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{{Short description|Mineral composed of sodium chloride}}
{{About|the mineral|the compound|sodium chloride|the general term|salt (chemistry)|other uses}}
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{{Use dmy dates|date=December 2017}}
{{Use British English|date=November 2024}}
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[[File:Rock salt (halitite) (Billianwala Salt Member, Salt Range Formation, Ediacaran to Lower Cambrian; Khewra Salt Mine, Salt Range, Pakistan) 14.jpg|thumb|Rock salt (halite)]]
In common usage, '''salt''' is a [[mineral]] composed primarily of [[sodium chloride]] (NaCl). When used in food, especially in granulated form, it is more formally called '''table salt'''. In the form of a natural [[crystalline]] mineral, salt is also known as '''rock salt''' or [[halite]]. Salt is essential for life in general (being the source of the essential [[Mineral (nutrient)|dietary mineral]]s [[Sodium#Biological role|sodium]] and [[Chlorine#Biological role|chlorine]]), and [[saltiness]] is one of the [[Basic tastes|basic human tastes]]. Salt is one of the oldest and most ubiquitous food [[seasoning]]s, and is known to uniformly improve the taste perception of food. [[Salting (food)|Salting]], [[brining]], and [[pickling]] are ancient and important methods of [[food preservation]].
Some of the earliest evidence of salt processing dates to around 6000 BC, when people living in the area of present-day Romania boiled [[spring (hydrology)|spring water]] to extract salts; a [[Salt in Chinese History#Ancient China, Qin and Han dynasties|salt works in China]] dates to approximately the same period.<ref>{{cite book |url=https://adams.marmot.org/Record/.b35134185 |title=Salt: a world history}}</ref> Salt was prized by the ancient [[Hebrews]], [[Ancient Greece|Greeks]], [[Ancient Rome|Romans]], [[Byzantine Empire|Byzantines]], [[Hittites]], [[Ancient Egypt|Egyptians]], and [[Ancient India|Indians]]. Salt became an important [[Commodity|article of trade]] and was transported by boat across the [[Mediterranean Sea]], along specially built [[salt road]]s, and across the [[Sahara]] on [[camel caravan]]s. The scarcity and universal need for salt have led nations to go to war over it and use it to raise [[Salt tax|tax]] revenues, for instance triggering the [[San Elizario Salt War|El Paso Salt War]] which took place in El Paso in the late 1860.<ref>{{Cite web |title=El Paso Salt Wars (U.S. National Park Service) |url=https://www.nps.gov/articles/000/el-paso-salt-wars.htm |access-date=2025-02-25 |website=www.nps.gov}}</ref> Salt is used in religious ceremonies and has other cultural and traditional significance.
Salt is processed from [[salt mining|salt mines]], and by the [[evaporation]] of seawater ([[sea salt]]) and mineral-rich spring water in shallow pools. The greatest single use for salt (sodium chloride) is as a [[Raw material|feedstock]] for the production of chemicals.{{sfnp|Westphal|Kristen|Wegener|Ambatiello|2010}} It is used to produce [[caustic soda]] and [[chlorine]], and in the manufacture of products such as [[polyvinyl chloride]], [[plastic]]s, and [[paper pulp]]. Of the annual global production of around three hundred million [[tonne]]s, only a small percentage is used for human consumption. Other uses include water conditioning processes, [[de-icing]] highways, and agricultural use.<ref>{{Cite web |title=How salt works and overview of deicing chemicals - Minnesota Stormwater Manual |url=https://stormwater.pca.state.mn.us/index.php/How_salt_works_and_overview_of_deicing_chemicals |access-date=2025-02-25 |website=stormwater.pca.state.mn.us}}</ref><ref>{{Cite web |last=jdlanier |date=2016-01-15 |title=The Impact of Salts on Plants and How to Reduce Plant Injury from Winter Salt Applications |url=https://ag.umass.edu/landscape/fact-sheets/impact-of-salts-on-plants-how-to-reduce-plant-injury-from-winter-salt |access-date=2025-02-25 |website=Center for Agriculture, Food, and the Environment |language=en}}</ref> Edible salt is sold in forms such as sea salt and table salt, the latter of which usually contains an [[anti-caking agent]] and may be [[iodised salt|iodised]] to prevent [[iodine deficiency]]. As well as its use in cooking and at the table, salt is present in many processed foods.
