Editing Human nutrition (section)

== Nutrients ==
{{Main|Nutrient}}

The seven major classes of nutrients are carbohydrates, [[fat]]s, [[dietary fiber|fiber]], [[dietary minerals|minerals]], [[protein]]s, [[vitamin]]s, and water.<ref name=WHO2004 /> Nutrients can be grouped as either [[macronutrients]] or [[micronutrients]] (needed in small quantities). Carbohydrates, fats, and proteins are macronutrients, and provide energy.<ref name=WHO2004 /> Water and fiber are macronutrients, but do not provide energy. The micronutrients are minerals and vitamins.<ref name=WHO2004>{{cite book | last1=World Health Organization, Food and Agricultural Organization of the United Nations | title=Vitamin and mineral requirements in human nutrition | date=2004 | publisher=World Health Organization | location=Geneva [u.a.] | isbn=978-9241546126 | edition=2. | url=https://www.who.int/nutrition/publications/micronutrients/9241546123/en/ | archive-url=https://web.archive.org/web/20121212005813/http://www.who.int/nutrition/publications/micronutrients/9241546123/en/ | url-status=dead | archive-date=12 December 2012}}</ref>

The macronutrients (excluding fiber and water) provide structural material (amino acids from which proteins are built, and lipids from which cell membranes and some signaling molecules are built), and [[Bioenergetics|energy]]. Some of the structural material can also be used to generate energy internally, and in either case it is measured in [[joule]]s or [[calorie|kilocalories]] (often called "Calories" and written with a capital 'C' to distinguish them from little 'c' calories). Carbohydrates and proteins provide 17&nbsp;kJ approximately (4&nbsp;kcal) of energy per gram, while fats provide 37&nbsp;kJ (9&nbsp;kcal) per gram.<ref name=Stryer>{{cite book | vauthors=Berg J, Tymoczko JL, Stryer L | title=Biochemistry | publisher=W.H. Freeman | edition=5th | location=San Francisco | year=2002 | isbn=978-0-7167-4684-3 | page=603}}</ref> However, the net energy derived from the macronutrients depends on such factors as absorption and digestive effort, which vary substantially from instance to instance.

Vitamins, minerals, fiber,<ref>{{cite web | url=http://www.webmd.com/food-recipes/features/get-the-facts-on-fiber | title=Get the Facts on Fiber | website=webmd.com | access-date=2020-01-04 | archive-date=2022-05-19 | archive-url=https://web.archive.org/web/20220519100104/https://www.webmd.com/food-recipes/features/get-the-facts-on-fiber | url-status=live}}</ref> and water do not provide energy, but are required for other reasons. A third class of dietary material, fiber (i.e., nondigestible material such as cellulose), seems also to be required, for both mechanical and biochemical reasons, though the exact reasons remain unclear. For all age groups, males on average need to consume higher amounts of macronutrients than females. In general, intakes increase with age until the second or third decade of life.<ref>{{Cite web | url=http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/95E87FE64B144FA3CA2568A9001393C0 | title=National Nutrition Survey: Nutrient Intakes and Physical Measurements | date=1995 | website=Australian Bureau of Statistics | access-date=2015-04-02 | archive-date=2023-01-09 | archive-url=https://web.archive.org/web/20230109225431/https://www.abs.gov.au/ausstats/abs%40.nsf/Lookup/95E87FE64B144FA3CA2568A9001393C0 | url-status=live}}</ref>

Some nutrients can be stored&nbsp;– the fat-soluble vitamins&nbsp;– while others are required more or less continuously. Poor health can be caused by a lack of required nutrients, or for some vitamins and minerals, too much of a required nutrient. ''Essential'' nutrients cannot be synthesized by the body, and must be obtained from food.

Molecules of carbohydrates and fats consist of carbon, hydrogen, and oxygen atoms. Carbohydrates range from simple [[monosaccharides]] (glucose, fructose, galactose) to complex [[polysaccharides]] (starch, glycogen). Fats are [[triglyceride]]s, made of assorted [[fatty acid]] [[monomers]] bound to a [[glycerol]] backbone. Some fatty acids, but not all, are [[essential fatty acids|essential]] in the diet: they cannot be synthesized in the body. Protein molecules contain nitrogen atoms in addition to carbon, oxygen, and hydrogen.<ref name=Nelson2005>{{cite book | vauthors=Nelson DL, Cox MM | year=2005 | title=Lehninger's Principles of Biochemistry | edition=4th | publisher=W. H. Freeman and Company | location=New York, New York}}</ref> The fundamental components of protein are nitrogen-containing [[amino acids]], some of which are [[essential amino acids|essential]] in the sense that humans cannot make them internally. Some of the amino acids can be converted (with the expenditure of energy) to glucose and can be used for energy production just as ordinary glucose, in a process known as [[gluconeogenesis]]. By breaking down existing protein, some glucose can be produced internally; the remaining amino acids are discarded, primarily as urea in urine. This occurs naturally when [[atrophy]] takes place, or during periods of starvation.<ref>"Biodegradable Polymers: An Overview." ''Encyclopedia'', n.d. Accessed April 23, 2025.</ref>


The list of nutrients that people are known to require is, in the words of [[Marion Nestle]], "almost certainly incomplete".<ref>{{cite book | author=Nestle, Marion | author-link=Marion Nestle | title=Food Politics: How the Food Industry Influences Nutrition and Health | publisher=University of California Press | page=413 | isbn=978-0-520-27596-6 | year=2013 | orig-year=2002}}</ref>

=== Carbohydrates ===
{{Main|Carbohydrate}}

[[File:GrainProducts.jpg|thumb|upright|[[cereal|Grain]] products: rich sources of complex and simple carbohydrates]]

Carbohydrates may be classified as [[monosaccharide]]s, [[disaccharide]]s or [[polysaccharide]]s depending on the number of monomer (sugar) units they contain. They are a diverse group of substances, with a range of chemical, physical and physiological properties.<ref>{{cite journal | vauthors=Cummings JH, Stephen AM | title=Carbohydrate terminology and classification | journal=European Journal of Clinical Nutrition | volume=61 | pages=S5-18 | date=December 2007 | issue=Suppl 1 | pmid=17992187 | doi=10.1038/sj.ejcn.1602936 | s2cid=3330936 | url=http://www.nature.com.ipacez.nd.edu.au/ejcn/journal/v61/n1s/pdf/1602936a.pdf}}{{dead link|date=May 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> They make up a large part of foods such as [[rice]], [[noodles]], [[bread]], and other [[grain]]-based products,<ref>{{cite web | url=http://www.carb-counter.net/breads/2320 | title=Grams of Carbohydrates in White Bread – Carb Counter | website=www.carb-counter.net | access-date=18 March 2016 | archive-date=31 May 2016 | archive-url=https://web.archive.org/web/20160531092114/http://www.carb-counter.net/breads/2320 | url-status=live}}</ref><ref>{{cite web | url=http://www.amrice.com/6-4.cfm | title=American Rice, Inc. | website=www.amrice.com | access-date=18 March 2016 | archive-date=19 March 2016 | archive-url=https://web.archive.org/web/20160319144117/http://www.amrice.com/6-4.cfm | url-status=dead}}</ref> but they are not an essential nutrient, meaning a human does not need to eat carbohydrates.<ref>{{cite journal | vauthors=Westman EC | title=Is dietary carbohydrate essential for human nutrition? | journal=The American Journal of Clinical Nutrition | volume=75 | issue=5 | pages=951–3; author reply 953–4 | date=May 2002 | pmid=11976176 | doi=10.1093/ajcn/75.5.951a | doi-access=free}}</ref>

