L-Tryptophan and 5-Hydroxytryptophan (5-HTP)
Supplements Review
Choose the Best
L-Tryptophan and 5-HTP Supplements. CL Tests Identify High Quality L-Tryptophan
and 5-HTP (5-Hydroxy-L-Tryptophan) at the Best Value.
Medically reviewed and
edited by Tod Cooperman, M.D. 
Last Updated
: 08/24/2021 | Initially Posted:
07/27/2018
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Table of Contents
Summary
·
What do they do? L-tryptophan is an essential amino acid
naturally found in meats and other foods. It is converted in the body to 5-HTP (which
is not found in foods), which is then converted to serotonin and melatonin
(see What It Is).
L-tryptophan can promote sleep, while 5-HTP has been used as an antidepressant,
although this effect has not been well-established. Both have been proposed for
other uses based on preliminary evidence (see What It Does).
·
Are they safe? L-tryptophan from a specific
manufacturer caused hundreds of cases of a serious immune disorder,
eosinophilia-myalgia syndrome (EMS), in the late 1980s. A more
pure form is now sold that seems to be much safer. However,
there is still some risk with even pure L-tryptophan, particularly at high
doses. 5-HTP in supplements is generally safe, but rare cases of EMS
have also been reported. (See Concerns and
Cautions).
·
Best choice? CL tested all supplements for a range of impurities. Among
those that passed testing and provided the best value, CL selected a Top Pick for
L-Tryptophan and a Top Pick for
5-HTP.
·
How to take them? L-tryptophan is taken for sleep at a
dose of about 1 gram (1,000 mg) shortly before bedtime, while other uses have
involved higher doses. 5-HTP is taken at a daily dose of about 300 mg to 900 mg
depending on the use, and divided during the day. (See What to Consider
When Using).
·
Cautions: In addition to the potential risk of EMS and some mild
side effects, these supplements should be used with caution in people taking
medications that affect serotonin, such as some antidepressants and migraine
medications (see Concerns and
Cautions).
What It Is:
L-Tryptophan
L-Tryptophan is an essential amino acid, meaning that
it must be obtained from foods, because the body is unable to make it.
L-Tryptophan is found in many protein-rich foods, including cheese, chicken,
eggs, fish, milk, nuts, soy, tofu, and turkey. The amount of L-tryptophan
generally obtained from a 100 gram (3.5 ounce) serving of these foods ranges from about 100 mg to 500 mg (see Tryptophan in Foods table below). In
foods, the L-tryptophan is bound to other amino acids. Most supplements
currently on the market provide L-tryptophan as a single amino acid, typically
at 500 mg per serving.
5-HTP
5-hydroxytryptophan (L-5-hydroxytryptophan or oxitriptan)
is also an amino acid, but is not essential and is not found in appreciable
amounts in the diet. 5-HTP is created in the body from tryptophan. In
supplements, 5-HTP is typically extracted from seeds of Griffonia simplicifolia.
What It Does:
L-Tryptophan
Through a series of steps, the body uses L-tryptophan to first make 5-HTP and
then serotonin and melatonin, neurotransmitters that promote good mood and
sleep.
As a supplement, L-tryptophan can increase sleepiness and decrease
the time needed to fall asleep — although it has not been shown to
increase sleep time. Best results have been found in people with mild insomnia
or needing longer-than-average times to fall asleep. Results have been mixed or
negative in entirely normal subjects, severe insomniacs, and people with
serious medical or psychiatric illness (Hartmann, J Psychiatr Res. 1982).
Some human research finds that L-tryptophan might help reduce feelings of
unhappiness, irritability and mood swings in women with premenstrual
dysphoric disorder (PMDD). Limited human research suggests that it might be
useful for treating depression, seasonal affective disorder (SAD), and sleep
apnea. For example, improvements in symptoms were reported in two of three
people with treatment-resistant unipolar depression and borderline personality
disorder who were given 1 to 2 grams of L-tryptophan daily (Thomas, Adv Integ
Med 2015). Other human research indicates that L-tryptophan might
help reduce cigarette cravings in people who are quitting smoking. Well-designed
and conducted human studies are needed to determine if L-tryptophan is
effective or ineffective for all of these conditions.
