Abstract
Serotonin (5-HT) synthesis in neurons is initiated by hydroxylation of the essen tial amino acid tryptophan. Treatments that raise the level of tryptophan in the brain can rapidly alter the rate at which it is converted to 5-HT. This paper compares the effect of 1, 2 and 3 g L-tryptophan administered 1 h before a plated meal on total food intake and carbohy drate and protein consumption in 10 obese subjects (group I) versus a lactose placebo in another 10 obese subjects (group II). The mean ± SD total calorie intakes were: group I 1188 ± 94 (1 g); 1031 ± 93 (2 g: p < 0.05) and 1016 ± 85 (3g: p<0.05); group II: 1294 ± 62. There was a progressive decrease in carbohydrate consumption (expressed as available monosac charide) in function of the tryptophan dose: placebo 131 ± 8 g; one g tryptophan 123 ± 9; two g 114 ± 13; three g 107 ± 10. Protein consumption was less affected. These results provide fur ther support for the view that serotoninergic mechanisms play a role in the regulation of human food intake. They are also consistent with the hypothesis that nutrients which increase 5-HT availability selectively alter carbohydrate consumption. Further studies with modified molecules of naturally occurring tryptophan (hydroxytryptophan hydrochloride or diethylpro pionate) may offer a potential field for the treatment of pathological ingestive behavior.
This is a preview of subscription content, log in via an institution to check access.
References
Wurtman R.J.: Dietary treatments that affect brain neurotransmitters: effect on calorie and nutrient intake In: Wurtman R.J., Wurtman J. (Eds.), Human Obesity. The New York Acad. Sci., New York, pp. 179–190, 1987.
Wurtman R.J.: Nutrients that modify brain function. Sci. Am. 243, 42–51, 1982.
Wurtman J.J., Wurtman R.J.: Drugs that enhance central serotoninergic transmission dimish elective carbohydrate consumption by rats. Life Sci. 24, 859–904, 1979.
Wurtman J.J., Wurtman R.J., Growdon J.H., Henry P., Lipscomb A., Zeisel S.H.: Carbo — hydrate craving in obese poeple: suppression by treatment affecting serotoninergic transmission. Int. J. Eating Disord., 1, 2–15, 1981.
Fernstrom J.D., Wurtman R.J.: Brain serotonin content: Physiological regulation by plasma neutral amino acids. Science, 178, 414–416, 1972.
Latham C.J., Blundelli J.E.: Evidence for the effect of tryptophan on the pattern of food consumption in free feeding and food deprived rats. Life Sci., 24, 1971–1976, 1981.
Ashley D.V., Curzon G.: Effects of long-term dietary tryptophan intake on determinants of 5-HT metabolism in the brain of young rats. J. Neurochem., 37, 505–509, 1981.
Fernstrom J.D., Wurtman R.J., Hammarstron- Wiklund B., Rand W.M., Munro H.N., Davidson C.S.: Diurnal variations in plasma concentrations of tryptoplan, tyrosine, and other neutral amino acids: effect of dietary protein intake. Am. J. Clin. Nutr., 32, 1912–1922, 1979.
Ashcroft G.W., Eccleston D., Crawford T.B.B.: 5-Hydroxyindole metabolism in rat brain: A study of intermediate metabolism using the techniques of tryptophan loading. J. Neurochem., 12, 483–492, 1965.
Eccleston D., Ashcroft G.W., Crawford T.B.B., Stanton J.B., Wood D., McTurk P.H.: Effect of tryptophan administration of 5-HIAA in cerebrospinal fluid in man. Neurosurg. Psychiatry, 33, 269–272, 1970.
Madras B.K., Cohen E.L., Messing R., Munro H.N., Wurtman R.J.: Relevance of serum tryptophan to tissue tryptophan concentrations. Metab. Clin. Exp., 23, 1107–1116, 1974.
Ashley D.V.M., Fleury M.O., Golay A., Moreder F., Leathwood P.D.: Evidence for diminished brain 5-HT biosynthesis in obese diabetic and non-diabetic humans. Am. J. Clin. Nutr., 42, 1240–1245, 1985.
Fernstrom J.D.: Brain Serotonin, food intake regulation and obesity In: Björntorp P., Brodolf B.N. (Eds.), Obesity. Philadelphia, J.B. Lippincott Co., 1992, pp. 411–423.
Young S.N.: The clinical psychopharmacology of tryptophan. In: Wurtman J., Wurtman J.J. (Eds.), Nutrition and the Brain. New York, Raven Press, vol. 7, 1985, pp. 49–88.
Smith B., Prockop D.J.: Central-nervous-system effects of ingestion of L-tryptophan by normal subjects. N. Engl. J. Med., 267, 1338–1341, 1962.
Fernstrom J.D., Wurtman R.J.: Brain serotonin content: Physiological dependence on plasma tryptophan levels. Science, 173, 149–152, 1971.
Hrboticky N., Leiter C.A., Anderson G.H.: Effects of L-tryptophan on short term food intake in lean men. Nutr. Res., 5, 595–607, 1985.
Silverstone T., Goodall E.: Serotoninergic mechanisms in human feeding. The pharmacological evidence. Appetite, 7, 85–97, 1986.
Leiter C.A., Hrboticky N., Anderson G.H.: Effects of L-tryptophan on Food Intake and Selection in Lean Men and Women. In: Wurtman R.J., Wurtman J. (Eds.), Human Obesity. New York, The New York Acad. Sci., 1987, pp. 327–328.
Hyman S.L., Coule J.T., Parke J.C., Porter C., Thomas G.H., Jankel W., Batshaw M.L.: Anorexia and altered serotonin metabolism in a patient with arginino-succinic aciduria. J. Pediatr., 108, 705–709, 1986.
Fierabracci V., Novelle M., Ciccavone A.M., Masiello P., Benzi L., Nonvalesi R., Bergamini E.: Effects of tryptophan loading in the aminoacids metabolism in type I diabetic patients. Diab. Metab., 1, 128–135, 1997.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Cavaliere, H., Medeiros-Neto, G. The anorectic effect of increasing doses of L-tryptophan in obese patients. Eat Weight Disord 2, 211–215 (1997). https://doi.org/10.1007/BF03339978
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF03339978