The Role of Protein in a Healthy Diet

Protein builds and maintains muscles, organs, connective tissues, skin, bones, teeth, blood, and your DNA (deoxyribonucleic acid). It helps the body heal when it is sick, wounded, or depleted. Without it, even mild exercise would weaken you to the point of exhaustion.

Protein contributes to the formation of enzymes. Almost all reactions that occur in the body, such as digestion, require enzymes. Enzymes are catalysts to these reactions, increasing the rate at which they occur.

There is protein in your blood, called antibodies. They serve as your body’s immune responders. They bind with and fight foreign invaders, like bacteria or toxins. Protein is found in hormones, your body’s chemical messengers. Hormones help regulate the body’s activities, maintaining balance, or homeostasis.


Soy, amaranth, and quinoa are the only plant species that contain complete protein. Soy is available in many forms, including beans, tofu, milk, and supplements. Amaranth and quinoa are grains available in health food stores, and many mainstream markets.

Amino Acids

Protein is composed of 20 amino acids. These acids link together in chains to form the variety of proteins your body needs. The length and shape of the chain determines the protein’s structure. Of the 20 amino acids, 11 of them are made by your body. These eleven acids are called nonessential because you do not need to consume them.

The remaining nine amino acids are called essential, and it is important that you eat these every day. Getting all nine essential amino acids is not hard, especially if you eat meat. Animal foods (which include meat, eggs, and dairy) contain the largest concentration of protein. Animal protein is considered complete, because it contains all nine essential amino acids.


Eating complementary protein means consuming both beans and grains every day. The beans can be pinto, kidney, black, lentils, garbanzo, split peas, or peanuts. Grains should be whole, including brown rice, whole-wheat pasta, bread, crackers, or tortillas. Sesame seeds also complement the protein of beans.

Plant foods also contain proteins, but few plants contain complete protein. This is one of the challenges of vegetarianism, because to stay healthy one must consume enough foods with the right mixture of amino acids. It sounds complicated, but grains, nuts, and legumes contain the proteins that are not found in other plants, so adding a variety of these to your diet does the trick.

Plant foods eaten in combination to create complete protein are called complementary proteins. When these foods are eaten over the course of a day, protein intake is complete. Protein derived from complementary plant proteins is considered a healthy alternative, and by many people, a superior one. Eating such combinations of plant foods not only completes the protein, but also provides other nutrients vital to good health as well, most notably fiber, vitamins, and minerals. And most plants do all that without saturated fat.

Cooking Protein

Cooked protein is also referred to as denatured. When denatured, protein changes its structure and stops functioning. In denaturation, the amino acids loosen, recoil, and tighten, which changes the appearance, texture, and flavor of the protein. If you watch an egg being cooked, you can see the denaturation happen within a minute or two as the albumen turns white.


Denaturation of protein doesn’t happen only in the kitchen. You’ve also seen it at your last visit to the beach. The waves break onto the sand, the tide rolls in and out, and that motion denatures the proteins in the sea water, creating sea foam.

Cooking protein does not necessarily require heat. Acid will denature protein, as it does in the Latin American dish seviche, in which seafood is marinated in lime. Salt is used to cook protein in cured meats, like ham, sausages, and salt cod. Pickled meats combine acid and salt for a double-whammy cooking method.

Even agitation can denature protein, as in the whipping of eggs. In this case prolonged agitation changes the egg’s structure, making it safe to eat. Meringue demonstrates this effect on the egg white, while yolks and whole eggs get this treatment in mayonnaise and emulsified salad dressings, like those used in Caesar salad.

Choosing Your Protein

People in the United States overconsume animal protein. To stay healthy and rebuild muscle the average adult needs only five to six ounces of complete protein each day. But a typical American diet consists of bacon and eggs for breakfast, a meat-filled sandwich for lunch, and a dinner featuring meat as its focus.

A healthy family needs a healthy diet of lean protein in moderation. Animal proteins are higher in fat and particularly saturated fat, which in turn makes them high in cholesterol. Plant foods, however, contain no cholesterol, less fat (in the form of plant oil), and lots of fiber.

Eating too little protein is not healthy, but neither is eating too much. Overeating protein does not build extra muscle. The protein your body does not utilize is stored as fat.

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