Protein nutrition mediates lean body mass homeostasis in the aging warfighter

The demographic shift of the average age in the United States and worldwide mandates that careful attention be paid to the nutritional and health needs of all segments of our older adult population. Well-defined changes in body composition occur in aging animals and humans. Characteristic of this change is the age-associated decline in skeletal muscle mass, sarcopenia. Data from observational studies of dietary intake and body composition suggest that a substantial proportion of adults over the age of 60 y consume less than the U.S.-recommended dietary allowance for protein and that greater dietary protein intake appears to reduce the decline in lean/muscle mass with aging. Studies of acute ingestion of high-quality dietary protein in healthy older adults suggest that the age-related blunting of protein synthetic capacity can be overcome with increased dietary protein intake. However, studies on chronic administration of high-quality protein supplements in cohorts of older adults are more equivocal with respect to improving or preserving muscle mass. This review highlights selective aspects of protein supplementation in older adults.