5-HTP
For Depression:
5-HTP is a direct
pre-cursor to serotonin and is able to cross the blood-brain barrier,
permitting it access to the central nervous system where the conversion to
serotonin occurs. Due to its ability to raise serotonin levels, like
antidepressant drugs, the primary use of 5-HTP is for depression. Several small
studies have compared 5-HTP to standard antidepressants. One 6-week study found
5-HTP of equal benefit to fluvoxamine (Luvox) at 50 mg three times daily, and
5-HTP caused fewer side effects than fluvoxamine. However
a drug comparison study like this does not rule-out a placebo effect. As there
are no published, placebo-controlled studies of 5-HTP for treating depression,
its role remains unproven.
A study in the UK among 18 men and women (average age 67)
with Parkinson's disease and REM sleep behavior
disorder (RBD) (characterized by intense dreams and behaviors such as
laughing, yelling, kicking during sleep) found that 50 mg of 5-HTP taken daily
for one month modestly improved self-reported functioning during activities of
daily living (i.e., bathing, eating, etc.), but did not improve
muscle atonia or reduce self-reported RBD frequency compared to placebo.
However, as there was a non statistically-significant
trend toward decreased RBD events with 5-HTP, the researchers suggested that
clinical trials using a higher dosage may be warranted (Meloni, Sleep Breath 2021 Aug).
Other Uses:
Some, but not all,
studies have found that 5-HTP may help prevent migraines, although not tension
headaches (See What to Consider When Using below for
dosage) (Jahromi, Neurol Sci 2019). Small studies of
just several weeks in duration have also indicated that 5-HTP may help with
weight loss by causing people to consume fewer calories and feel full after
eating.
A study also found that
5-HTP can help people with fibromyalgia, a condition characterized by tender
muscles, fatigue, and sleep disturbances and which is often treated with
antidepressants. In people suffering from anxiety disorders, 5-HTP was found to
be effective, but not as effective as the drug clomipramine.
Quality Concerns and
Tests Performed:
As
discussed in the Concerns and Cautions section, in 1989,
L-tryptophan supplements were associated with more than 1,500 cases of a
serious medical condition called eosinophilia-myalgia syndrome (EMS). Epidemiology
studies traced the cause of EMS to consumption of L-tryptophan made by the
Japanese company Showa Denko that was contaminated with one or more
unidentified substances (Back, J Rheumatol,
1993 ). The United States Pharmacopeia (USP) has approved a
method for testing both L-tryptophan and 5-HTP that sets strict limits on
certain chemical contaminants. ConsumerLab.com applied these limits in its
tests of L-tryptophan and 5-HTP. In addition, ConsumerLab
limited its selection of products to only one type of L-tryptophan, known
as TryptoPure, which appears to be safer
than that made by Showa Denko (although there remains a possibility that some
people may have a predisposition to develop EMS from exposure even to pure
L-tryptophan). ConsumerLab also tested each product
for potential contamination with the heavy metals lead, arsenic, and cadmium,
and all tablets or caplets were tested for proper pill disintegration. For
details about how products were selected, tested, evaluated, see How Products Were Evaluated.
What CL Found:
L-Tryptophan
As noted earlier and described further below (see Concerns and Cautions), in light of the
history of contamination with L-tryptophan, we limited our selection of
products to just those made with TryptoPure —
a brand of L-tryptophan manufactured by bacterial fermentation using a
different bacteria than that used in the production of L-tryptophan that caused
EMS in many people. We selected two different brands. Both passed our tests,
containing no detectable amounts of the contaminants for which we tested.
Top Pick for L-Tryptophan —
As both Doctor's Best Best L-Tryptophan With TryptoPure and Swanson
Ultra L-Tryptophan TryptoPure passed our
tests and each provide 500 mg of L-tryptophan (as TryptoPure in
a veggie cap), our choice of Top Pick came down to price: It
is Doctor's Best, which costs 20 cents per capsule, 7 cents
less than Swanson. Although both capsules are large and of equal
width, Doctor's Best is slightly shorter, making it a little
easier to swallow. (Keep in mind that there is still some risk with even pure L-tryptophan, particularly
at high doses.)
