Effect of meal composition on mood.

The influence of simple carbohydrate, complex carbohydrate, protein, and delayed meal conditions on plasma tryptophan ratios and mood of normal subjects was investigated. In Experiment 1, 27 women consumed 1 of 4 meal conditions, had blood samples drawn, and completed mood assessment measures before and at 5 times during the next 3 hr. Experiment 2 replicated Experiment 1 except that blood samples were not drawn and an additional simple carbohydrate condition was included. The carbohydrate meal conditions elevated blood glucose levels and plasma ratio of tryptophan to other large neutral amino acids over that of the protein condition. A decline in feelings of fatigue and distress occurred 30 min postprandial regardless of condition and persisted for the rest of the study.