Monosaccharides contain one sugar unit, disaccharides two, and polysaccharides three or more. Monosaccharides include [[glucose]], [[fructose]] and [[galactose]].<ref>{{Cite web | url=http://healthyeating.sfgate.com/carbohydrates-contain-monosaccharides-1181.html | title=Carbohydrates That Contain Monosaccharides | website=Healthy eating | date=22 May 2012 | access-date=2015-04-17 | archive-date=2022-10-04 | archive-url=https://web.archive.org/web/20221004231344/https://healthyeating.sfgate.com/carbohydrates-contain-monosaccharides-1181.html | url-status=live}}</ref> Disaccharides include [[sucrose]], [[lactose]], and [[maltose]]; purified [[sucrose]], for instance, is used as table sugar.<ref>{{Cite journal | title=Principles of human nutrition | date=2015 | journal=Medicine | doi=10.1016/j.mpmed.2014.11.009 | volume=43 | issue=2 | pages=61–65 | last1=Lean | first1=Michael E.J. | s2cid=220865321}}</ref> Polysaccharides, which include [[starch]] and [[glycogen]], are often referred to as 'complex' carbohydrates because they are typically long multiple-branched chains of sugar units.

Traditionally, simple carbohydrates were believed to be absorbed quickly, and therefore raise blood-glucose levels more rapidly than complex carbohydrates. This is inaccurate.<ref>{{cite book | last=Otto | first=H | title=Diabetik Bei Diabetus Mellitus | year=1973 | publisher=Verlag Hans Huber | location=Bern}}</ref><ref>{{cite journal | last=Crapo | first=P | author2=Reaven, Olefsky | journal=Diabetes | year=1977 | volume=26 | pages=1178–83 | doi=10.2337/diabetes.26.12.1178 | pmid=590639 | title=Postprandial plasma-glucose and -insulin responses to different complex carbohydrates | issue=12}}</ref><ref>{{cite journal | last=Crapo | first=P | author2=Kolterman, Waldeck | author3=Reaven, Olefsky | journal=Am J Clin Nutr | year=1980 | volume=33 | pages=1723–28 | pmid=6996472 | title=Postprandial hormonal responses to different types of complex carbohydrate in individuals with impaired glucose tolerance | issue=8 | doi=10.1093/ajcn/33.8.1723}}</ref><ref>{{cite journal | last=Jenkins | first=David | author2=Jenkins, Alexandra L. | author3=Wolever, Thomas M.S. | author4=Thompson, Lilian H. | author5=Rao, A. Venkat | doi=10.1111/j.1753-4887.1986.tb07585.x | pmid=3703387 | title=Simple and complex carbohydrates | journal=Nutrition Reviews | date=February 1986 | volume=44 | issue=2 | pages=44–49}}</ref> Some simple carbohydrates (e.g., fructose) follow different metabolic pathways (e.g., [[fructolysis]]) that result in only a partial [[catabolism]] to glucose, while, in essence, many complex carbohydrates may be digested at the same rate as simple carbohydrates.<ref>{{cite web | title=The Nutrition Source: Carbohydrates | url=http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/carbohydrates/index.html | publisher=Harvard School of Public Health | access-date=7 July 2011 | archive-date=7 July 2011 | archive-url=https://web.archive.org/web/20110707013735/http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/carbohydrates/index.html | url-status=live}}</ref> The [[World Health Organization]] recommends that added sugars should represent no more than 10% of total energy intake.<ref>[https://web.archive.org/web/20041204172930/http://whqlibdoc.who.int/trs/WHO_TRS_916.pdf "WHO Technical Report Series. Diet, nutrition and the prevention of chronic diseases."] Report of a Joint WHO/FAO Expert Consultation; Geneva 2003. Retrieved 7 March 2011</ref>

The most common plant carbohydrate nutrient {{ndash}} starch {{ndash}} varies in its absorption. Starches have been classified as rapidly digestible starch, slowly digestible starch and [[resistant starch]].<ref>{{cite journal | last1=Englyst | first1=K.N. | last2=Liu | first2=S. | last3=Englyst | first3=H.N. | title=Nutritional characterization and measurement of dietary carbohydrates | journal=Eur J Clin Nutr | date=2007 | volume=61 | issue=Suppl 1 | pages=S19-39 | doi=10.1038/sj.ejcn.1602937 | pmid=17992185 | s2cid=4218364}}</ref> Starches in plants are resistant to digestion (resistant starch), but cooking the starch in the presence of water can break down the starch granule and releases the glucose chains, making them more easily digestible by human digestive enzymes.<ref>{{cite journal | last1=Wang | first1=Yi | last2=Chen | first2=Long | last3=Yang | first3=Tianyi | last4=Ma | first4=Yun | last5=McClements | first5=David Julian | last6=Ren | first6=Fei | last7=Tian | first7=Yaoqi | last8=Jin | first8=Zhengyu | title=A review of structural transformations and properties changes in starches during thermal processing of foods | journal=Food Hydrocolloids | date=2020 | volume=113 | page=106543 | doi=10.1016/j.foodhyd.2020.106543 | s2cid=230574900 | url=http://www.sciencedirect.com/science/article/pii/S0268005X20329179}}</ref> Historically, food was less processed and starches were contained within the food matrix, making them less digestible.<ref>{{cite journal | last1=Chen | first1=Lying | last2=Liu | first2=Ruining | last3=Qin | first3=Chengyong | last4=Meng | first4=Yan | last5=Zhang | first5=Jie | last6=Wang | first6=Yun | last7=Xu | first7=Guifa | title=Sources and intake of resistant starch in the Chinese diet | journal=Asia Pac J Clin Nutr | date=2010 | volume=19 | issue=2 | pages=274–282 | doi=10.6133/apjcn.2010.19.2.18 | pmid=20460244 | url=http://dx.doi.org/10.6133/apjcn.2010.19.2.18 | access-date=2021-02-26 | archive-date=2023-01-24 | archive-url=https://web.archive.org/web/20230124005339/https://www.airitilibrary.com/Publication/alDetailedMesh?DocID=09647058-201005-201306110032-201306110032-274-282 | url-status=live}}</ref> Modern food processing has shifted carbohydrate consumption from less digestible and resistant starch to much more rapidly digestible starch.<ref name="Lockyer RS Review">{{cite journal | last1=Lockyer | first1=S. | last2=Nugent | first2=A.P. | title=Health effects of resistant starch | journal=Nutrition Bulletin | date=2017 | volume=42 | issue=1 | pages=10–41 | doi=10.1111/nbu.12244 | s2cid=89991088 | doi-access=free}}</ref><ref>{{cite book | last1=Birkett | first1=A.M. | last2=Brown | first2=I.L. | title=Chapter 4: Resistant Starch and Health. In Technology of Functional Cereal Products | date=2008 | publisher=Woodhead Publishing Ltd – CRC Press LLC | location=Boca Raton, FL | isbn=978-1-84569-177-6 | pages=63–85}}</ref> For instance, the resistant starch content of a traditional African diet was 38 grams/day.<ref>{{cite journal | last1=O'Keefe | first1=Stephen J.D. | last2=et | first2=al. | title=Fat, fibre and cancer risk in African Americans and rural Africans | journal=Nat Commun | date=2015 | volume=6 | issue=1 | page=6342 | doi=10.1038/ncomms7342 | pmid=25919227 | pmc=4415091 | bibcode=2015NatCo...6.6342O}}</ref> The resistant starch consumption from countries with high starch intakes has been estimated to be 30-40 grams/day.<ref name="Baghurst Review">{{cite journal | last1=Baghurst | first1=P.A. | last2=Baghurst | first2=K.I. | last3=Record | first3=S.J. | title=Dietary fibre, non-starch polysaccharides and resistant starch – a review | journal=Food Australia | date=1996 | volume=48 | issue=3 | page=S1-S35 | url=http://agris.fao.org/agris-search/search.do?recordID=US201301518409 | access-date=2021-02-26 | archive-date=2022-01-19 | archive-url=https://web.archive.org/web/20220119195548/https://agris.fao.org/agris-search/search.do?recordID=US201301518409 | url-status=live}}</ref> In contrast, the average consumption of resistant starch in the United States was estimated to be 4.9 grams/day (range 2.8-7.9 grams of resistant starch/day).<ref name="Murphy RS Review">{{cite journal | last1=Murphy | first1=M.M. | last2=Douglass | first2=J.S. | last3=Birkett | first3=A. | title=Resistant starch intakes in the United States | journal=J Am Diet Assoc | date=2008 | volume=108 | issue=1 | pages=67–78 | doi=10.1016/j.jada.2007.10.012 | pmid=18155991}}</ref>