[[Sodium]] is an [[Mineral (nutrient)|essential element]] for human health via its role as an [[electrolyte]] and [[osmosis|osmotic solute]].<ref name=USDA2015/><ref name="IOM2013">{{cite book |url=http://books.nap.edu/openbook.php?record_id=18311 |title=Sodium intake in populations: assessment of evidence |year=2013 |publisher=Institute of Medicine of the National Academies |editor-first1=Brian L. |editor-last1=Strom |editor-first2=Ann L. |editor-last2=Yaktine |editor-first3=Maria |editor-last3=Oria |access-date=17 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20131019135047/http://books.nap.edu/openbook.php?record_id=18311 |archive-date=19 October 2013 |df=dmy-all |doi=10.17226/18311 |pmid=24851297 |isbn=978-0-309-28295-6 |author1=Committee on the Consequences of Sodium Reduction in Populations |last2=Food Nutrition |first2=Board |author3=Board on Population Health Public Health Practice |last4=Institute Of |first4=Medicine |last5=Strom |first5=B. L. |last6=Yaktine |first6=A. L. |last7=Oria |first7=M.}}</ref><ref name=CDC/> However, excessive salt consumption increases the risk of [[cardiovascular diseases]] such as [[hypertension]]. Such [[health effects of salt]] have long been studied. Accordingly, numerous world health associations and experts in developed countries recommend reducing consumption of popular salty foods.<ref name=CDC/><ref name="efsa">{{cite web |url=http://www.efsa.europa.eu/en/press/news/050622 |title=EFSA provides advice on adverse effects of sodium |publisher=European Food Safety Authority |date=22 June 2005 |access-date=9 June 2016 |archive-date=4 August 2017 |archive-url=https://web.archive.org/web/20170804134312/http://www.efsa.europa.eu/en/press/news/050622 |url-status=live }}</ref> The [[World Health Organization]] recommends that adults consume less than 2,000 mg of sodium, equivalent to 5 grams of salt, per day.<ref name=WHO2013/><ref>{{cite journal |title=Europe PMC |url=https://europepmc.org/article/med/22465720 |access-date=2021-06-07 |journal=Presse Médicale |year=2012 |pmid=22465720 |last1=Delahaye |first1=F. |volume=41 |issue=6 Pt 1 |pages=644–649 |doi=10.1016/j.lpm.2012.02.035 |archive-date=7 June 2021 |archive-url=https://web.archive.org/web/20210607031645/https://europepmc.org/article/med/22465720 |url-status=live |url-access=subscription }}</ref>
== History
{{Main|History of salt}}
[[File:Salzproduktion-Halle.jpg|thumb|Salt production in [[Halle, Saxony-Anhalt]] (1670)]]
[[File:Salinas de Maras, Peru-20Sept2013.jpg|thumb|Ponds near [[Salt Mines of Maras|Maras, Peru]], fed from a mineral spring and used for salt production since [[Periodization of pre-Columbian Peru|pre-Inca times]] ]]
All through history, the availability of salt has been pivotal to civilization. What is now thought to have been the first city in Europe is [[Solnitsata]], in [[Bulgaria]], which was a salt mine, providing the area now known as the [[Balkans]] with salt since 5400 BC.<ref>LA Times<br />[https://www.latimes.com/science/la-xpm-2012-nov-01-la-sci-sn-oldest-european-town-20121101-story.html Bulgarians find oldest European town, a salt production center] {{Webarchive |url=https://web.archive.org/web/20190504234136/https://www.latimes.com/science/la-xpm-2012-nov-01-la-sci-sn-oldest-european-town-20121101-story.html |date=4 May 2019 }}</ref> Salt was the best-known food preservative, especially for meat, for many thousands of years.