the accuracy of information.
Copyright
ConsumerLab.com, LLC, 2021 All rights reserved. Not to be reproduced,
excerpted, or cited in any fashion without the express written permission of
ConsumerLab.com LLC
ConsumerTips™:
What to Consider When
Buying:
In the products evaluated, the labeled amounts of magnesium ranged from 133 mg
to 500 mg per serving. This large range should be considered when comparing
products, particularly as most people only need a dose of 100 to 200 mg to
bring them to the daily requirement, and exceeding 350 mg per day (for adults)
from a supplement is not advisable unless you are treating deficiency. The
limit is lower for children. (See dosage information below)
Look carefully at labels
Product labels should indicate the amount of actual magnesium (or
"elemental" magnesium) per dosage unit. This is important because
magnesium often makes up less than half of the weight of magnesium compounds.
For example, the amount of magnesium in magnesium gluconate is only 5.8%, and
it is 12% in magnesium chloride hexahydrate, 11.2% in magnesium citrate (or
16.2% if in the form of trimagnesium dicitrate), 14.1% in magnesium glycinate,
20.2% in magnesium sulfate, 41.67% in magnesium hydroxide, and 60.3% in
magnesium oxide.
An example of an incorrectly labeled product identified in ConsumerLab.com's
review in 2012 is shown below. At first glance, this label seems to contain
"720 mg" of magnesium, but only a small amount of this (115 mg) was
actually listed as elemental magnesium. Making matters worse, our testing
showed that even that amount was not correct. We found only 52 mg of magnesium.
If this product had been properly made and labeled and actually provided 115 mg
of elemental magnesium, the label should have read: "Magnesium (as
magnesium citrate)....115 mg" -- although since 115 mg is only about 16%
of the claimed magnesium citrate, the form of magnesium would likely have been
trimagnesium dicitrate, which was not specified.
Choosing the right form of
magnesium
Magnesium is sold in several different chemical forms that affect the body in
different ways, so it is important to choose the right form for a particular
condition. In the table below, we summarize information about different forms
of magnesium, including details about bioavailability, laxative effects,
antacid effects, and whether the form is beneficial for increasing magnesium
levels.
Comparison of Forms of
Magnesium
|
Form of Magnesium |
Percent Absorbed |
Laxative Effects |
Good for Increasing Mg Levels |
Antacid Effects |
Additional Comments |
|
Mg aspartate |
42% |
At higher doses |
Yes |
No |
Increased absorption
when powder form is dissolved in water |
|
24% |
No |
Yes |
No |
||
|
Similar to Mg sulfate |
At typical doses |
No |
Yes |
||
|
Mg citrate |
30% |
At higher doses |
Yes |
No |
|
|
20%; may be similar to
Mg aspartate and lactate |
At typical doses |
Yes |
No |
Better as a liquid
than as a pill |
|
|
19%; similar to Mg
chloride |
At higher doses |
Yes |
No |
May be more expensive |
|
|
May be less than Mg
aspartate |
No |
Yes |
No |
May be more expensive |
|
|
Similar to Mg sulfate |
At typical doses;
fast-acting |
No |
Yes |
Also known as
"milk of magnesia" |
|
|
42% |
At higher doses |
Yes |
No |
Sustained release
increases absorption |
|
|
Uncertain |
At higher doses |
Yes |
No |
||
|
Uncertain |
No |
No |
No |
Possible safety
concerns. |
|
|
23% |
At typical doses |
No |
Yes |
Increased absorption
from liposomal formulation or from effervescent tablets |
|
|
4% |
At typical doses;
potent |
No |
No |
Also known as
"Epsom salt" |
|
|
Uncertain |
No |
Uncertain |
No |
||
|
Mg
threonate |
Uncertain |
No |
Yes |
No |
Sources: Ranade, Am J Ther. 2001; Guerrera, Am Fam Physician 2009; Driessens, Mag Bulletin 1993; Firoz, Magnes res 2001; Schuchardt, Curr Nutr Food Sci 2017
·
Forms that are absorbed well by the body without
causing significant laxative effects — such as magnesium chloride, bisglycinate
(also referred to as magnesium glycinate or diglycinate), and glycerophosphate
— tend to be good options for increasing levels of magnesium in the body. Other
forms such as magnesium citrate, gluconate, aspartate and lactate can also
increase levels of magnesium, but these forms can have laxative effects at high
doses (Mühlbauer, Eur J Clin Pharmacol 1991; Driessens, Mag Bulletin 1993; Schuette, JPEN J Parenter Enteral Nutr 1994; Ranade, Am J Ther 2001; DiSilvestro, FASEB 2013).