=== Fat ===
{{more medical citations needed|section|date=April 2019}}
{{Main|Fat}}

A molecule of dietary fat typically consists of several [[fatty acid]]s (containing long chains of carbon and hydrogen atoms), bonded to a [[glycerol]]. They are typically found as [[triglyceride]]s (three fatty acids attached to one glycerol backbone). Fats may be classified as [[saturated fat|saturated]] or [[unsaturated fat|unsaturated]] depending on the chemical structure of the fatty acids involved. Saturated fats have all of the [[carbon atoms]] in their fatty acid chains bonded to [[hydrogen atom]]s, whereas unsaturated fats have some of these carbon atoms [[Double bond|double-bonded]], so their molecules have relatively fewer hydrogen atoms than a saturated fatty acid of the same length. Unsaturated fats may be further classified as monounsaturated (one double-bond) or polyunsaturated (many double-bonds). Furthermore, depending on the location of the double-bond in the fatty acid chain, unsaturated fatty acids are classified as [[omega-3]] or [[omega-6]] fatty acids. [[Trans fat]]s are a type of unsaturated fat with ''trans''-isomer bonds; these are rare in nature and in foods from natural sources; they are typically created in an industrial process called (partial) [[hydrogenation]]. There are nine kilocalories in each gram of fat. Fatty acids such as [[conjugated linoleic acid]], [[catalpic acid]], [[eleostearic acid]] and [[punicic acid]], in addition to providing energy, represent potent immune modulatory molecules.<ref>{{cite book | author=National Research Council Committee on Diet and Health | editor-last1=Motulsky | editor-first1=Arno G. | editor-last2=Bierman | editor-first2=Edwin L. | editor-last3=Goodman | editor-first3=DeWitt S. | editor-last4=Mccormick | editor-first4=Donald B. | editor-last5=Arnaud | editor-first5=Claude D. | editor-last6=Iii | editor-first6=John C. Bailar | editor-last7=Blackburn | editor-first7=Henry | editor-last8=Bray | editor-first8=George A. | editor-last9=Carroll | editor-first9=Kenneth K. | editor-last10=Howe | editor-first10=Geoffrey R. | editor-last11=Hurley | editor-first11=Lucille S. | editor-last12=Kolonel | editor-first12=Laurence N. | editor-last13=Mcgill | editor-first13=Henry C. | editor-last14=Miller | editor-first14=Anthony B. | editor-last15=Page | editor-first15=Lot B. | editor-last16=Schieken | editor-first16=Richard M. | editor-last17=Shekelle | editor-first17=Richard B. | editor-last18=Tobian | editor-first18=Louis | editor-last19=Williams | editor-first19=Eleanor R. | display-editors=0 | date=1989 | chapter=Fats and Other Lipids | pages=159–258 | chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK218759/ | title=Diet and health: Implications for reducing chronic disease risk | url=https://www.ncbi.nlm.nih.gov/books/NBK218743/pdf/Bookshelf_NBK218743.pdf#page=176 | publication-place=Washington, DC | publisher=National Academies Press | language=en | doi=10.17226/1222 | doi-access=free | isbn=978-0-309-03994-9 | oclc=19457013 | pmid=25032333}} Also available from [https://nap.nationalacademies.org/read/1222/chapter/10 nationalacademies.org], with page numbers, but with Greek characters [[transliteration|transliterated]].</ref><ref>{{Cite journal | last1=Field | first1=Catherine J | last2=Robinson | first2=Lindsay | date=July 2019 | title=Dietary Fats | url=https://linkinghub.elsevier.com/retrieve/pii/S2161831322004136 | journal=Advances in Nutrition | language=en | volume=10 | issue=4 | pages=722–724 | doi=10.1093/advances/nmz052 | pmc=6628852 | pmid=31147674}}</ref>

Saturated fats (typically from animal sources) have been a staple in many world cultures for millennia. Unsaturated fats (e. g., vegetable oil) are considered healthier, while trans fats are to be avoided. Saturated and some trans fats are typically solid at room temperature (such as [[butter]] or [[lard]]), while unsaturated fats are typically liquids (such as [[olive oil]] or [[flaxseed oil]]). Trans fats are very rare in nature, and have been shown to be highly detrimental to human health, but have properties useful in the [[food processing]] industry, such as rancidity resistance.<ref>{{Cite journal | last=Klonoff | first=David C. | date=24 June 2016 | title=Replacements for Trans Fats—Will There Be an Oil Shortage? | pmc=2769584 | journal=Journal of Diabetes Science and Technology | language=en | volume=1 | issue=3 | pages=415–22 | doi=10.1177/193229680700100316 | pmid=19885099}}</ref>

==== Essential fatty acids ====
{{Main|Essential fatty acids}}
{{more medical citations needed|section|date=February 2020}}

Most fatty acids are non-essential, meaning the body can produce them as needed, generally from other fatty acids and always by expending energy to do so. However, in humans, at least two fatty acids are [[essential fatty acid|essential]] and must be included in the diet. An appropriate balance of essential fatty acids—[[omega-3]] and [[omega-6 fatty acid]]s—seems also important for health, although definitive experimental demonstration has been elusive. Both of these "omega" long-chain [[unsaturated fat|polyunsaturated fatty acids]] are [[substrate (biochemistry)|substrates]] for a class of [[eicosanoid]]s known as [[prostaglandin]]s, which have roles throughout the human body.<ref name="kaur-2014" />

