5-HTP (5-hydroxy-L-tryptophan) is the substance that the brain uses to make serotonin — a neurotransmitter that regulates
emotions, sleep-wake cycles, appetite, and general feelings of well-being.
When the body’s serotonin levels are inadequate, the result can be depression, excessive eating, and sleep disorders. Serotonin
deficiencies may also play a role in migraine headaches, fibromyalgia, panic attacks, delirium tremens, sleep terrors, and
What we can’t tell you
In the U.S. and some other industrialized countries, government agencies like the U.S. Food and Drug Administration have adopted
censorship as a method for intensifying their control over the supplement industry and its customers. Thus, FDA regulations
prohibit us from telling you that any of our products are effective as medical treatments, even if they are, in fact, effective.
Accordingly, we will limit our discussion of 5-HTP to a brief summary of recent 5-hydroxytryptophan research, and let you
draw your own conclusions about what medical conditions it may be effective in treating.
A good, brief summary of 5-HTP as a treatment for various conditions is the one by Birdsall in the abstract to his 1998 review. A more detailed summary is the one provided by Thorne Research, Inc.
Most, if not all, studies of 5-HTP as medical treatments are based on the concept that the underlying medical conditions involve
serotonin. The treatments depend on the fact that 5-HTP crosses the blood-brain barrier and is then converted into serotonin.
Although many physicians believe that 5-HTP supplementation will not raise serotonin levels unless combined with a drug like
carbidopa — to prevent 5-HTP from being metabolized before it reaches the nervous system — this notion has been refuted by experiments
with oral 5-HTP in both rats and humans. When used orally, without the aid of other drugs, 5-HTP does significantly raise serotonin levels in the brain.
On the other hand, it has been suggested that the metabolism of 5-HTP outside the brain may be accelerated if 5-HTP is used
in combination with vitamin B6. Little has been done to examine this issue, so to be on the safe side, it would make sense to avoid B6 supplements on days
when one is using 5-HTP.
The dosages of 5-HTP used in most clinical trials range from 100 mg/day in children to as much as 400 mg/day in adults. These
daily dosages are usually divided into three spaced doses about 8 hours apart. The exception is in the use of 5-HTP for insomnia,
where the daily dosage is taken all at once, before bedtime. Clinicians usually design 5-HTP regimens that start with a ramping-up
period, using smaller doses for two weeks.
5-HTP is well absorbed whether it is taken with food or by itself.
5-HTP and depression
5-HTP has been of interest as an antidepressant for several decades. It has shown good results in a number of clinical trials,
and given null results in others. A meta-analysis done on this medical literature in 2002 resulted in a claim that all of the clinical trials published up
to that time were of poor quality and allowed no conclusions to be drawn. On the other hand, critics of such meta-analyses say that these analyses are the products of extreme and obsessive statistical
finickiness and that they ‘throw the baby out with the bathwater’.
It is true, in any case, that clinical studies and very large numbers of anecdotal reports attest to the effectiveness of
5-HTP as an antidepressant in some people. (The same can be said of prescription antidepressants, such as fluoxetine (Prozac®) and paroxetine (Paxil®) — they are effective for some, and ineffective for others. Patients often have to try a series of these drugs before finding
one that works.)
5-HTP and appetite
The ability of 5-HTP to inhibit appetite was first noted in rats in 1964. The mechanism appears to involve the raising of serotonin levels. Several dozen research papers on the subject have appeared
since then, including a few reports of clinical trials both in diabetic patients and in obese patients without diabetes, with the result that 5-HTP is widely regarded as effective in reducing the appetite and bodyweight of people who overeat. Nevertheless, the medical profession has preferred much more expensive treatments with prescription drugs, some of which
have proved to be harmful to patients.
5-HTP and sleep disorders
The effects of 5-HTP on sleep date from 1971, when it was studied as a treatment for insomnia. Despite the encouraging results of early studies, and countless positive anecdotal reports over the years, medical research has almost completely ignored it as an insomnia
In a clinical trial in 2004 researchers reported that 5-HTP is a very effective treatment for sleep terrors in children. After six months, 84% of the patients who used 5-HTP at 2 mg/kg were free of sleep terrors, as compared with only 28% of
the comparison group. Sleep terrors (a.k.a. ‘night terrors’) are a type of nightmare from which it is difficult to awaken.
5-HTP and fibromyalgia
Fibromyalgia is an ailment characterized by musculoskeletal pain (both diffuse and localized), fatigue, lowered pain thresholds,
and nonrestorative sleep. Multiple lines of evidence suggest that a decline in serotonin production may be involved. Clinical trials in fibromyalgia patients in the early 1990s demonstrated significantly lessened symptoms. Since that time, little or no research work has been done to follow up on these promising leads.
5-HTP and migraine
5-HTP was first reported to improve migraine headaches in the early 1970s. Since then, several dozen reports have been published on the subject, and almost a dozen clinical trials have been conducted
— most of them showing some efficacy of 5-HTP for prevention of migraines and other headaches. Dosages ranged from 100 mg/day in children to 400 mg/day in adults, in divided doses.
