Background: The Chinese population has been undergoing a rapid transition to a high-fat diet.Furthermore,monosodium L-glutamate (MSG) is becoming widely used as a daily food additive.Since little information is available on the effects of oral MSG and dietary fat supplementation on the amino acid balance in tissues,we want to determine whether the interaction between fat and MSG influences amino acid metabolism in this study.Methods and results: Four equal nitrogen and equal digestive energy diets (basal diet,high fat diet,basal diet with 3% MSG and high fat diet with 3% MSG) are designed and be provided to growing pigs.By determining the status of amino acid absorption and distribution in tissues,the effects of dietary fat and MSG,both alone and in combination on amino acid pools in tissues in growing pigs were evaluated.Dietary fat and MSG each promoted the absorption of amino acids in jejunum.Dietary fat can enhance the amino acid pool in plasma and muscle,while MSG enhances the amino acid pool in the kidney.Conclusions: Both dietary fat and MSG clearly influence amino acid metabolism in solo.However,there was little interaction between the effects of dietary fat and MSG.