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A nutrient is a component in foods that an organism uses to survive and grow. Macronutrients provide the bulk energy an organism's metabolic system needs to function while micronutrients provide the necessary cofactors for metabolism to be carried out. Both types of nutrients can be acquired from the environment.[1] Micronutrients are used to build and repair tissues and to regulate body processes while macronutrients are converted to, and used for, energy. Methods of nutrient intake are different for plants and animals. 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 work to break down macronutrients for energy and utilize micronutrients for both metabolism and anabolism (constructive synthesis) in the body.

Organic nutrients consist of carbohydrates, fats, proteins (or their building blocks, amino acids), and vitamins. Inorganic chemical compounds such as dietary minerals, water (H2O), and oxygen may also be considered nutrients.[2] A nutrient is considered essential if it must be obtained from an external source either because the organism cannot synthesize it or because insufficient quantities are produced. Nutrients needed in very small amounts are called micronutrients while those needed in large quantities are called macronutrients. The effects of nutrients are dose-dependent; shortages are called deficiencies.[3]


Types of nutrientEdit

Good sources of magnesium: bran muffins, pumpkin seeds, barley, buckwheat flour, low-fat vanilla yogurt, trail mix, halibut steaks, garbanzo beans, lima beans, soybeans, and spinach

Macronutrients are defined in several different ways.[4]

Substances that provide energyEdit

Although alcohol provides energy, and can thus be compared to macronutrients, it is not a substance that is essential for normal function. The acetic acid in vinegar also provides a similar amount of energy per gram, but again, it is not a nutrient because it is not essential for normal function.

Fat has an energy content of 9 kcal/g (~37.7 kJ/g); proteins and carbohydrates 4 kcal/g (~16.7 kJ/g). Ethanol (grain alcohol) has an energy content of 7 kcal/g (~29.3 kJ/g).[5]

Substances that support metabolismEdit

  • Dietary minerals are generally trace elements, salts, or ions such as copper and iron. Some of these minerals are essential to human metabolism.
  • Vitamins are organic compounds essential to the body. They usually act as coenzymes or cofactors for various proteins in the body.
  • Water is an essential nutrient and is the solvent in which all the chemical reactions of life take place.
The strip of a green alga (Enteromorpha) along this shore indicates that there is a nearby source of nutrients (probably nitrates or ammonia from a small estuary).

Plants absorb nutrients from the soil or the atmosphere, or from water (mainly aquatic plants). An exception are the carnivorous plants, which externally digest nutrients from animals before ingesting them.[6]

The chemical elements consumed in the greatest quantities by plants are carbon, hydrogen, and oxygen. These are present in the environment in the form of water and carbon dioxide; energy is provided by sunlight.[7] Nitrogen, phosphorus, and sulfur are also needed in relatively large quantities. Together, the "Big Six" are the elemental macronutrients for all organisms,[8] often represented by the acronym CHNOPS.[9] Usually they are sourced from inorganic (e.g. carbon dioxide, water, nitrate, phosphate, sulfate) or organic (e.g. carbohydrates, lipids, proteins) compounds, although elemental diatomic molecules of nitrogen and (especially) oxygen are often used.

Other chemical elements are also necessary to carry out various life processes and build structures; see fertilizer and micronutrient for more information.

Rich sources of copper: oysters, beef or lamb liver, Brazil nuts, blackstrap molasses, cocoa, and black pepper. Good sources: lobster, nuts and sunflower seeds, green olives, and wheat bran.

Some of these are considered micronutrients in certain organisms. The mnemonic C. HOPKN'S CaFe Mg (to be used as C. Hopkins coffee mug) is used by some students to remember the list as: carbon, hydrogen, oxygen, phosphorus, potassium, nitrogen, sulfur, calcium, iron, and magnesium. Silicon, chloride, sodium, copper, zinc, and molybdenum are sometimes also included, but are in other cases considered micronutrients.[10]

Essential and non-essential nutrientsEdit

Nutrients are frequently categorized as essential and nonessential.

Essential nutrientsEdit

Essential nutrients are unable to be synthesized internally (either at all, or in sufficient quantities), and so must be consumed by an organism from its environment.[11]

For humans, these include essential fatty acids, essential amino acids, vitamins, and certain dietary minerals. Oxygen and water are also essential for human survival, but are generally not considered "food" when consumed in isolation. There are no "essential carbohydrates", animals can synthesize all the types of carbohydrates needed for growth.

