Editing Nutrition (section)

== In organisms ==

=== Animal ===
{{main|Animal nutrition}}
[[File:Alcedo atthis eating a tadpole.jpg|alt=see caption|thumb|A [[kingfisher]] eating a [[tadpole]] near the [[Ariège (river)|Ariège river]], France]]
Animals are heterotrophs that consume other organisms to obtain nutrients. [[Herbivore]]s are animals that eat plants, [[carnivore]]s are animals that eat other animals, and [[omnivore]]s are animals that eat both plants and other animals.{{Sfn|Wu|2017|p=1}} Many herbivores rely on bacterial fermentation to create digestible nutrients from indigestible plant cellulose, while obligate carnivores must eat animal meats to obtain certain vitamins or nutrients their bodies cannot otherwise synthesize. Animals generally have a higher requirement of energy in comparison to plants.<ref>{{cite web |last1=National Geographic Society |date=21 January 2011 |title=Herbivore |url=https://www.nationalgeographic.org/encyclopedia/herbivore/ |access-date=1 May 2017 |website=[[National Geographic Society]] |language=en |archive-date=25 February 2017 |archive-url=https://web.archive.org/web/20170225044420/http://www.nationalgeographic.org/encyclopedia/herbivore/ |url-status=live|author1-link=National Geographic Society }}</ref> The macronutrients essential to animal life are carbohydrates, [[amino acid]]s, and [[fatty acid]]s.{{Sfn|Wu|2017|pp=2–4}}<ref>{{Cite web |title=Nutrition: What Plants and Animals Need to Survive {{!}} Organismal Biology |url=https://organismalbio.biosci.gatech.edu/nutrition-transport-and-homeostasis/nutrition-needs-and-adaptations/ |access-date=2022-11-02 |website=organismalbio.biosci.gatech.edu}}</ref>

All macronutrients except water are required by the body for energy, however, this is not their sole physiological function. The energy provided by macronutrients in food is measured in kilocalories, usually called Calories, where 1 Calorie is the amount of energy required to raise 1 kilogram of water by 1 degree Celsius.<ref>{{Cite web |date=2018-12-21 |title=4.2: Nutrients |url=https://bio.libretexts.org/Bookshelves/Human_Biology/Book%3A_Human_Biology_(Wakim_and_Grewal)/04%3A_Nutrition/4.2%3A_Nutrients |access-date=2022-11-02 |website=Biology LibreTexts |language=en}}</ref>

Carbohydrates are molecules that store significant amounts of energy. Animals digest and metabolize carbohydrates to obtain this energy. Carbohydrates are typically synthesized by plants during metabolism, and animals have to obtain most carbohydrates from nature, as they have only a limited ability to generate them. They include [[sugar]]s, [[oligosaccharide]]s, and [[polysaccharide]]s. [[Glucose]] is the simplest form of carbohydrate.{{Sfn|Mann|Truswell|2012|pp=21–26}} Carbohydrates are broken down to produce glucose and [[short-chain fatty acid]]s, and they are the most abundant nutrients for herbivorous land animals.{{Sfn|Wu|2017|pp=193–194}} Carbohydrates contain 4 calories per gram.

Lipids provide animals with fats and oils. They are not soluble in water, and they can store energy for an extended period of time. They can be obtained from many different plant and animal sources. Most dietary lipids are [[triglyceride]]s, composed of [[glycerol]] and fatty acids. [[Phospholipid]]s and [[sterol]]s are found in smaller amounts.{{Sfn|Mann|Truswell|2012|pp=49–55}} An animal's body will reduce the amount of fatty acids it produces as dietary fat intake increases, while it increases the amount of fatty acids it produces as carbohydrate intake increases.{{Sfn|Wu|2017|p=271}} Fats contain 9 calories per gram.

