Ginkgo (Ginkgo Biloba) Supplements Review
Choose the Best Ginkgo
Biloba Supplement. Finding Real Ginkgo Isn't Easy — 60% Fail ConsumerLab's Tests of Quality.
Medically reviewed and
edited by Tod Cooperman, M.D. 
Last Updated
: 09/20/2021 | Initially Posted:
03/03/2018
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Table of Contents
Summary
·
What is ginkgo? Ginkgo supplements contain leaf extracts
of the Ginkgo biloba tree, but there is concern over the
quality of extracts due to reported adulteration. (See What It Is).
·
Do ginkgo supplements work? Preliminary evidence suggests that
ginkgo may modestly improve limited aspects of memory and cognition in healthy
individuals, but stronger evidence indicates no significant benefit from ginkgo
in preventing or treating Alzheimer's disease or other dementias. Preliminary
evidence suggests ginkgo may be helpful in other conditions such as vertigo,
intermittent claudication and Raynaud's disease. (See What It Does).
·
What did CL's tests of ginkgo find? Only 4 of the 10
popular ginkgo supplements ConsumerLab.com selected for testing were
"Approved" in testing. An additional three products tested
through CL's voluntary Quality Certification Program were also
"Approved."
·
Problems with ginkgo: One product was discovered to contain no
more than 3% of its listed amount of ginkgo extract. Several others appear to
be have been adulterated ("spiked") with
compounds from plants other than ginkgo — a common trick to make low-quality
ginkgo appear to be higher in quality. (See What CL Found and use the Results table).
·
Top Pick for ginkgo: Among the "Approved" products,
ConsumerLab chose its Top Pick based
on quality, dosage, and value: The product costs only 9 cents per 120 mg dose,
while other "Approved" products cost two to thirty times as
much for the same amount of ginkgo extract.
·
What to look for in ginkgo supplements? Ginkgo biloba (leaf)
extracts used in clinical trials are typically standardized to contain 24% flavonol glycosides and 6% terpene lactones -- look for
this on labels (but don't trust it unless it's been tested by a reputable 3rd party). (See ConsumerTips™).
·
Safety and side effects of ginkgo: Ginkgo is generally
safe but can cause mild side effects. However, people with bleeding disorders,
on blood-thinners or diabetes medication, and those trying to conceive should
not take ginkgo. For details, see Concerns and Cautions.
Update
Update:
Doctor's Best Extra Strength Ginkgo 120 mg (3/13/18)
ConsumerLab.com received an email today from Doctor's Best, Inc. regarding CL's
conclusion in this Review that Doctor's Best Extra Strength Ginkgo 120
mg "may be low-quality ginkgo extract spiked with flavonols from another source as suggested by unnaturally
high amount of unhydrolyzed quercetin found". The company claimed that its
product is not adulterated nor "spiked," noting that the ingredient
is from a contract manufacturer that confirms the identity and purity of its
ginkgo extract based on the profile of its flavanol glycosides, rutin < 4%, and genistein < 0.5%.
Unfortunately, the standards applied by its contract manufacturer fail to
include a limit on the amount of unhydrolyzed quercetin, as required by the USP
of ginkgo extracts and applied by CL. This is used to identify spiking
(adulteration) of ginkgo extracts with quercetin from other sources.
Furthermore, the < 0.5% genistein specification used by the manufacturer is
not a compendial specification. It is generally considered that genistein does
not naturally occur in ginkgo and finding it in ginkgo extracts may be an
indication of adulteration. Genistein was found in the Doctor's Best product.
ConsumerLab.com therefore stands by its rating of this Doctor's Best product
as "Not Approved."
Further Update (3/19/18): Doctor's Best's contract
manufacturer, Ethical Naturals, Inc., informed CL on March 16 that the Chinese
company from which it purchases its ginkgo extract has recently modified its
production process and, as a result, Ethical Naturals will, in the near future,
provide a ginkgo extract that conforms to the USP requirements. It acknowledged
that the extract in the Doctor's Best product tested by CL did
not meet the USP requirement. It contended, however, that the elevated level of
unhydrolyzed quercetin present was the result of a pesticide removal process
and not due to adulteration — although this contention appears to be at least partially
based on results of a 2015 inspection by the Chinese FDA.