{{sfnp|Barber|1999|p=136}} A very ancient salt-works operation has been discovered at the Poiana Slatinei archaeological site next to a salt spring in [[Vânători-Neamţ|Lunca]], [[Neamț County]], Romania. Evidence indicates that [[Neolithic]] people of the [[Cucuteni-Trypillian culture|Precucuteni Culture]] were boiling the salt-laden spring water through the process of [[briquetage]] to extract salt as far back as 6050 BC.{{sfnp|Weller|Dumitroaia|2005}} The salt extracted from this operation may have directly correlated with the rapid growth of this society's population soon after production began.{{sfnp|Weller|Brigand|Nuninger|2008|pp=225–30}} The harvest of salt from the surface of [[Xiechi Lake]] near [[Yuncheng, Shanxi|Yuncheng]] in [[Shanxi]], China, dates back to at least 6000 BC, making it one of the oldest verifiable saltworks.{{sfnp|Kurlansky|2002|pp=18–19}}
There is more salt in animal tissues, such as meat, blood, and milk, than in plant tissues.<ref name=HMSO/> [[Nomad]]s who subsist on their flocks and herds do not eat salt with their food, but agriculturalists, feeding mainly on cereals and vegetable matter, need to supplement their diet with salt.<ref name="EB">{{cite web |url=http://www.britannica.com/EBchecked/topic/519712/salt-NaCl |title=Salt (NaCl) |last=Wood |first=Frank Osborne |publisher=Encyclopædia Britannica online |access-date=9 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20150502184136/http://www.britannica.com/EBchecked/topic/519712/salt-NaCl |archive-date=2 May 2015 |df=dmy-all}}</ref> With the spread of civilization, salt became one of the world's main trading commodities. It was of high value to the ancient Hebrews, the Greeks, the Romans, the Byzantines, the Hittites and other peoples of antiquity. In the Middle East, salt was used to seal an agreement ceremonially, and the ancient Hebrews made a "[[covenant of salt]]" with God and sprinkled salt on their offerings to show their trust in him.<ref>{{cite web |url=http://www.torahclass.com/archived-articles/1036-featured-article-sp-940659465 |title=Covenant of salt |last=Suitt |first=Chris |work=Rediscovering the Old Testament |publisher=Seed of Abraham Ministries |access-date=12 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20160305032105/http://torahclass.com/archived-articles/1036-featured-article-sp-940659465 |archive-date=5 March 2016 |df=dmy-all}}</ref> An ancient practice in time of war was [[salting the earth]]: scattering salt around in a defeated city to symbolically prevent plant growth. The [[Bible]] tells the story of King [[Abimelech]] who was ordered by God to do this at [[Shechem]],<ref>{{cite journal |last=Gevirtz |first=Stanley |year=1963 |title=Jericho and Shechem: A Religio-Literary Aspect of City Destruction |journal=Vetus Testamentum |volume=13 |issue=1 |pages=52–62 |jstor=1516752 |doi=10.2307/1516752}}</ref> and various texts claim that the [[Roman Republic|Roman]] general [[Scipio Aemilianus Africanus]] ploughed over and sowed the city of [[Carthage]] with salt after it was defeated in the [[Third Punic War]] (146 BC),<ref>{{cite book |last1=Ripley |first1=George |last2=Dana |first2=Charles Anderson |title=The New American Cyclopædia: a Popular Dictionary of General Knowledge |volume=4 |page=497 |year=1863 |url=https://books.google.com/books?id=bK4rAAAAYAAJ&q=carthage+sowing+salt&pg=PA497 |url-status=live |archive-url=https://web.archive.org/web/20150906143613/https://books.google.com/books?id=bK4rAAAAYAAJ&pg=PA497&dq=carthage+sowing+salt&q=carthage+sowing+salt |archive-date=6 September 2015 |df=dmy-all}}</ref> although this story is now considered to be entirely apocryphal.
