Tryptophan is a nutritionally essential amino acid for humans because it cannot be synthesized sufficiently in the body. Besides serving as a building block for proteins, tryptophan is also critical to nervous and immune systems. Tryptophan and its metabolites (e.g., serotonin and melatonin) may regulate food intake, reproduction, immunity, neurological function, and anti-stress responses of humans.

In the paper of Amino Acid, researchers in the Institute of Subtropical Agriculture, Chinese Academy of Sciences (ISA) feed the rats (as a model for human) with either tryptophan at doses of 200 mg/kg body weight per day or saline (control group) for 7 days, so as to investigate the effects of tryptophan on protein metabolism.

The team found tryptophan supplementation enhanced protein accretion and reduced fat deposition and modulated intestinal microbial metabolism in the body of rats. “Our investigation has found more functions of tryptophan. Thus, adequate intake of this amino acid from the diet is crucial for growth, development, and health. This new founding should be taken into consideration to optimize our diets.” said Yulong Yin, an academician researcher at ISA and corresponding author on the paper. “Dietary supplementation tryptophan may be beneficial for (1) ameliorating health problems at various stages of the life cycle (e.g., fetal growth restriction, neonatal morbidity and mortality, weaning-associated intestinal dysfunction and wasting syndrome, obesity, diabetes, cardiovascular disease, the metabolic syndrome, and infertility); (2) optimizing efficiency of metabolic transformations to enhance muscle growth and athletic performance, while preventing excess fat deposition and reducing adiposity. Thus, tryptophan has important functions in both nutrition and health.”

The study entitled “Metabolomic analysis of amino acid and fat metabolism in rats with l-tryptophan supplementation” has been published in the July issue of Amino Acids, details could be found at http://dx.doi.org/10.1007/s00726-014-1823-y