Healthy eating is critical for health and well-being. Ingestion of a protein-rich meal can lead to a systemic increase in amino acid availability, which can directly stimulate the rate of muscle protein synthesis. Protein or protein-rich food is an effective but inexpensive way for increasing muscle mass. In this regard, it seems to be a practical strategy for maintaining muscle protein synthesis when facing the challenge of sarcopenia. But is it? Can low-protein diets achieve the same effects?

Recently, a team of researchers from China Agricultural University and the Institute of Subtropical Agriculture, Chinese Academy of Sciences (ISA) together conducted a study to investigate the effects of reduced dietary protein levels on the free amino acid profile and mRNA expression of the selected amino acid transceptors in different fiber type of skeletal muscle (longissimus dorsi, psoas major, biceps femoris) of growing pigs.

The researchers found that reducing the dietary protein level by 3 points of percentage less than recommended level could upregulate the mRNA expression of amino acid transeptors and enhance the absorption of free amino acid, which may promote protein synthesis in skeletal muscle of growing pigs. Accordingly, there was no difference in the weights of different types of skeletal muscle between pigs fed those low-protein diets and those fed diets with recommended protein levels. There seems to be a relationship between amino acid transceptors response to the dietary protein level in skeletal muscle tissue of different fiber type. This would be helpful for low-protein diets to achieve the same effects as high-protein diets.

The research was the jointly supported by National Basic Research Program of China (2013CB127305, 2012CB124704), National Nature Science Foundation of China (31372325, 31110103909, 31330075), Youth Innovation Promotion Association CAS (2015), Nature Science Foundation of Hunan Province (2015JJ2146) and The Chinese Academy of Science STS Project (KFJ-EW-STS-063).

The study entitled "Reduced dietary protein level influences the free amino acid and gene expression profiles of selected amino acid transceptors in skeletal muscle of growing pigs" has been published in April 2016 of Journal of Animal Physiology and Animal Nutrition, details could be found at http://onlinelibrary.wiley.com/doi/10.1111/jpn.12514/full.