Effects of Protein Intake
In studies of older adult populations lower protein intake has been associated with lean mass loss. Animal protein supplementation studies in older adults have shown lean mass gains potentially related to amino acid composition.
In terms of mechanisms, evidence suggests that protein-related activation of the rapamycin complex 1 pathway may play a role, the authors suggested. The activity of this signaling pathway decreases with age.
Rapamycin, a compound used to prevent organ transplant rejection, has been associated with delayed aging. In the body, dietary protein and exercise activate this pathway, thereby stimulating muscle protein synthesis and possibly improving physical function.
As for the differential associations of plant and animal protein on the chronic disease domain of the healthy aging phenotype, Dr. Ardisson Korat and coauthors said plant protein has been associated with favorable levels of important risk factors for cardiometabolic diseases, such as reduced LDL cholesterol, lower blood pressure, and insulin sensitivity, as well as decreased levels of proinflammatory markers.
Conversely, total and animal protein intakes have been positively associated with concentrations of insulin-like growth factor 1, which is implicated in the growth of malignant cells in breast and prostate tissue.
This study is the first step in evaluating the long-term health effect of protein intake in midlife, the relevant development window for most chronic conditions, the NHS study authors said. More research is needed, however, to corroborate the study findings in other populations and identify underlying mechanisms.
This study was supported by the USDA Agricultural Research Service and the National Institutes of Health. The authors reported no conflicts of interest. The commentators disclosed no relevant competing interests.