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{{Short description|Substance that an organism uses to live}}
{{Redirect|Nutrients|nutrition in humans|Human nutrition|nutrition in animals|Animal nutrition|nutrition in plants|Plant nutrition|the journal|Nutrients (journal)}}
A '''nutrient''' is a [[Chemical substance|substance]] used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to [[animal]]s, [[plant]]s, [[fungus|fungi]], and [[protist]]s. Nutrients can be incorporated into cells for [[metabolism|metabolic purposes]] or [[excretion|excreted]] by cells to create non-cellular structures, such as [[hair]], [[scale (anatomy)|scales]], [[feather]]s, or [[exoskeleton]]s. Some nutrients can be metabolically converted to smaller molecules in the process of releasing energy, such as for [[carbohydrate]]s, [[lipid]]s, [[protein (nutrient)|protein]]s, and [[fermentation]] products ([[ethanol]] or [[vinegar]]), leading to end-products of water and [[carbon dioxide]]. All organisms require water. Essential nutrients for animals are the energy sources, some of the [[amino acid]]s that are combined to create [[protein]]s, a subset of [[fatty acid]]s, [[vitamin]]s and certain [[mineral (nutrient)|minerals]]. Plants require more diverse minerals absorbed through roots, plus carbon dioxide and oxygen absorbed through leaves. [[fungus|Fungi]] live on dead or living organic matter and meet nutrient needs from their host.

Different types of organisms have different essential nutrients. Ascorbic acid ([[vitamin C]]) is essential, meaning it must be consumed in sufficient amounts, to humans and some other animal species, but some animals and plants are able to synthesize it. Nutrients may be [[organic compound|organic]] or inorganic: organic compounds include most compounds containing carbon, while all other chemicals are inorganic. Inorganic nutrients include nutrients such as [[iron]], [[selenium]], and [[zinc]], while organic nutrients include, among many others, energy-providing compounds and vitamins.

A classification used primarily to describe nutrient needs of animals divides nutrients into [[list of macronutrients|macronutrients]] and [[micronutrient]]s. Consumed in relatively large amounts ([[gram]]s or [[ounce]]s), macronutrients (carbohydrates, [[fat]]s, proteins, water) are primarily used to generate energy or to incorporate into tissues for growth and repair. Micronutrients are needed in smaller amounts ([[milligram]]s or [[microgram]]s); they have subtle [[biochemistry|biochemical]] and [[physiology|physiological]] roles in cellular processes, like [[vascular smooth muscle|vascular functions]] or [[action potential|nerve conduction]]. Inadequate amounts of essential nutrients, or diseases that interfere with absorption, result in a deficiency state that compromises growth, survival and reproduction. Consumer advisories for dietary nutrient intakes, such as the United States [[Dietary Reference Intake]], are based on deficiency outcomes and provide macronutrient and micronutrient guides for both lower and [[Tolerable upper intake levels|upper limits]] of intake. In many countries, macronutrients and micronutrients in significant content are required by regulations to be displayed on food product labels. Nutrients in larger quantities than the body needs may have harmful effects. Edible plants also contain thousands of compounds generally called [[phytochemical]]s which have unknown effects on disease or health, including a diverse class with non-nutrient status called [[polyphenol]]s, which remain poorly understood as of 2017.

== Types ==
{{Main|Nutrition}}

=== Macronutrients ===
Macronutrients are defined in several ways.
* The [[chemical element]]s humans consume in the largest quantities are [[carbon]], [[hydrogen]], [[nitrogen]], [[oxygen]], [[phosphorus]], and [[sulphur]], summarized as [[CHNOPS]].
* The chemical compounds that humans consume in the largest quantities and provide bulk energy are classified as [[carbohydrate]]s, [[protein]]s, and [[fat]]s. Water must be also consumed in large quantities but does not provide caloric value.
* [[Calcium]], [[sodium]], [[potassium]], [[magnesium]], and [[chloride]] ions, along with phosphorus and sulfur, are listed with [[list of macronutrients|macronutrients]] because they are required in large quantities compared to [[micronutrient]]s, i.e., vitamins and other minerals, the latter often described as trace or ultratrace minerals.