Protein consumed by animals is broken down to amino acids, which would be later used to synthesize new proteins. Protein is used to form cellular structures, fluids,{{Sfn|Mann|Truswell|2012|pp=70–73}} and [[enzyme]]s (biological [[catalyst]]s). Enzymes are essential to most [[Metabolism|metabolic]] processes, as well as [[DNA replication]], [[DNA repair|repair]], and [[Transcription (genetics)|transcription]].<ref name="EXPASY2000">{{cite journal |vauthors=Bairoch A |date=January 2000 |title=The ENZYME database in 2000 |journal=[[Nucleic Acids Research]] |volume=28 |issue=1 |pages=304–05 |doi=10.1093/nar/28.1.304 |pmc=102465 |pmid=10592255 }}</ref> Protein contains 4 calories per gram.

Much of [[Ethology|animal behavior]] is governed by nutrition. [[Animal migration|Migration patterns]] and [[Seasonal breeder|seasonal breeding]] take place in conjunction with food availability, and [[courtship display]]s are used to display an animal's health.{{Sfn|Simpson|Raubenheimer|2012|pp=3–4}} Animals develop positive and negative associations with foods that affect their health, and they can instinctively avoid foods that have caused [[toxic injury]] or nutritional imbalances through a [[conditioned food aversion]]. Some animals, such as rats, do not seek out new types of foods unless they have a nutrient deficiency.{{Sfn|Simpson|Raubenheimer|2012|pp=39–41}}

==== Human ====
{{main|Human nutrition|Cooking}}
Early human nutrition consisted of foraging for nutrients, like other animals, but it diverged at the beginning of the [[Holocene]] with the [[Neolithic Revolution]], in which humans developed agriculture to produce food. The Chemical Revolution in the 18th century allowed humans to study the nutrients in foods and develop more advanced methods of [[food preparation]]. Major advances in economics and technology during the 20th century allowed [[mass production]] and [[food fortification]] to better meet the nutritional needs of humans.<ref>{{Cite book |last=Trüeb |first=Ralph M. |title=Nutrition for Healthy Hair |publisher=[[Springer Science+Business Media|Springer]] |year=2020 |isbn=978-3-030-59920-1 |pages=3–15 |chapter=Brief History of Human Nutrition |doi=10.1007/978-3-030-59920-1_2 }}</ref> [[Human behavior]] is closely related to human nutrition, making it a subject of [[social science]] in addition to biology. Nutrition in humans is balanced with eating for pleasure, and optimal diet may vary depending on the demographics and health concerns of each person.{{Sfn|Mann|Truswell|p=1|2012}}

Humans are omnivores that eat a variety of foods. Cultivation of [[cereal]]s and production of [[bread]] has made up a key component of human nutrition since the beginning of agriculture. Early humans hunted animals for meat, and modern humans domesticate animals to consume their meat and eggs. The development of [[animal husbandry]] has also allowed humans in some cultures to consume the [[milk]] of other animals and process it into foods such as [[cheese]]. Other foods eaten by humans include nuts, seeds, fruits, and vegetables. Access to domesticated animals as well as [[vegetable oil]]s has caused a significant increase in human intake of fats and oils. Humans have developed advanced methods of [[food processing]] that prevent contamination of pathogenic microorganisms and simplify the production of food. These include drying, freezing, heating, milling, pressing, packaging, refrigeration, and irradiation. Most cultures add [[herb]]s and [[spice]]s to foods before eating to add flavor, though most do not significantly affect nutrition. Other additives are also used to improve the safety, quality, flavor, and nutritional content of food.{{Sfn|Mann|Truswell|pp=409–437|2012}}

Humans obtain most carbohydrates as starch from cereals, though sugar has grown in importance.{{Sfn|Mann|Truswell|2012|pp=21–26}} Lipids can be found in [[animal fat]], [[butterfat]], vegetable oil, and [[leaf vegetable]]s, and they are also used to increase flavor in foods.{{Sfn|Mann|Truswell|2012|pp=49–55}} Protein can be found in virtually all foods, as it makes up cellular material, though certain methods of food processing may reduce the amount of protein in a food.{{Sfn|Mann|Truswell|2012|p=86}} Humans can also obtain energy from [[ethanol]], which is both a food and a drug, but it provides relatively few essential nutrients and is associated with nutritional deficiencies and other health risks.{{Sfn|Mann|Truswell|2012|pp=109–120}}

