Complementary Proteins

By: Nikki Nies

We all know there are simple and complex carbohydrates, but how many people are familiar with the different types of proteins? Yes, not all proteins are made the same! Complement proteins, made of amino acids, are those that come together to form a higher quality protein. There are twenty amino acids, with ten considered essential to be obtained from the body as the body can not produce them. These include valine, leucine, isoleucine, methionine, cysteine, phenylalanine, tyrosine, tryptophan, threonine and lysine. Limiting amino acids, such as cysteine, tryptophan, cysteine and methionine’s intake are monitored since if diet becomes too low in one of the amino acids, it will limit usefulness of other amino acids consumed. For example, while beans are high in lysine, they are low in methionine and cysteine. While grains are high lysine, they are low in methionine and cysteine, making eating grains and beans at the same meal a great pairing, called complementary proteins.

A vegetarian requires complementary proteins from foods in order to obtain the complete package of essential amino acids. Vegetarians obtain their protein sources from vegetable sources, which do not always contain all the essential amino acids in adequate amounts. Besides soy protein, plant proteins are not complete protein sources. Therefore, by pairing incomplete protein foods (i.e. beans and rice together), it forms complementary proteins and ensures one obtains enough of the limiting amino acids.

The best way to ensure you’re obtaining all necessary vitamins and minerals in your daily meals is to keep a variety of foods on hand. Of course, protein can be found in beans, nuts, nut butters, peas and soy products. Aside from all of the essential amino acids, people on a vegan diet also need adequate intake of iron, calcium, zinc and vitamin B-12, which are found abundantly in animal foods. Leafy greens, dried fruits and fortified breakfast cereals will help you to add these important nutrients to the vegan diet.

While all animal proteins, soy and quinoa are complete proteins, other plant based proteins, such as whole grains, beans and nuts are incomplete, but when combined with other foods forms essential amino acid. Legumes, such as peas, lentils, peanuts and beans, are great to eat when paired with whole grains. Some common combinations include black bean and corn salad with brown rice, split pea soup with barley, peanut butter on whole wheat toast and/or pinto beans in a whole wheat pita. Legumes provide an essential amino acid called lysine, which is low in many grains. Whole grains provide methionine and cysteine, which are low in legumes, or beans, peas, lentils and peanuts.

Lacto-ovo vegetarians may have an easier time pairing foods since they eat dairy and eggs, which are great sources of complete proteins.