The gluconate and glycerophosphate forms may also be more expensive. [Note: The branded product ReMag (tested in
this Review) is promoted on the Internet as a "picometer-ionic form of
magnesium." It is magnesium chloride dissolved in water. It is promoted as
having no laxative effect, which, being magnesium chloride, should be
essentially true. We are not aware, however, of any published studies
with ReMag.]
·
Forms that are not absorbed well — such as magnesium hydroxide,
carbonate, oxide and sulfate — are not recommended as an oral
supplement for magnesium replacement. These forms tend to be better options
for use as laxatives (Ranade, Am J Ther 2001; Firoz, Magnes Res 2001; Walker, Magnes Res 2003). Magnesium hydroxide
(milk of magnesia) is particularly fast acting as a laxative, and magnesium
sulfate (Epsom salt) is the most potent. (The sulfate form may also be used
intravenously under medical supervision for seizures, uterine tetany and other
acute conditions.)
·
Forms such as magnesium carbonate and trisilicate are good
options for use as an antacid. Magnesium hydroxide and oxide can
also work but, as noted above, may cause diarrhea.
·
Magnesium citrate and trimagnesium dicitrate may help
reduce migraine headaches (Koseoglu, Magnes Res 2008; Peikert, Cephalalgia 1996). Magnesium taurate
has been proposed for the prevention of migraines (McCarty Med Hypotheses 1996), but it hasn't
been evaluated in people.
·
Magnesium malate might improve fibromyalgia pain,
but it is unclear if this form has greater benefit than other forms (Russell, J Rheumatol 1995). Topical magnesium
products have also been evaluated for fibromyalgia, but these forms do not
appear to be helpful and may cause irritation.
·
Magnesium-L-threonate might improve memory (Slutsky, Neuron 2010; Liu, J Alzheimer's Dis 2016),
but the evidence is still preliminary (see the What It Does section for details).
However, as noted earlier, maintaining adequate intake
of magnesium in general may optimize cognitive function and reduce the risk of
developing dementia.
·
Magnesium bisglycinate might reduce leg cramps during
pregnancy. Magnesium oxide, lactate and citrate do not appear
to help with leg cramps.
·
Other forms: Some websites claim that magnesium orotate is
better absorbed than other forms, but research does not support this (Andermann, Eur J Drug Metab Pharmacokinet 1982).
Furthermore, this form of magnesium can cost up to nine times more than other
magnesium products. To get, for example, 200 mg of magnesium from magnesium
orotate supplements you might spend 10 to 18 cents. In contrast, you can get
the same amount of magnesium for as little as 3 cents. There are also potential
safety concerns (see Concerns and Cautions).
Magnesium bicarbonate is a liquid formed through the reaction of carbonic acid
and magnesium hydroxide. It is occasionally sold as a supplement, but more
commonly, made from "home recipes" combining magnesium hydroxide
(milk of magnesia) and seltzer water and described as a "health
tonic" and/or less expensive alternative to mineral water. There is some
evidence that it might increase levels of magnesium in the body (Day, BMC Res Notes 2010), but there is no
evidence that it works better than other forms described above.
In addition to different chemical forms, the way in
which a magnesium supplement is formulated can make it more
useful for certain purposes, mainly by affecting magnesium's absorption and
bioavailability:
·
A liposomal formulation of magnesium oxide (Sucrosomial magnesium),
which typically has low absorption, has been shown to be absorbed slightly
better than magnesium citrate or magnesium bisglycinate, suggesting that
liposomal formulations may improve bioavailability of magnesium forms with low
absorption (Brilli, Eur Rev Med Pharmacol Sci 2018).
·
Magnesium oxide also appears to be absorbed
better from effervescent tablets than from capsules, possibly
due to increased ionization of magnesium from magnesium oxide (Siener, Urol Res 2011). Similarly, magnesium
aspartate in powder form dissolved in water appears to be
absorbed slightly better than from tablet form (Mühlbauer, Eur J Clin Pharmacol 1991),
although the powder form can have an unpleasant taste, which would not be
noticeable with a tablet. Also, keep in mind that powders need to be well
dissolved before ingestion (see Concerns and
Cautions).