The omega-3 [[eicosapentaenoic acid]] (EPA), which can be made in the human body from the omega-3 essential fatty acid [[alpha-linolenic acid]] (ALA), or taken in through marine food sources, serves as a building block for series 3 prostaglandins (e.g., weakly [[Inflammation|inflammatory]] PGE3). The [[Dihomo-γ-linolenic acid|omega-6 dihomo-gamma-linolenic acid]] (DGLA) serves as a building block for series 1 prostaglandins (e.g. anti-inflammatory PGE1), whereas [[arachidonic acid]] (AA) serves as a building block for series 2 [[prostaglandin]]s (e.g. pro-inflammatory PGE 2). Both DGLA and AA can be made from the omega-6 [[linoleic acid]] (LA) in the human body, or can be taken in directly through food.<ref name="kaur-2014">{{Cite journal | last1=Kaur | first1=Narinder | last2=Chugh | first2=Vishal | last3=Gupta | first3=Anil K. | date=October 2014 | title=Essential fatty acids as functional components of foods- a review | journal=Journal of Food Science and Technology | language=en | volume=51 | issue=10 | pages=2289–2303 | doi=10.1007/s13197-012-0677-0 | issn=0022-1155 | pmc=4190204 | pmid=25328170}}</ref> An appropriately balanced intake of omega-3 and omega-6 partly determines the relative production of different [[prostaglandin]]s. In industrialized societies, people typically consume large amounts of processed vegetable oils, which have reduced amounts of the essential fatty acids along with too much of omega-6 fatty acids relative to omega-3 fatty acids.<ref>{{cite journal | last1=Krupa | first1=Kristina N. | title=Omega-3 Fatty Acids | date=2024 | website=StatPearls | url=http://www.ncbi.nlm.nih.gov/books/NBK564314/ | access-date=2024-08-12 | place=Treasure Island (FL) | publisher=StatPearls Publishing | pmid=33231984 | last2=Fritz | first2=Kristina | last3=Parmar | first3=Mayur}}</ref>

The conversion rate of omega-6 DGLA to AA largely determines the production of the prostaglandins PGE1 and PGE2. Omega-3 EPA prevents AA from being released from membranes, thereby skewing prostaglandin balance away from pro-inflammatory PGE2 (made from AA) toward anti-inflammatory PGE1 (made from DGLA). The conversion (desaturation) of DGLA to AA is controlled by the enzyme [[desaturase|delta-5-desaturase]], which in turn is controlled by hormones such as [[insulin]] (up-regulation) and [[glucagon]] (down-regulation).

=== Fiber ===
{{Main|Dietary fiber}}
{{more medical citations needed|section|date=October 2024}}
Dietary fiber is a [[carbohydrate]], specifically a [[polysaccharide]], which is incompletely absorbed in humans and in some animals. Fiber slows down the absorption of sugar in the gut. The [[Microbiome of humans|microbiome]] converts fiber into signals that stimulate gut hormones, which in turn control how quickly the stomach empties, regulate blood sugar levels, and influence feelings of hunger. Like all carbohydrates, when fiber is digested, it can produce four [[calorie]]s (kilocalories) of energy per gram, but in most circumstances, it accounts for less than that because of its limited absorption and digestibility.

The two subcategories are ''insoluble'' and ''soluble'' fiber.

;Insoluble dietary fiber
:Includes [[cellulose]], a large carbohydrate polymer that is indigestible by humans, because humans do not have the required enzymes to break it down, and the human digestive system does not harbor enough of the types of microbes that can do so.
:Includes [[resistant starch]], an insoluble starch that resists digestion either because it is protected by a shell or food matrix (Type 1 resistant starch, RS1), maintains the natural starch granule (Type 2 resistant starch, RS2), is retrograded and partially crystallized (Type 3 resistant starch, RS3), has been chemically modified (Type 4 resistant starch, RS4) or has complexed with a lipid (Type 5 resistant starch, RS5).<ref name="Lockyer RS Review" /> Natural sources of resistant starch (RS1, RS2 and RS3) are fermented by the microbes in the human digestive system to produce short-chain fatty acids which are utilized as food for the colonic cells or absorbed.<ref name="Lockyer RS Review" />

;Soluble dietary fiber
:Comprises a variety of [[oligosaccharides]], [[waxes]], [[esters]], and other carbohydrates that dissolve or gelatinize in water. Many of these soluble fibers can be fermented or partially fermented by microbes in the human digestive system to produce short-chain fatty acids which are absorbed and therefore introduce some caloric content.<ref>{{Cite journal | last1=Hervik | first1=Astrid Kolderup | last2=Svihus | first2=Birger | date=2019 | title=The role of fiber in energy balance | journal=Journal of Nutrition and Metabolism | volume=2019 | pages=4983657 | doi=10.1155/2019/4983657 | issn=2090-0724 | pmc=6360548 | pmid=30805214 | doi-access=free}}</ref>

Whole grains, beans, and other [[legumes]], fruits (especially [[plum]]s, [[prune]]s, and [[fig]]s), and vegetables are good sources of dietary fiber. Fiber has three primary mechanisms, which in general determine their health impact: bulking, viscosity and fermentation.<ref name="Gallaher Fiber Review">{{cite book | last1=Gallaher | first1=Daniel D. | title=Chapter 8 – Dietary Fiber in Present Knowledge in Nutrition | date=2006 | publisher=ILSI Press | location=Washington DC | isbn=978-1-57881-199-1 | pages=102–110 | edition=Ninth Edition, Volume I}}</ref> Fiber provides bulk to the intestinal contents, and insoluble fiber facilitates [[peristalsis]]&nbsp;– the rhythmic muscular contractions of the intestines which move contents along the digestive tract. Some soluble and insoluble fibers produce a solution of high [[viscosity]]; this is essentially a gel, which slows the movement of food through the intestines. Fermentable fibers are used as food by the [[microbiome]], mildly increasing bulk, and producing [[short-chain fatty acid]]s and other metabolites, including vitamins, hormones, and glucose. One of these metabolites, [[butyrate]], is important as an energy source for colon cells, and may improve [[metabolic syndrome]].<ref>{{cite journal | last1=Bridgeman | first1=Stephanie C. | last2=Northrop | first2=Wendy | last3=Melton | first3=Phillip E. | last4=Ellison | first4=Gaewyn C. | last5=Newsholme | first5=Philip | last6=Mamotte | first6=Cyril D.S. | title=Butyrate generated by gut microbiota and its therapeutic role in metabolic syndrome | journal=Pharmacological Research | date=1 October 2020 | volume=160 | page=105174 | doi=10.1016/j.phrs.2020.105174 | pmid=32860943 | s2cid=221373075 | url=http://www.sciencedirect.com/science/article/pii/S1043661820314821}}</ref><ref>{{cite journal | last1=Wang | first1=Yong | last2=Chen | first2=Jing | last3=Song | first3=Ying-Han | last4=Zhao | first4=Rui | last5=Xia | first5=Lin | last6=Chen | first6=Yi | last7=Cui | first7=Ya-Ping | last8=Rao | first8=Zhi-Yong | last9=Zhou | first9=Yong |last10=Zhuang |first10=Wen | last11=Wu | first11=Xiao-Ting | title=Effects of the resistant starch on glucose, insulin, insulin resistance, and lipid parameters in overweight or obese adults: a systemic review and meta-analysis | journal=Nutrition & Diabetes | date=5 June 2019 | volume=9 | issue=1 | page=19 | doi=10.1038/s41387-019-0086-9 | pmid=31168050 | pmc=6551340 | url=https://doi.org/10.1038/s41387-019-0086-9 | access-date=22 February 2021 | archive-date=24 January 2023 | archive-url=https://web.archive.org/web/20230124005320/https://www.nature.com/articles/s41387-019-0086-9 | url-status=live}}</ref>