5-HTP
All three of the 5-HTP supplements that we selected for testing passed our
tests, as did a product tested through our voluntary Quality Certification Program.
All four of these products listed their source of 5-HTP as Griffonia simplicifolia seed,
which is something we suggest looking for on 5-HTP labels. Very low levels of
impurities were found in each product, but none of these exceeded USP limits;
the levels found are shown in the Results table below.
Top Pick for 5-HTP — As noted, all
of the 5-HTP products passed testing. However, some were significantly more expensive
than others. The least expensive was BioScience
Nutrition 5-HTP. A 2-capsule serving of this supplement, providing 200
mg of 5-HTP, is 30 cents. It was initially our Top Pick; however,
the product no longer seems to be available -- it now appears to be sold under
the Arazo Nutrition brand,
but we have not tested this product. Our Top Picks for 5-HTP
are now Finest Nutrition [Walgreens], which is very similar in
formulation and strength to BioScience,
but is 48 cents for two 100-mg capsules and, if you prefer a timed-release
tablet that contains 200 mg, a tablet of Natrol
5-HTP is 37 cents. If you want an enteric-coated caplet, you can
purchase Natural Factors 5-HTP, but you'll pay a lot more -- 70
cents for two caplets.
Be aware that all of the 5-HTP supplements in this Review include
calcium as an added ingredient and BioScience
Nutrition contains the most — 328 mg per 2 capsule serving. This is a
lot of calcium — about as much as you'd want to get per serving from a calcium
supplement. However, if you already get enough calcium, choose one of the
supplements with less calcium. For example Finest
Nutrition, although more expensive, provides only 126 mg of calcium per
2-capsule serving, and Natrol has
the least — 55 mg per 1 tablet serving. The reason for calcium in these
products is not clear — it may have been added as a flow agent to help with
manufacturing.
Test Results by Product:
Listed
alphabetically below are the test results for two L-tryptophan and four 5-HTP
supplements. ConsumerLab.com selected five of these products for testing. One
product (indicate with a CL flask) is included for having passed the same
testing through ConsumerLab.com's voluntary CL's
voluntary Quality Certification Program.
Shown for each product is the labeled amount of L-tryptophan or 5-HTP per pill
as well as the suggested serving size, price, and calculated cost to obtain
either 500 mg of L-tryptophan or 200 mg of 5-HTP. 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
claim for L-tryptophan or 5-HTP, USP requirements regarding contaminants, met
FDA labeling requirements, and all regular or enteric coated tablets and
caplets were able to properly break apart in solution.
|
RESULTS OF CONSUMERLAB.COM TESTING OF L-TRYPTOPHAN AND 5-HTP
SUPPLEMENTS |
||||||
|
Product Name, Listed
Amount of 5-HTP/L-Tryptophan per Unit, Serving Size, and Suggested Daily
Serving on Label |
Claimed Amount of
5-HTP and L-Tryptophan Per Labeled Daily Serving |
—TEST RESULTS— |
Cost For Daily
Suggested Serving On Label |
|||
|
OVERALL RESULTS: |
Contained Labeled
Amount of 5-HTP and L-Tryptophan |
Did Not Exceed
Contamination Limits for: |
Disintegrated
Properly |
|||
|
L-Tryptophan Products: (Note: There is still some concern of adverse reactions, even with
Approved products.) |
[Cost per 500 mg
L-Tryptophan] |
|||||
|
|
500 mg (TryptoPure®) |
APPROVED |
|
|
NA |
$0.20 |
|
|
500 mg (TryptoPure®) |
APPROVED |
|
|
NA |
$0.27-$0.54 |
|
5-HTP Products: |
[Cost per 200 mg
5-HTP] |
|||||
|
|
200 mg |
APPROVED |
|
|
NA |
$0.30 |
|
|
200 mg |
APPROVED |
|
|
NA |
$0.48 |
|
|
200 mg |
APPROVED |
|
|
NA |
$0.37 |
|
|
200 mg to 300 mg |
APPROVED |
|
|
|
$0.70-$1.05 |
|
|
||||||
|
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:
L-Tryptophan
There are various suppliers, particularly from Japan, China, Canada and the
U.S., of L-tryptophan. Many of these produce L-tryptophan as an amino acid feed
additive for livestock. A major Japanese supplier of amino acids, Ajinomoto,
provides a branded product called TryptoPure,
which, according to its website, is manufactured
under cGMP conditions and is also used as an active pharmaceutical ingredient
in pharmaceutical products and in infant formulas. Apparently, it was the only
L-tryptophan that was permitted to be imported for pharmaceutical use from 1989
to 2005, subsequent to problems associated with L-tryptophan produced by a
different company (see Concerns and Cautions -- EMS below).