·
Magnesium chloride may be better as a liquid than
as a pill, as this form of magnesium is hygroscopic i.e., it attracts water,
and pills containing this form can quickly become
"wet" from moisture in the air.
·
Enteric-coatings may reduce magnesium absorption, as the
coating may delay the release of magnesium and make it less available for
absorption in the intestine (Fine, J Clin Invest 1991).
Such formulations may also not be suitable for people with disorders of gastric
and intestinal motility, as suggested by a case in which a man accumulated 21
enteric-coated magnesium chloride tablets (which had been given over 4 days) in
his stomach. The patient had evidence of mild pylorospasm (which can delay
passage of stomach contents into the duodenum) and suspected gastric motor
dysfunction. (Chapron, Ann Pharmacother 1994).
Taking magnesium with calcium?
Products that contain calcium in addition to magnesium are
sometimes touted as improving the absorption of the other, however, this is not
the case and it is not necessary to take extra calcium when supplementing with
magnesium, nor vice versa. Nor is a specific ratio of the two minerals known to
produce superior absorption (although some evidence suggests that, for
cognitive benefits, people over age 65 should maintain a calcium/magnesium
ratio between 1.7 and 2.3).
Some laboratory and animal experiments have suggested that calcium and
magnesium can inhibit absorption of the other. It is not clear if this is the
case in people. A study in healthy males found that increased magnesium intake
of 826 mg daily did not affect absorption of calcium taken at 241 and 812 mg
daily, nor did the calcium affect magnesium absorption (Spencer, J Am Coll Nutr 1994). However,
the amounts given in this study were each divided into three doses per
day, the magnesium was taken with meals, and the calcium
was taken 2 hours after meals — so they were not given
together, nor in very large doses. Furthermore, magnesium oxide was used,
which, as noted earlier, is not among the best absorbed forms of magnesium.
Until there is more research, it would seem best to take doses of magnesium and
calcium that are more than 250 mg at least 2 hours apart from one another to
assure maximum absorption.
What to Consider When Using:
The daily requirement for magnesium can be obtained through food sources
without much difficulty, and it is thought that the great majority of
individuals in developed countries have an adequate intake.
|
Food |
Magnesium (mg) |
|
Almonds, dry roasted, (1 oz) |
80 |
|
Spinach, boiled (½ cup) |
78 |
|
Cashews, dry roasted (1 oz.) |
74 |
|
Peanuts, oil roasted (¼ cup) |
63 |
|
Cereal, shredded wheat (2 large biscuits) |
61 |
|
Soymilk, plain or vanilla (1 cup) |
61 |
|
Black beans, cooked (½ cup) |
60 |
|
Edamame, shelled, cooked (½ cup) |
50 |
|
Dark chocolate 60
to 90% cacao solids (1 oz.) |
50 |
|
Potato, baked with skin, (3.5 oz.) |
43 |
|
Rice, brown, cooked (½ cup) |
42 |
|
Yogurt, plain, low fat (8 oz.) |
42 |
|
Breakfast cereals, |
42 |
|
Oatmeal, instant, 1 packet |
36 |
|
Kidney beans, canned (½ cup) |
35 |
|
Banana (1 medium) |
32 |
|
Salmon, pink, canned (3
oz.) |
27 |
Source: National Institutes of Health
Magnesium Fact Sheet 2020 ; USDA National Nutrient Database for
Standard Reference Legacy (2018)
The
recommended daily allowance (RDA) of magnesium is 80 mg for children 1 to 3,
130 mg for those 4 to 8, and 240 mg for those 9 to 13. For males 14 to 18 it is
410 mg, for those 19 to 30 it falls to 400 mg, and for those 31 years and older
it is 420 mg. For females 14 to 18 it is 360 mg, for those 19 to 30 it falls to
310 mg, and for those 31 years and older it is 320 mg. However, for pregnant
women it is 400 mg if 18 years or younger, 350 mg if 19 to 30, and 360 mg if 31
or older. For lactating women it is 360 mg if 18 years
or younger, 310 mg if 19 to 30, and 320 mg if 31 or older.
Bear in mind that the
recommended amounts noted above are for total daily magnesium intake. The
average daily intake of magnesium from food sources in the United States is
approximately 320 mg; thus supplementation is likely
to increase magnesium intake above nutritional needs for many.