Salt may have been used for [[barter]] in connection with the [[obsidian]] trade in [[Anatolia]] in the [[Neolithic|Neolithic Era]].<ref>{{cite journal |last1=Golbas |first1=Alper |last2=Basobuyuk |first2=Zeynel |year=2012 |title=The role of salt in the formation of the Anatolian culture |journal=Batman University: Journal of Life Sciences |volume=1 |issue=1 |pages=45–54 |url=https://www.academia.edu/2340259 |url-status=live |archive-url=https://web.archive.org/web/20131211234508/http://www.academia.edu/2340259/Anadolu_Kultur_Olusumunda_Tuzun_Rolu-_The_Role_of_Salt_in_the_Formation_of_the_Anatolian_Culture |archive-date=11 December 2013 |df=dmy-all}}</ref> Salt was included among funeral offerings found in [[ancient Egypt]]ian tombs from the third millennium BC, as were salted birds, and salt fish.{{sfnp|Kurlansky|2002|p=38}} From about 2800 BC, the Egyptians began exporting salt fish to the [[Phoenicia]]ns in return for [[Lebanon cedar]], glass, and the dye [[Tyrian purple]]; the Phoenicians traded Egyptian salted fish and salt from [[North Africa]] throughout their Mediterranean trade empire.{{sfnp|Kurlansky|2002|pp=44}} [[Herodotus]] described salt trading routes across Libya back in the 5th century BC. In the early years of the Roman Empire, roads were built for the transportation of salt from the salt imported at [[Ostia (Rome)|Ostia]] to the capital.<ref>{{cite news |title=A brief history of salt |url=http://content.time.com/time/magazine/article/0,9171,925341,00.html |newspaper=Time Magazine |date=15 March 1982 |access-date=11 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20160509161416/http://content.time.com/time/magazine/article/0%2C9171%2C925341%2C00.html |archive-date=9 May 2016 |df=dmy-all}}</ref>
In Africa, salt was used as currency south of the Sahara, and slabs of rock salt were used as coins in [[Ethiopia|Abyssinia]].<ref name="EB" /> The [[Tuareg people|Tuareg]] have traditionally maintained routes across the [[Sahara]] especially for the transportation of salt by [[Azalai]] (salt caravans). The caravans still cross the desert from southern Niger to [[Bilma]], although much of the trade now takes place by truck. Each camel takes two bales of [[fodder]] and two of trade goods northwards and returns laden with salt pillars and dates.<ref>{{cite web |url=http://www.bradshawfoundation.com/africa/tuareg_salt_caravans/ |title=Tuareg Salt Caravans of Niger, Africa |last=Paolinelli |first=Franco |publisher=Bradshaw Foundation |access-date=11 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20160803184735/http://www.bradshawfoundation.com/africa/tuareg_salt_caravans/ |archive-date=3 August 2016 |df=dmy-all}}</ref> In Gabon, before the arrival of Europeans, the coast people carried on a remunerative trade with those of the interior by the medium of sea salt. This was gradually displaced by the salt that Europeans brought in sacks, so that the coast natives lost their previous profits; as of the late 1950s, sea salt was still the currency best appreciated in the interior.<ref>{{cite book |last=Schweitzer |first=Albert |title=African Notebook |year=1958 |publisher=Indiana University Press}}</ref>
[[Salzburg]], [[Hallstatt]], and [[Hallein]] lie within {{cvt|17|km}} of each other on the river Salzach in central Austria in an area with extensive salt deposits. [[Salzach]] means "salt river" while Salzburg means "salt castle", both taking their names from the [[German language|German]] word {{lang|de|Salz}}, salt. Hallstatt was the site of the world's first [[Salt mining|salt mine]].<ref>{{cite web |url=http://www.virtualvienna.net/columns/billie/hallstatt/hallstatt.html |title=Hallstatt's White Gold: Salt |first=Billie Ann |last=Lopez |work=Virtual Vienna Net |access-date=3 March 2013 |url-status=dead |archive-url=https://web.archive.org/web/20070210142713/http://www.virtualvienna.net/columns/billie/hallstatt/hallstatt.html |archive-date=10 February 2007}}</ref> The town gave its name to the [[Hallstatt culture]] that began mining for salt in the area in about 800 BC. Around 400 BC, the townsfolk, who had previously used [[pickaxe]]s and [[shovel]]s, began [[open pan salt making]]. During the first millennium BC, Celtic communities grew rich trading salt and [[Salt-cured meat|salted meat]] to [[Ancient Greece]] and [[Ancient Rome]] in exchange for wine and other luxuries.{{sfnp|Barber|1999|p=136}}