In 2016, the U.S. FDA approved a qualified [[health claim]] stating that resistant starch might reduce the risk of [[type 2 diabetes]], but with qualifying language for product labels that only limited scientific evidence exists to support this claim. The FDA requires specific labeling language, such as the guideline concerning resistant starch: "High-amylose maize resistant starch may reduce the risk of type 2 diabetes. FDA has concluded that there is limited scientific evidence for this claim."<ref name="FDA approved health claim RS2 resistant starch">{{cite web | last1=Balentine | first1=Douglas | title=Letter announcing decision for a health claim for high-amylose maize starch (containing type-2 resistant starch) and reduced risk of type 2 diabetes mellitus | url=https://www.regulations.gov/docket?D=FDA-2015-Q-2352 | website=www.regulations.gov | publisher=U.S. Food and Drug Administration | access-date=16 December 2016 | archive-date=20 December 2016 | archive-url=https://web.archive.org/web/20161220200555/https://www.regulations.gov/docket?D=FDA-2015-Q-2352 | url-status=live}}</ref>

=== Amino acids ===
[[File:Myoglobin.png|thumb|right|Proteins are chains of amino acids found in many nutritious foods. Pictured above is a computer rendering of [[myoglobin]], a protein found in muscles.]]
{{further|Protein (nutrient)|Protein quality|Amino acid score}}

Proteins are the basis of many animal body structures (e.g. muscles, skin, and hair) and form the [[enzyme]]s that control chemical reactions throughout the body. Each protein molecule is composed of [[amino acids]] which contain nitrogen and sometimes sulphur (these components are responsible for the distinctive smell of burning protein, such as the keratin in hair). The body requires amino acids to produce new proteins (protein retention) and to replace damaged proteins (maintenance). Amino acids are soluble in the digestive juices within the small intestine, where they are absorbed into the blood. Once absorbed, they cannot be stored in the body, so they are either metabolized as required or excreted in the urine.{{medical citation needed|date=July 2015}} Proteins consist of amino acids in different proportions. The most important aspect and defining characteristic of protein from a nutritional standpoint is its amino acid composition.<ref name="DRI">Dietary Reference Intakes: The Essential Guide to Nutrient Requirements, published by the Institute of Medicine's Food and Nutrition Board, currently available online at {{cite web | url=http://fnic.nal.usda.gov/dietary-guidance/dietary-reference-intakes/dri-reports | title=DRI Reports {{pipe}} Food and Nutrition Information Center | access-date=14 July 2014 | url-status=dead | archive-url=https://web.archive.org/web/20140705140516/http://fnic.nal.usda.gov/dietary-guidance/dietary-reference-intakes/dri-reports | archive-date=5 July 2014}}</ref>

For all animals, some amino acids are ''[[essential amino acid|essential]]'' (an animal cannot produce them internally so they must be eaten) and some are ''[[non-essential amino acid|non-essential]]'' (the animal can produce them from other nitrogen-containing compounds). About twenty amino acids are found in the human body, and about ten of these are essential. The synthesis of some amino acids can be limited under special pathophysiological conditions, such as prematurity in the infant or individuals in severe catabolic distress, and those are called conditionally essential.<ref name="DRI" />

A diet that contains adequate amounts of amino acids (especially those that are essential) is particularly important in some situations: during early development and maturation, pregnancy, lactation, or injury (a burn, for instance). A [[complete protein]] source contains all the essential amino acids; an incomplete protein source lacks one or more of the essential amino acids. It is possible with [[protein combination]]s of two incomplete protein sources (e.g., rice and beans) to make a complete protein source, and characteristic combinations are the basis of distinct cultural cooking traditions. However, complementary sources of protein do not need to be eaten at the same meal to be used together by the body.<ref>{{cite journal | author=American Dietetic Association | title=Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets | journal=Journal of the American Dental Association | year=2003 | volume=103 | issue=6 | pages=748–65 | pmid=12778049 | doi=10.1053/jada.2003.50142 | last2=Dietitians Of | first2=Canada}}</ref> Excess amino acids from protein can be converted into glucose and used for fuel through a process called [[gluconeogenesis]].

There is an ongoing debate about the differences in nutritional quality and adequacy of protein from [[Veganism|vegan]], [[Vegetarianism|vegetarian]] and animal sources, though many studies and institutions have found that a well-planned vegan or vegetarian diet contains enough high-quality protein to support the protein requirements of both sedentary and active people at all stages of life.<ref>{{cite journal | vauthors=Alexandrov NV, Eelderink C, Singh-Povel CM, Navis GJ, Bakker SJ, Corpeleijn E | title=Dietary Protein Sources and Muscle Mass over the Life Course: The Lifelines Cohort Study | journal=Nutrients | volume=10 | issue=10 | pages=1471 | date=October 2018 | pmid=30308987 | pmc=6212815 | doi=10.3390/nu10101471 | doi-access=free}}</ref><ref>{{cite web | url=https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/protein/ | title=Protein | date=18 September 2012 | website=The Nutrition Source | language=en-us | access-date=31 October 2019 | archive-date=27 October 2019 | archive-url=https://web.archive.org/web/20191027201530/https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/protein/ | url-status=live}}</ref><ref>{{cite journal | vauthors=Rogerson D | title=Vegan diets: practical advice for athletes and exercisers | journal=Journal of the International Society of Sports Nutrition | volume=14 | pages=36 | date=13 September 2017 | issue=1 | pmid=28924423 | pmc=5598028 | doi=10.1186/s12970-017-0192-9 | doi-access=free}}</ref><ref name="dinu">{{cite journal | vauthors=Dinu M, Abbate R, Gensini GF, Casini A, Sofi F | title=Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies | journal=Critical Reviews in Food Science and Nutrition | volume=57 | issue=17 | pages=3640–3649 | date=November 2017 | pmid=26853923 | doi=10.1080/10408398.2016.1138447 | url=https://flore.unifi.it/bitstream/2158/1079985/4/Vegetarian%2c%20vegan%20diets%20and%20multiple%20he...meta-analysis%20of%20observational%20studies.pdf | hdl=2158/1079985 | s2cid=10073754 | access-date=2018-08-02 | archive-date=2023-01-24 | archive-url=https://web.archive.org/web/20230124005332/https://flore.unifi.it/rm-password-login | url-status=live}}</ref>

=== Water ===
{{Main|Drinking water}}
[[File:TapWater-china.JPG|thumb|left|A manual [[water]] [[pump]] in [[China]]]]
Water is excreted from the body in multiple forms; including [[urine]] and [[Human feces|feces]], [[sweating]], and by [[water vapour]] in the exhaled breath. Therefore, it is necessary to adequately rehydrate to replace lost fluids.