In humans, poor nutrition can cause deficiency-related diseases, such as [[blindness]], [[anemia]], [[scurvy]], [[preterm birth]], [[stillbirth]] and [[cretinism]],<ref name="Whitney-Rolfes-lead">{{cite book |last1=Whitney |first1=Ellie |title=Understanding Nutrition |last2=Rolfes |first2=Sharon Rady |publisher=Wadsworth, [[Cengage Learning]] |year=2013 |isbn=978-1-133-58752-1 |edition=13 |pages=667, 670}}</ref> or nutrient-excess conditions, such as [[obesity]]<ref>{{cite web |date=7 June 2021 |title=Defining Adult Overweight and Obesity |url=https://www.cdc.gov/obesity/adult/defining.html |website=[[Centers for Disease Control and Prevention]] |access-date=22 September 2021 |archive-date=28 September 2021 |archive-url=https://web.archive.org/web/20210928174006/https://www.cdc.gov/obesity/adult/defining.html |url-status=live}}</ref> and [[metabolic syndrome]].<ref>{{cite web |title=Metabolic syndrome – PubMed Health |publisher=[[National Center for Biotechnology Information]] |url=http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0004546 |archive-url=https://web.archive.org/web/20110205042451/http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0004546 |archive-date=5 February 2011 |url-status=dead |access-date=17 October 2011}}</ref> Other conditions possibly affected by nutrition disorders include [[cardiovascular disease]]s,<ref>{{cite web|url=http://www.umm.edu/altmed/articles/omega-3-000316.htm |title=Omega-3 fatty acids |archive-url=https://web.archive.org/web/20080709084934/http://www.umm.edu/altmed/articles/omega-3-000316.htm |archive-date=9 July 2008 |website=Umm.edu |date=5 October 2011 |access-date=17 October 2011}}</ref> [[diabetes]],<ref>{{cite book |url=https://permanent.fdlp.gov/lps125227/Eating_Diabetes.pdf |title=What I need to know about eating and diabetes |date=2007 |publisher=U.S. Department of Health and Human Services, National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, National Diabetes Information Clearinghouse |oclc=656826809 |access-date=22 September 2021 |archive-date=8 August 2022 |archive-url=https://web.archive.org/web/20220808135741/https://permanent.fdlp.gov/lps125227/Eating_Diabetes.pdf |url-status=live}}</ref><ref>{{cite web|url=http://www.helpguide.org/life/healthy_diet_diabetes.htm |title=Diabetes Diet and Food Tips: Eating to Prevent and Control Diabetes |archive-url=https://web.archive.org/web/20110520045538/http://www.helpguide.org/life/healthy_diet_diabetes.htm |archive-date=20 May 2011 |website=Helpguide.org |access-date=17 October 2011}}</ref> and [[osteoporosis]].<ref>{{cite web|url=http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/ |title=Dietary Supplement Fact Sheet: Vitamin D |archive-url=https://web.archive.org/web/20110706053514/http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/ |archive-date=6 July 2011 |website=[[Office of Dietary Supplements]], [[US National Institutes of Health]] |access-date=17 August 2021}}</ref> Undernutrition can lead to [[wasting]] in acute cases, and [[stunted growth|stunting]] of [[marasmus]] in chronic cases of malnutrition.<ref name="Whitney-Rolfes-lead" />

==== Domesticated animal ====
In [[domesticated animal]]s, such as [[pet]]s, [[livestock]], and [[working animal]]s, as well as other [[Captivity (animal)|animals in captivity]], nutrition is managed by humans through [[animal feed]]. [[Fodder]] and [[forage]] are provided to livestock. Specialized [[pet food]] has been manufactured since 1860, and subsequent research and development have addressed the nutritional needs of pets. [[Dog food]] and [[cat food]] in particular are heavily studied and typically include all essential nutrients for these animals. Cats are sensitive to some common nutrients, such as [[taurine]], and require additional nutrients derived from meat. Large-breed puppies are susceptible to overnutrition, as small-breed dog food is more energy dense than they can absorb.<ref>{{Cite book |last=Taylor |first=Mark B. |title=Caring for Family Pets: Choosing and Keeping Our Companion Animals Healthy |publisher=[[ABC-CLIO]] |year=2011 |isbn=978-0-313-38527-8 |editor-last=Davis |editor-first=Radford G. |pages=177–194 |chapter=Pet Nutrition}}</ref>

