Anutrient is asubstance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies toanimals,plants,fungi andprotists. Nutrients can be incorporated into cells formetabolic purposes orexcreted by cells to create non-cellular structures such ashair,scales,feathers, orexoskeletons. Some nutrients can be metabolically converted into smaller molecules in the process of releasing energy such as forcarbohydrates,lipids,proteins andfermentation products (ethanol orvinegar) leading to end-products of water andcarbon dioxide. All organisms require water. Essential nutrients for animals are the energy sources, some of theamino acids that are combined to createproteins, a subset offatty acids,vitamins and certainminerals. Plants require more diverse minerals absorbed through roots, plus carbon dioxide and oxygen absorbed through leaves.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 to humans and some animal species but most other animals and many plants are able to synthesize it. Nutrients may beorganic or inorganic: organic compounds include most compounds containing carbon, while all other chemicals are inorganic. Inorganic nutrients include nutrients such asiron,selenium, andzinc, while organic nutrients include, protein, fats, sugars and vitamins.
A classification used primarily to describe nutrient needs of animals divides nutrients intomacronutrients andmicronutrients. Consumed in relatively large amounts (grams orounces), macronutrients (carbohydrates,fats, proteins, water) are primarily used to generate energy or to incorporate into tissues for growth and repair. Micronutrients are needed in smaller amounts (milligrams ormicrograms); they have subtlebiochemical andphysiological roles in cellular processes, likevascular functions ornerve 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 StatesDietary Reference Intake, are based on the amount required to prevent deficiency and provide macronutrient and micronutrient guides for both lower andupper limits of intake. In many countries, regulations require that food product labels display information about the amount of any macronutrients and micronutrients present in the food in significant quantities. Nutrients in larger quantities than the body needs may have harmful effects.[1] Edible plants also contain thousands of compounds generally calledphytochemicals which have unknown effects on disease or health including a diverse class with non-nutrient status calledpolyphenols which remain poorly understood as of 2024.
The chemical compounds that humans consume in the largest quantities and provide bulk energy are classified ascarbohydrates,proteins, andfats. Water must be also consumed in large quantities but does not provide caloric value.
Calcium,sodium,potassium,magnesium, andchloride ions, along with phosphorus and sulfur, are listed withmacronutrients because they are required in large quantities compared tomicronutrients, i.e., vitamins and other minerals, the latter often described as trace or ultratrace minerals.[3]
Fats consist of aglycerin molecule with threefatty acids attached. Fatty acid molecules contain a -COOH group attached to unbranchedhydrocarbon chains connected by single bonds alone (saturated fatty acids) or by both double and single bonds (unsaturated fatty acids). Fats are needed for construction and maintenance ofcell membranes, to maintain a stable body temperature, and to sustain the health of skin and hair. Because the body does not manufacture certain fatty acids (termedessential fatty acids), they must be obtained through one's diet.
Ethanol is not an essential nutrient, but it does provide calories. TheUnited States Department of Agriculture uses a figure of 6.93kilocalories (29.0 kJ) per gram of alcohol (5.47 kcal or 22.9 kJ perml) for calculating food energy.[4] Fordistilled spirits, a standard serving in the U.S. is 44 ml (1.5 US fl oz), which at 40% ethanol (80proof) would be 14 grams and 98 calories.
Dietary minerals, such aspotassium,sodium, andiron, are elements native toEarth, and cannot be synthesized. They are required in the diet inmicrogram ormilligram amounts. As plants obtain minerals from the soil, dietary minerals derive directly from plants consumed or indirectly from edible animal sources.[8]
Vitamins are organic compounds required inmicrogram ormilligram amounts.[9] The importance of each dietary vitamin was first established when it was determined that a disease would develop if that vitamin was absent from the diet.[9]
Anessential nutrient is a nutrient required for normal physiological function that cannot be synthesized in the body – either at all or in sufficient quantities – and thus must be obtained from adietary source.[10][11] Apart fromwater, which is universally required for the maintenance ofhomeostasis in mammals,[12] essential nutrients are indispensable for various cellularmetabolic processes and for the maintenance and function of tissues and organs.[13] The nutrients considered essential for humans comprise nine amino acids, two fatty acids, thirteenvitamins, fifteenminerals andcholine.[13] In addition, there are several molecules that are considered conditionally essential nutrients since they are indispensable in certain developmental and pathological states.[13][14][15]
Vitamins occur in a variety of related forms known asvitamers. The vitamers of a given vitamin perform the functions of that vitamin and prevent symptoms of deficiency of that vitamin. Vitamins are those essential organic molecules that are not classified as amino acids or fatty acids. They commonly function asenzymatic cofactors, metabolic regulators orantioxidants. Humans require thirteen vitamins in their diet, most of which are actually groups of related molecules (e.g.vitamin E includestocopherols andtocotrienols):[20] vitamins A, C, D, E, K,thiamine (B1),riboflavin (B2),niacin (B3),pantothenic acid (B5),pyridoxine (B6),biotin (B7),folate (B9), andcobalamin (B12). 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.[21]
Minerals are theexogenouschemical elements indispensable for life. Although the four elements:carbon,hydrogen,oxygen, andnitrogen (CHON) 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 acidsmethionine andcysteine.
