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Effects of normal meals rich in carbohydrates or proteins on plasma tryptophan and tyrosine ratios.
Am J Clin Nutr. 2003 Jan; 77(1):128-32.AJ

Abstract

BACKGROUND

The delivery of circulating tryptophan to the brain and its conversion to serotonin vary directly with plasma concentrations of tryptophan and inversely with those of other large neutral amino acids (LNAAs). Although carbohydrate-rich, protein-free formula diets have been shown to elevate, and high-protein diets to depress, the tryptophan-LNAA ratio, few data are available about this ratio's responses to actual meals.

OBJECTIVE

We determined whether carbohydrate-rich or protein-rich breakfasts, such as those Americans normally eat, produce substantial differences in the plasma tryptophan-LNAA ratio and in the corresponding ratio for tyrosine, the precursor of brain dopamine and norepinephrine.

DESIGN

Nine overnight-fasted subjects consumed, 3-7 d apart, a carbohydrate-rich (69.9 g carbohydrate and 5.2 g protein) and a protein-rich (15.4 g carbohydrate and 46.8 g protein) breakfast. Blood samples collected at baseline and after 40, 80, 120, and 240 min were assayed for tryptophan, tyrosine, the 5 other LNAAs, and insulin.

RESULTS

The carbohydrate-rich and protein-rich breakfasts had significantly different effects on both the plasma tryptophan-LNAA and tyrosine-LNAA ratios (each P < 0.01). Among the 8 subjects who consumed both breakfasts, the median difference for tryptophan:LNAA was 54% (range: 36-88%) and for tyrosine:LNAA was 28% (range: 10-64%). Insulin concentrations rose significantly after the carbohydrate but not after the protein meal.

CONCLUSIONS

High-carbohydrate and high-protein breakfasts similar to those Americans normally eat can cause substantial differences in the plasma tryptophan ratio and thus, probably, in brain tryptophan concentrations and serotonin synthesis. Such meals also change the plasma tyrosine ratio and may thereby modify catecholamine synthesis.

Authors+Show Affiliations

Clinical Research Center, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge 02139, USA. dick@mit.eduNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

12499331

Citation

Wurtman, Richard J., et al. "Effects of Normal Meals Rich in Carbohydrates or Proteins On Plasma Tryptophan and Tyrosine Ratios." The American Journal of Clinical Nutrition, vol. 77, no. 1, 2003, pp. 128-32.
Wurtman RJ, Wurtman JJ, Regan MM, et al. Effects of normal meals rich in carbohydrates or proteins on plasma tryptophan and tyrosine ratios. Am J Clin Nutr. 2003;77(1):128-32.
Wurtman, R. J., Wurtman, J. J., Regan, M. M., McDermott, J. M., Tsay, R. H., & Breu, J. J. (2003). Effects of normal meals rich in carbohydrates or proteins on plasma tryptophan and tyrosine ratios. The American Journal of Clinical Nutrition, 77(1), 128-32.
Wurtman RJ, et al. Effects of Normal Meals Rich in Carbohydrates or Proteins On Plasma Tryptophan and Tyrosine Ratios. Am J Clin Nutr. 2003;77(1):128-32. PubMed PMID: 12499331.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of normal meals rich in carbohydrates or proteins on plasma tryptophan and tyrosine ratios. AU - Wurtman,Richard J, AU - Wurtman,Judith J, AU - Regan,Meredith M, AU - McDermott,Janine M, AU - Tsay,Rita H, AU - Breu,Jeff J, PY - 2002/12/25/pubmed PY - 2003/1/15/medline PY - 2002/12/25/entrez SP - 128 EP - 32 JF - The American journal of clinical nutrition JO - Am J Clin Nutr VL - 77 IS - 1 N2 - BACKGROUND: The delivery of circulating tryptophan to the brain and its conversion to serotonin vary directly with plasma concentrations of tryptophan and inversely with those of other large neutral amino acids (LNAAs). Although carbohydrate-rich, protein-free formula diets have been shown to elevate, and high-protein diets to depress, the tryptophan-LNAA ratio, few data are available about this ratio's responses to actual meals. OBJECTIVE: We determined whether carbohydrate-rich or protein-rich breakfasts, such as those Americans normally eat, produce substantial differences in the plasma tryptophan-LNAA ratio and in the corresponding ratio for tyrosine, the precursor of brain dopamine and norepinephrine. DESIGN: Nine overnight-fasted subjects consumed, 3-7 d apart, a carbohydrate-rich (69.9 g carbohydrate and 5.2 g protein) and a protein-rich (15.4 g carbohydrate and 46.8 g protein) breakfast. Blood samples collected at baseline and after 40, 80, 120, and 240 min were assayed for tryptophan, tyrosine, the 5 other LNAAs, and insulin. RESULTS: The carbohydrate-rich and protein-rich breakfasts had significantly different effects on both the plasma tryptophan-LNAA and tyrosine-LNAA ratios (each P < 0.01). Among the 8 subjects who consumed both breakfasts, the median difference for tryptophan:LNAA was 54% (range: 36-88%) and for tyrosine:LNAA was 28% (range: 10-64%). Insulin concentrations rose significantly after the carbohydrate but not after the protein meal. CONCLUSIONS: High-carbohydrate and high-protein breakfasts similar to those Americans normally eat can cause substantial differences in the plasma tryptophan ratio and thus, probably, in brain tryptophan concentrations and serotonin synthesis. Such meals also change the plasma tyrosine ratio and may thereby modify catecholamine synthesis. SN - 0002-9165 UR - https://www.unboundmedicine.com/medline/citation/12499331/Effects_of_normal_meals_rich_in_carbohydrates_or_proteins_on_plasma_tryptophan_and_tyrosine_ratios_ L2 - https://academic.oup.com/ajcn/article-lookup/doi/10.1093/ajcn/77.1.128 DB - PRIME DP - Unbound Medicine ER -