Tryptophan feeding adversely influences pregnancy.

Additional tryptophan during pregnancy reduces embryo and neonate survival in the golden hamster, Mesocricetus auratus. Relatively small doses of exogenous serotonin have been reported to cause abortions in several vertebrate species (1, 2, 3, 4, 5). Smaller doses reduce litter sizes, increase still births and neonate abnormalities, and otherwise influence pregnancy adversely. These effects are produced by serotonin throughout pregnancy, beginning at implantation (6). The availability of tryptophan is probably the most important rate limiting factor in serotonin synthesis (7). Inasmuch as tryptophan is an essential amino acid and is not synthesized by the body, the diet is the sole source; studies have shown that increases (8) or decreases (9) in dietary tryptophan lead to concomitant changes in serotonin content. Because tryptophan is employed in humans to promote sleep (10, 11, 12) and to decrease appetite (13) we felt it might be important to test whether increased amounts of diet tryptophan can adversely influence pregnancy.