Choline is an essential nutrient.[22][23][24] The cholines are a family of water-solublequaternary ammonium compounds.[25][26] Choline is the parent compound of the cholines class, consisting of ethanolamine having three methyl substituents attached to the amino function.[27] 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.[28]
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 includepremature birth, limited nutrient intake, rapid growth, and certain disease states.[14]Inositol,taurine,arginine,glutamine andnucleotides are classified as conditionally essential and are particularly important in neonatal diet and metabolism.[14]
Non-essential nutrients are substances within foods that can have a significant impact on health.Dietary fiber is not absorbed in the human digestive tract.[29]Soluble fiber is metabolized to butyrate and other short-chain fatty acids by bacteria residing in the large intestine.[30][31][32] Soluble fiber is marketed as serving aprebiotic function with claims for promoting "healthy" intestinal bacteria.[33]
Ethanol (C2H5OH) is not an essential nutrient, but it does supply approximately 29 kilojoules (7 kilocalories) of food energy per gram.[34] For spirits (vodka, gin, rum, etc.) a standard serving in the United States is 44 millilitres (1+1⁄2 US fluid ounces), which at 40%ethanol (80proof) would be 14 grams and 410 kJ (98 kcal). At 50%alcohol, 17.5 g and 513 kJ (122.5 kcal). Wine and beer contain a similar amount of ethanol in servings of 150 and 350 mL (5 and 12 US fl oz), respectively, but these beverages also contribute to food energy intake from components other than ethanol. A 150 mL (5 US fl oz) serving of wine contains 420 to 540 kJ (100 to 130 kcal). A 350 mL (12 US fl oz) serving of beer contains 400 to 840 kJ (95 to 200 kcal).[35]
According to the U.S. Department of Agriculture, based onNHANES 2013–2014 surveys, women ages 20 and up consume on average 6.8grams of alcohol per day and men consume on average 15.5 grams per day.[36] Ignoring the non-alcohol contribution of those beverages, the average ethanol contributions to daily food energy intake are 200 and 450 kJ (48 and 108 kcal), respectively. Alcoholic beverages are consideredempty calorie foods because, while providing energy, they contribute no essential nutrients.[34]
By definition,phytochemicals include all nutritional and non-nutritional components of edible plants.[37] Included as nutritional constituents areprovitamin Acarotenoids,[38] whereas those without nutrient status are diversepolyphenols,flavonoids,resveratrol, andlignans that are present in numerous plant foods.[39] Some phytochemical compounds are under preliminary research for their potential effects on human diseases and health.[37][38][39] However, the qualification for nutrient status of compounds with poorly defined propertiesin vivo is that they must first be defined with aDietary Reference Intake level to enable accurate food labeling,[40] a condition not established for most phytochemicals that are claimed to provide antioxidant benefits.[41]
An inadequate amount of a nutrient is a deficiency. Deficiencies can be due to several 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.[1] 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.[1] Nutrient toxicity occurs when excess consumption of a nutrient does harm to an organism.[42]
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 theWorld Health Organization andFood 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".[43]
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.[44][45][46] For example, forvitamin C, recommended intakes range from 40 mg/day in India[47] to 155 mg/day for the European Union.[48] 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 insufficient information to establish EARs and RDAs. Countries establishtolerable 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, except calcium and vitamin D, all data date from 1997 to 2004.[17]
* The daily recommended amounts of niacin and magnesium are higher than the tolerable upper limit because, for both nutrients, the ULs identify the amounts that will not increase the 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 occur so that the ULs may differ based on the source.[44][45]
EAR U.S. Estimated Average Requirements.
RDA U.S. Recommended Dietary Allowances; higher for adults than children and may be even higher for pregnant or lactating women.
AI U.S. Adequate Intake; AIs are established when there is insufficient information to set EARs and RDAs.
PRI Population Reference Intake is the European Union equivalent of RDA; it is higher for adults than for children and maybe even higher for pregnant or lactating women. 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).
Plants absorb carbon, hydrogen, and oxygen from air and soil ascarbon dioxide and water.[49] Other nutrients are absorbed from soil (exceptions include some parasitic or carnivorous plants). Counting these, there are 17 important nutrients for plants:[50] 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, andsulfur are also needed in relatively large quantities. Together, thesesix are the elemental macronutrients for allorganisms.[51]They are sourced from inorganic matter (for example, carbon dioxide, water,nitrates,phosphates,sulfates, anddiatomic molecules of nitrogen and, especially, oxygen) and organic compounds such as carbohydrates, lipids, proteins.
^abcCarver J (2006). "Conditionally essential nutrients: choline, inositol, taurine, arginine, glutamine and nucleotides". In Thureen PJ, Hay WW (eds.).Neonatal Nutrition and Metabolism. Cambridge, UK: Cambridge University Press. pp. 299–311.doi:10.1017/CBO9780511544712.020.ISBN9780511544712.
^Choline. The Metabolomics Innovation Centre, University of Alberta, Edmonton, Canada. 17 August 2016. Retrieved13 September 2016.{{cite encyclopedia}}:|website= ignored (help)
^ab"Phytochemicals". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis, OR. February 2016. Retrieved31 December 2017.
^ab"Carotenoids". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis, OR. August 2016. Retrieved31 December 2017.
^ab"Flavonoids". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis, OR. February 2016. Retrieved31 December 2017.
^New Link in Chain of Life,Wall Street Journal, 2010-12-03, accessed 5 December 2010. "Until now, however, they were all thought to share the same biochemistry, based on the Big Six, to build proteins, fats, and DNA."