Macronutrients provide energy:
* [[Carbohydrate]]s are compounds made up of types of [[sugar]]. Carbohydrates are classified according to their number of sugar units: [[monosaccharide]]s (such as [[glucose]] and [[fructose]]), [[disaccharide]]s (such as [[sucrose]] and [[lactose]]), [[oligosaccharide]]s, and [[polysaccharide]]s (such as [[starch]], [[glycogen]], and [[cellulose]]).
* [[Protein]]s are [[organic compound]]s that consist of [[amino acid]]s joined by [[peptide bond]]s. Since the body cannot manufacture some of the amino acids (termed [[essential amino acid]]s), the diet must supply them. Through digestion, [[protein]]s are [[protein catabolism|broken down]] by [[protease]]s back into free amino acids.
* [[Fat]]s consist of a [[glycerin]] molecule with three [[fatty acid]]s attached. Fatty acid molecules contain a -COOH group attached to unbranched [[hydrocarbon]] chains connected by single bonds alone ([[Saturated fat|saturated fatty acids]]) or by both double and single bonds ([[Unsaturated fat|unsaturated fatty acids]]). Fats are needed for construction and maintenance of [[cell membrane]]s, to maintain a stable body temperature, and to sustain the health of skin and hair. Because the body does not manufacture certain fatty acids (termed [[essential fatty acid]]s), they must be obtained through one's diet.
* [[Alcoholic drink|Ethanol]] is not an essential nutrient, but it does provide calories.The [[United States Department of Agriculture]] uses a figure of {{convert|6.93|kcal|lk=in|}} per gram of alcohol ({{convert|5.47|kcal|disp=or|abbr=on}} per [[millilitre|ml]]) for calculating food energy. For [[distilled spirit]]s, a standard serving in the U.S. is {{cvt|1.5|USoz|order=flip}}, which at 40% ethanol (80 [[Alcohol proof|proof]]) would be 14 grams and 98 calories.

{| class="wikitable"
|+
!Biomolecule
!Kilocalories per 1 gram
|Protein
|4
|-
|Carbohydrate
|4
|-
|Ethanol
|7
|-
|Fat
|9
|}

=== Micronutrients ===
Micronutrients support metabolism.
* [[Dietary mineral]]s are generally trace elements, salts, or ions such as copper and iron. Some of these minerals are essential to human metabolism.
* [[Vitamin]]s are organic compounds essential to the body. They usually act as [[coenzyme]]s or [[cofactor (biochemistry)|cofactors]] for various proteins in the body.

== Essentiality ==

=== Essential nutrients ===
{{anchor|Essential nutrients}}
An '''essential nutrient''' is a nutrient required for normal physiological function that cannot be synthesized in the body&nbsp;– either at all or in sufficient quantities&nbsp;– and thus must be obtained from a [[Diet (nutrition)|dietary]] source. Apart from [[water]], which is universally required for the maintenance of [[homeostasis]] in mammals, essential nutrients are indispensable for various cellular [[metabolic process]]es and for the maintenance and function of tissues and organs. The nutrients considered essential for humans comprise nine amino acids, two fatty acids, thirteen [[vitamin]]s, fifteen [[Mineral (nutrient)|minerals]] and [[choline]]. In addition, there are several molecules that are considered conditionally essential nutrients since they are indispensable in certain developmental and pathological states.

====Amino acids====
{{Main|Essential amino acid}}
An essential amino acid is an amino acid that is required by an organism but cannot be synthesized ''[[de novo synthesis|de novo]]'' by it, and therefore must be supplied in its diet. Out of the twenty standard protein-producing amino acids, nine cannot be [[endogenous]]ly synthesized by humans: [[phenylalanine]], [[valine]], [[threonine]], [[tryptophan]], [[methionine]], [[leucine]], [[isoleucine]], [[lysine]], and [[histidine]].

