Nutritional Consequences of Excess Amino Acid Intake

  • Hamish N. Munro
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 105)


Various mechanisms respond to intakes of amino acids in excess of those required for normal tissue function. When excessive amounts of amino acids are taken, catabolism by enzymes in the liver and elsewhere is accelerated when intake exceeds requirements. In addition, changes in the free amino acid levels in the brain signal the nervous system centers regulating food consumption, and eating patterns are affected. This central nervous system mechanism may even determine the proportions of protein and of energy-yielding nutrients chosen in the diet through a mechanism regulated by the entry of tryptophan and other neurotransmitter precursors into the brain. These observations on protective mechanisms are considered in relation to effects obtained by feeding disproportionate amounts of amino acids. Intakes of large amounts of amino acids can produce toxicities, in which plasma concentrations of the administered amino acid rise to very high levels. Antagonisms arise from feeding excess of one amino acid that can be relieved by feeding a structurally related amino acid. Finally, amino acid imbalances are produced by adding surpluses of essential amino acids other than the essential amino acid most limiting for growth; the growth depression caused by this addition can be relieved by adding more of the most limiting amino acid to the diet. In all circumstances involving feeding with disproportionate amounts of amino acids, there is evidence of changes in brain amino acid levels. It is suggested that these changes play an important role in initiating protective responses against abnormal amino acid intakes.


Free Amino Acid Essential Amino Acid Neutral Amino Acid Plasma Amino Acid Amino Acid Intake 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Anderson, G.H. (1977) Regulation of protein intake by plasma amino acids. In, ‘Advances in Nutritional Research’, H.N. Draper (Editor). Vol. 1, Plenum Publishing Corp.Google Scholar
  2. Anderson, G.H., Blendis, L.M., Shillabeer, G. and Krulewitz, J. (1978) Correlation between the plasma tryptophan to neutral amino acid ratio and dietary protein-energy selection in man. Fed. Proc., 37, 360.Google Scholar
  3. Benevenga, N.J. and Harper, A.E. (1967) Alleviation of methionine and homocystine toxicity in the rat. J. Nutr., 93, 44–52.Google Scholar
  4. Benton, D.A., Harper, A.E., Spivey, H.E. and Elvehjem, C.A. (1956b) Leucine, isoleucine and valine relationships in the rat. Arch. Biochem. Biophys,, 60, 147–155.Google Scholar
  5. Brookes, I.M., Owen, F.N. and Garrigus, U.S. (1972) Influence of amino acid level in the diet upon amino acid oxidation by the rat. J. Nutr. 102, 27–34.Google Scholar
  6. Elwyn, D. (1970) The role of the liver in regulation of amino acid and protein metabolism. In, Mammalian Protein Metabolism H.N. Munro (Editor) Vol. 4, pp. 523–571, Academic Press, New York.Google Scholar
  7. Fauconneau, G. and Michel, M.C. (1970) The role of the gastrointestinal tract in the regulation of protein metabolism. In, Mammalian Protein Metabolism, H.N. Munro (Editor), Vol. 4, pp. 481–522, Academic Press, New York.Google Scholar
  8. Fernstrom, J.D., Madras, B.K., Munro, H.N. and Wurtman, R.J. (1974) Nutritional control of the synthesis of 5-hydroxytryptamine in the brain. In, Aromatic Amino Acids in the Brain, Ciba Foundation Symposium. pp. 153–173, Elsevier, New York.Google Scholar
  9. Harper, A.E. (1964) Amino acid toxicities and imbalances. In, Mammalian Protein Metabolism, H.N. Munro and J.B. Allison (Editors), Vol. 2, pp. 87–134, Academic Press, New York.Google Scholar
  10. Harper, A.E. (1973) Effects of disproportionate amounts of amino acids. In, Improvement of Protein Nutriture. pp. 138–166, National Academy of Sciences, Washington, D.C.Google Scholar
  11. Ichihara, A. and Koyama, E. (1966) Transaminase of branched chain amino acids. J. Biochem., Tokyo, 59, 160–169.Google Scholar
  12. Jones, J.D. 1964. Lysine-arginine antagonism in the chick. J. Nutr. 84, 313–321.Google Scholar
  13. Kumta, U.S. and Harper, A.E. (1960) Amino acid balance and imbalance. III. Quantitative studies of imbalances in diets containing fibrin. J. Nutr. 70, 141–146.Google Scholar
  14. Kumta, U.S. and Harper, A.E. (1962) Amino acid balance and imbalance. IX. Effect of amino acid imbalance on blood amino acid pattern. Proc. Soc. Exp. Biol. Med., 110, 512–517.Google Scholar
  15. Miller, L.L. (1962) The role of the liver and the non-hepatic tissues in the regulation of free amino acid levels in the blood. In, Amino Acid Pools, J.T. Holden, Editor. pp. 708–21. Elsevier, Amsterdam.Google Scholar
  16. Munro, H.N. (1970) Free amino acid pools and their role in regulation. In, Mammalian Protein Metabolism, H.N. Munro, Editor. Vol. 4, pp. 299–386, Academic Press, N.Y.Google Scholar
  17. Munro, H.N., Fernstrom, J.D. and Wurtman,R.J. (1975) Insulin, plasma amino acid imbalance, and hepatic coma. Lancet, I, 722.Google Scholar
  18. Neame, K.D. (1966) Effect of neutral and amino acids and basic amino acids on uptake of L-histidine by intestinal mucosa, testis, spleen, and kidney in vitro: a comparison with effect in brain. J. Physiol. 185, 627–645.Google Scholar
  19. Pardridge, W.M. (1977) Regulation of amino acid availability to the brain. In, Nutrition and the Brain. R.J. Wurtman and J.J. Wurtman, Editors. Vol. 1, pp. 141–204, Raven Press, New York.Google Scholar
  20. Pawlak, M. and Pion, R. (1968) Influence de la supplementation des proteines de ble par des doses croissantes de lysine sur la teneur en acides amines libres du sang et du muscle du rat en croissance. Annls Biol. anim. Biochim. Biophys. 8, 517–30.Google Scholar
  21. Peng, Y., Tews, J.K. and Harper, A.E. (1972) Amino acid imbalance, protein intake, and changes in rat brain and plasma amino acids. Am. J. Physiol. 222, 314–321.Google Scholar
  22. Peng, Y., Gubin, J., Harper, A.E., Vavich, M.G. and Kemmerer, A. R. (1973) Food intake regulation: Amino acid toxicity and changes in rat brain and plasma amino acids. J. Nutr., 103, 608–617.Google Scholar
  23. Rogers, Q.R. and Leung, P.M.B. (1973) The influence of amino acids on the neuroregulation of food intake. Fed. Proc., 32, 1709.Google Scholar
  24. Sauberlich, H.E. (1961) Studies on the toxicity and antagonism of amino acids for weanling rats. J. Nutr., 75, 61–72.Google Scholar
  25. Young, V.R. and Munro, H.N. (1973) Plasma and tissue tryptophan levels in relation to tryptophan requirements of weanling and adult rats. J. Nutr., 103, 1756–1763.Google Scholar

Copyright information

© Plenum Press, New York 1978

Authors and Affiliations

  • Hamish N. Munro
    • 1
  1. 1.Department of Nutrition and Food ScienceMassachusetts Institute of TechnologyCambridgeUSA

Personalised recommendations