Early recommendations for the quantity of water required for maintenance of good health suggested that six to eight glasses of water daily is the minimum to maintain proper [[Tissue hydration|hydration]].<ref>{{cite web | url=https://www.bbc.co.uk/health/healthy_living/nutrition/drinks_water.shtml | title=Healthy Water Living | publisher=BBC. Retrieved 1 February 2007 | archive-url=https://web.archive.org/web/20070101100025/http://www.bbc.co.uk/health/healthy_living/nutrition/drinks_water.shtml | archive-date=1 January 2007}}</ref> However, the notion that a person should consume eight glasses of water per day cannot be traced to a credible scientific source.<ref>{{cite journal | title="Drink at least eight glasses of water a day." Really? Is there scientific evidence for "8 × 8"? | journal=American Journal of Physiology. Regulatory, Integrative and Comparative Physiology | volume=283 | issue=5 | pages=R993–R1004 | doi=10.1152/ajpregu.00365.2002 | pmid=12376390 | year=2002 | last1=Valtin | first1=Heinz}}</ref> The original water intake recommendation in 1945 by the Food and Nutrition Board of the [[United States National Research Council|National Research Council]] read: "An ordinary standard for diverse persons is 1 milliliter for each calorie of food. Most of this quantity is contained in prepared foods."<ref>Food and Nutrition Board, National Academy of Sciences. Recommended Dietary Allowances, revised 1945. National Research Council, Reprint and Circular Series, No. 122, 1945 (Aug), pp. 3–18.</ref> More recent comparisons of well-known recommendations on fluid intake have revealed large discrepancies in the volumes of water we need to consume for good health.<ref name="Le Bellego">{{cite journal | vauthors=Le Bellego L, Jean C, Jiménez L, Magnani C, Tang W, Boutrolle I | title=Understanding fluid consumption patterns to improve healthy hydration | journal=Nutr Today | year=2010 | volume=45 | issue=6 | pages=S22–S26 | doi=10.1097/NT.0b013e3181fe4314 | s2cid=76128311 | doi-access=free}}</ref> Therefore, to help standardize guidelines, recommendations for water consumption are included in two recent [[European Food Safety Authority]] (EFSA) documents (2010): (i) Food-based dietary guidelines and (ii) Dietary reference values for water or adequate daily intakes (ADI).<ref name="Scientific Opinion on Dietary Reference Values for water">{{cite journal | author=EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) | doi=10.2903/j.efsa.2010.1459 | title=Scientific Opinion on Dietary Reference Values for Water | journal=EFSA Journal | year=2010 | volume=8 | issue=3 | page=1459 | s2cid=79245852 | url=http://orbit.dtu.dk/files/6350877/5.Scientific.pdf | archive-url=https://web.archive.org/web/20170922040703/http://orbit.dtu.dk/files/6350877/5.Scientific.pdf | archive-date=2017-09-22 | url-status=live}}{{open access}}</ref> These specifications were provided by calculating adequate intakes from measured intakes in populations of individuals with "desirable osmolarity values of urine and desirable water volumes per energy unit consumed".<ref name="Scientific Opinion on Dietary Reference Values for water" />

For healthful hydration, the current EFSA guidelines recommend total water intakes of 2.0 L/day for adult females and 2.5 L/day for adult males. These reference values include water from drinking water, other beverages, and from food. About 80% of our daily water requirement comes from the beverages we drink, with the remaining 20% coming from food.<ref>{{cite journal | last1=Armstrong | first1=Lawrence E. | last2=Pumerantz | first2=Amy C. | last3=Roti | first3=Melissa W. | last4=Judelson | first4=Daniel A. | last5=Watson | first5=Greig | last6=Dias | first6=Joao C. | last7=Sökmen | first7=Bülent | last8=Casa | first8=Douglas J. | last9=Maresh | first9=Carl M. | last10=Lieberman | first10=Harris | last11=Kellogg | first11=Mark | year=2005 | title=Fluid, electrolyte, and renal indices of hydration during 11 days of controlled caffeine consumption | journal=International Journal of Sport Nutrition and Exercise Metabolism | publication-place=Champaign, Illinois | publisher=Human Kinetics Publishers | volume=15 | issue=3 | pages=252–265 | issn=1526-484X | pmid=16131696 | doi=10.1123/ijsnem.15.3.252 | url=https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=640f49f096f9a01e2c3ef103945a39830a12cd5c <!-- https://www.researchgate.net/profile/Mark-Kellogg/publication/7628664_Fluid_electrolyte_and_renal_indices_of_hydration_during_11_days_of_controlled_caffeine_consumption/links/09e4150bf9c40a8468000000/Fluid-electrolyte-and-renal-indices-of-hydration-during-11-days-of-controlled-caffeine-consumption.pdf -->}}</ref> Water content varies depending on the type of food consumed, with fruit and vegetables containing more than cereals, for example.<ref name="FAO">[http://www.fao.org/docrep/003/x9892e/x9892e00.htm "FAO Corporate Document Repository. Food Balance Sheets- A Handbook."] {{Webarchive|url=https://web.archive.org/web/20190217073049/http://www.fao.org/docrep/003/X9892E/X9892E00.HTM |date=2019-02-17 }} Retrieved 7 March 2011</ref> These values are estimated using country-specific food balance sheets published by the Food and Agriculture Organisation of the United Nations.<ref name="FAO" />

The EFSA panel also determined intakes for different populations. Recommended intake volumes in the elderly are the same as for adults as despite lower energy consumption, the water requirement of this group is increased due to a reduction in renal concentrating capacity.<ref name="Scientific Opinion on Dietary Reference Values for water" /> [[Pregnant]] and [[breastfeeding]] women require additional fluids to stay hydrated. The EFSA panel proposes that pregnant women should consume the same volume of water as non-pregnant women, plus an increase in proportion to the higher energy requirement, equal to 300 mL/day.<ref name="Scientific Opinion on Dietary Reference Values for water" /> To compensate for additional fluid output, breastfeeding women require an additional 700 mL/day above the recommended intake values for non-lactating women. Dehydration and over-hydration&nbsp;– too little and too much water, respectively&nbsp;– can have harmful consequences. Drinking too much water is one of the possible causes of [[hyponatremia]], i.e., low serum sodium.<ref name="Scientific Opinion on Dietary Reference Values for water" /><ref>{{cite journal | pmc=1770067 | title=Fatal water intoxication | journal=Journal of Clinical Pathology | date=October 2003 | pmid=14514793 | volume=56 | issue=10 | vauthors=Farrell DJ, Bower L | pages=803–04 | doi=10.1136/jcp.56.10.803-a}}</ref>