====Fatty acids====
{{Main|Essential fatty acid}}
Essential fatty acids (EFAs) are [[fatty acid]]s that humans and other animals must ingest because the body requires them for good health but cannot [[Biosynthesis|synthesize]] them. 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]]).

====Vitamins====
{{Main|Vitamin}}
Vitamins are organic molecules essential for an organism that are not classified as amino acids or fatty acids. They commonly function as [[enzymatic cofactor]]s, metabolic regulators or [[antioxidant]]s. Humans require thirteen vitamins in their diet, most of which are actually groups of related molecules (e.g. [[vitamin E]] includes [[tocopherol]]s and [[tocotrienol]]s): vitamins A, C, D, E, K, [[thiamine]] (B<sub>1</sub>), [[riboflavin]] (B<sub>2</sub>), [[Niacin (nutrient)|niacin]] (B<sub>3</sub>), [[pantothenic acid]] (B<sub>5</sub>), [[pyridoxine]] (B<sub>6</sub>), [[biotin]] (B<sub>7</sub>), [[folate]] (B<sub>9</sub>), and [[cobalamin]] (B<sub>12</sub>). The requirement for vitamin D is conditional, as people who get sufficient exposure to ultraviolet light, either from the sun or an artificial source, synthesize vitamin D in the skin.

====Minerals====
{{Main|Mineral (nutrient)}}
Minerals are the [[exogenous]] [[chemical element]]s indispensable for life. Although the four elements: [[carbon]], [[hydrogen]], [[oxygen]], and [[nitrogen]], are essential for life, they are so plentiful in food and drink that these are not considered nutrients and there are no recommended intakes for these as minerals. The need for nitrogen is addressed by requirements set for protein, which is composed of nitrogen-containing amino acids. [[Sulfur]] is essential, but again does not have a recommended intake. Instead, recommended intakes are identified for the sulfur-containing amino acids methionine and cysteine.

The essential nutrient elements for humans, listed in order of [[Reference Daily Intake|Recommended Dietary Allowance]] (expressed as a mass), are [[potassium]], [[chloride]], [[sodium]], [[calcium]], [[phosphorus]], [[magnesium]], [[iron]], [[zinc]], [[manganese]], [[copper]], [[iodine]], [[chromium]], [[molybdenum]], [[selenium]]. Additionally, [[cobalt]] is a component of Vitamin B<sub>12</sub> which is essential. There are other minerals which are essential for some plants and animals, but may or may not be essential for humans, such as [[boron]] and [[silicon]].

====Choline====
{{Main|Choline}}
Choline is an essential nutrient. The cholines are a family of water-soluble [[quaternary ammonium compound]]s. Choline is the parent compound of the cholines class, consisting of ethanolamine having three methyl substituents attached to the amino function. Healthy humans fed artificially composed diets that are deficient in choline develop fatty liver, liver damage, and muscle damage. Choline was not initially classified as essential because the human body can produce choline in small amounts through phosphatidylcholine metabolism.

=== Conditionally essential ===
Conditionally essential nutrients are certain organic molecules that can normally be synthesized by an organism, but under certain conditions in insufficient quantities. In humans, such conditions include [[Preterm birth|premature birth]], limited nutrient intake, rapid growth, and certain disease states. [[Inositol]], [[taurine]], [[arginine]], [[glutamine]] and [[nucleotides]] are classified as conditionally essential and are particularly important in neonatal diet and metabolism.

=== Non-essential ===
Non-essential nutrients are substances within foods that can have a significant impact on health. Insoluble [[dietary fiber]] is not absorbed in the human digestive tract, but is important in maintaining the bulk of a [[bowel movement]] to avoid [[constipation]]. [[Soluble fiber]] can be metabolized by bacteria residing in the large intestine. Soluble fiber is marketed as serving a [[Prebiotic (nutrition)|prebiotic]] function with claims for promoting "healthy" intestinal bacteria. Bacterial metabolism of soluble fiber also produces [[short-chain fatty acid]]s like [[butyric acid]], which may be absorbed into intestinal cells as a source of [[food energy]].

