5-HTP (Hydroxytryptophan)
5-Hydroxytryptophan: a clinically-effective serotonin precursor.
Birdsall TC.
Altern Med Rev. 1998 Aug;3(4):271-80
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 behaviour, 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
5-Hydroxytryptophan: A Review of Its Antidepressant Efficacy and Adverse Effects
BYERLEY, WILLIAM F. MD; JUDD, LEWIS L. MDV; REIMHERR, FRED W. MD;
GROSSER, BERNARD I. MD
Journal of Clinical Psychopharmacology: 1987 Jun;7:127-137
Alterations in serotonin metabolism may be an important factor in the etiology and treatment of depression. In this regard, 5-hydroxytryptophan (5-HTP), a serotonin precursor, has been given to patients with depression. Although a review of these studies suggests that 5-HTP possesses anti-depressant properties, additional trials are clearly indicated. Following a discussion of the pharmacology of 5-HTP, the authors highlight adverse effects associated with its administration to depressed patients, neurologic subjects, and normal individuals. Relatively few adverse effects are associated with its use in the treatment of depressed patients. PMID: 3298325
Eating behavior and adherence to dietary prescriptions in obese adult subjects treated with 5-hydroxytryptophan
C Cangiano, F Ceci, A Cascino, M Del Ben, A Laviano, M Muscaritoli, F Antonucci and F Rossi-Fanelli
American Journal of Clinical Nutrition 1992 Nov, Vol 56, 863-867
Previous observations have shown that oral administration of 5- hydroxytryptophan (5-HTP) without dietary prescriptions causes anorexia, decreased food intake, and weight loss in obese subjects. To confirm these data over a longer period of observation and to verify whether adherence to dietary restriction could be improved by 5-HTP, 20 obese patients were randomly assigned to receive either 5-HTP (900 mg/d) or a placebo. The study was double-blinded and was for two consecutive 6-wk periods. No diet was prescribed during the first period, a 5040-kJ/d diet was recommended for the second. Significant weight loss was observed in 5-HTP-treated patients during both periods. A reduction in carbohydrate intake and a consistent presence of early satiety were also found. These findings together, with the good tolerance observed, suggest that 5-HTP may be safely used to treat obesity. PMID: 1384305
A functional food product for the management of weight.
Bell SJ, Goodrick GK.
Crit Rev Food Sci Nutr. 2002 Mar;42(2):163-78.
More than half of Americans have a body mass index of 25 kg/m2 or more, which classifies them as overweight or obese. Overweight or obesity is strongly associated with comorbidities such as type 2 diabetes mellitus, hypertension, heart disease, gall bladder disease, and sleep apnea. Clearly, this is a national health concern, and although about 30 to 40% of the obese claim that they are trying to lose weight or maintain weight after weight loss, current therapies appear to have little effect. None of the current popular diets are working, and there is room for innovation. With the advancing science of nutrition, several nutrients – low-glycemic-index carbohydrates, 5-hydroxytryptophan, green tea extract, and chromium – have been identified that may promote weight loss. The first two nutrients decrease appetite, green tea increases the 24-h energy expenditure, and chromium promotes the composition of the weight lost to be fat rather than lean tissue. These have been assembled in efficacious doses into a new functional food product and described in this review. The product is undergoing clinical testing; each component has already been shown to promote weight loss in clinical trials. PMID: 11934132
Increases in avoidance responding produced by REM sleep deprivation or serotonin depletion are reversed by administration of 5-hydroxytryptophan.
Smith RL, Kennedy CH.
Behav Brain Res. 2003 Mar 18;140(1-2):81-6.