BulkSupplements.com Ginkgo Biloba (3/13/18)
ConsumerLab.com was informed by a CL member yesterday that the member
contacted BulkSupplements.com because its Ginkgo
biloba product did not pass CL's tests in this Review. CL's tests
revealed only tiny amounts of the expected compounds, indicating that the
product contained "no more than 3% of its listed amount of ingredient."
Although the member did not provide CL with the actual exchange, it was noted
that the company only supplied "...info about what wasn't in the product
(heavy metals, etc.) with no information about what was actually in it."
However, the member added, "I believe I identified the problem, which is
terminology. Your review was basically of standardized ginkgo biloba
extracts...but if you check the Bulk Supplements packaging — there is no
mention of "standardized" — although the product clearly lists in its
Supplement Facts that it contains "Ginkgo Biloba Extract."
The USP has specific requirements for powdered ginkgo extract, regardless of
whether it claims to be "standardized" or not, and CL follows the USP
specifications. The BulkSupplements.com product contained
0.56% flavanol glycosides — instead of the expected USP minimum of 22%, and
0.01% terpene lactones — instead of the expected minimum of 5.4%. Furthermore,
it did not meet the terpene lactone requirements of even plain dried ginkgo
leaf, which is 0.1%, not the 0.01% found.
ConsumerLab.com, therefore, stands by its rating of this BulkSupplements.com product
as "Not Approved."
What It Is:
Ginkgo
in dietary supplements is made from leaves of the Ginkgo biloba tree
and contain a variety of phytochemicals including flavonol
glycosides and terpene lactones. Sometimes the dried, powdered leaves are used
in supplements, although clinical studies exclusively used extracts.
What It Does:
Ginkgo is one of many dietary supplement ingredients that have
been used to help prevent or treat memory disorders. Other such ingredients tested
and reviewed by ConsumerLab.com include acetyl-L-carnitine, huperzine A, ginseng, niacinamide, fish/marine oils and vitamin E. [Note:
Vinpocetine may cause miscarriage or fetal harm and
should not be taken by women who are pregnant or who could become pregnant. The
FDA has also tentatively concluded that vinpocetine, which is a synthetic
compound, does not meet the definition of a dietary supplement ingredient,
although the agency has not yet made a final ruling. See the Warning (9/16/16)
for more information. Also see the Warning (10/14/15)
about vinpocetine supplements which were found to contain no vinpocetine.]
Ginkgo biloba leaf extract (GBE) has been widely used to increase
cognitive functions in elderly people and delay the progression of Alzheimer's
disease. However, significant studies have cast doubt on its efficacy for some
of these uses. A review of over 30 clinical trials (Birks, Cochrane Database 2007) found "inconsistent
and unconvincing" evidence that ginkgo had benefits for individuals
with dementia or cognitive impairment. The largest randomized
controlled trial to date, a six-year clinical study funded by the National
Institutes of Health (DeKosky 2008, JAMA) among over 3,000 people 75
years or older, showed no effect for ginkgo in preventing dementia or
Alzheimer's disease. This study utilized the ginkgo extract EGb 761 (Schwabe Pharmaceuticals) (120 mg twice daily).
Further analyses of that study's results (Snitz 2009, JAMA)
showed that ginkgo also failed to improve memory and prevent cognitive decline. Similarly, a large, 5-year study in France also found that
ginkgo extract did not reduce the risk of progression to Alzheimer's disease
compared with placebo (Vellas, Lancet Neuro 2012). The study
involved 2,854 individuals aged 70 or older who had reported memory complaints
to their doctor. The ginkgo extract EGb 761 (120 mg
twice daily) was used in the study.
