Proteins perform highly specialized functions in our body. They do most of the work in cells and are required for the structure, function, and regulation of the body’s tissues and organs. Basically, proteins are long chains of amino acids.
There are twenty different amino acids, and these amino acids can be combined into many different types of proteins. Nine of these amino acids the human body either cannot make at all or cannot make in sufficient quantity to meet its needs. These nine amino acids are called essential amino acids because they must come from food.
The non-essential amino acids are just as important as the essential amino acids, but the body can make them from other amino acids. However, sometimes a non-essential amino acid can become conditionally essential if , for example, the diet doesn’t provide enough of the amino acid it is made from, or if the body cannot make the conversion.
Proteins have numerous functions in the body. Some proteins function as building materials for body structures. The structure of all body cells require protein. Protein is used to build skin, body tissues, muscles, hair, and fingernails. Protein collagen forms the matrix for bones, teeth, ligaments and tendons. Protein collagen also repairs tissues.
Proteins function as enzymes. Enzymes are smaller proteins that catalyze or speed up chemical reactions. Enzymes are responsible for most of the chemical reactions in body cells. Enzymes often need vitamins or minerals for activation. About half of the protein we eat every day is used to make new enzymes. Some hormones are proteins. Hormones act like messengers turning on and off body processes in response to the body’s needs. Some hormones that are protein include insulin, thyroid hormone, histamine, adrenaline, and serotonin.
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.