This story is a part of The Elemental Guide to Vitamins. Here are the vitamins and supplements that are covered: multivitamins, vitamin D, vitamin C, calcium, B vitamins, omega-3, vitamin E, fiber, protein, and probiotics.
The human diet is composed of three so-called “macronutrients.” These are fats, carbohydrates, and protein. Protein can come from plants or animals, and it’s made up of chains of amino acids, which the body uses to build, repair, and maintain muscle and tissue.
While diets heavy in unhealthy carbohydrates or fats are often implicated in the development of obesity and disease, a lot of evidence suggests eating protein comes with perks, especially for people who are trying to build muscle or lose weight. A 2008 review in the American Journal of Clinical Nutrition found that protein increases feelings of fullness more so than fat or carbs. Protein also revs up the body’s natural calorie-burning processes and helps maintain “fat-free mass,” which is another way of saying muscle. There’s also evidence that protein combined with weight training can help older adults avoid sarcopenia, a gradual loss of muscle that puts them at risk for falls, fractures, and debilitating weakness.
For all these reasons, a lot of people today supplement their diets with protein powders or other products even though recent research has found the diets of most Americans, and especially American men, are not low in protein. These supplements come in a vast array of flavors and formulas. One is whey protein, which comes from cow’s milk and is popular among athletes because it’s digested quickly and contains certain amino acids that promote muscle growth. Meanwhile, casein protein — which also comes from cow’s milk — has an amino acid profile that may help people burn calories even when they’re asleep.
By suffusing the diet with protein-packed foods and supplements, the hope is that these products will increase metabolism, snuff out hunger, and maximize exercise gains. And there’s evidence that protein can do all this and more. Based on these findings, some experts argue the average person should be consuming more protein, including protein from supplements.
Diets heavy in protein “may somewhat enhance muscle-building in the short term, but in the long term, you may be accelerating the onset of age-related diseases.”
“I’d recommend at least 1.2 grams [of protein] per kilogram of body weight per day, and there’s good evidence for benefits at intakes higher than that,” says Stuart Phillips, a professor and the director of the Centre for Nutrition, Exercise, and Health Research at Canada’s McMaster University. For a 160-pound adult, that works out to roughly 86 grams of protein per day. (A single medium-sized chicken breast contains roughly 35 grams of protein, and a small bowl of black beans packs about 25 grams.) The National Institutes of Health (NIH) says even higher protein intakes seem to be safe.
But not all researchers are gung ho about protein. Heavy intakes promote protein synthesis in the body, which helps build muscle, but there may be a downside. “We think increased protein synthesis can lead to dysfunction and damage of cells,” says Mark Mattson, a neuroscientist at the NIH and an adjunct professor at Johns Hopkins School of Medicine.
Mattson has conducted years of research on fasting diets and the effect of different eating patterns on cellular and metabolic health. He says that diets heavy in protein “may somewhat enhance muscle-building in the short term, but in the long term, you may be accelerating the onset of age-related diseases.”
There’s also evidence that heavy protein intakes may lead to unhealthy shifts in the makeup of the microbiome and the byproducts those gut microorganisms produce. While most of the research in this area is preliminary, “long-term protein supplementation may have a negative impact on gut microbiota of athletes and, consequently, have negative repercussions on athlete’s future health,” wrote the authors of a 2019 study published in the journal Nutrients.
The bottom line: Taken together, the evidence to date suggests that protein supplements come with benefits — especially in the short term — but maybe also some risks. Most people get enough protein through their diet, but for the average person, using protein powder as needed or desired is likely fine.
This story is a part of The Elemental Guide to Vitamins.