===Non-nutrients===
[[Ethanol]] (C<sub>2</sub>H<sub>5</sub>OH) is not an essential nutrient, but it does supply approximately {{convert|7|kcal|kJ|order=flip|abbr=off}} of food energy per gram. For spirits (vodka, gin, rum, etc.) a standard serving in the United States is {{convert|1+1/2|USfloz|ml|order=flip|abbr=off}}, which at 40%{{nbsp}}ethanol (80{{nbsp}}proof) would be 14 grams and {{convert|98|kcal|kJ|order=flip|abbr=on}}. At 50%{{nbsp}}alcohol, 17.5&nbsp;g and {{convert|122.5|kcal|kJ|order=flip|abbr=on}}. Wine and beer contain a similar amount of ethanol in servings of {{convert|5|and|12|USfloz|mL|order=flip|abbr=on}}, respectively, but these beverages also contribute to food energy intake from components other than ethanol. A {{convert|5|USfloz|mL|order=flip|abbr=on}} serving of wine contains {{convert|100|to|130|kcal|kJ|order=flip|abbr=on}}. A {{convert|12|USfloz|mL|order=flip|abbr=on}} serving of beer contains {{convert|95|to|200|kcal|kJ|order=flip|abbr=on}}. According to the U.S. Department of Agriculture, based on [[NHANES]] 2013–2014 surveys, women ages 20 and up consume on average 6.8{{nbsp}}grams of alcohol per day and men consume on average 15.5 grams per day. Ignoring the non-alcohol contribution of those beverages, the average ethanol contributions to daily food energy intake are {{convert|48|and|108|kcal|kJ|order=flip|abbr=on}}, respectively. Alcoholic beverages are considered [[empty calorie]] foods because, while providing energy, they contribute no essential nutrients.

By definition, [[phytochemical]]s include all nutritional and non-nutritional components of edible plants. Included as nutritional constituents are [[provitamin]] A [[carotenoid]]s, whereas those without nutrient status are diverse [[polyphenol]]s, [[flavonoid]]s, [[resveratrol]], and [[lignan]]s – often claimed to have [[antioxidant]] effects – that are present in numerous plant foods. A number of phytochemical compounds are under preliminary research for their potential effects on human diseases and health. However, the qualification for nutrient status of compounds with poorly defined properties ''[[in vivo]]'' is that they must first be defined with a [[Dietary Reference Intake]] level to enable accurate food labeling, a condition not established for most phytochemicals that are claimed to be antioxidant nutrients.

==Deficiencies and toxicity==
''See [[Vitamin]], [[Mineral (nutrient)]], [[Protein (nutrient)]]''

An inadequate amount of a nutrient is a deficiency. Deficiencies can be due to a number of causes including an inadequacy in nutrient intake, called a dietary deficiency, or any of several conditions that interfere with the utilization of a nutrient within an organism. 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. Nutrient toxicity occurs when excess consumption of a nutrient does harm to an organism.

In the United States and Canada, recommended dietary intake levels of essential nutrients are based on the minimum level that "will maintain a defined level of nutriture in an individual", a definition somewhat different from that used by the [[World Health Organization]] and [[Food and Agriculture Organization]] of a "basal requirement to indicate the level of intake needed to prevent pathologically relevant and clinically detectable signs of a dietary inadequacy".

In setting human nutrient guidelines, government organizations do not necessarily agree on amounts needed to avoid deficiency or maximum amounts to avoid the risk of toxicity. For example, for [[vitamin C]], recommended intakes range from 40&nbsp;mg/day in India to 155&nbsp;mg/day for the European Union. The table below shows U.S. Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for vitamins and minerals, PRIs for the European Union (same concept as RDAs), followed by what three government organizations deem to be the safe upper intake. RDAs are set higher than EARs to cover people with higher than average needs. Adequate Intakes (AIs) are set when there is not sufficient information to establish EARs and RDAs. Countries establish [[tolerable upper intake levels]], also referred to as upper limits (ULs), based on amounts that cause adverse effects. Governments are slow to revise information of this nature. For the U.S. values, with the exception of calcium and vitamin D, all of the data date from 1997 to 2004.

