The quality of vegetable proteins can be improved by combining different plant proteins. Combine one plant protein that is low in one amino acid, with another plant protein that is high in that amino acid complement each other. Another way to complement a plant protein is to combine it with a small amount of animal protein. When complementary proteins are eaten together or within the course of the day all essential amino acids are provided.
Wheat and rice are low in lysine, an essential amino acid. Beans are low in methionine, another essential amino acid. Since both contain reasonable amounts of the other essential amino acids, rice and beans, or peanut butter and bread complement each other to make a complete protein. Combining either plant protein with an animal protein source such as macaroni and cheese also makes a complete protein mixture. For example, Corn is low in two amino acids; lysine and tryptophane.
Combining beans or other legumes with corn adds these two amino acids to corn and makes a complete protein. Pinto beans and corn bread, beans and corn tortillas are complementary protein mixtures.
If more protein is consumed than the body needs to build or repair body tissues or to provide energy they are converted by the body into fat and stored for later use. In this process nitrogen groups are removed from the amino acids which are converted into urea and removed from the body by the kidneys.
Most Americans do not suffer from a lack of protein. The Recommended Dietary Allowance for adults for protein is 0.8 grams protein per kilogram body weight. The Dietary Guidelines for Americans recommend that about 12 to 15% of our daily calories is recommended to come from protein. Adequate protein needs can easily be met by following the Food Guide Pyramid. For example, six bread, cereal, rice or pasta servings provide about 18 grams of protein; 3 vegetable servings provide 6 grams of protein; 2 milk servings provide 16 grams of protein; and 2 meat or meat alternative servings provide about 35 grams of protein. This totals to 75 grams of protein which is higher than recommendations for most people.
Many individuals limit meat and dairy foods to lower fat and cholesterol or for weight loss. However, lowering fat in the diet doesn’t mean omitting meat and dairy products. These foods are part of a well balanced diet.
Protein and amino acid supplements are promoted for a variety of reasons. Protein and amino acid supplements don’t perform miracles and they can cause harm. For example many claims are made regarding protein or amino acid supplements building muscles; however, using muscles builds muscles, not taking supplements. In foods, protein is not found as single amino acids, and single amino acids do not offer any benefit to the body.