Vegetarian diet and mood:
The link between diet composition and mood in women on weight-reducing diets of a 1,000 kcal per day for 6 weeks was examined. Researchers found that mood during the last 3 weeks of the diet were significantly better in the “vegetarian” than in the “mixed” diet group. A significant relationship was also observed between low carbohydrate intake and decline in mood (r = -0.74; p less than 0.01) and between the ratio of plasma tryptophan to other large neutral amino acids (a predictor of tryptophan flow into brain) and global mood (r = -0.52; p less than 0.05). These findings suggest that group differences are related to differences in carbohydrate intake. The authors propose that in situations of relatively low carbohydrate intake serotonin levels are low due to reduced tryptophan availability which can prompt a decline in mood. (34)