The effect of D-Histidine on appetite in rats

D type amino acid is the optical isomer of L type amino acid and they can be found in daily food. Therefore, we are exposed to the D type amino acid in daily bases. However, the effect of D type amino acid after consuming remains uncertain. Recently the appetite-suppressing effect of L-histidine has been reported. This mechanism is understood as the conversion of L-histidine to histamine in the brain and therefore suppressing the appetite. In contrast, whether D-histidine has the same effect or not remains unknown. Therefore, D-histidine was given to rats to examine whether there was any influence to the food intake habit. Here we report that D-histidine suppress the appetite without affecting the brain histamine concentration. We also observed that serum zinc concentration, a mineral which is important for normal palate, was not affect by the D-His administration. Thus, we show for the first time that D-histidine may have an anti-appetite effect through an unknown pathway.