Acute Effects of Meals on Brain Tryptophan and Serotonin in Humans

  • S. N. Young
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 294)


Under normal circumstances, tryptophan hydroxylase, the rate-limiting enzyme on the pathway from tryptophan to serotonin, is about half saturated with tryptophan. This is true for both rats (Grahame-Smith, 1971) and humans (Young and Gauthier, 1981). As a result, alterations in brain tryptophan can influence serotonin synthesis. Brain tryptophan is in some circumstances altered by food intake, leading to the rather surprising conclusion that a neurotransmitter, serotonin, which is involved in the control of a number of important mental functions, can be influenced by the diet. As discussed below, in the rat, protein and carbohydrate meals have opposite effects on brain serotonin. There is also evidence that serotonin can influence macronutrient selection, leading to the suggestion that serotonin may be a part of a system regulating dietary intake (Wurtman and Wurtman, 1986). Thus, a carbohydrate meal would raise brain serotonin which would inhibit subsequent carbohydrate selection, thereby ensuring that protein and carbohydrate intakes would stay within certain limits over the long run.


Plasma Amino Acid Brain Serotonin Protein Meal Large Neutral Amino Acid Seasonal Affective Disorder 
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  1. Anderson, G.H., 1979, Control of protein and energy intake: role of plasma amino acids and brain neurotransmitters, Can. J. Physiol. Pharmacol., 57: 1043–1057.PubMedCrossRefGoogle Scholar
  2. Ashley, D.V.M., Barclay, D.V., Chauffard, F.A., Moennoz, D., and Leathwood, P.D., 1982, Plasma amino acid responses in humans to evening meals of differing nutritional composition, Am. J. Clin. Nutr., 36: 143–153.PubMedGoogle Scholar
  3. Ashley, D.V.M., Liardon, R., and Leathwood, P.E., 1985, Breakfast meal composition influences plasma tryptophan to large neutral amino acid ratios of healthy lean young men, J. Neural Transm., 63: 271–283.PubMedCrossRefGoogle Scholar
  4. Craig, A., 1986, Acute effects of meals on perpetual and cognitive efficiency, Nutr. Rev., 44: 163–171.PubMedCrossRefGoogle Scholar
  5. Etienne, P., Young, S.N., and Sourkes, T.L., 1976, Inhibition by albumin of tryptophan uptake by rat brain, Nature, 262: 144–145.PubMedCrossRefGoogle Scholar
  6. Fernstrom, J.D., and Wurtman, R.J., 1971, Brain serotonin content: increase following ingestion of carbohydrate diet, Science, 174: 1023–1025.PubMedCrossRefGoogle Scholar
  7. Fernstrom, J.D., Wurtman, R.J., Hammarstrom-Wiklund, B., Rand, W.M., Munro, H.N., and Davidson, C.S., 1979, Diurnal variations in plasma concentrations of tryptophan, tyrosine, and other neutral amino acids: effect of dietary protein intake, Am. J. Clin. Nutr., 32: 1912–1922.PubMedGoogle Scholar
  8. Gessa, G.L., Biggio, G., Fadda, F., Corsini, G.V., and Tagliamonte, A., 1974, Effect of the oral administration of tryptophan-free amino acid mixtures on serum tryptophan, brain tryptophan and serotonin metabolism, J. Neurochem., 22: 869–870.PubMedCrossRefGoogle Scholar
  9. Glaeser, B.S., Maher, T.J., and Wurtman, R.J., 1983, Changes in brain levels of acidic, basic and neutral amino acids after consumption of single meals containing various proportions of proteins, J. Neurochem., 41: 1016–1021.PubMedCrossRefGoogle Scholar
  10. Grahame-Smith, D.G., 1971, Studies in vivo on the relationship between tryptophan, brain 5-HT synthesis and hyperactivity in rats treated with a monoamine oxidase inhibitor and L-tryptophan, J. Neurochem., 18: 1053–1066.PubMedCrossRefGoogle Scholar