Be aware that current
supplement labels may not reflect the latest Daily Value (DV) for magnesium. In
2016, the FDA announced that the DV for
magnesium for adults and children age 4 and over is now 420 mg
(increased from 400 mg). However, not all labels are required to reflect this
change until January 2021. So, for now, if you see 100% as the "%DV,"
that means the product provides 400 mg per serving.
Testing for magnesium levels
Magnesium is not normally part of routine blood tests and not considered the
most reliable marker of magnesium sufficiency because levels in blood plasma do
not necessarily reflect levels in tissues. However, a normal range in blood
plasma is considered to be 1.7 to 2.2 mg/dL (0.85 to 1.10 mmol/L) (NIH Fact Sheet; Medline Plus, NIH).
There is no single blood
test or other type of test to accurately measures magnesium levels in the whole
body. When magnesium deficiency is suspected, doctors may use a combination of
testing and assessment of symptoms, to diagnose deficiency.
Serum magnesium
concentration (SMC) is the most commonly used blood test and may be valuable
for detecting severe and sudden changes in magnesium status. However, only 1%
of total body magnesium is found in the blood, so this test does not measure
the majority of magnesium in the body, including magnesium found in soft
tissue, muscle and bone. For this reason, it's possible to have a serum
magnesium concentration within normal range but still have a deficiency in
total body magnesium (Jahnen-Dechent, Clin Kidney J 2012).
Similarly, blood tests
can measure magnesium levels within red blood cells (RBC), which gives an idea
of magnesium status in the recent past. Levels tend to be are somewhat higher
(1.65 - 2.65 mmol/L), but these levels also do not reflect total body magnesium
(Swaminathan, Clin Biochem Rev 2003).
A third type of blood
test measures the "serum ionized (free) magnesium concentration,"
which represents the largest portion of magnesium in the blood, and may be the
most biologically active (Jahnen-Dechent, Clin Kidney J 2012). --
however, not all researchers agree on this last point, and, due to the
specialized equipment, materials and training needed for the test, it is rarely
used outside of a research setting (Elin, Mag Res 2010).
A magnesium retention or
"loading" test is considered the "gold standard" in
magnesium testing by some experts (Ismail, Clin Chem Lab Med 2010); this test
involves receiving a large oral or intravenous dose of magnesium, and then
measuring how much is excreted in the urine. The oral version of this test can
indicate problems with intestinal absorption of magnesium. The intravenous
version reflects amounts of magnesium in bone, and deficiency is diagnosed if
less than 90% of the magnesium is excreted (the body will retain more magnesium
in the bone when it is deficient). However, because this test is so
time-consuming, it is also rarely used outside of a research setting (Ismail, Clin Chem Lab Med 2010; Jahnen-Dechent, Clin Kidney J 2012).
The 24-hour excretion
test, commonly offered in hospitals, measures levels of magnesium in the urine
at various times over a 24 hour period (as amounts in
urine fluctuate the course of a night and day). This can be helpful for
evaluating kidney function, but not overall magnesium status (Elin, Mag Res 2010).
A test which involves
swabbing under the tongue and measuring the magnesium in these skin cells (EXA
Test) has been promoted as a non-invasive and accurate measure of magnesium
levels. A small study authored, in part, by the owner of the company that sells
this test found that levels of magnesium in swabbed samples correlated with
magnesium levels in coronary artery tissue (obtained during surgery) (Haigney, Circulation 1995). However, this test
is not mentioned in reviews of known testing methods (Ismail, Clin Chem Lab Med 2010; Jahnen-Dechent, Clin Kidney J 2012).
Dosing
and how to take
When used as a treatment, magnesium is often recommended at doses of 250 to 600
mg daily.
To reduce the frequency
and severity of migraine headaches, 600 mg daily (taken in divided doses) of
magnesium citrate or trimagnesium dicitrate has been shown to be helpful (Koseoglu, Magnes Res 2008; Peikert, Cephalalgia 1996).
Magnesium specifically
from supplements can often cause diarrhea — which is why it is an ingredient in
many laxatives. Diarrhea is particularly common in products also containing
aluminum. Taking magnesium with food can reduce the occurrence of
diarrhea.