Several products on the market indicate that they are made with the TryptoPure brand of L-tryptophan. TryptoPure, unlike the L-tryptophan sold by Showa
Denko in the late 1980s, has not been associated with causing large numbers of
cases of EMS. Although both forms are produced by fermentation using bacteria
genetically modified to overproduce L-tryptophan, the manufacture of TryptoPure appears to utilize strains of E.coli or Corynebacteria as
opposed to Bacillus amyloliquefaciens (ITCBlog, Ajinomoto court filing 2016). However, be aware
that some people may have a predisposition to develop EMS from exposure even to
pure L-tryptophan.
From food: As note earlier, substantial amounts of
L-tryptophan are found in foods, particularly meats and cheeses — many of which
provide 200 to 300 mg of L-tryptophan per 100 gram (3 ounce) serving, as shown
in the table below.
|
Tryptophan in Foods |
|
|
Food |
Tryptophan |
|
egg, white, dried |
1,000 |
|
spirulina, dried |
930 |
|
cod, Atlantic, dried |
700 |
|
soybeans, mature, raw |
590 |
|
cheese, Parmesan, shredded |
560 |
|
caribou, cooked |
460 |
|
sesame seeds, toasted |
370 |
|
turkey, breast, meat & skin, cooked |
330 |
|
cheese, cheddar |
320 |
|
sockeye, cooked |
310 |
|
sunflower seed, toasted |
300 |
|
perch, Atlantic, cooked |
270 |
|
pork, chop, raw, blade, lean only |
250 |
|
salmon, pink, canned |
250 |
|
pork, chop, cooked, blade, lean only |
240 - 410 |
|
turkey, breast, meat & skin, raw |
240 |
|
chicken, breast, meat & skin, raw |
240 |
|
beef, rib eye, lean, raw |
230 |
|
salmon, Atlantic, wild, raw |
220 |
|
Australian lamb, leg and sirloin, chop,
boneless, lean & fat, raw |
210 |
|
perch, Atlantic, raw |
210 |
|
beef, rib eye, lean, cooked |
170 - 410 |
|
egg, hard boiled |
150 |
|
wheat flour, white, all-purpose |
130 |
|
baking chocolate, unsweetened |
130 |
|
rice, white, long grain, raw |
80 |
|
milk, whole |
70 |
|
oatmeal, cooked |
40 |
|
potatoes, russet, raw |
20 |
|
banana |
10 |
|
Source: USDA Nutrient Data provided to
ConsumerLab.com (9/8/10) by Robin Thomas at USDA on 9.8.10. Additional data
available at https://ndb.nal.usda.gov/ndb/. |
|
5-HTP
5-HTP as an ingredient is much more expensive than
L-tryptophan. Based on ConsumerLab.com's experience
with other supplements, high ingredient costs can lead some companies to try to
cut corners. Be careful not to confuse any listed amount of Griffonia simplicifolia seed
(from which 5-HTP is extracted) with the actual amount of 5-HTP, which will be
a much smaller amount. It is possible to produce 5-HTP by fermentation, similar
to how L-tryptophan is produced, but it may be better to purchase 5-HTP made by
extraction: Look for products that list their source of 5-HTP as Griffonia simplicifolia seed
in the Supplements Facts panel on the label.
