Q: My son has decided to follow a vegan diet. He also works out regularly. Will he be able to get enough protein?
A: Diane L. McKay, PhD, an assistant professor at both the Friedman School of Nutrition Science and Policy, answers: “Never fear! A plant-based diet can provide all the protein the body needs.
“Proteins are built from 20 amino acids. The body can manufacture 11 of them, and the other nine (the essential amino acids) need to come from food. Animal proteins are ‘complete’—they have all nine essential amino acids in amounts the body needs. Most plant proteins are “incomplete” (missing one or more essential amino acids). But eating a variety of plant foods will supply all nine.
“Think of proteins as colorful LEGO® towers. During digestion, the towers are broken down into individual bricks (like proteins are broken into amino acids). The body uses these ‘bricks’ to build whatever proteins it needs. One ‘plant’ tower may be missing a blue brick, and another is missing a red brick, but once they are broken down, you still have a pile with all the colors. That is what happens when a grain is combined with a legume (think of rice and beans or hummus and pita). It was once thought that these foods needed to be eaten at the same time, but we now know getting a variety of foods over a day or two is fine.
“The key to getting enough protein (and other nutrients) on a vegan diet is to consume a variety of healthy choices. All plants have some protein, but beans, lentils, nuts, and seeds have the most (although it is incomplete). Soy is an exception. Like animal proteins, soy contains all the essential amino acids, so edamame, tofu, soymilk and tempeh are great choices. (Soymilk is the only plant-based milk with protein amounts and quality similar to cow’s milk.) Some grains, specifically quinoa and amaranth, are also complete proteins. As long as your son regularly eats a variety of protein-rich plant foods and meets his energy needs, he will be fine!”
Diane L. McKay, PhD, is director of Tufts University’s Friedman Online Graduate Certificate Programs and an assistant professor at the Friedman School of Nutrition Science and Policy. See her comments on getting adequate protein on a vegan diet on this page.