Excessive
magnesium levels in the blood can cause dangerous side effects, but oral
supplements taken as directed seldom dangerously raise blood levels in
individuals with healthy kidneys -- which regulate magnesium status. Tolerable
Upper Intake Levels (ULs) have been established for magnesium supplement
intake. The UL is defined as "a level of chronic daily intake judged to be
likely to pose no risk of adverse health effects to the most sensitive members
of the healthy population." The UL recommendations (which apply
specifically to magnesium consumed from supplements or other medications) are
65 mg for children 1 to 3 and 110 mg for those 4 to 8. For individuals 9 years
and older the UL is 350 mg. Note that the ULs for supplements sometimes are
actually lower than the respective RDAs, because side effects are not likely to
occur from magnesium obtained from solely from foods.
Magnesium
and calcium are "macrominerals:" meaning that their RDAs are
relatively high compared to "microminerals," such as zinc, for which
only a few milligrams or microgram amounts are needed. Both magnesium and
calcium supplements can interfere with the absorption of
"microminerals." As a result, it is probably best to take
microminerals at a different time of day from a magnesium or calcium
supplement. Because of the bulk of both magnesium and calcium, they are
generally not found in multivitamin/multimineral products in doses equivalent
to their RDAs and are often sold separately or combined.
Some calcium supplements
contain the trace mineral boron,
typically in amounts ranging from less than 1 mg up to about 6 mg per daily
serving. Some, but not all evidence suggests that boron may reduce calcium loss
in the urine, especially when magnesium intake is low (Neilson, FASEB J 1987). Although some
preliminary research suggests boron supplementation in doses of 3 mg to 10 mg
per day may be helpful for osteoarthritis and osteoporosis, one small trial
found no increase in spine or thigh bone mineral density in postmenopausal
women who took 3 mg of boron daily for one year compared to placebo (Biquet, Osteoporos Int 1996). Americans typically
get an average of about 1 mg to 1.25 mg of boron daily from foods such as leafy
vegetables, raisins, prunes, non-citrus fruits like apples, and some grains (Rainey, J Am Diet Assoc 1999). There is no
established daily requirement for boron, but there is an upper tolerable intake
level of 20 mg for per day for adults. Be aware that even at doses of 3 mg to
10 mg daily, boron may increase estrogen levels in both women and men (Neilson, FASEB J 1987; Naghii, Biol Trace Elem Res 1997). This may be
of particular concern for women on hormonal therapy or those with a history of
estrogen-sensitive cancer.
Storage
Be aware that magnesium chloride is extremely hygroscopic
— it attracts and holds water — even in moderate humidity, which can cause
pills to become wet and disintegrate. Keep magnesium chloride pills in a sealed
container, along with any desiccant packet with which they may have come. Also,
keep magnesium chloride pills away from other pills, including
softgels, because the absorbed water can cause disintegration of those pills
(in addition to prematurely activating enzymes and probiotics). It is wise to
keep all forms of magnesium out of humidity, although they can be stored with
other pills.
Concerns and Cautions:
Magnesium
supplements may cause stomach upset, nausea, vomiting and diarrhea.
(If you are taking magnesium for a reason other than its laxative effect, such
as correcting a deficiency, you may want to choose a form which is less likely
to cause diarrhea — see Choosing the right form of magnesium).
Although rare, excessive intake of magnesium (above the ULs)
may result in too much magnesium in the blood (hypermagnesemia),
causing nausea, headache, flushing, warmth, lightheadedness, thirst, low blood
pressure, drowsiness, muscle weakness, slowed breathing, and even death.
Outside of serious medical conditions, injury or illness, the most common cause
of elevated blood levels of magnesium is excessive intake of
magnesium-containing laxatives or supplements, especially in people with
constipation, bowel injuries or decreased small bowel motility, or those
taking anticholinergic drugs (such as certain drugs for Parkinson's disease) or
narcotic drugs (Birrer, J Emerg Med 2002). This
is of particular concern in people with poor kidney function, as they may have
trouble excreting excess magnesium. For example, a 74-year-old woman with
chronic constipation and impaired kidney function developed hypermagnesemia
after consuming 30 ounces (3 full bottles) of liquid magnesium
citrate in an attempt to treat her constipation. Normally no more than 1 bottle
(10 ounces) should be consumed over 24 hours, with each ounce providing about
1,745 mg of magnesium citrate (providing 290 mg of magnesium according the
study and Drug Facts panels on magnesium citrate bottles). In effect, she
consumed several thousand milligrams of magnesium. This
resulted in respiratory distress, low blood pressure, and injury to her
intestine due to decreased blood flow, which then perforated and required
surgical repair (Hubbard, BMJ Case Rep 2021).
