Protein restriction exerts wide effects on cellular processes, including amino acid metabolism, energy metabolism, autophagy, inflammation, immune response, signaling pathways, and gut microbiota.
A research team led by Prof. YIN Yulong from the Institute of Subtropical Agriculture (ISA) of the Chinese Academy of Sciences found that long-term protein restriction improved host metabolism and gut microbiota in pig model. In addition, it is reported that protein restriction is an effective strategy for preventing and promoting health span from yeast to human.
In their study, researchers further summarized the increasingly sophisticated understanding of protein restriction with focuses on metabolic reprogramming in cancers.
They indicated that metabolic disorders (especially for amino acid metabolism), autophagy, and specific signaling pathways, for example, insulin-like growth factor 1, mammalian target of rapamycin, and fibroblast growth factor 21 were widely noticed or altered in cancer cells and cancer patients, which, in turn, further mediated cancer metabolism and proliferation.
Meanwhile, evidence demonstrated that dietary low-protein diets could reverse cancer metabolism, tumor growth, and overall mortality by metabolic reprograming and stimulation of specific nutrient signaling pathways (Figure 1), suggesting a prevention and therapeutic potential for cancer patients.
However, the researchers highlighted that caution must be exercised to avoid low protein diets in old people (age > 65), as low protein diets failed to provide enough amino acids and become malnourished in older subjects with lowered absorbing and metabolic abilities.
The research was supported by the National Key R&D Program of China, National Basic Research Program of China (973), National Natural Science Foundation of China, Hunan Key Research Program, and China Agriculture Research System.
Their studies entitled "Effects of Long-Term Protein Restriction on Meat Quality, Muscle Amino Acids, and Amino Acid Transporters in Pigs" and "Protein restriction and cancer" were published in Journal of Agricultural and Food Chemistry and NCBI, respectively.
Figure 1: Working model of protein restriction in cancers. Five pathways are mainly involved in the mechanism of protein restriction in cancers, including FGF21, IGF-1, mTOR, amino acid reprograming, and autophagy. (Imaged by ISA)
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