The word ''[[salary]]'' comes from the [[Latin]] word for salt. The reason for this is unknown; a persistent modern claim that the [[Roman Legion]]s were sometimes paid in salt is baseless.<ref>{{cite web |title=Economics of NaCl: Salt made the world go round |work=Mr Block Archive |author=Bloch, David |url=http://www.salt.org.il/frame_econ.html |access-date=19 December 2006 |df=dmy-all |archive-date=29 January 2007 |archive-url=https://web.archive.org/web/20070129144818/http://www.salt.org.il/frame_econ.html |url-status=live }}</ref><ref>{{cite news |title=The history of salt production at Droitwich Spa |work=BBC |url=http://news.bbc.co.uk/local/herefordandworcester/hi/people_and_places/religion_and_ethics/newsid_8473000/8473037.stm |access-date=28 March 2011 |date=21 January 2010 |df=dmy-all |archive-date=22 February 2014 |archive-url=https://web.archive.org/web/20140222150314/http://news.bbc.co.uk/local/herefordandworcester/hi/people_and_places/religion_and_ethics/newsid_8473000/8473037.stm |url-status=live }}</ref> The word ''salad'' literally means "salted", and comes from the ancient Roman practice of salting [[leaf vegetable]]s.{{sfnp|Kurlansky|2002|pp=64}}
Wars have been fought over salt. [[Republic of Venice|Venice]] won the [[Salt War (1304)]] with [[Padua]] over supplying the product in certain areas and the [[War of Ferrara (1482–1484)]] for the same reason.<ref name=Cowen/><ref>{{cite book |last1=Fontana |first1=Emanuele |title=Dizionario Biografico degli Italiani - Volume 81 |date=2014 |publisher=Treccani |url=https://www.treccani.it/enciclopedia/paolino-da-venezia-vescovo-di-pozzuoli_(Dizionario-Biografico)/ |chapter=PAOLINO da Venezia, vescovo di Pozzuoli}}</ref> It played a role in the [[American Revolution]] and the [[San Elizario Salt War]]. Cities on overland trade routes grew rich by levying [[Duty (economics)|duties]],<ref name=Cowen/> and towns like [[Liverpool]] flourished on the export of salt extracted from the salt mines of [[Cheshire]].<ref>{{cite web |url=http://www.igg.org.uk/gansg/12-linind/salt.htm |title=Salt |last=Smith |first=Mike |year=2003 |work=Goods & Not So Goods: Lineside Industries |access-date=15 October 2013 |url-status=dead |archive-url=https://web.archive.org/web/20111124114738/http://www.igg.org.uk/gansg/12-linind/salt.htm |archive-date=24 November 2011 |df=dmy-all}}</ref> Various governments have at different times imposed salt taxes on their peoples. The voyages of [[Christopher Columbus]] are said to have been financed from salt production in southern Spain, and the oppressive [[Gabelle|salt tax in France]] was one of the causes of the [[French Revolution]]. After being repealed, this tax was reimposed by [[Napoleon]] when he became emperor to pay for his [[Napoleonic Wars|foreign wars]], and was not finally abolished until 1946.<ref name=Cowen>{{cite web |url=http://mygeologypage.ucdavis.edu/cowen/~gel115/salt.html |title=The Importance of Salt |last=Cowen |first=Richard |date=1 May 1999 |access-date=15 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20160507083302/http://mygeologypage.ucdavis.edu/cowen/~GEL115/salt.html |archive-date=7 May 2016 |df=dmy-all}}</ref> In 1930, [[Mahatma Gandhi]] led a crowd of 100,000 protestors on the "Dandi March" or "[[Salt Satyagraha]]", during which they made their own salt from the sea as a demonstration of their opposition to the [[History of the British salt tax in India|colonial salt tax]]. This act of [[civil disobedience]] inspired numerous Indians and transformed the [[Indian independence movement]] into a national struggle.{{sfnp|Dalton|1996|p=72}}
== Physical properties ==
{{Anchor|Chemistry}}
{{main|Sodium chloride}}
[[File:Single grain of table salt (electron micrograph).jpg|thumb|[[Scanning electron microscope|SEM]] image of a grain of table salt]]
Salt is mostly [[sodium chloride]] (NaCl). [[Sea salt]] and mined salt may contain [[trace element]]s. Mined salt is often refined. Salt crystals are translucent and cubic in shape; they normally appear white but impurities may give them a blue or purple tinge. When dissolved in water sodium chloride separates into Na<sup>+</sup> and Cl<sup>−</sup> ions, and the solubility is 359 grams per litre.<ref>{{cite encyclopedia |url=http://www.britannica.com/EBchecked/topic/519712/salt-NaCl |title=Salt (NaCl) |last1=Wood |first1=Frank Osborne |last2=Ralston |first2=Robert H. |encyclopedia=Encyclopædia Britannica |access-date=16 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20150502184136/http://www.britannica.com/EBchecked/topic/519712/salt-NaCl |archive-date=2 May 2015 |df=dmy-all}}</ref> From cold solutions, salt crystallises as the [[water of hydration|dihydrate]] NaCl·2H<sub>2</sub>O. Solutions of sodium chloride have very different properties from those of pure water; the [[freezing point]] is −21.12 °C (−6.02 °F) for 23.31 wt% of salt, and the [[boiling point]] of saturated salt solution is around 108.7 °C (227.7 °F).{{sfnp|Westphal|Kristen|Wegener|Ambatiello|2010}}
==Edible salt==
{{See also|List of edible salts|Salt substitute}}
[[File:Comparison of Table Salt with Kitchen Salt.png|thumb|Comparison of table salt with [[kitchen salt]]. Shows a typical salt shaker and salt bowl with salt spread before each on a black background.]]