Humans can derive energy from a wide variety of fats, carbohydrates, proteins, and simple chemicals such as ethanol and acetic acid.

Non-essential nutrientsEdit

Non-essential nutrients are substances within foods can still have a significant impact on health, whether beneficial or toxic. For example, dietary fiber is not absorbed by the human digestive tract, but is important in maintaining the bulk of a bowel movement to avoid constipation. A subset, known as soluble fiber, can be metabolized by bacteria residing in the large intestine. Soluble fiber is marketed as serving a Probiotic (nutrition) function - promoting 'healthy' intestinal bacteria - even though there is not yet a scientific consensus on benefits of probiotics. Bacterial metabolism of soluble fiber is also thought to product short-chain fatty acids, which may be absorbed into intestinal cells as sources of calories.[citation needed]

Nonessential nutrients are those nutrients that can be made by the body; they may often also be absorbed from consumed food.[11] The majority of animals ultimately derive their essential nutrients from plants,[11] though some animals may consume mineral-based soils to supplement their diet.

Interest has recently increased in phytochemicals, which include many non-essential substances which may or may not have health benefits.[1] These are not nutrients (or non-essential nutrients) by a strict definition, but labeling and marketing of dietary supplements can conflate these substances into a nutrients category.

Deficiencies and toxicityEdit

An inadequate amount of a nutrient is a deficiency. Deficiencies can be due to a number of causes including inadequacy in nutrient intake called dietary deficiency, or conditions that interfere with the utilization of a nutrient within an organism.[3] Some of the conditions that can interfere with nutrient utilization include problems with nutrient absorption, substances that cause a greater than normal need for a nutrient, conditions that cause nutrient destruction, and conditions that cause greater nutrient excretion.[3]

Nutrient toxicity occurs when an excess of a nutrient does harm to an organism.[12]

See alsoEdit


  1. ^ a b Whitney, Elanor and Sharon Rolfes. 2005. Understanding Nutrition, 10th edition, p 6. Thomson-Wadsworth.
  2. ^ FRANCES SIZER; ELLIE WHITNEY (12 November 2007). NUTRITION: CONCEPTS AND CONTROVERSIES. Cengage Learning. pp. 26–. ISBN 978-0-495-39065-7. Retrieved 12 October 2010. 
  3. ^ a b c Audrey H. Ensminger (1994). Foods & nutrition encyclopedia. CRC Press. pp. 527–. ISBN 978-0-8493-8980-1. Retrieved 12 October 2010. 
  4. ^ Mark Kern (12 May 2005). CRC desk reference on sports nutrition. CRC Press. pp. 117–. ISBN 978-0-8493-2273-0. Retrieved 12 October 2010. 
  5. ^ Coyle EF. 1995. Fat metabolism during exercise. Sports science exchange 8(6):59-65
  6. ^ David Sadava; H. Craig Heller; David M. Hillis; May Berenbaum (2009). Life: The Science of Biology. Macmillan. pp. 767–. ISBN 978-1-4292-1962-4. Retrieved 12 October 2010. 
  7. ^ J. Benton Jones (1998). Plant nutrition manual. CRC Press. pp. 34–. ISBN 978-1-884015-31-1. Retrieved 14 October 2010. 
  8. ^ New Link in Chain of Life, Wall Street Journal, 2010-12-03, accessed 2010-12-05. "Until now, however, they were all thought to share the same biochemistry, based on the Big Six, to build proteins, fats and DNA."
  9. ^ CHNOPS: The Six Most Abundant Elements of Life, Pearson BioCoach, 2010, accessed 2010-12-09. "Most biological molecules are made from covalent combinations of six important elements, whose chemical symbols are CHNOPS. ... Although more than 25 types of elements can be found in biomolecules, six elements are most common. These are called the CHNOPS elements; the letters stand for the chemical abbreviations of carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur."
  10. ^ Perry, David A (1994). Forest ecosystems. Baltimore: Johns Hopkins University Press. ISBN 978-0-8018-4987-9. 
  11. ^ a b c 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. 
  12. ^ "Nutrient Toxicity". Nutrition Reviews. 39 (6): 249–256. 2009. doi:10.1111/j.1753-4887.1981.tb07453.x. 

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