A short-term (6-week) study of ginkgo (240 mg once daily)
funded by Schwabe Pharmaceuticals (Kaschel, Phytomed 2011) using its EGb
761 among healthy, middle-aged people found that, compared to placebo, it
improved memory recall (i.e., a detailed list of
appointments), although it did not improve recognition (of a driving route),
nor self-perceived mood or well being. While this may
suggest a potential, limited, short-term role for ginkgo among healthy
individuals to improve memory, a review of 10 earlier short-term studies in
healthy individuals found no significant positive effects on memory, executive
function, or attention (Laws, Human Psychopharm
2012). Studies included in the review were performed with EGb761 and
two similar preparations (Li1370 and Blackmore's).
Another study funded by the makers of EGb
761 found that among 60 men and women with self-reported memory impairment, 240
mg of the extract taken once daily for two months modestly improved cognitive
flexibility (the ability to transition from one task or concept to another),
but did not improve attention or prospective memory
(remembering to perform a planned task, i.e. participants were asked to fill
out a postcard and mail the post card two days later) compared to placebo (Beck, Hum Psychopharmacol 2016).
In summary, on the whole, current evidence indicates no significant benefit
for ginkgo in preventing or treating Alzheimer's disease or other dementias. It
may modestly improve limited aspects of memory and cognition in healthy
individuals, but this evidence comes from small, company-funded studies.
Ginkgo may decrease symptoms of vertigo. In a
clinical study of people with vertigo, 47% of those who took 160 mg of Ginkgo
biloba daily for 3 months completely recovered, versus 18% of those
taking a placebo (Haguenauer, Press Med
1986). A dose of 80 mg of Ginkgo biloba taken
twice daily has been shown to reduce vertigo and dizziness associated with
certain vestibular disorders (Cesarani, Adv Ther 1998).
Ginkgo is also used for reducing pain while walking
in intermittent claudication and reducing painful attacks
of Raynaud's disease. One small study among men and women with
Raynaud's disease found that 120 mg of Ginkgo biloba extract (Seredrin, Health Perception) taken three times per day (a
total daily dose of 360 mg) for two months reduced the average weekly number of
self-reported attacks (from 13 to 6) compared to placebo (from 14 to 10),
although it did not decrease the severity or duration of the attacks (Muir, Vasc Med 2002).
Ginkgo is also used in treating tension glaucoma and symptoms
of premenstrual syndrome (PMS). Contrary to earlier understanding,
human studies have found ginkgo ineffective for treating tinnitus (ringing
of the ear) and preventing altitude sickness. (See ConsumerTips™ for
usage information).
Quality Concerns and
Tests Performed:
Neither
the U.S. government nor any other agency is responsible for routinely testing
dietary supplements for their contents or quality. In order to help consumers identify products of better quality,
ConsumerLab.com purchased and tested ginkgo supplements for the quality of
their ingredients and other relevant parameters as described below. See Testing Method for more details.
ConsumerLab.com's review of ginkgo products in 1999
found that nearly one quarter of the thirty brands tested did not have the
expected levels of chemical marker compounds, despite claims to have been
"standardized." Even worse, testing in 2003 found that seven of nine
ginkgo products lacked adequate levels of certain marker compounds, and six
products failed testing for the same reason in 2005. Five of seven ginkgo
supplements failed CL testing in 2008.
To reduce their costs, some manufacturers (or their ingredient suppliers)
provide less ginkgo than claimed or use material that has been adulterated or
"spiked" with one or more compounds or extracts from other plants
that can trick simple chemical tests. This makes a product with little or no
real ginkgo appear to be the real thing. In fact, it is now believed that
ginkgo is among the most adulterated herbs on the market.
To better understand how ginkgo can be adulterated, it is important to know
that Ginkgo biloba extract (GBE) used in most clinical trials
is a 50:1 extract, meaning it requires about 50 pounds of dried leaves to make
1 pound of extract, making it an expensive product to manufacture. It contains
two major groups of phytochemicals called flavonol
glycosides and terpene lactones. Specifically, the extracts shown to work in clinical
trials have contained at least 5% terpene lactones (consisting of 2.6%
bilobalide and 2.8% ginkgolides A, B and C) and at least 22% flavonol glycosides (consisting of a minimum of 9.5%
quercetin, 10.5% kaempferol, and 2% isorhamnetin). The flavonol
glycosides are believed to confer antioxidant activity and the terpene lactones
may be responsible for a dilatory effect on blood vessels. Bilobalide, one of
the terpene lactones, may also increase brain activity by affecting GABA
receptors and enhancing the excitability of neurons in the hippocampus of the
brain, which is associated with learning and memory.