=== Minerals ===
{{right|{{Periodic table (for higher organisms)}}}}
{{Main|Mineral (nutrient)|Composition of the human body}}
Dietary minerals are [[inorganic compounds|inorganic]] [[chemical element]]s required by living organisms,<ref name="Mitchell, Dakota and Haroun, Lee 2012 279">{{cite book | author1=Mitchell, Dakota | author2=Haroun, Lee | title=Introduction to Health Care | year=2012 | edition=3 | publisher=Delmar Cengage | isbn=978-1-4354-8755-0 | page=279}}</ref> other than the four elements [[carbon]], [[hydrogen]], [[nitrogen]], and [[oxygen]] that are present in nearly all [[organic chemistry|organic molecules]]. Some have roles as [[Cofactor (biochemistry)|cofactors]], while others are [[electrolyte]]s.<ref>{{cite book | author1=Nelson, D.L. | author2=Cox, M.M. | title=Lehninger Principles of Biochemistry | edition=3rd | publisher=Worth Publishing | location=New York | year=2000 | isbn=978-1-57259-153-0}}</ref> The term "mineral" is archaic, since the intent is to describe simply the less common elements in the diet. Some are heavier than the four just mentioned – including several [[metals]], which often occur as ions in the body. Some dietitians recommend that these be supplied from foods in which they occur naturally, or at least as complex compounds, or sometimes even from natural inorganic sources (such as [[calcium carbonate]] from ground [[oyster]] shells). Some are absorbed much more readily in the ionic forms found in such sources. On the other hand, minerals are often artificially added to the diet as supplements; the most well-known is likely iodine in [[iodized salt]] which prevents [[goiter]].<ref>{{Cite journal | last1=Datta | first1=Mridul | last2=Vitolins | first2=Mara Z. | date=2016-10-02 | title=Food Fortification and Supplement Use – Are there Health Implications? | journal=Critical Reviews in Food Science and Nutrition | volume=56 | issue=13 | pages=2149–2159 | doi=10.1080/10408398.2013.818527 | issn=1040-8398 | pmc=4692722 | pmid=25036360}}</ref>

==== Macrominerals ====
Elements with recommended dietary allowance ([[Recommended Dietary Allowance|RDA]]) greater than 150&nbsp;mg/day are, in alphabetical order:
*[[Calcium]] (Ca<sup>2+</sup>) is vital to the health of the muscular, circulatory, and digestive systems; is indispensable to the building of bone; and supports the synthesis and function of blood cells. For example, calcium is used to regulate the contraction of muscles, nerve conduction, and the clotting of blood. It can play this role because the Ca<sup>2+</sup> ion forms stable [[coordination complex]]es with many organic compounds, especially [[protein]]s; it also forms compounds with a wide range of solubility, enabling the formation of the [[skeleton]].<ref>{{Cite web | url=https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/ | title=Office of Dietary Supplements – Calcium | website=ods.od.nih.gov | language=en | access-date=31 October 2019 | archive-date=17 March 2018 | archive-url=https://web.archive.org/web/20180317073525/https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/ | url-status=live}}</ref> Food sources include yogurt, milk, cheese, leafy greens, tofu, and fortified beverages.<ref>{{Cite web |title=Food Sources of Calcium {{!}} Dietary Guidelines for Americans |url=https://www.dietaryguidelines.gov/food-sources-calcium |access-date=2024-10-05 |website=www.dietaryguidelines.gov}}</ref>
*[[Chlorine]] as [[chloride]] ions; electrolyte; see sodium, below.
* [[Magnesium]], required for processing [[Adenosine triphosphate|ATP]] and related reactions (builds bone, causes strong [[peristalsis]], increases flexibility, increases alkalinity). Approximately 50% is in bone, the remaining 50% is almost all inside body cells, with only about 1% located in extracellular fluid. Food sources include oats, buckwheat, tofu, nuts, caviar, green leafy vegetables, legumes, and chocolate.<ref name="mahan">{{cite book | title=Krausw's Food and the Nutrition Care Process | edition=13th | publisher=Elsevier | location=St. Louis | year=2012 | isbn=978-1-4377-2233-8 | author1=L. Kathleen Mahan | author2=Janice L. Raymond | author3=Sylvia Escott-Stump}}</ref><ref name="USDA DB">{{Cite web | url=https://fdc.nal.usda.gov/ | title=USDA National Nutrient Database for Standard Reference, SR26, 2013 | access-date=2022-10-19 | archive-date=2023-01-15 | archive-url=https://web.archive.org/web/20230115162310/http://fdc.nal.usda.gov/ | url-status=live}}</ref>
* [[Phosphorus]], required component of bones; essential for energy processing.<ref>{{cite book | author=D. E. C. Corbridge | title=Phosphorus: An Outline of its Chemistry, Biochemistry, and Technology | edition=5th | publisher=Elsevier | location=Amsterdam | year=1995 | isbn=978-0-444-89307-9}}</ref> Approximately 80% is found in the inorganic portion of bones and teeth. Phosphorus is a component of every cell, as well as important metabolites, including DNA, RNA, ATP, and phospholipids. Also important in pH regulation. It is an important electrolyte in the form of [[phosphate]].<ref>{{Cite web | url=https://www.msdmanuals.com/en-in/professional/endocrine-and-metabolic-disorders/electrolyte-disorders/overview-of-disorders-of-phosphate-concentration | title=Overview of Disorders of Phosphate Concentration – Endocrine and Metabolic Disorders | website=MSD Manual Professional Edition | language=en-IN | access-date=31 October 2019 | archive-date=5 August 2019 | archive-url=https://web.archive.org/web/20190805043750/https://www.msdmanuals.com/en-in/professional/endocrine-and-metabolic-disorders/electrolyte-disorders/overview-of-disorders-of-phosphate-concentration | url-status=live}}</ref> Food sources include cheese, egg yolk, milk, meat, fish, poultry, whole-grain cereals, and many others.<ref name="mahan" />
* [[Potassium]], an electrolyte (heart and nerve function). With sodium, potassium is involved in maintaining normal water balance, osmotic equilibrium, and acid-base balance. In addition to calcium, it is important in the regulation of neuromuscular activity. Food sources include bananas, avocados, nuts, vegetables, potatoes, legumes, fish, and mushrooms.<ref name="USDA DB" />
* [[Sodium]], a common food ingredient and [[electrolyte]], found in most foods and manufactured consumer products, typically as [[sodium chloride]] (salt). Excessive sodium consumption can deplete [[calcium]] and [[magnesium]].<ref>{{Cite web | url=http://www.fao.org/docrep/004/Y2809E/y2809e0k.htm | title=Chapter 14. Magnesium | website=Food and Agriculture Organization of the United States | access-date=2020-01-03 | archive-date=2019-11-01 | archive-url=https://web.archive.org/web/20191101125852/http://www.fao.org/docrep/004/Y2809E/y2809e0k.htm | url-status=live}}</ref> Sodium has a role in the etiology of [[hypertension]] demonstrated from studies showing that a reduction of table salt intake may reduce blood pressure.<ref>{{Cite journal | last=Ha | first=Sung Kyu | date=1 June 2014 | title=Dietary salt intake and hypertension | pmc=4105387 | journal=Electrolytes & Blood Pressure | volume=12 | issue=1 | pages=7–18 | doi=10.5049/EBP.2014.12.1.7 | issn=1738-5997 | pmid=25061468}}</ref><ref>{{Cite journal | last1=Wang | first1=Miao | last2=Moran | first2=Andrew E. | last3=Liu | first3=Jing | last4=Qi | first4=Yue | last5=Xie | first5=Wuxiang | last6=Tzong | first6=Keane | last7=Zhao | first7=Dong | date=1 December 2015 | title=A Meta-Analysis of Effect of Dietary Salt Restriction on Blood Pressure in Chinese Adults | journal=Global Heart | volume=10 | issue=4 | pages=291–299.e6 | doi=10.1016/j.gheart.2014.10.009 | issn=2211-8179 | pmc=4529389 | pmid=26014655}}</ref>

