The role of specific nutriments in sarcopenia associated with chronic diseases: A focus on cancer

In chronic diseases, a combination of decreased food intake and metabolic abnormalities can lead to skeletal muscle (SM) loss. Many studies have shown that a decrease in mass, density, or strength of SM is linked to decreased survival. SM wasting has also been associated with disease-specific outcomes, such as increased susceptibility to chemotherapy toxicities in cancer, postoperative complications for surgery, decreased cardiac function in heart failure patients, and increased encephalopathy for liver cirrhosis. But the main issue concerns the possibility of reducing or correcting these muscle disorders. In catabolic situations, which are often observed in chronic diseases, there is a reduced protein synthetic response to food intake which has been termed anabolic resistance. This anabolic resistance could in part be counteracted by increasing protein or amino acids (AAs) intake or by the administration of specific AAs. In cancer patients, studies showed that early in tumor evolution, there is a decrease in muscle protein anabolism and that by increasing protein intake or administration of specific AAs, this anabolic resistance could be reversed. Despite many similarities, there are many mechanisms underlying the development of sarcopenia in chronic diseases and it would be naive to imagine that a unique therapeutic strategy or a specific nutriment could minimize SM wasting for all clinical situations. Branched chain AA and leucine are theoretically good nutriment candidates; however, the methodology and the quality of the studies are too varied to make any firm recommendations. These nutritional treatments should be associated with several complementary treatments. Omega 3 fatty acids, physical activity, or antiinflammatory drugs are potentially important elements for increasing anabolic effects to result in a gain in muscle mass and improved function.