{| class="wikitable"
|-
! rowspan="2"|Nutrient !! rowspan="2"|U.S. EAR !! rowspan="2"|Highest U.S.<br>RDA or AI !! rowspan="2"|Highest EU<br>PRI or AI!! colspan="3"|Upper limit !! rowspan="2"|Unit
|-
! U.S. !! EU  !! Japan
|-
| [[Vitamin A]] || 625 || 900 || 1300 || 3000 || 3000 || 2700 || µg
|-
| [[Vitamin C]] || 75 || 90 || 155 || 2000 || ND || ND || mg
|-
| [[Vitamin D]] || 10 || 15 || 15 || 100 || 100 || 100 || µg
|-
| [[Vitamin K]] || NE || 120 || 70 || ND || ND || ND || µg
|-
| [[Tocopherol|α-tocopherol]] (Vit E) || 12 || 15 || 13 || 1000 || 300 || 650-900 || mg
|-
| [[Thiamin]] (Vit B<sub>1</sub>) || 1.0 || 1.2 || 0.1&nbsp;mg/MJ || ND || ND || ND || mg
|-
| [[Riboflavin]] (Vit B<sub>2</sub>) || 1.1 || 1.3 || 2.0 || ND || ND || ND || mg
|-
| [[Niacin (nutrient)|Niacin]]* (Vit B<sub>3</sub>) || 12 || 16 || 1.6&nbsp;mg/MJ || 35 || 10 || 60-85 || mg
|-
| [[Pantothenic acid]] (Vit B<sub>5</sub>) || NE || 5 || 7 || ND || ND || ND || mg
|-
| [[Vitamin B6|Vitamin B<sub>6</sub>]] || 1.1 || 1.3 || 1.8 || 100 || 25 || 40-60 || mg
|-
| [[Biotin]] (Vit B<sub>7</sub>) || NE || 30 || 45 || ND || ND || ND || µg
|-
| [[Folate]] (Vit B<sub>9</sub>) || 320 || 400 || 600 || 1000 || 1000 || 900-1000 || µg
|-
| [[Cobalamin]] (Vit B<sub>12</sub>) || 2.0 || 2.4 || 5.0 || ND || ND || ND || µg
|-
| [[Choline]] || NE || 550 || 520 || 3500 || ND || ND || mg
|-
| [[Calcium]] || 800 || 1000 || 1000 || 2500 || 2500 || 2500 || mg
|-
| [[Chloride]] || NE || 2300 || NE || 3600 || ND || ND || mg
|-
| [[Chromium]] || NE || 35 || NE || ND || ND || ND || µg
|-
| [[Copper]] || 700 || 900 || 1600 || 10000 || 5000 || 10000 || µg
|-
| [[Fluoride]] || NE || 4 || 3.4 || 10 || 7 || ____ || mg
|-
| [[Iodine]] || 95 || 150 || 200 || 1100 || 600 || 3000 || µg
|-
| [[Iron]] || 6 || 18 <small>(females)</small><br>8<small> (males)</small> || 16 <small>(females)</small><br>11<small> (males)</small> || 45 || ND || 40-45 || mg
|-
| [[Magnesium]]* || 350 ||  420 || 350 || 350 || 250 || 350 || mg
|-
| [[Manganese]] || NE || 2.3 || 3.0 || 11 || ND || 11 || mg
|-
| [[Molybdenum]] || 34 || 45 || 65 || 2000 || 600 || 450-550 || µg
|-
| [[Phosphorus]] || 580 || 700 || 640 || 4000 || ND || 3000 || mg
|-
| [[Potassium]] || NE || 4700 || 4000 || ND || ND || 2700-3000 || mg
|-
| [[Selenium]] || 45 || 55 || 70 || 400 || 300 || 330-460 || µg
|-
| [[Sodium]] || NE || 1500 || NE || 2300 || ND || 3000-3600 || mg
|-
| [[Zinc]] || 9.4 || 11 || 16.3 || 40 || 25 || 35-45 || mg
|}

