What are proteins? Proteins are made up of amino acids, which are a protein’s building blocks. Twenty different amino acids combine to form all the proteins the body needs. Some of these amino acids can’t be made by your body, so you have to get them from a food source: these are known as essential amino acids. Complete proteins such as milk, eggs, cheese, and meat sources provide these essential amino acids. An incomplete protein contains only small amounts of one or several amino acids.

What Proteins Do

Proteins are the body’s main building blocks, the vital nutrients that fuel the body’s ability to grow and maintain itself in good health and to help ward off infections. In fact, every cell in your body, including your skin, hair, and nails, contains proteins. Eating enough protein can also help you keep fit and trim and even lose a few unwanted pounds. Next to water, protein accounts for the largest component in your body. But your body’s proteins are in constant flux, always being renewed and replaced as your cells grow and repair themselves.

Protein Sources

Animal-based diets obviously provide plenty of protein, but eating a varied plant-based diet can, too. Dairy foods such as milk, cheese, and yogurt are excellent protein sources. Such nondairy sources as eggs, beans, and soy products, even fruits and seeds, contain enough proteins to round out the typical vegetarian diet.

How much protein do people need? According to the CDC, the recommended daily allowance (RDA) for protein for adult women is forty-six grams a day; for adult men, fifty-six grams a day. A well-planned and varied vegetarian diet for any age group will contain enough daily proteins. The USDA’s MyPyramid shows how vegetarians can get enough proteins if their diet includes beans; nuts; nut butters; peas; soy products; and, for lacto-ovó vegetarians, eggs.

Complementary Proteins

Because not all proteins are alike, some experts say that you need to build complete proteins by combining amino acids or protein sources so that you eat enough complete proteins. Complementary proteins are two or more incomplete protein sources that together provide adequate amounts of all the essential amino acids. Some experts insist that combining protein sources—say, combining rice with beans with their differing types of amino acids—provides all the essential amino acids.

Others disagree, saying that the myth of complementary proteins is just that, a myth. Eating a varied plant diet with ample calories assures vegetarians they are getting complete proteins. Who has the final say? For your needs, talk to a nutritionist.