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There are three principal classes of macronutrients: carbohydrate, protein and fat. [1] Macronutrients are defined as a class of chemical compounds which humans consume in relatively large quantities compared to vitamins and minerals which provide humans with energy.
The most important aspect and defining characteristic of protein from a nutritional standpoint is its amino acid composition. [2] Proteins are polymer chains made of amino acids linked together by peptide bonds. During human digestion, proteins are broken down in the stomach to smaller polypeptide chains via hydrochloric acid and protease actions.
Primary nutritional groups are groups of organisms, divided in relation to the nutrition mode according to the sources of energy and carbon, needed for living, growth and reproduction. The sources of energy can be light or chemical compounds; the sources of carbon can be of organic or inorganic origin.
Protein combining or protein complementing is a dietary theory for protein nutrition that purports to optimize the biological value of protein intake. According to the theory, individual vegetarian and vegan foods may provide an insufficient amount of some essential amino acids, making protein combining with multiple complementary foods necessary to obtain a meal with "complete protein".
In 2001, the American Heart Association’s Nutrition Committee issued a recommendation against some high-protein diets such as the Atkins diet and Protein Power. [5] The committee noted potential health risks of these diets and how there are no long-term scientific studies to support their efficacy and safety. [5]
In a plant-based diet there is the perceived issue of amino acid content of various individual foods. A satisfying diet however, will include minimum requirements of all essential amino acids . In addition to grains, such as corn, rice, or wheat, vegetable protein also occurs in legumes, which include beans and peanuts.
The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code.
This page was last edited on 24 October 2008, at 07:35 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may apply.