What to Consider When Using:
L-Tryptophan
As a sleep aid, the most common recommendation is 1 gram of L-tryptophan taken
at bedtime. A small study found that 1 gram given 20 minutes before bedtime was
able to significantly reduce the time needed to fall asleep and that lower
doses (down to just ¼ gram) also appeared to provide some benefit (Hartmann, J Nerv Ment Dis. 1979). Doses higher than 1 gram may
also be effective, but it may be prudent to use the lowest effective dose.
For premenstrual dysphoric disorder the total daily dose is 6 grams of
L-tryptophan (an extremely high dose) (Steinberg, Adv Exp Med Biol. 1999).
As an aid for quitting smoking, the daily dose is 50 mg/kg of L-tryptophan,
which equates to 4 g per day (a high dose) for an 80 kg (176 lb) person, together with a high carbohydrate diet and
conventional smoking cessation techniques (Bowen, J Behav Med. 1991).
5-HTP
Dosage used with 5-HTP are as follows:
— For depression, 300 mg daily (100 mg in three doses)
— For migraine, 400 to 600 mg daily (in divided doses)
— For weight loss, 900 mg daily (300 mg in three doses)
— For fibromyalgia, 300 mg daily (100 mg in three doses)
Concerns and Cautions:
L-Tryptophan
Eosinophilia-Myalgia Syndrome (EMS):
In 1989, L-tryptophan supplements were associated with a number of cases of a
serious medical condition called eosinophilia-myalgia syndrome (EMS),
characterized by debilitating muscle pain and a high number of eosinophils (a
type of white blood cell) in the blood. While most patients recovered after
withdrawal and treatment (typically with corticosteroids), cases of death or
permanent disability were reported. The FDA issued a Public Advisory against
the use of L-tryptophan and recalled all over-the-counter dietary supplements
in tablet or capsule form containing 100 mg or more L-tryptophan in a daily
dose. Additionally, the FDA imposed an import alert blocking foreign shipments
of manufactured L-tryptophan. Eventually, more than 1,500 cases of EMS,
including 38 deaths, were reported to the U.S. Centers for Disease Control and
Prevention (CDC), although the true incidence of the disorder is thought to be
much higher.
With the passage of the Dietary Supplement Health and Education Act in 1994,
L-tryptophan became available again as a supplement in the U.S. if manufactured
domestically. The import alert was cancelled in 2005 based on insufficient
evidence to warrant detention without physically inspecting each foreign
source. L-Tryptophan is now sold under many brands and is available from a
variety of ingredient suppliers. This does not mean, however, that the FDA has
established that L-tryptophan supplements are safe.
Some epidemiology studies traced the cause of EMS to consumption of
L-tryptophan made by the Japanese company Showa Denko that was contaminated
with one or more unidentified substances. (Back, J Rheumatol, 1993).
In fact, according to one report from South Carolina, 29% of people who used
that brand developed definite EMS, and the risk increased as dose increased
such that risk of EMS was 13% at a dose of 250 to 1,500 mg/day, rising to 50%
for doses over 4,000 mg/day (Kamb, JAMA 1992).
Ongoing research indicates that the most statistically significant contaminant,
known as Peak AAA, was shown to be formed by the reaction of L-tryptophan with
fatty acids from bacterial cell membranes (as would be present during the
fermentation process used to produce L-tryptophan). Showa Denko used a
genetically engineered strain of Bacillus amyloliquefaciens in
its fermentation (Klarsov, Tox Letters
2018). However, continuing research also indicates a role for
"pure" tryptophan itself and a possible predisposition by some people
to develop EMS from exposure to L-tryptophan. (MedWatch Continuing Education
Article 1996, p.6). These theories draw on the fact that some cases
of EMS occurred with L-tryptophan that was relatively pure (99.6%) or made by a
company other than Showa Denko. One theory is that large doses of L-tryptophan
as a single amino acid cause an increase in formation of metabolites which can
inhibit the destruction of histamines which, in turn, can cause both
eosinophilia and myalgia (Smith, Inflammation Research 2005). Other
research suggests that people with functional somatic syndromes , including
fibromyalgia, chronic fatigue syndrome (CFS), irritable bowel syndrome (IBS)
and multiple chemical sensitivity, are prone to develop an allergic reaction
toward one of the contaminants and, to a lesser extent, to pure L-tryptophan,
indicating that an autoimmune reaction may be involved (Barth, Clin Exp Immunol. 2001).