One way of adulterating ginkgo is to use little actual ginkgo extract and spike
it with less expensive sources of flavonol
glycosides. This will trick a test that looks only at the total amount of flavonol glycosides and not the wider chemical spectrum
specific to ginkgo. The tests used by ConsumerLab.com reveal this type of
adulteration by showing the ratios of specific flavonal
glycosides and comparing them to established standards. For example, although
ginkgo contains the compound quercetin (a flavonol
glycoside), much of it is hydrolyzed during a proper extraction. If ConsumerLab finds an unusually high amount of unhydrolyzed
quercetin in a product listing ginkgo as its only ingredient, this is evidence
that another quercetin-containing plant was used to spike a low
quality ginkgo extract. Manufacturers who do not rigorously test their
raw materials may end up purchasing this type of adulterated ginkgo — typically
at much lower cost than high-quality ingredient. [For more on this subject, see
the bulletin "Adulteration of Ginkgo biloba Leaf Extract" (Gaffner, American Botanical
Council 2018).]
Another way to test for ginkgo in supplements is "DNA
barcoding," i.e., checking for ginkgo-specific DNA. This method can tell
whether ginkgo is in a product but, unfortunately, it cannot conclusively say
if ginkgo is not in a product because some processes used in producing ginkgo
as an ingredient (such as prolonged high heat in producing an extract) may
destroy DNA. This method also can't determine how much ginkgo
is present.
A DNA barcode study of 40 ginkgo supplements sold in the U.S. found 31 to
contain ginkgo DNA (Little, Genome 2014 --
products not named in study). The DNA in three products was not usable for testing
and DNA could not be found in six products, all of which were extracts, making
it impossible to say whether ginkgo was or was not used to make the extracts.
In each of these six, rice DNA was found, although this is not surprising as
rice is commonly listed as a filler in ginkgo supplements.
ConsumerLab.com's past tests have also detected lead
contamination in some ginkgo products made with leaf powder (as
opposed to extract, which is cleaner). Lead is a potential
contaminant in natural products. In children, infants, and fetuses, even low
levels of lead can adversely affect neurobehavioral development and cognitive
function. In adults, lead at somewhat higher levels can cause elevated blood
pressure, anemia, and adversely affect the nervous and reproductive systems.
Lead is of particular concern during pregnancy as the mother can transfer it to
the fetus. Any products that listed whole herb ingredients, such as ginkgo
leaf, as opposed to extracts, were tested for lead as well as cadmium and
arsenic.
Any product in tablet form (excluding chewable and time-release tablets) was
tested for its ability to properly break apart (disintegrate) in solution —
which is necessary for ingredients to be absorbed.
What CL Found:
Only 4 of the 10 popular ginkgo supplements ConsumerLab.com
selected for testing were "Approved" for their quality and label
accuracy in testing, having the chemical profile of pure ginkgo extract at the
strength listed. An additional 3 products tested through CL's Quality Certification Program were
also "Approved" in testing. The following products were
"Approved":
·
GNC Herbal Plus Ginkgo Biloba 120 mg
·
Life Extension Ginkgo Biloba
·
Nature Made Ginkgo Biloba
·
Nature's Way Ginkgold
·
Nutrilite Memory Builder
·
Pure Encapsulations Memory Pro
·
The Vitamin Shoppe Ginkgo Biloba Extract
The following products
were "Not Approved":
·
BulkSupplements.com Ginkgo Biloba, a powder that comes in
a bag, listed nothing but ginkgo biloba extract as its ingredient -- 175 mg of
extract per 1/16 tsp. However, only tiny amounts of the expected
compounds were found, indicating that the product contained no more
than 3% of its listed amount of ingredient. What makes up the other 97% of
the powder? We have no idea. A tip-off as to the quality of this product may
have been its extremely low cost — coming out to just 1 cent per 120 mg of
extract, which is several times lower than for any other product.
