Protein helps repair and build muscle—that’s why it’s smart to recover after a hard workout with a smoothie, energy bites, or another high-protein snack. But until now, researchers haven’t been sure whether plant-based protein aids your tired muscles as well as meat. The results of a new study published today in the American Journal of Clinical Nutrition are good news for both vegetarians and meat eaters: Plant protein and animal protein appear to benefit muscle health equally.
Researchers looked at the health records of nearly 3,000 men and women ages 19 to 72, as well as food questionnaires that the participants filled out. The researchers estimated the participants’ total protein intake as well as their dietary percentages of protein from specific sources, such as fast food, full-fat or low-fat dairy, red meat, fish, chicken, and legumes. They also looked at participants’ lean muscle mass, bone mineral density, and quadriceps strength—all measures that are important for fitness, health, and better functioning, especially as we get older.
When the researchers compared this data, they found that people who consumed the least amount of protein overall also had the lowest measures of muscle mass and strength. But the type of protein people ate didn’t seem to matter: After the researchers adjusted for other factors, they found the differences in protein sources had no impacts on musculoskeletal health, for men or for women.
According to the study authors, these results suggest that eating more protein is related to better muscle health. This becomes especially important in middle-age and later in life, they add, since people tend to lose muscle as they get older. (Protein intake did not have a significant effect on bone-mineral density in this study, although it has in previous research.)
Lead author Kelsey Mangano, PhD, assistant professor of nutritional sciences at the University of Massachusetts Lowell, says the study delivers a message that meat and veggie lovers can both celebrate: “As long as a person is exceeding the recommended daily allowance for protein, no matter the source in their diet, they can improve their muscle health,” she says.
In other words, people who want to go meatless can still build muscle with the help of quinoa, peas, nuts, beans, and soy. And if you prefer to refuel after exercise with a turkey and cheese sandwich? That works too.
The study was observational in nature, so it was unable to draw any cause-and-effect conclusions—and since the participants’ age range was so broad, the findings should be replicated in older adults who tend to get less protein on a daily basis, says Mangano. (For people who don't consume enough protein, she speculates, the type they eat may become more important.)
It's also important to remember that the study only looked at bone and muscle health—just two components of good health overall. “When we think about our health as a whole it is important to decrease intakes of saturated fat, sodium, and added sugars,” says Mangano, who is also a registered dietitian.
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“Therefore, people should choose their protein sources keeping overall dietary recommendations in mind,” she continues. “Choose protein sources that are lean—limiting saturated fat—and also those that are low in sodium.” That means avoiding processed meats like bacon, for example.
When it comes to other benefits—like, say, living longer or losing weight—some studies have suggested that plant-based protein may have a bit of an edge. But when looking at the research as a whole, says Mangano, “there is no clear evidence whether animal or vegetable sources may be more beneficial for overall health.”