Diet - protein; Complete protein; Incomplete protein
When proteins are digested, amino acids are left. The human body needs a number of amino acids to break down food. Amino acids need to be eaten in large enough amounts for optimal health.
Amino acids are found in animal sources such as meats, milk, fish, soy, and eggs, as well as in plant sources such as beans, legumes, and nut butters. You do not need to eat animal products to get all the protein you need in your diet.
Amino acids are classified into three groups:
Essential amino acids cannot be made by the body, and must be supplied by food. They do not need to be eaten at one meal. The balance over the whole day is more important. The nine essential amino acids are:
Nonessential amino acids are made by the body from essential amino acids or in the normal breakdown of proteins. They include:
Conditional amino acids are usually not essential, except in times of illness and stress. They include:
Protein foods are no longer described as being "complete proteins" or "incomplete proteins."
Escott-Stump S. Nutrition and Diagnosis-Related Care. 6th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2008.
United States Department of Agriculture. Center for Nutrition Policy and Promotion. Dietary Guidelines for Americans. 2010. National Academy Press, Washington, DC, 2010.
National Academy of Sciences. Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academy Press. Washington, DC, 2005.
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