·
Doctor's Best Extra Strength Ginkgo, ProCaps Laboratories Andrew Lessman
Ginkgo Biloba 120, and Source Naturals Ginkgo-24 each
promised 120 mg of ginkgo extract per capsule or tablet. Each also listed
concentrations of flavonol glycosides and terpene
lactones that one would expect from high-quality ginkgo extract. However, each
was found to contain much more unhydrolyzed quercetin than the 0.5%
allowed by the United States Pharmacopeia (USP), signifying adulteration with
some other botanical ingredient (a known problem in the market, as explained in
the Quality Concerns section above).
Two additional products
contained unusually high concentrations of unhydrolyzed quercetin. However, as
both products -- Metagenics GinkgoRose and NOW Double Strength Ginkgo
Biloba 120 mg -- list additional botanical ingredients that could
potentially be sources of unhydrolyzed quercetin, it is uncertain as to whether
or not the products contain adulterated ginkgo. Therefore, ConsumerLab.com gave
these two products the approval status of "Uncertain."
Top Pick:
Based
on quality, dosage, and value, ConsumerLab.com's Top
Pick among the tested ginkgo extract supplements is Life
Extension Ginkgo Biloba. It provides the dose of ginkgo most commonly
used in clinical trials (120 mg) and the correct concentrations of flavonol glycosides and terpene lactones, showed no sign of
adulteration (based on tests for unhydrolyzed quercetin and rutin),
and costs the least among the Approved products to obtain 120 mg of ginkgo
extract — just 9 cents per vegetarian capsule. To get the same
amount of ginkgo extract from the other Approved products would cost 2
to 30 times as much. Some of the more expensive products included other
ingredients with some evidence of an effect on memory or cognition, but none of
these formulas have been clinically proven to work, let alone been clinically
tested.
Suggested use information on the Life Extension bottle are
to take one are to take one capsule daily, although twice daily is more in-line
with what has been used clinically. [Update
(9/17/21): The label on Life Extension Ginkgo Biloba has been updated to
suggest taking one capsule twice daily — which is more in-line with clinical
use.]
Test Results by Product:
Listed
alphabetically below are the test results for thirteen ginkgo-containing
supplements. ConsumerLab.com selected 10 products. Three other products (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 is the claimed amount and form of ginkgo and the serving
size recommended on the label. The full list of ingredients is available for
each product by clicking on the word "Ingredients" in the first
column. Products listed as "Approved" met their label claims and ConsumerLab.com's quality criteria (see Passing Score). Be aware that suggested
serving sizes on labels may not reflect an appropriate dosage for your intended
use. Adjustments may be necessary. Be sure to compare the "Daily Suggested
Serving" in the second column to dose information provided in What to Consider When Using. Cost and price
comparisons appear in the last column along with other notable listed
ingredients and special designations.