==== Trace minerals ====
Many elements are required in smaller amounts (microgram quantities), usually because they play a [[catalytic]] role in [[enzymes]].<ref name=lipp>{{cite book | author1=Lippard, S. J. | author2=Berg, J. M. | title=Principles of Bioinorganic Chemistry | publisher=University Science Books | location=Mill Valley, CA | year=1994 | isbn=978-0-935702-73-6}}</ref> Some trace mineral elements (RDA < 200&nbsp;mg/day) are, in alphabetical order:{{medical citation needed|date=July 2015}}
* [[Cobalt]] as a component of the [[vitamin B12|vitamin B<sub>12</sub>]] family of [[coenzyme]]s
* [[Copper]] required component of many redox enzymes, including [[cytochrome c oxidase]] (see [[Copper in health]])
* [[Chromium]] required for sugar metabolism
* [[Iodine]] required not only for the biosynthesis of [[thyroxin]], but probably, for other important organs as breast, stomach, salivary glands, thymus etc. (see [[Iodine deficiency]]); for this reason iodine is needed in larger quantities than others in this list, and sometimes classified with the macrominerals;<ref>{{cite journal | vauthors=Kapil U | title=Health consequences of iodine deficiency | journal=Sultan Qaboos University Medical Journal | volume=7 | issue=3 | pages=267–72 | date=December 2007 | pmid=21748117 | pmc=3074887}}</ref> Nowadays it is most easily found in iodized salt, but there are also natural sources such as ''[[Kombu]]''.<ref>{{cite journal | vauthors=Zava TT, Zava DT | title=Assessment of Japanese iodine intake based on seaweed consumption in Japan: A literature-based analysis | journal=Thyroid Research | volume=4 | issue=1 | pages=14 | date=October 2011 | pmid=21975053 | pmc=3204293 | doi=10.1186/1756-6614-4-14 | doi-access=free}}</ref><ref>{{cite journal | last1=Yeh | first1=Tai Sheng | last2=Hung | first2=Nu Hui | last3=Lin | first3=Tzu Chun | date=1 June 2014 | title=Analysis of iodine content in seaweed by GC-ECD and estimation of iodine intake | journal=Journal of Food and Drug Analysis | volume=22 | issue=2 | pages=189–196 | doi=10.1016/j.jfda.2014.01.014 | issn=1021-9498 | doi-access=free | pmc=9359334}}</ref>
* [[Iron]] required for many enzymes, and for [[hemoglobin]] and some other proteins
* [[Manganese]] (processing of oxygen)
* [[Molybdenum]] required for [[xanthine oxidase]] and related oxidases
* [[Selenium]] required for [[peroxidase]] (antioxidant proteins)
* [[Zinc]] required for several enzymes such as [[carboxypeptidase]], [[Alcohol dehydrogenase#Human|liver alcohol dehydrogenase]], [[carbonic anhydrase]]

==== Ultratrace minerals ====
Ultratrace minerals are an as yet unproven aspect of human nutrition, and may be required at amounts measured in very low ranges of μg/day. Many [[ultratrace element]]s have been suggested as essential, but such claims have usually not been confirmed. Definitive evidence for efficacy comes from the characterization of a biomolecule containing the element with an identifiable and testable function. These include:<ref>{{cite journal | last=Nielsen | first=Forrest H. | date=1998 | title=Ultratrace elements in nutrition: Current knowledge and speculation | journal=The Journal of Trace Elements in Experimental Medicine | language=en | volume=11 | issue=2–3 | pages=251–274 | doi=10.1002/(SICI)1520-670X(1998)11:2/3<251::AID-JTRA15>3.0.CO;2-Q | issn=1520-670X}}</ref><ref>{{cite journal | vauthors=Nielsen FH | title=How should dietary guidance be given for mineral elements with beneficial actions or suspected of being essential? | journal=The Journal of Nutrition | volume=126 | issue=9 Suppl | pages=2377S–2385S | date=September 1996 | pmid=8811801 | doi=10.1093/jn/126.suppl_9.2377S | doi-access=free}}</ref>
* Bromine
* Arsenic
* Nickel
* Fluorine
* Boron
* Lithium
* Strontium
* Silicon
* Vanadium

=== Vitamins ===
{{Main|Vitamin}}

Except for [[vitamin D]], vitamins are essential nutrients,<ref name="Mitchell, Dakota and Haroun, Lee 2012 279" /> necessary in the diet for good health. Vitamin D can be synthesized in the skin in the presence of [[UVB radiation]]. (Many animal species can synthesize [[vitamin C]], but humans cannot.) Certain vitamin-like compounds that are recommended in the diet, such as [[carnitine]], are thought useful for survival and health, but these are not "essential" dietary nutrients because the human body has some capacity to produce them from other compounds. Moreover, thousands of different [[phytochemicals]] have recently been discovered in food (particularly in fresh vegetables), which may have desirable properties including [[antioxidant]] activity (see below); experimental demonstration has been suggestive but inconclusive. Other essential nutrients not classed as vitamins include [[essential amino acid]]s (see [[#Amino Acids|above]]), [[essential fatty acid]]s (see [[#Essential fatty acids|above]]), and the minerals discussed in the preceding section.{{medical citation needed|date=July 2015}}

Vitamin deficiencies may result in disease conditions: [[goiter]], [[scurvy]], [[osteoporosis]], impaired [[immune system]], disorders of cell [[metabolism]], certain forms of cancer, symptoms of premature [[aging]], and poor [[psychology|psychological health]] (including [[eating disorders]]), among many others.<ref>{{cite book | year=2005 | title=Modern Nutrition in Health and Disease | publisher=Lippincott Williams and Wilkins | isbn=978-0-7817-4133-0 | author=Shils}}</ref>

Excess levels of some vitamins are also dangerous to health. The Food and Nutrition Board of the Institute of Medicine has established Tolerable Upper Intake Levels (ULs) for seven vitamins.<ref>{{cite book | editor1=Institute of Medicine | editor-last2=Ross | editor-first2=A. Catharine | editor-last3=Taylor | editor-first3=Christine L. | editor-last4=Yaktine | editor-first4=Ann L. | editor-last5=Del Valle | editor-first5=Heather B. | date=30 March 2011 | title=Dietary reference intakes for calcium and vitamin D | publication-place=Washington, DC | publisher=National Academies Press | isbn=978-0-309-16394-1 | doi=10.17226/13050 | oclc=721907472 | pmid=21796828 | at=pp. [https://nap.nationalacademies.org/read/13050/chapter/24#1112 1112]-1113, Table: Dietary reference intakes (DRIs): Tolerable upper intake levels, vitamins | url=https://www.ncbi.nlm.nih.gov/books/NBK56068/table/summarytables.t7/?report=objectonly | archive-date=2022-06-29 | archive-url=https://web.archive.org/web/20220629190328/https://www.ncbi.nlm.nih.gov/books/NBK56068/table/summarytables.t7/?report=objectonly | url-status=live | author1=Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium | last2=Ross | first2=A. C. | last3=Taylor | first3=C. L. | last4=Yaktine | first4=A. L. | last5=Del Valle | first5=H. B. }}</ref>