Our objective was to directly compare the effects of rapid eye movement (REM) sleep deprivation (REMSD) and serotonin 5-hydroxytryptamine (5-HT) depletion on free-operant avoidance behavior in rats. These experiments were designed to determine if declining 5-HT levels observed during REMSD might mediate the increases in avoidance responding observed in REM sleep deprived rats. Rats were trained on a free-operant avoidance task. Following training, the animals were assigned to one of three sleep conditions (REMSD, tank control, or cage control). Animals in each sleep condition were exposed to four 5-HT manipulations: (a) saline plus saline; (b) p-chlorophenylalanine (PCPA) plus saline; (c) saline plus 5-hydroxytryptophan (5-HTP) and (d) PCPA plus 5-HTP. Both REMSD and 5-HT depletion via PCPA resulted in an increase in avoidance responding that was reversed by administration of 5-HTP. REMSD and 5-HT depletion via PCPA resulted in increased avoidance efficiency and were reversed by 5-HTP administration, but only changes following PCPA injection were statistically significant. Decreases in 5-HT levels that occur during REMSD likely mediate increases in avoidance responding. PMID: 12644281
5 -Hydroxytryptophan: A Review of Its Antidepressant Efficacy and Adverse Effects
BYERLEY, WILLIAM F. MD; JUDD, LEWIS L. MDV; REIMHERR, FRED W. MD;
GROSSER, BERNARD I. MD
Journal of Clinical Psychopharmacology: 1987 Jun;7:127-137
Alterations in serotonin metabolism may be an important factor in the etiology and treatment of depression. In this regard, 5-hydroxytryptophan (5-HTP), a serotonin precursor, has been given to patients with depression. Although a review of these studies suggests that 5-HTP possesses anti-depressant properties, additional trials are clearly indicated. Following a discussion of the pharmacology of 5-HTP, the authors highlight adverse effects associated with its administration to depressed patients, neurologic subjects, and normal individuals. Relatively few adverse effects are associated with its use in the treatment of depressed patients. PMID: 3298325
Eating behavior and adherence to dietary prescriptions in obese adult subjects treated with 5-hydroxytryptophan
C Cangiano, F Ceci, A Cascino, M Del Ben, A Laviano, M Muscaritoli, F Antonucci and F Rossi-Fanelli
American Journal of Clinical Nutrition 1992 Nov, Vol 56, 863-867
Previous observations have shown that oral administration of 5- hydroxytryptophan (5-HTP) without dietary prescriptions causes anorexia, decreased food intake, and weight loss in obese subjects. To confirm these data over a longer period of observation and to verify whether adherence to dietary restriction could be improved by 5-HTP, 20 obese patients were randomly assigned to receive either 5-HTP (900 mg/d) or a placebo. The study was double-blinded and was for two consecutive 6-wk periods. No diet was prescribed during the first period, a 5040-kJ/d diet was recommended for the second. Significant weight loss was observed in 5-HTP-treated patients during both periods. A reduction in carbohydrate intake and a consistent presence of early satiety were also found. These findings together, with the good tolerance observed, suggest that 5-HTP may be safely used to treat obesity. PMID: 1384305
A functional food product for the management of weight.
Bell SJ, Goodrick GK.
Crit Rev Food Sci Nutr. 2002 Mar;42(2):163-78.
More than half of Americans have a body mass index of 25 kg/m2 or more, which classifies them as overweight or obese. Overweight or obesity is strongly associated with comorbidities such as type 2 diabetes mellitus, hypertension, heart disease, gall bladder disease, and sleep apnea. Clearly, this is a national health concern, and although about 30 to 40% of the obese claim that they are trying to lose weight or maintain weight after weight loss, current therapies appear to have little effect. None of the current popular diets are working, and there is room for innovation. With the advancing science of nutrition, several nutrients – low-glycemic-index carbohydrates, 5-hydroxytryptophan, green tea extract, and chromium – have been identified that may promote weight loss. The first two nutrients decrease appetite, green tea increases the 24-h energy expenditure, and chromium promotes the composition of the weight lost to be fat rather than lean tissue. These have been assembled in efficacious doses into a new functional food product and described in this review. The product is undergoing clinical testing; each component has already been shown to promote weight loss in clinical trials. PMID: 11934132
Increases in avoidance responding produced by REM sleep deprivation or serotonin depletion are reversed by administration of 5-hydroxytryptophan.
Smith RL, Kennedy CH.
Behav Brain Res. 2003 Mar 18;140(1-2):81-6.
Our objective was to directly compare the effects of rapid eye movement (REM) sleep deprivation (REMSD) and serotonin 5-hydroxytryptamine (5-HT) depletion on free-operant avoidance behavior in rats. These experiments were designed to determine if declining 5-HT levels observed during REMSD might mediate the increases in avoidance responding observed in REM sleep deprived rats. Rats were trained on a free-operant avoidance task. Following training, the animals were assigned to one of three sleep conditions (REMSD, tank control, or cage control). Animals in each sleep condition were exposed to four 5-HT manipulations: (a) saline plus saline; (b) p-chlorophenylalanine (PCPA) plus saline; (c) saline plus 5-hydroxytryptophan (5-HTP) and (d) PCPA plus 5-HTP. Both REMSD and 5-HT depletion via PCPA resulted in an increase in avoidance responding that was reversed by administration of 5-HTP. REMSD and 5-HT depletion via PCPA resulted in increased avoidance efficiency and were reversed by 5-HTP administration, but only changes following PCPA injection were statistically significant. Decreases in 5-HT levels that occur during REMSD likely mediate increases in avoidance responding. PMID: 12644281