Taking a very large dose of magnesium (1,000 mg as
magnesium oxide) along with 100 mg of L-dopa/10 mg of carbidopa reduced the
absorption of L-dopa by 35.3% and the absorption of carbidopa by 80.9% in
healthy people, suggesting that at least some forms of magnesium may reduce the
effectiveness of drugs for Parkinson's disease (Kashihara, Eur J Clin Pharmacol 2019).
If using a powder form of magnesium, be sure to completely
dissolve the powder in water before taking it. Swelling and irritation
to the esophagus, leading to eventual scarring and narrowing of the esophagus,
was reported for a 40-year-old man who ingested 1 teaspoon of magnesium citrate
powder (providing 630 mg of elemental magnesium) without first
dissolving it in water as recommended (Assal, Can J Gastroenterol Hepatol 2014). We
are unaware of similar injury when magnesium is taken as recommended.
Individuals with kidney disease cannot properly control
levels of electrolytes in the body; for this reason, the use of magnesium (or
any other mineral) can be very dangerous. There may be risks for people with
severe heart disease or diseases of the intestines as well. Laboratory and
animal studies suggest magnesium may have anticoagulant/antiplatelet effects (Hsiao, J Biomed Sci 2004; Kh, J Hypertens 2000). In healthy people,
intravenous magnesium sulfate has been shown to increase anti-platelet activity
and bleeding time by 48% (Ravn, Thromb Haemost 1996), while in people
with coronary artery disease, oral magnesium oxide (800 mg - 1,200 mg/day) was
not found to increase anti-platelet activity, but did inhibit
platelet-dependent thrombosis (Shechter, Magnes Res 2000).
To be safe, people taking blood-thinning medications, such as
warfarin (Coumadin), clopidogrel (Plavix), heparin, indomethacin (Indocin) and
ticlopidine (Ticlid), should consult with their physician before taking
magnesium.
Magnesium hydroxide may increase the absorption and/or rate of absorption
of sulfonylurea anti-diabetes drugs such as glibenclamide
(DiaBeta, Micronase, Glynase) and glimepiride (Amaryl) (Neuvonen Br J Clin Pharmacol 1991; Kivisto, Clin Pharmacol Ther 1991), which
could potentially affect blood sugar control.
Magnesium should be taken two or more hours apart from the
following medications:
·
Some statin drugs: Certain forms of magnesium which have an
antacid effect (namely, magnesium hydroxide, oxide, carbonate, and trisilicate)
may reduce drug levels of some cholesterol-lowering statin medications. This
has been demonstrated for Crestor (rosuvastatin calcium) in a study which found
that taking Crestor along with the antacid Maalox (which contains magnesium
hydroxide and aluminum hydroxide) reduced blood levels of the drug by an
average of 54% compared to taking the drug alone. Taking the antacid two hours
after the drug had a smaller effect, but still reduced drug levels by 22%. The
study did not evaluate the effect of taking the antacid prior to the drug nor
the effect of repeated, long-term antacid use (Martin, Curr Med Res Opin 2008).
Based on this study, the label on Crestor states that if using an antacid with
aluminum hydroxide and magnesium hydroxide, the antacid should be taken at
least 2 hours after Crestor. A preliminary study suggests a similar, although
smaller effect (a 34% reduction in drug when taken with Maalox) for Lipitor
(atorvastatin) (Yang, Pharm Res 1996 — not online).
·
Tetracycline antibiotics: Magnesium can reduce the absorption of
tetracycline antibiotics including tetracycline (Achromycin, Sumycin),
demeclocycline (Declomycin), doxycycline (Vibramycin) and minocycline
(Minocin); these medications should be taken 1 hour before or 2 hours after
magnesium supplements and/or magnesium-containing antacids or laxatives (NIH 2017).
·
Quinolone antibiotics: Magnesium can reduce the absorption of
quinolone antibiotics such as ciprofloxacin (Cipro), levofloxacin (Levaquin),
moxifloxacin (Avelox) and ofloxacin (Floxin). For example, taking antacids
containing magnesium hydroxide or aluminum hydroxide has been shown to reduce
the bioavailability of ciprofloxacin by as much as 90%; for this reason,
quinolone antibiotics should be taken either 2 hours before or 6 hours after
taking magnesium supplements and/or magnesium-containing antacids or laxatives
(Cipro Prescribing Information 2016).