Since the return of L-tryptophan to the market, there has been one published
case report of EMS (Allen, Arthritis & Rheumatism
2011). In addition, the FDA has received two other reports of
possible EMS and two reports of muscle pain associated with L-tryptophan from
January 2003 through August 2010. The published report is of a 44-year old woman in Illinois who developed symptoms within
3 weeks of starting to use 1,500 mg per day of L-tryptophan in early 2009. She
developed swelling of the arms and legs followed by muscle pain and weakness.
Over the next four weeks there was a progressive thickening and hardening of
the skin. These changes persisted and were present six months later when seen
by physicians at a university. At that time, blood tests revealed elevated
white cells with a high proportion of eosinophils (24%). Treatment with a
steroid and an immunosuppressant corrected the white blood cell count and
resulted in modest improvement in muscle strength and weakness. However, skin
hardening and neuropathy progressed. Although physicians did not have the
actual product that was used (Uber Rest from Heartland Products --,
a division of Ajinomoto that makes TryptoPure),
analysis of pills obtained from another bottle from the same lot showed no
impurities. The patient was taking other supplements, none of which have been
associated with EMS. However, the patient was found to have the HLA-DRB1*04
allele, a genetic risk factor for the development of EMS among L-tryptophan
users (increasing the odds of developing EMS to four times that of a person
without the marker). The authors of the report note that this case should raise
awareness of the potential of EMS among current L-tryptophan users.
Talk with your healthcare provider before using L-tryptophan supplements if you
have kidney or liver disease, eosinophilia (high levels of one type of white
blood cells) or a condition involving your muscles. Stop using L-tryptophan and
contact your healthcare provider if you develop symptoms of EMS, such as muscle
pain, fatigue, nerve pain, rash or skin changes.
Other Concerns and Cautions with L-Tryptophan:
L-Tryptophan increases serotonin levels in the brain and may increase the risk
of a serious condition called serotonin syndrome when taken with drugs that
also increase serotonin levels. People taking serotonin-enhancing drugs (as
well as the supplement St. John's wort) should consult with their healthcare
provider before using L-tryptophan. Drugs that increase serotonin levels in the
brain include antidepressants, Delsym (dextromethorphan), Demerol (meperidine),
Meridia (sibutramine), monoamine oxidase inhibitors
(MAOIs), "triptan" anti-migraine drugs and Ultram (tramadol).
L-Tryptophan can cause respiratory depression of the fetus and it should not be
used during pregnancy nor if a woman is breast feeding.
More common side effects of L-tryptophan include abdominal gas, drowsiness,
headache, heartburn, stomachache, nausea and vomiting.
5-HTP
Side effects with 5-HTP have generally been limited to short-term, mild
digestive distress (e.g., heartburn, nausea, diarrhea) and possible allergic
reactions.
Unlike L-tryptophan, cases of eosinophilia-myalgia syndrome (EMS) have not been
reported with 5-HTP in the U.S. However, three cases of EMS (occurring between
2001 and 2012) associated with 5-HTP use have been reported in France, all
involving individuals in their fifties. One women had
taken 5-HTP for 3 years and developed scleroderma and itching. Another women had taken 5-HTP for 1 year and developed joint
pain, muscle weakness in all limbs, an "altered state," weight loss
and, after another year on 5-HTP, fasciitis. A man taking 5-HTP for 1 year
developed diffuse muscle pain and scleroderma. The conditions of both women
improved significantly after 5-HTP was stopped and corticosteroids were given.
