Monosodium glutamate (MSG) is currently used as a flavor enhancer in human nutrition.Supplemental glutamate may impact metabolism.In this study,we investigate the effects of three doses of MSG (0.06,0.5 and 1.0 g/kg body weight/day) on several biochemical parameters.Results indicate that although MSG supplementation had little effects on body weight,it dose-dependently decreased serum free fatty acid concentration,and transiently increased the plasma concentrations of leucine,isoleucine,phenylalanine,alanine,glutamate and aspartate.MSG at the highest dose tested increased the plasma GLPl concentration whilst decreasing leptin concentration.In addition,MSG supplementation decreased plasma glutathion-S-transferase activity whilst increasing superoxide dismutase activity.In the colonic luminal content,MSG supplementation was able to increase acetate,propionate and butyrate concentrations.Although small intestine morphology was little affected by MSG supplementation,the expression of the EAACl glutamate transporter was slightly but significantly increased following supplementation with this flavor enhancer.It is concluded that MSG supplementation modifies nutrient plasma concentration,affects hormonal profile as well as plasma concentration of enzymes related to the control of reactive oxygen species.In addition,MSG supplementation increases the short-chain fatty acid colonic luminal concentrations and affect on small intestine mucosa morphology.The consequences of such biochemical changes in this experimental model is discussed.