·
Sotalol: Magnesium and antacids containing magnesium hydroxide and
aluminum oxide can reduce blood levels and effectiveness of sotalol (Betapace,
Sotylize, Sorine), a medication prescribed for heart rhythm disorders such as
atrial fibrillation; for this reason, this medication should not be taken
within 2 hours of taking magnesium (Betapace Prescribing Information
2010).
·
Gabapentin (Neurontin): Taking an antacid containing magnesium
hydroxide and aluminum hydroxide can decrease the bioavailability of gabapentin
by 20%; this medication should be taken at least two hours after taking
magnesium hydroxide and/or magnesium hydroxide-containing antacids or laxatives
(Neurontin Prescribing Information 2017).
·
Levothyroxine (Synthroid): Antacids containing aluminum hydroxide
and magnesium hydroxide (such as Maalox) should be taken at least
four hours before or after taking levothyroxine, as they may delay or prevent
the absorption of the drug (Synthroid Prescribing Information
2017).
Potassium-sparing
diuretics such as triamterene (Dyrenium) and spironolactone
(Aldactone), may increase magnesium levels in the blood. Do not take magnesium
with the potassium-sparing diuretic amiloride (Midamor), as serious
interactions can occur (Henderson, Ugeskr Laeger 1987).
Magnesium can interfere with the effectiveness of cellulose sodium
phosphate, a drug which lowers calcium levels in the urine and helps
prevent kidney stones. Do not take magnesium or magnesium-containing antacids
or laxative within one hour of taking this drug.
Magnesium carbonate, magnesium citrate, and magnesium hydroxide can interfere
with sodium polystyrene sulfonate (a drug which removes excess
potassium from the body) and should not be taken at the same time (PDR 2017).
Given intravenously, magnesium sulfate has been reported cause low blood
pressure when taken with the calcium channel blocker nifedipine
(Adalat, Procardia) (Koontz, Am J Obstet Gynecol 2004);
it's possible that very high doses of oral magnesium taken with calcium channel
blocker drugs may also have this effect, although this has not been reported in
clinical studies.
Magnesium hydroxide and magnesium trisilicate may reduce the absorption
of digoxin (Lanoxin, Digox); there is some evidence that
digoxin in capsules may be less likely to be affected than digoxin in tablet
form (Rodin, Clin Pharmacokinet 1988).
Taking digoxin lowers magnesium levels in the body, which can increase the risk
of digoxin toxicity and heart arrhythmias. If you are taking this drug, your
physician should monitor your magnesium levels and supervise any use of
magnesium (Rao, J Emerg Med 2013).
The immunosuppressant drug tacrolimus can cause low blood
levels of magnesium in kidney transplant patients; supplementation with
magnesium is often required, but should be done under physician supervision (Niederstadt, Transplant Proc 1997).
A number of other drugs, including oral contraceptives, estrogen replacement
therapy and loop and thiazide diuretics can also decrease magnesium levels in
the body.
There has been concern that coffee might
decrease levels of magnesium in the body, but this concern does not appear to
be valid. Due its caffeine content, drinking coffee, especially in excess, may
cause a modest loss of magnesium, e.g., 20 ounces of coffee may cause an adult
to lose 4 mg of magnesium, which is not much (Kynast-Gales, J Am Coll Nutr 1994). However,
coffee also provides magnesium — about 7 mg per 8-ounce cup of brewed coffee
and 24 mg per 1-ounce serving of espresso (Higdon, Crit Rev Food Sci Nutr 2006), so
drinking coffee would more than offset any loss due to its caffeine. In fact,
observational studies have linked increased coffee intake with higher levels of
magnesium (Salazar-Martinez, Ann Intern Med 2004; van Dam, Diabetes Care 2006). There is also
concern that coffee may reduce the absorption of magnesium due to its oxalates
(which can bind to magnesium and other minerals), but laboratory experiment
showed that, after exposure to simulated gastrointestinal conditions, the
magnesium in both instant and brewed coffee remains bioavailable (i.e., able to
be absorbed) (Stelmach, Food Chem 2016).
Use of certain antacid medications, including H2
blockers such as cimetidine (Tagamet), famotidine (Pepcid AC) and
ranitidine (Zantac), and proton pump inhibitors such as
esomeprazole (Nexium) and lansoprazole (Prevacid), may decrease the laxative
effect of magnesium. Some experts recommend a dose of 755 mg or more of
magnesium (from 1,250 mg of magnesium oxide) if magnesium is being taken as a
laxative along with these medications (Yamasaki, Eur J Clin Pharmacol 2014).
