Effects of carbohydrates on brain tryptophan availability and stress performance

• Published in: Biological psychology Vol. 76; no. 1; pp. 83 - 90
• Main Author: Markus, C.R.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier B.V 01.09.2007; Elsevier Science
• Subjects: 5-HT; Adolescent; Adult; Affect - physiology; Amino Acids - metabolism; Arousal - physiology; Behavioral psychophysiology; Biological and medical sciences; Brain - metabolism; Carbohydrates; Dietary Carbohydrates - metabolism; Double-Blind Method; Female; Fundamental and applied biological sciences. Psychology; Glucose Solution, Hypertonic - administration & dosage; Humans; Hydrocortisone - metabolism; Male; Mood; Pain Measurement; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Stress; Stress, Physiological - physiopathology; Tryptophan; Tryptophan - metabolism; Tryptophan; Carbohydrates; Mood; 5-HT; Performance; Stress; Availability; Affect affectivity; Physical performance; Serotonin; Central nervous system; Encephalon; Aminoacid; Neurotransmitter; Carbohydrate
• ISSN: 0301-0511; 1873-6246
• DOI: 10.1016/j.biopsycho.2007.06.003

Although glucose intake has been associated with enhanced mental performance, this does not follow a clear synchronized relationship and findings are inconsistent. Given the brain's need for glucose during demanding conditions, glucose intake may be beneficial for stress performance. Brain serotonin may be involved as a postprandial mechanism initiated by increases in plasma tryptophan to the sum of the other large neutral amino acids (Trp/LNAA ratio). We tested whether carbohydrate drinks compared to placebo drinks increase the plasma Trp/LNAA ratio and improve stress performance and mood. Thirty-seven healthy subjects were monitored in a double-blind placebo-controlled study for performance when continuously exposed to cold pressor stress; 2 h after carbohydrate- or placebo-intake. Cold pressor stress significantly increased cortisol and reduced mood and cognitive performance, whereas carbohydrates significantly increased plasma Trp/LNAA and positively influenced performance and mood under stress.