A nutrient is a chemical element or substance that is used by an organism to survive and grow. At the level of chemical elements, all life-forms require carbon C, hydrogen H, nitrogen N, oxygen O, phosphorus P and sulfur S in relatively large amounts, but the chemical forms in which these elements are obtained differ greatly between organisms. Many other elements are necessary or beneficial in smaller quantities.
A distinction is often made between macronutrients, which are assimilated in large amounts, and micronutrients, which are only needed in small amounts. A nutrient is an essential nutrient for a particular species if it is absolutely required for the successful completion of the organism's life cycle and it must be obtained from an external source, either because the organism cannot synthesize it or because it cannot produce it in sufficient quantities.[1] Nutrient shortages are called deficiencies.[2]
Plants take in nutrients directly from the soil through their roots and from the atmosphere through their leaves. Animals and protists have specialized digestive systems that extract nutrients from food to provide energy (catabolism) and material for anabolism (constructive synthesis).
Human nutrition edit
Amino acids edit
Out of the twenty standard protein-producing amino acids, nine cannot be endogenously synthesized by humans: phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine.[3][4]
Fatty acids edit
Essential fatty acids (EFAs) are fatty acids that humans must ingest because the body requires them for good health but cannot synthesize them.[5] Only two fatty acids are known to be essential for humans: alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid).[6]
Vitamins edit
Vitamins are organic molecules essential for an organism that are not classified as amino acids or fatty acids. They commonly function as enzymatic cofactors, metabolic regulators or antioxidants. Humans require thirteen vitamins in their diet, most of which are actually groups of related molecules (e.g. vitamin E includes tocopherols and tocotrienols).[7]
Minerals edit
Minerals are the exogenous chemical elements indispensable for an organism which are not provided by the other essential nutrients. The elements provided by essential amino acids, fatty acids and vitamins are carbon, hydrogen, oxygen, nitrogen and sulfur. For humans, the "major minerals" are calcium, phosphorus, potassium, sodium, chlorine, and magnesium. "Minor minerals" include metals such as iron, zinc, manganese and copper.
Conditionally essential nutrients edit
Conditionally essential nutrients are certain organic molecules that can normally be synthesized by an organism, but under certain conditions such biosynthesis is not enough to prevent a deficiency syndrome. In humans, such conditions include prematurity, limited nutrient intake, rapid growth, and certain disease states.[8] Choline, inositol, taurine, arginine, glutamine and nucleotides are classified as conditionally essential and are particularly important in neonatal diet and metabolism.[8]
Animal nutrition edit
Plant nutrition edit
Plant nutrition is the study of the chemical elements and compounds necessary for plant growth, plant metabolism and their external supply. Plants can photosynthesize, using sunlight to convert carbon dioxide gas from the atmosphere into energy-rich carbon compounds that can be used in subsequent biochemical processes. Plant nutrition is therefore largely concerned with the supply of inorganic compounds.
References edit
- ^ John Griffith Vaughan; Catherine Geissler; Barbara Nicholson; Elisabeth Dowle; Elizabeth Rice (2009). The new Oxford book of food plants. Oxford University Press US. pp. 212–. ISBN 978-0-19-954946-7. Retrieved 13 October 2010.
- ^ Audrey H. Ensminger (1994). Foods & nutrition encyclopedia. CRC Press. pp. 527–. ISBN 978-0-8493-8980-1. Retrieved 12 October 2010.
- ^ Young VR (1994). "Adult amino acid requirements: the case for a major revision in current recommendations" (PDF). J. Nutr. 124 (8 Suppl): 1517S–1523S. doi:10.1093/jn/124.suppl_8.1517S. PMID 8064412.
- ^ Dietary Reference Intakes: The Essential Guide to Nutrient Requirements, published by the Institute of Medicine's Food and Nutrition Board, currently available online at "Archived copy". Archived from the original on 2014-07-05. Retrieved 2014-07-14.
{{cite web}}: CS1 maint: archived copy as title (link) - ^ Robert S. Goodhart; Maurice E. Shils (1980). Modern Nutrition in Health and Disease (6th ed.). Philadelphia: Lea and Febinger. pp. 134–138. ISBN 0-8121-0645-8.
- ^ Whitney Ellie; Rolfes SR (2008). Understanding Nutrition (11th ed.). California: Thomson Wadsworth. p. 154.
- ^ Brigelius-Flohé R, Traber MG; Traber (1999). "Vitamin E: function and metabolism". FASEB J. 13 (10): 1145–1155. doi:10.1096/fasebj.13.10.1145. PMID 10385606. S2CID 7031925.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ a b Cite error: The named reference
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