CLINICAL STUDIES USING 5-HTP TO COMBAT CENTRAL NERVOUS SYSTEM DISORDERS

As early as 1970, there have been at least 15 studies that have evaluated the clinical effects of 5-HTP. The studies examined a total of 511 patients with different types of depression. Of these 511 subjects, 285 (56%) showed significant improvement while taking 5-HTP.

Table 1. Clinical trials of 5-HTP use in depression.

Adapted from Van Praag and Lemus

5-HTP was given in combination with a peripheral decarboxylase inhibitor (a)

(Source: Full rights from Thorne Research, Inc. www.thorne.com; used by permission.)

Altern Med Rev. 2000 Feb;5(1):64-71.

 Use of neurotransmitter precursors for treatment of depression.

Meyers S.

Lawrence Berkeley National Laboratory, Berkeley, CA, USA. spmeyers@lbl.gov

Insufficient activity of the neurotransmitters serotonin and norepinephrine is a central element of the model of depression most widely held by neurobiologists today. In the late 1970s and 1980s, numerous studies were performed in which depressed patients were treated with the serotonin precursors L-tryptophan and 5-hydroxytryptophan (5-HTP), and the dopamine and norepinephrine precursors tyrosine and L-phenylalanine. This article briefly reviews the published research on the efficacy of neurotransmitter precursors in treating depression, highlights the findings of studies, and discusses issues regarding the interpretation of those findings. The nature of the studies makes it difficult to draw firm conclusions regarding the efficacy of neurotransmitter precursors for treating depression. While there is evidence that precursor loading may be of therapeutic value, particularly for the serotonin precursors 5-HTP and tryptophan, more studies of suitable design and size might lead to more conclusive results. However, the evidence suggests neurotransmitter precursors can be helpful in patients with mild or moderate depression.

PMID: 10696120 [PubMed - indexed for MEDLINE]
Altern Med Rev 1998;3(4):271-280

5-Hydroxytryptophan: a clinically-effective serotonin precursor.

Birdsall TC.

73541.2166@compuserve.com

5-Hydroxytryptophan (5-HTP) is the intermediate metabolite of the essential amino acid L-tryptophan (LT) in the biosynthesis of serotonin. Intestinal absorption of 5-HTP does not require the presence of a transport molecule, and is not affected by the presence of other amino acids; therefore it may be taken with meals without reducing its effectiveness. Unlike LT, 5-HTP cannot be shunted into niacin or protein production. Therapeutic use of 5-HTP bypasses the conversion of LT into 5-HTP by the enzyme tryptophan hydroxylase, which is the rate-limiting step in the synthesis of serotonin. 5-HTP is well absorbed from an oral dose, with about 70 percent ending up in the bloodstream. It easily crosses the blood-brain barrier and effectively increases central nervous system (CNS) synthesis of serotonin. In the CNS, serotonin levels have been implicated in the regulation of sleep, depression, anxiety, aggression, appetite, temperature, sexual behavior, and pain sensation. Therapeutic administration of 5-HTP has been shown to be effective in treating a wide variety of conditions, including depression, fibromyalgia, binge eating associated with obesity, chronic headaches, and insomnia.

PMID: 9727088 [PubMed - indexed for MEDLINE]

Biol Psychiatry. 1987 Feb;22(2):205-12.

Therapeutic indications for serotonin-potentiating compounds: a hypothesis.

van Praag HM, Kahn R, Asnis GM, Lemus CZ, Brown SL.

The original antidepressants, tricyclics and MAO inhibitors, increase the availability in the brain of both 5-HT and NA. Prompted by clinical findings suggestive of 5-HT disturbances in depression, drugs were developed that increase 5-HT selectively. Data are presented that suggest that broad-spectrum compounds may provide better conditions for antidepressant effects than the 5-HT-selective ones. The hypothesis is proposed that 5-HT potentiators are partial antidepressants, in that they predominantly reduce the anxiety/aggressive component of the depressive syndrome, and deserve to be tested in conditions with heightened anxiety and/or aggression irrespective of the nosological diagnosis. Tentative evidence relates diminished 5-HT metabolism to disordered impulse control. Based on these data, trials of 5-HT potentiators in impulse control disorders unrelated to aggressive drives seem warranted.

PMID: 2434148 [PubMed - indexed for MEDLINE]

J Affect Disord. 1985 Mar-Apr;8(2):197-200.

L-5-hydroxytryptophan in the treatment of anxiety disorders.

Kahn RS, Westenberg HG.

Ten outpatients suffering from anxiety states (Anxiety Disorders: DSM-III) were treated with L-5-hydroxytryptophan and carbidopa. A significant reduction in anxiety was observed on three different anxiety scales. It is suggested that 5-HT systems may be involved in the mediation of anxiety.

PMID: 3157732 [PubMed - indexed for MEDLINE]

Biol Psychiatry. 1981 Mar;16(3):291-310.

Management of depression with serotonin precursors.

van Praag HM.

5-HT precursors are used in depressions on the basis of the 5-HT hypothesis--a hypothesis which postulates that a cerebral 5-HT deficiency can play a role in the pathogenesis of depressions. This article presents a survey of the results obtained by this therapeutic strategy. There are strong indications that 5-HTP is of therapeutic value, particularly in the 5-HT-deficient subgroup of vital depressions. In the same subgroup, one controlled study has so far also shown a prophylatic 5-HTP effect. The results of tryptophan studies are less unequivocal, possibly due to pharmacokinetic factors. Another possible explanation might be that, unlike 5-HTP research, tryptophan studies have so far disregarded the patient's serotonergic status. 5-HT research in depressions has also yielded the concept of the biochemical classifiability of depressions. This may become an important supplement to the conventional criteria of classification of depressions: symptomatology, etiology, and course.

PMID: 6164407 [PubMed - indexed for MEDLINE]

Folia Psychiatr Neurol Jpn. 1978;32(2):223-30.

Clinical evaluation of 5-hydroxy-L-tryptophan as an antidepressant drug. Nakajima T, Kudo Y, Kaneko Z. Effectiveness of 5-hydroxy-L-trytophan as an antidepressant drug was studied with 59 patients with depressive symptoms using Rating Scale for Depression made by Clinico-Psychopharmacology Research Group in Japan for a preparatory step of a double blind clinical study of 5-hydroxy-L-tryptophan treatment of depression. A daily dose of 150--300 mg of 5-hydroxyl-L-tryptophan was administered for three weeks. Favorable responses were observed in 40 patients (67.8%), of whom 13 patients were markedly improved. These effects were noticed in 32 patients (80% of the improved patients) within a week of the treatment. Analysis of General Improvement Rating in the various subtypes of depressive symptoms indicated that endogenous depression and involutional or senile depression were the preferable indication of 5-hydroxy-L-tryptophan loading. The main side effects of 5-hydroxy-L-tryptophan were gastrointestinal disturbances which were minimized by the simultaneous administration of metoclopromide or trihexyphenidyl. PMID: 307522 [PubMed - indexed for MEDLINE] Taking New Life may help support the brain’s chemical imbalance of serotonin and fatty acids in the brain and minerals in the body. New Life may increase the natural availability of supply of serotonin and fatty acids in the brain and minerals in the body, which may help promote mental health and enhance mood. This innovative formulation may help you attain a positive outlook on a new life.