Differential effect of the 5-HTT gene-linked polymorphic region on emotional eating during stress exposure following tryptophan challenge

TPH intake significantly increased the plasma TRP/large neutral amino acid ratio (P<.0001) in the L′/L′ group (70%) compared to the S′/S′ group (30%). TPH reduced food intake in both groups, but in the L′/L′ group, it also reduced stress-induced negative mood (P=.037) and the desire for sweet, high-fat foods (P=.011) regardless of dietary restraint. Conclusions: Since TPH caused a greater increase in the plasma TRP/large neutral amino acid ratio in the L′/L′ group compared to S′/S′ group, the exclusive beneficial effects of L′/L′ genotype may be due to enhanced brain 5-HT function.