|
RESULTS OF CONSUMERLAB.COM TESTING OF GINKGO SUPPLEMENTS |
||||||
|
Product Name, Amount
Listed of Ginkgo Extract per Unit, and Suggested Daily Serving on Label |
Claimed Amounts Per
Daily Serving of Ginkgo Extract, Flavonol
Glycosides and Terpene Lactones |
--TEST RESULTS-- |
Cost For Daily
Suggested Serving On Label |
|||
|
OVERALL RESULTS: |
Contained Labeled Or Minimum Expected Amounts of Flavonol
Glycosides and Terpene Lactones |
Did Not Exceed Limits for: Lead, Cadmium and Arsenic2 |
Disinte-grated Properly |
|||
|
|
350 mg to 525 mg |
NOT APPROVED |
Found only 0.98 mg flavonol glycosides (less than 3% of expected amount) and
0.01 mg terpene lactones (only 0.1% of expected amount) per 1/16 tsp. serving
of powder |
NA |
NA |
$0.03-$0.04 |
|
|
120 mg |
NOT APPROVED |
|
NA |
NA |
$0.07 |
|
|
120 mg to 240 mg |
APPROVED |
|
NA |
NA |
$0.17-$0.34 |
|
|
120 |
APPROVED |
|
NA |
NA |
$0.09 |
|
|
160 mg to 240 mg |
UNCERTAIN |
|
NA |
|
$1.15-$1.73 |
|
|
180 mg |
APPROVED |
|
NA |
NA |
$0.50 |
|
|
120 mg to 240 mg |
APPROVED |
|
NA |
|
$0.46-$0.92 |
|
|
120 mg |
UNCERTAIN |
|
|
NA |
$0.12 |
|
|
120 mg |
APPROVED |
|
NA |
|
$2.38 |
|
|
120 mg9 |
NOT APPROVED |
|
NA |
NA |
$0.219 |
|
|
60 mg |
APPROVED |
|
NA |
NA |
$1.47 |
|
|
120 mg |
NOT APPROVED |
|
NA |
|
$0.19 |
|
|
120 mg to 240 mg |
APPROVED |
|
NA |
NA |
$0.15-$0.30 |
|
|
||||||
|
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. |
||||||
|
Copyright ConsumerLab.com, LLC, 2018. 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:
Consumers
seeking products most similar to those used in clinical studies should seek
those containing Ginkgo biloba leaf extract (GBE). The plant
chemicals in the extract are about 50 times more concentrated than in dried
ginkgo leaf. Contamination with lead, cadmium, and arsenic is also uncommon
with extracts, as the extraction process may remove impurities. The extract
should be standardized for the specific compounds tested for in this study.
This is often summarized as 24% flavonol glycosides
and 6% terpene lactones, or in terms of milligrams for a 40 mg pill, 9.6 mg and
2.4 mg, of each respectively. Although rarely listed on labels, products should
ideally also be standardized for the following specific flavonol
glycosides and terpene lactones: quercetin (minimum 9.5%), kaempferol (minimum
10.5%), isorhamnetin (minimum 2.0%), ginkgolides A, B, C (minimum 2.8%), and
bilobalide (minimum 2.6%). These specifications are based on those for EGb761
(Schwabe Pharmaceuticals), the most studied form of ginkgo extract.
What to Consider When Using:
For Alzheimer's disease and vascular dementia the total daily dose is 120
to 240 mg; however, the evidence supporting ginkgo for this use is weak at best
(see What It Does). A single daily dose of 240 mg
has also been used for these two conditions and for memory function in healthy
individuals. The total daily dose of ginkgo extract is often divided into 2 or
3 smaller doses taken over the course of the day. The total daily doses for
other conditions, include: improving cognitive function, 120 to 600 mg;
reducing walking pain in intermittent claudication, 120 to 240 mg; vertigo, 120
to 160 mg; Reynaud's syndrome, 360 mg; tension glaucoma, 120 mg; and, PMS, 80
mg two times daily beginning on day 16 of the current menstrual cycle until day
5 of the next cycle.
Concerns and Cautions:
Alzheimer's disease and other types of severe
age-related mental impairment are too serious to treat on your own and the
symptoms of these diseases could be confused with those of other serious
conditions. It is advisable to see your doctor before self-medicating for
severe memory or cognitive problems. In a small percentage of individuals,
ginkgo may produce some unwanted side effects (particularly in high doses) such
as nervousness, headache, and stomachache. People with bleeding
disorders, or who have had a stroke or are at risk for a stroke, should
avoid ginkgo-containing products to avoid potentially serious problems. Stop
taking ginkgo products at least 2 weeks before planned surgeries.
Ginkgo might increase the risk of bleeding complications during and after
surgery.
Like many pharmacologically active herbs and other dietary supplements,
potential interactions can occur with other nutrients or drugs, particularly
the blood-thinning drug warfarin (Coumadin®) or aspirin. Ginkgo may
also increase the risk of seizures in people with epilepsy and reduce the
effectiveness of anti-seizure drugs.
People with diabetes should be aware that ginkgo can alter
blood sugar levels and responses to blood sugar-lowering medications.