The man stopped taking 5-HTP, but his condition was not further reported. It is
unclear if and how 5-HTP might cause EMS, and the occurrence is rare.
Nevertheless, if you use 5-HTP, be aware of symptoms of EMS (as described
above), which may not occur until years into treatment, and, if they occur,
stop taking 5-HTP and seek medical treatment (Auffret, Fund &
Clin Pharm Suppl 2013, Abstract P2-204).
There is concern with using 5-HTP with the drug carbidopa (used in Parkinson's
disease), as there are reports of this combination causing skin changes similar
to those that occur in scleroderma. Combining 5-HTP with other serotonergic
drugs may increase the risk of serotonin syndrome (discussed above for
L-tryptophan).
Children have been given 5-HTP without harmful effects, but there is a concern
that it could cause seizures in developmentally disabled children, e.g., those
with Down's syndrome. Its safety in pregnant or nursing women and those with
liver or kidney disease has not been established.
One report in 1998 discovered an unidentified substance termed "peak
X" in a pharmaceutical product comprised of a combination of 5-HTP,
tetrahydrobiopterin and l-dopa/carbidopa. This raised
concern because this substance was assumed to be similar to a substance found
in L-tryptophan which was linked by some investigators to EMS, discussed above.
However, better analytical testing has yet to confirm the presence of
"peak X" in the "tainted" pharmaceutical product or other
5-HTP samples (Das, Toxicology Letters 2004).
A case of mania was reported in an individual given 5-HTP (300 mg daily) who
was taking antidepressants, including the monoamine oxidase inhibitor (MAOI)
phenelzine, although it is uncertain to what extent 5-HTP contributed to the
mania (Pardo, Gen Hosp Psych 2012).
In Dogs: Although there have been anecdotal reports of low
doses of 5-HTP (1 mg/kg by mouth every 12 hours) used for the treatment of
anxiety and reactivity in dogs, high doses of 5-HTP can cause a potentially
fatal, serotonin-like syndrome and toxicity in dogs. This occurred in a 17 lb.
Dachshund after ingesting 29 tablets of its owner's 5-HTP supplement (Natrol 5-HTP Fast Dissolve Tablets). Each tablet
contained 100 mg of 5-HTP and 820 mg of xylitol, which is also toxic to
dogs. The dog exhibited symptoms of serotonin-syndrome and/or
xylitol toxicosis, including agitation and seizures, rapid and irregular
heartbeat, high blood pressure, low blood sugar and coma. After three days of
hospitalization and treatment the dog recovered (Ortolani, Clin Case Reports 2019).
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 L-tryptophan and
5-Hydroxy-L-tryptophan (5-HTP)
Parkinson's Disease: 5-HTP for Sleep?
8/24/2021
Can supplementation with
5-HTP reduce sleep disturbances in people with Parkinson's disease? See what a
recent study found in the What It Does section of our L-Tryptophan
and 5-HTP Supplements Review.
Also see our answer to the question: Do supplements
help with Parkinson's disease treatment or prevention?
1/19/2019
Be sure to keep your
supplements away from pets -- especially if they taste sweet. A dog overdosed
on its owner's fast-dissolving tablets, putting it in a coma, according to a
recent report. For details, see the Concerns and Cautions section
of the L-tryptophan and 5-HTP Supplements Review.
8/04/2013
Three cases of
eosinophilia-myalgia syndrome (EMS) have been reported among people taking
5-HTP, a compound related to L-tryptophan. EMS is a debilitating immune
condition which has occurred in people taking L-tryptophan, but there were no
previous reports of it being caused by 5-HTP. Get the details in the the updated review article on L-Tryptophan and 5-HTP >>
L-Tryptophan -- Still a Problem?
11/20/2011
A woman in Illinois
taking L-tryptophan for insomnia developed the same serious problems that
resulted in L-tryptophan being temporarily removed from the market several
years ago. Is L-tryptophan any safer now than it was before? For more
information, see the update to the L-Tryptophan and 5-HTP
Review Article.
Related CL Answers (3)