Sarcopenia, the gradual loss of muscle mass that can occur with aging, affects 15 percent of people over age 65, and 50 percent of people over age 80. As we lose muscle mass, we lose strength, and if we lose too much, our ability to function suffers. Fortunately, emerging research is shedding new light on the role dietary protein plays in maintaining muscle, functionality, and health as we age.
Some of this gradual, age-associated loss of muscle mass, strength, and function has to do with a decrease in activity, but not all of it. “Like many complex syndromes of older adults, many factors contribute to sarcopenia,” says Roger A. Fielding, PhD, director of the Human Nutrition Research Center on Aging (HNRCA) Nutrition, Exercise Physiology and Sarcopenia laboratory. “Decreased physical activity, hormonal changes, increase in low-grade inflammatory processes, and changes in dietary intake that include decline in protein intake are all involved.”
Protein and Muscle: The body’s ability to manufacture muscle from protein decreases a bit with aging, so increasing dietary protein—in concert with muscle-building exercise—could help to maintain muscle mass and strength. “We know that in extreme conditions of protein malnutrition people lose muscle mass pretty rapidly,” says Fielding. “But even in older individuals who are taking in protein around the recommended levels, consuming lower amounts of protein is associated with higher rate of muscle loss than consuming higher amounts of protein.”
Paul F. Jacques, DSc, a professor at the Friedman School of Nutrition Science and Policy and senior scientist at the HNRCA Nutritional Epidemiology Team, and his colleagues found higher protein intake may translate to less frailty, disability, or physical dysfunction “We found that higher protein intake was associated with a 30 percent lower risk of losing functional integrity with time,” says Jacques. “This is observational data, but it clearly demonstrates the potential importance of a higher protein diet.”