Although rare, Ginkgo biloba fruit
can result in contact dermatitis (following topical exposure)
and mucosal symptoms of the mouth and anus (following oral exposure) (Sugiura, Glob J Allergy 2016; Chiu J Am Acad
Dermatol 2002). A 36 year-old man is
reported to have developed itchiness at the tip of his penis within the first
day of taking Trunature Ginkgo Biloba
with Vinpocetine. Redness developed during the next 3 to 4 days. When he
stopped taking the supplement, the itchiness stopped and the redness resolved
over a period of two weeks. The symptoms returned when he restarted the
product, suggesting what is known as a "fixed drug eruption" — when
repeat exposure to an agent results in a new skin lesion as the same location
that was previously affected — commonly the lips, hands, and genitalia (Cohen, J Clin Aesthet Dermatol
2017). A case of Stevens-Johnson syndrome, severe skin reaction
resulting in blistering and skin loss, also appears to have occurred due to
ingestion of a Ginkgo biloba extract (Yuste, Actas Dermosifiliogr 2005).
Although uncommon, more than twenty cases
of low sodium levels in the blood (hyponatremia) associated
with ginkgo use have been reported to the World Health Organization. Symptoms
may include nausea, headache, confusion, and fatigue. Two additional, separate,
cases have been reported in New Zealand involving a 70-year-old man and a
66-year-old woman each of whom developed low sodium levels after taking ginkgo
supplements (dosage and brands not specified) daily for three to six weeks. The
condition resolved after stopping supplementation (Hamilton, Intern Med J 2019).
Couples trying to conceive, especially those who have had difficulty
conceiving, should avoid ginkgo-containing products. Ginkgo might interfere
with fertilization and conception.
There is a lack of evidence for the effectiviness
and safety of ginko in women who are pregnant
or nursing (Amir, Aust Fam Physician 2011).
A toxicology study by the U.S. National Institutes of Health found that a
ginkgo extract from China caused cancers of the thyroid gland in
male and female rats and male mice, as well as cancers of the liver in male and
female mice given the extract five times each week for two years (NTP 2013). However, it is unclear whether this
represents a cancer concern for people using ginkgo, particularly as the dose
given per kilogram of body weight averaged several hundred times that normally
taken by people.
Ginkgo leaves and seeds contain ginkgolic acids known
to produce sensitizing, mutagenic, and carcinogenic effects in-vitro (i.e.,
in the laboratory)(Gawron-Gzella, Acta
Pol Pharm 2010). However, the concentration of ginkgolic acids is greatly reduced in ginkgo extracts due
to purification steps and is not known to present a toxicity concern in
extract-based products. All of the ginkgo products reviewed by ConsumerLab.com
in this Review are extracts.
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 Ginkgo Supplements
11/16/2019
The use of Ginkgo biloba
has been associated with an electrolyte imbalance. For details, see the Concerns and Cautions section
of the Ginkgo Supplements Review. Also see our Top Pick for Ginkgo.
12/12/2017
Although not common, be
aware that skin reactions have been reported from taking Ginkgo biloba. The
most recent report involved a young man who experienced symptoms the same day
he began taking a popular ginkgo supplement. See the details in the
"Concerns and Cautions" section of the Ginkgo Supplements Review >>
Ginkgo for Memory and Cognition?
8/17/2016
A branded ginkgo biloba
extract improved a measure of cognition in men and women with self-reported
memory impairment -- but did not improve memory. Get the
details, plus more about the evidence for ginkgo and our tests of products, in
the Ginkgo Biloba Supplements Review
>>
4/21/2013
According to a new study
from the government, animals given an extract of Ginkgo biloba for
two years developed cancers of the thyroid and liver. Should you be concerned?
See the "Concerns and Cautions" section of the Ginkgo Biloba Supplements Review for
more information, as well our assessment of ginkgo's usefulness, and our tests
of ginkgo supplements
9/30/2012
The evidence for Ginkgo
biloba in preventing and treating Alzheimer's disease and other
dementias has become fairly negative. But is there still hope for its use in
improving memory in healthy individuals? The answer seems to be in, according
to a new analysis of 10 placebo-controlled trials in healthy people. Get the
answer in the update to the Ginkgo Supplements Review.
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