  11. Lieberman, H.R., Spring, B.J., and Garfield, G.S., 1986, The behavioral effects of food constituents: strategies used in studies of amino acids, protein, carbohydrate and caffeine, Nutr. Rev., Suppl., 44: 61–70.CrossRefGoogle Scholar
  12. Oldendorf, W.H., and Szabo, J., 1976, Amino acid assignment to one of three blood-brain barrier amino acid carriers, Am. J. Physiol., 230: 94–98.PubMedGoogle Scholar
  13. Pardridge, W.M., and Choi, T., 1986, Amino acid transport at the human bloodbrain barrier, Fed. Proc, 45: 2073–2078.PubMedGoogle Scholar
  14. Perez-Cruet, J., Chase, T.N., and Murphy, D.L., 1974, Dietary regulation of brain tryptophan metabolism by plasma ratio of free tryptophan and neutral amino acids in humans, Nature, 248: 693–695.PubMedCrossRefGoogle Scholar
  15. Rosenthal, N.E., and Hefferman, M.M., 1986, Bulimia, carbohydrate craving, and depression: a central connection?, in: “Nutrition and the Brain, Volume 7, Food Constituents Affecting Normal and Abnormal Behaviors”, Wurtman, R.J., and Wurtman, J.J., eds., Raven Press, New York, pp. 139–166.Google Scholar
  16. Spring, B., Mailer, O., Wurtman, J., Digman, L., and Cozolino, L., 1983, Effects of protein and carbohydrate meals on mood and performance: interactions with sex and age, J. Psychiatr. Res., 17: 155–167.CrossRefGoogle Scholar
  17. Teff, K.L., and Young, S.N., 1988, Effects of carbohydrate and protein administration of rat tryptophan and 5-hydroxytryptamine: differential effects on the brain, intestine, pineal, and pancreas, Can. J. Physiol. Pharmacol., 66: 683–688.PubMedCrossRefGoogle Scholar
  18. Teff, K.L., Young, S.N., and Blundell, J.E., 1989a, The effect of protein or carbohydrate breakfasts on subsequent plasma amino acid levels, satiety and nutrient selection in normal males, Pharmacol. Biochem. Behav., 34: 829–837.PubMedCrossRefGoogle Scholar
  19. Teff, K.L., Young, S.N., Marchand, L., and Botez, M.I., 1989b, Acute effect of protein or carbohydrate breakfasts on human cerebrospinal fluid monoamine precursor and metabolite levels, J. Neurochem., 52: 235–241.PubMedCrossRefGoogle Scholar
  20. Wurtman, J.J., and Wurtman, R.J., 1977, Fenfluramine and fluoxetine spare protein consumption while suppressing calorie intake by rats, Science, 198: 1178–1180.PubMedCrossRefGoogle Scholar
  21. Wurtman, R.J., and Wurtman, J.J., 1986, Carbohydrate craving, obesity and brain serotonin, Appetite, Suppl., 7: 99–103.PubMedCrossRefGoogle Scholar
  22. Yokogoshi, H., and Wurtman, R.J. 1986, Meal composition and plasma amino acid ratios: effect of various proteins or carbohydrates, and of various protein concentrations, Metabolism, 35: 837–842.PubMedCrossRefGoogle Scholar
  23. Young, S.N., 1986, The clinical psychopharmacology of tryptophan, in: “Nutrition and the Brain, Volume 7, Food Constituents Affecting Normal and Abnormal Behaviors”, Wurtman, R.J., and Wurtman, J.J., eds., Raven Press, New York, pp. 49–88.Google Scholar
  24. Young, S.N., and Gauthier, S., 1981, Effect of tryptophan administration on tryptophan, 5-hydroxyindoleacetic acid and indoleacetic acid in human lumbar and cisternal cerebrospinal fluid, J. Neurol. Neurosurg. Psych., 44: 323–328.CrossRefGoogle Scholar
  25. Young, S.N., Tourjman, S.V., Teff, K.L., Pihl, R.O., and Anderson, G.H., 1988, The effect of lowering plasma tryptophan on food selection in normal males, Pharmacol. Biochem. Behav., 31: 149–152.PubMedCrossRefGoogle Scholar
  26. Yuwiler, A., Oldendorf, S.M., Geller, E., and Braun, L., 1977, Effect of albumin binding and amino acid competition on tryptophan uptake into brain, J. Neurochem., 28: 1015–1023.PubMedCrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1991

Authors and Affiliations

  • S. N. Young
    • 1
  1. 1.Dept. of PsychiatryMcGill UniversityMontrealCanada

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