5-HTP and panic attacks
In a 2004 clinical study, panic disorder patients were made to breathe a 35% atmosphere of carbon dioxide, which typically
induces a panic reaction. Those who had been pretreated with 200 mg of 5-HTP had significantly reduced panic symptoms compared
with those treated with placebo.
5-HTP and coughing
Serotonin acts as a modulator of the cough reflex. With this in mind, researchers in 1986 showed that 5-HTP had the ability
to depress the cough reflex in cats. In 1993 a similar result was shown in humans. In these experiments the 5-HTP was administered intravenously, but there is no reason to think that oral supplementation
would not have similar effects, since the key element is the conversion of 5-HTP to serotonin in the brain — which occurs
whether 5-HTP is taken orally or intravenously.
Are 5-HTP supplements useful for the conditions and purposes mentioned above? We aren’t allowed to tell you, so you should
take a look at some of the references cited here, and then decide for yourself.
5-Hydroxytryptophan: a clinically-effective serotonin precursor.
Altern Med Rev. 1998 Aug;3(4):271-80
5-Hydroxytryptophan [monograph, PDF, 20KB]
Thorne Research, Inc.
5-Hydroxy-L-tryptophan suppresses food intake in food-deprived and stressed rats.
Pharmacol Biochem Behav. 2004 Jan;77(1):137-43
Amer A, Breu J, McDermott J, Wurtman RJ, Maher TJ
Are tryptophan and 5-hydroxytryptophan effective treatments for depression? A meta-analysis.
Aust N Z J Psychiatry. 2002 Aug;36(4):488-91
Shaw K, Turner J, Del Mar C.
Eating, drinking and activity in rats following 5-hydroxytryptophan (5-htp) administration
Psychopharmacologia. 1964 Jun 8;17:417-23
Joyce D, Mrosovsky N
Eating behavior and adherence to dietary prescriptions in obese adult subjects treated with 5-hydroxytryptophan.
Am J Clin Nutr. 1992 Nov;56(5):863-7
Cangiano C, Ceci F, Cascino A, Del Ben M, Laviano A, Muscaritoli M, Antonucci F, Rossi-Fanelli F
Effects of oral 5-hydroxy-tryptophan on energy intake and macronutrient selection in non-insulin dependent diabetic patients.
Int J Obes Relat Metab Disord. 1998 Jul;22(7):648-54
Cangiano C, Laviano A, Del Ben M, Preziosa I, Angelico F, Cascino A, Rossi-Fanelli F
Pharmacological treatment of obesity. Past, present, and future.
Minn Med. 2000 Nov;83(11):21-6
Effects of 5-hydroxytryptophan on the sleep of normal human subjects.
Electroencephalogr Clin Neurophysiol. 1971 Jun;30(6):505-9
Wyatt RJ, Zarcone V, Engelman K, Dement WC, Snyder F, Sjoerdsma A
[Effect of 5-hydroxytryptophan, a serotonin precursor, on sleep disorders] [Article in French]
Ann Med Psychol (Paris). 1977 May;1(5):792-8
Soulairac A, Lambinet H
L-5-Hydroxytryptophan treatment of sleep terrors in children.
Eur J Pediatr. 2004 Jul;163(7):402-7. Epub 2004 May 14
Bruni O, Ferri R, Miano S, Verrillo E
From Wikipedia, the free encyclopedia
Fibromyalgia and the serotonin pathway.
Altern Med Rev. 1998 Oct;3(5):367-75
Double-blind study of 5-hydroxytryptophan versus placebo in the treatment of primary fibromyalgia syndrome.
J Int Med Res. 1990 May-Jun;18(3):201-9
Caruso I, Sarzi Puttini P, Cazzola M, Azzolini V
Primary fibromyalgia syndrome and 5-hydroxy-L-tryptophan: a 90-day open study.
J Int Med Res. 1992 Apr;20(2):182-9
Puttini PS, Caruso I
The ingestion of serotonin precursors (L-5-hydroxytryptophan and L-tryptophan) improves migraine headache.
Headache. 1973 Apr;13(1):19-22
Acute L-5-hydroxytryptophan administration inhibits carbon dioxide-induced panic in panic disorder patients.
Psychiatry Res. 2002 Dec 30;113(3):237-43
Schruers K, van Diest R, Overbeek T, Griez E
Involvement of central serotonergic mechanisms in the cough reflex.
Jpn J Pharmacol. 1986 Dec;42(4):531-8
Kamei J, Hosokawa T, Yanaura S, Hukuhara T
Effects of 5-hydroxytryptamine and 5-hydroxytryptophan infusion on the human cough reflex.
J Appl Physiol. 1993 Jan;74(1):396-401
Stone RA, Worsdell YM, Fuller RW, Barnes PJ
5-HTP and the B6 controversy