Some concerns have been raised about the safety of magnesium orotate due
to its orotic acid content. Research in animals shows that doses of 100
mg/kg/day or more of orotic acid have tumor promoting effects in experimental
tumors. Lower doses of 50 mg/kg/day did not have this effect (Laconi, Carcinogenesis 1993, Laconi, Carcinogenesis 1993, Laconi, Carcinogenesis 1988). Based on these
data, a panel of the European Food Safety Authority (EFSA) concluded that
orotic acid-containing products, such as magnesium orotate, represent a safety
concern when used in amounts of 100 mg/kg or more daily (e.g., 7,000 mg for a
70 kg [154 lb] adult) (EFSA Journal 2009).
Until more is known about these potential risks, it may be best not to use
magnesium orotate.
High doses of magnesium or other minerals (calcium,
zinc, and ferrous iron) from supplements may decrease the absorption of
carotenoids, such as beta-carotene, lycopene and astaxanthin, from foods
and/or supplements. This is likely due to a reaction between carotenoids and
the divalent ions of calcium, magnesium, certain forms of iron,
and zinc, making the carotenoids less bioavailable (Borel, Br J Nutr 2017; Corte-Real, Food Chem 2016). It is
best to take carotenoid supplements at a different time of day than a
supplement or meal containing large amounts of a mineral (e.g., hundreds of
milligrams of calcium or magnesium).
As with other forms of magnesium, ingesting large
quantities of Epsom salt (magnesium sulfate) can result in
weakness, vomiting, shortness of breath and irregular heartbeat (Milne, BMJ Case Reports 2009).
A case of liver injury was reported in a 38-year-old man in India consuming 3
tablespoons of Epsom salt in warm water daily to help dissolve his gallstones.
After 12 days of this treatment, he developed loss of appetite, dark urine,
yellowing of the skin, and elevated liver enzymes and bilirubin. These symptoms
resolved and liver function normalized approximately one month after he stopped
taking the Epsom salt. His treating doctors noted that his non-alcoholic fatty
liver disease may have made him more susceptible to liver injury from magnesium
ingestion (Philips, BMJ Case Reports 2017).
A healthy 31-year-old woman lost consciousness and eventually died of cardiac
arrest after gargling with large amounts of Epsom salt frequently
over a period of several weeks as a treatment for halitosis (bad breath). Her
blood levels of magnesium were found to be extremely high (23.6 mg/dL -- normal range is 1.7 mg/dL to 2.2 mg/dL);
in the two days prior to her death she had used an entire box of Epsom salt for
gargling (Birrer, J Emerg Med 2002).
Information on this site
is provided for informational purposes only. It is not an endorsement of any
product nor is it meant to substitute for the advice provided by physicians or
other healthcare professionals. The information contained herein should not be
used for diagnosing or treating a health problem or disease. Consumers should
inform their healthcare providers of the dietary supplements they take.
Latest Clinical Research Updates for Magnesium Supplements
Magnesium for Metabolic Syndrome?
12/10/2021
Can magnesium
supplementation lower blood sugar and blood pressure in people with metabolic
syndrome? Learn what a new study found in the What It Does section of the Magnesium
Supplements Review. Also see our Top Picks among magnesium supplements.
How Forms of Magnesium Compare
7/31/2021
Magnesium supplements are
used to raise magnesium levels (which requires good absorption from the gut),
as laxatives, and as antacids. The best form of magnesium depends on why you're
taking it. To help you choose the right form, we've put together a magnesium comparison table. Also see our Top Picks among magnesium supplements.
7/21/2021
Does supplementation with
magnesium (as magnesium L-threonate, Magtein) improve cognition in people with
dementia? Find out in the Dementia & Cognition section of our
Magnesium Supplements Review.
7/13/2021
Can magnesium
supplementation reduce leg cramps? See what a recent analysis of the data
showed for leg cramps in pregnant women. Also see the evidence for use
by older men and women in our Magnesium
Supplements Review.
Also see our answer to the question: Do magnesium
creams, sprays and oils help with muscle pain and cramps? How about
supplements?
Caution With Too Much Magnesium
6/26/2021
Magnesium can be an
effective laxative, but taking too much magnesium can be very dangerous, as was
recently reported. Get the details in the Concerns and Cautions section of our
Magnesium Supplements Review.
Also see our answer to the question: Which
supplements can help treat constipation?
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