<nowiki>*</nowiki> The daily recommended amounts of niacin and magnesium are higher than the tolerable upper limit because, for both nutrients, the ULs identify the amounts which will not increase risk of adverse effects when the nutrients are consumed as a serving of a dietary supplement. Magnesium supplementation above the UL may cause diarrhea. Supplementation with niacin above the UL may cause flushing of the face and a sensation of body warmth. Each country or regional regulatory agency decides on a safety margin below when symptoms may occur, so the ULs may differ based on source.

'''EAR''' U.S. Estimated Average Requirements.

'''RDA''' U.S. Recommended Dietary Allowances; higher for adults than for children, and may be even higher for women who are pregnant or lactating.

'''AI'''  U.S. Adequate Intake; AIs established when there is not sufficient information to set EARs and RDAs.

'''PRI''' Population Reference Intake is European Union equivalent of RDA; higher for adults than for children, and may be even higher for women who are pregnant or lactating. For Thiamin and Niacin, the PRIs are expressed as amounts per megajoule (239 kilocalories) of food energy consumed.

'''Upper Limit'''  Tolerable upper intake levels.

'''ND'''  ULs have not been determined.

'''NE'''  EARs, PRIs or AIs have not yet been established or will not be (EU does not consider chromium an essential nutrient).

==Plant==
{{Main|Plant nutrition|Fertilizer}}

Plant nutrients consist of more than a dozen minerals absorbed through roots, plus carbon dioxide and oxygen absorbed or released through leaves. All organisms obtain all their nutrients from the surrounding environment.

Plants absorb carbon, hydrogen and oxygen from air and soil in the form of [[carbon dioxide]] and water. Other nutrients are absorbed from soil (exceptions include some parasitic or carnivorous plants). Counting these, there are 17 important nutrients for plants: these are macronutrients; nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sulfur (S), magnesium (Mg), carbon (C), oxygen(O) and hydrogen (H), and the micronutrients; iron (Fe), boron (B), chlorine (Cl), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo) and nickel (Ni). In addition to carbon, hydrogen and oxygen; [[nitrogen]], [[phosphorus]], and [[sulfur]] are also needed in relatively large quantities. Together, the "Big Six" are the elemental '''macronutrients''' for all [[biological life|organisms]].
They are sourced from inorganic matter (for example, [[carbon dioxide]], [[water]], [[nitrate]]s, [[phosphate]]s, [[sulfate]]s, and [[diatomic molecule]]s of nitrogen and, especially, oxygen) and organic matter ([[carbohydrate]]s, [[lipid]]s, [[protein]]s).

== See also ==<!-- Please respect alphabetical order -->
{{Columns-list|colwidth=30em|
* [[Food composition]]
* [[Nutrient cycle]]
* [[Nutrient density]]
* [[Nutrition]]
* [[Nutritionism]]
* [[List of macronutrients]]
* [[List of micronutrients]]
* [[List of phytochemicals in food]]
* [[River Continuum Concept]]
* [[Table of food nutrients]]
}}

== External links ==
{{Commons category|Nutrients}}
* [https://web.archive.org/web/20161008111338/https://fnic.nal.usda.gov/sites/fnic.nal.usda.gov/files/uploads/recommended_intakes_individuals.pdf USDA. Dietary Reference Intakes]

{{二次利用|date=11 December 2022}}
[[Category:Chemical oceanography]]
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[[Category:Nutrients| ]]
[[Category:Edaphology]]
[[Category:Biology and pharmacology of chemical elements]]
[[Category:Nutrition]]
[[Category:Essential nutrients]]