=== Plant ===
{{Main|Plant nutrition}}
[[File:Photosynthesis en.svg|thumb|Schematic of photosynthesis in plants. The carbohydrates produced are stored in or used by the plant.]]
Most plants obtain nutrients through inorganic substances [[Plant nutrients in soil|absorbed from the soil]] or the atmosphere. Carbon, hydrogen, oxygen, nitrogen, and sulfur are essential nutrients that make up organic material in a plant and allow enzymic processes. These are absorbed ions in the soil, such as [[bicarbonate]], [[nitrate]], [[ammonium]], and [[sulfate]], or they are absorbed as gases, such as carbon dioxide, water, oxygen gas, and [[sulfur dioxide]]. Phosphorus, boron, and silicon are used for [[esterification]]. They are obtained through the soil as [[phosphate]]s, [[boric acid]], and [[silicic acid]], respectively. Other nutrients used by plants are potassium, sodium, calcium, magnesium, manganese, chlorine, iron, copper, zinc, and molybdenum.{{Sfn|Mengel|Kirkby|Kosegarten|Appel|2001|pp=1–3}}

Plants uptake essential elements from the soil through their [[root]]s and from the air (consisting of mainly nitrogen and oxygen) through their [[Leaf|leaves]]. Nutrient uptake in the soil is achieved by [[cation exchange]], wherein [[root hair]]s pump [[hydrogen ion]]s (H<sup>+</sup>) into the soil through [[proton pump]]s. These hydrogen ions displace [[cation]]s attached to negatively charged soil particles so that the cations are available for uptake by the root. In the leaves, [[stomata]] open to take in carbon dioxide and expel [[oxygen]].{{Sfn|Mengel|Kirkby|Kosegarten|Appel|2001|pp=111–135}} Although [[nitrogen]] is plentiful in the Earth's atmosphere, very few plants can use this directly. Most plants, therefore, require nitrogen compounds to be present in the soil in which they grow. This is made possible by the fact that largely inert atmospheric nitrogen is changed in a [[nitrogen fixation]] process to biologically usable forms in the soil by bacteria.<ref>{{cite web |last1=Lindemann |first1=W.C. |last2=Glover |first2=C.R. |date=2003 |url=http://aces.nmsu.edu/pubs/_a/A129/welcome.html |title=Nitrogen Fixation by Legumes |archive-url=https://web.archive.org/web/20130517232720/http://aces.nmsu.edu/pubs/_a/A129/welcome.html |archive-date=17 May 2013 |website=[[New Mexico State University]]}}</ref>

As these nutrients do not provide the plant with energy, they must obtain energy by other means. [[Green plant]]s absorb energy from [[sunlight]] with [[chloroplasts]] and convert it to usable energy through [[photosynthesis]].{{Sfn|Mengel|Kirkby|Kosegarten|Appel|2001|pp=136–137}}

=== Fungus ===
{{See also|Fungiculture}}
Fungi are chemoheterotrophs that consume external matter for energy. Most fungi absorb matter through the root-like mycelium, which grows through the organism's source of nutrients and can extend indefinitely. The fungus excretes [[Fungal extracellular enzyme activity|extracellular enzymes]] to break down surrounding matter and then absorbs the nutrients through the cell wall. Fungi can be parasitic, saprophytic, or symbiotic. Parasitic fungi attach and feed on living hosts, such as animals, plants, or other fungi. Saprophytic fungi feed on dead and decomposing organisms. Symbiotic fungi grow around other organisms and exchange nutrients with them.<ref>{{Cite book |last=Charya |first=M. A. Singara |title=Plant Biology and Biotechnology |publisher=[[Springer Science+Business Media|Springer]] |year=2015 |isbn=978-81-322-2286-6 |editor1-last=Bahadur |editor1-first=Bir |pages=197–215 |chapter=Fungi: An Overview |doi=10.1007/978-81-322-2286-6_7 |editor2-last=Rajam |editor2-first=Manchikatla Venkat |editor3-last=Sahijram |editor3-first=Leela |editor4-last=Krishnamurthy |editor4-first=K. V.}}</ref>

