Q. How much protein should be in my diet?
A. According to the US Centers for Disease Control, most Americans get more protein than they need. The Recommended Dietary Allowances for adults aged 19-70 is 46 grams of protein for women and 56 grams of protein for men. Americans average about 15 percent of their calories from protein (or 75 grams in a 2,000-calorie diet).
Is all this protein good or bad? Frank Hu, a professor of nutrition and epidemiology at the Harvard School of Public Health, says that there is evidence that moderately high-protein diets help people lose weight, at least in the short term, and some studies have suggested they may lower heart disease risk.
But it’s hard to disentangle the effects of protein from other components of food. “We should not only care about the amount of protein,” Hu says, “but the type of protein and the so-called ‘protein package.’” Red meat, dairy products, and eggs may have lots of protein but also have saturated fats. Beans, seeds, whole grains, nuts, and fish provide more beneficial nutrients along with protein, and are often less calorie-dense.
Emerging research shows that getting a little extra protein may be helpful at older ages, as a way to stave off muscle loss and frailty with aging. But again, Hu says, focusing on protein from plant-based foods is best. “If there’s too much protein and it comes from animal sources, it may have other health consequences,” he says.