=== Protist ===
[[Protist]]s include all [[eukaryote]]s that are not animals, plants, or fungi, resulting in great diversity between them. [[Algae]] are photosynthetic protists that can produce energy from light. Several types of protists use mycelium similar to those of fungi. [[Protozoa]] are heterotrophic protists, and different protozoa seek nutrients in different ways. [[Flagellate]] protozoa use a [[flagellum]] to assist in hunting for food, and some protozoa travel via infectious spores to act as parasites.<ref>{{Cite book |title=Handbook of the Protists |publisher=[[Springer Science+Business Media|Springer]] |year=2017 |isbn=978-3-319-28149-0 |editor1-last=Archibald |editor1-first=John M. |edition=2nd |pages=2–4 |doi=10.1007/978-3-319-28149-0 |lccn=2017945328 |editor2-last=Simpson |editor2-first=Alastair G. B. |editor3-last=Slamovits |editor3-first=Claudio H.}}</ref> Many protists are mixotrophic, having both phototrophic and heterotrophic characteristics. Mixotrophic protists will typically depend on one source of nutrients while using the other as a supplemental source or a temporary alternative when its primary source is unavailable.<ref>{{Cite journal |last=Jones |first=Harriet |date=1997 |title=A classification of mixotrophic protists based on their behaviour |journal=Freshwater Biology |volume=37 |issue=1 |pages=35–43 |doi=10.1046/j.1365-2427.1997.00138.x |bibcode=1997FrBio..37...35J }}</ref>

=== Prokaryote ===
{{Further|Microbial metabolism}}
[[File:Metabolism-en.svg|thumb|Simplified view of [[Metabolism|cellular metabolism]]]]
[[Prokaryote]]s, including [[bacteria]] and [[archaea]], vary greatly in how they obtain nutrients across nutritional groups. Prokaryotes can only transport soluble compounds across their cell envelopes, but they can break down chemical components around them. Some lithotrophic prokaryotes are [[extremophile]]s that can survive in nutrient-deprived environments by breaking down inorganic matter.<ref>{{cite book |doi=10.1016/B978-044452748-6.00164-4 |chapter=Geology, Life and Habitability |title=Treatise on Geophysics |date=2007 |last1=Southam |first1=G. |last2=Westall |first2=F. |pages=421–437 |isbn=978-0-444-52748-6 |chapter-url=https://elib.dlr.de/97967/1/10-14-Geology-Life-and-Habitability_2015_Treatise-on-Geophysics-Second-Edition-.pdf }}</ref> Phototrophic prokaryotes, such as [[cyanobacteria]] and [[Chloroflexia]], can engage in photosynthesis to obtain energy from sunlight. This is common among bacteria that form in mats atop geothermal springs. Phototrophic prokaryotes typically obtain carbon from assimilating carbon dioxide through the [[Calvin cycle]].<ref>{{cite book |doi=10.1007/0-387-30742-7_3 |chapter=The Phototrophic Way of Life |title=The Prokaryotes |date=2006 |last1=Overmann |first1=Jörg |last2=Garcia-Pichel |first2=Ferrau |pages=32–85 |isbn=978-0-387-25492-0 }}</ref>

Some prokaryotes, such as ''[[Bdellovibrio]]'' and [[Ensifer (bacterium)|''Ensifer'']], are predatory and feed on other single-celled organisms. Predatory prokaryotes seek out other organisms through [[chemotaxis]] or random collision, merge with the organism, degrade it, and absorb the released nutrients. Predatory strategies of prokaryotes include attaching to the outer surface of the organism and degrading it externally, entering the cytoplasm of the organism, or by entering the [[Periplasm|periplasmic space]] of the organism. Groups of predatory prokaryotes may forgo attachment by collectively producing [[Hydrolysis|hydrolytic]] enzymes.<ref>{{cite journal |last1=Martin |first1=Mark O. |title=Predatory prokaryotes: an emerging research opportunity |journal=Journal of Molecular Microbiology and Biotechnology |date=September 2002 |volume=4 |issue=5 |pages=467–477 |pmid=12432957 }}</ref>