Salt is essential to the health of humans and other animals, and it is one of the [[Basic tastes#Basic tastes|five basic taste sensations]].<ref>{{cite web |url=http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Taste.html |title=The sense of taste |date=16 March 2013 |access-date=16 October 2013 |url-status=dead |archive-url=https://web.archive.org/web/20160408080806/http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/T/Taste.html |archive-date=8 April 2016 |df=dmy-all}}</ref> It is known to uniformly improve the taste perception of food, including otherwise unpalatable food.<ref>{{cite book |url=https://www.ncbi.nlm.nih.gov/books/NBK50958/ |title=Strategies to Reduce Sodium Intake in the United States|section=3 — Taste and Flavor Roles of Sodium in Foods: A Unique Challenge to Reducing Sodium Intake |author=Institute of Medicine (US) Committee on Strategies to Reduce Sodium Intake |editor1=Jane E. Henney |editor2=Christine L. Taylor |editor3=Caitlin S. Boon |isbn=978-0-309-14806-1 |publication-date=2010 |publisher=National Academies Press |___location=Washington, DC |accessdate=29 October 2022 |archive-date=9 May 2021 |archive-url=https://web.archive.org/web/20210509080305/https://www.ncbi.nlm.nih.gov/books/NBK50958/ |url-status=live}}</ref> Salt is used in many cuisines, and it is often found in [[salt shaker]]s on diners' eating tables for their personal use on food. Salt is also an ingredient in many manufactured foodstuffs. Table salt is a refined salt containing about 97 to 99 percent [[sodium chloride]].<ref>{{cite web |title=Tesco Table Salt 750g |url=http://www.tesco.com/superstore/xpi/8/xpi50042778.htm |publisher=Tesco |access-date=5 December 2010 |quote=Nutritional analysis provided with Tesco Table Salt states 38.9 percent sodium by weight which equals 97.3 percent sodium chloride |url-status=live |archive-url=https://web.archive.org/web/20090511004300/http://www.tesco.com/superstore/xpi/8/xpi50042778.htm |archive-date=11 May 2009 |df=dmy-all}}</ref><ref>[http://www.wasalt.com.au/Table.html Table Salt] {{webarchive |url=https://web.archive.org/web/20070805064907/http://www.wasalt.com.au/Table.html |date=5 August 2007 }}. Wasalt.com.au. Retrieved 7 July 2011.</ref><ref>[http://www.codexalimentarius.net/download/standards/3/CXS_150e.pdf The international Codex Alimentarius Standard for Food Grade Salt] {{webarchive |url=https://web.archive.org/web/20120314012629/http://www.codexalimentarius.net/download/standards/3/CXS_150e.pdf |date=14 March 2012 }}. (PDF). Retrieved 7 July 2011.</ref> Usually, [[anticaking agents]] such as [[sodium aluminosilicate]] or [[magnesium carbonate]] are added to make it free-flowing. [[Iodized salt]], containing [[potassium iodide]], is widely available. Some people put a [[desiccant]], such as a few grains of uncooked [[rice]]<ref>{{cite web |url=http://www.newton.dep.anl.gov/askasci/gen01/gen01420.htm |title=Rice in Salt Shakers |publisher=Ask a Scientist |access-date=29 July 2008 |url-status=live |archive-url=https://web.archive.org/web/20110314162037/http://www.newton.dep.anl.gov/askasci/gen01/gen01420.htm |archive-date=14 March 2011 |df=dmy-all}}</ref> or a [[saltine cracker]], in their salt shakers to absorb extra moisture and help break up salt clumps that may otherwise form.<ref>{{cite web |url=http://ww3.komotv.com/story/1454284/food-freshness?redirected=true |archive-url=https://web.archive.org/web/20110820105950/http://ww3.komotv.com/story/1454284/food-freshness?redirected=true |archive-date=20 August 2011 |title=Food Freshness |publisher=KOMO News |access-date=8 July 2011}}</ref>
===
Some table salt sold for consumption contains additives that address a variety of health concerns, especially in the developing world. The identities and amounts of additives vary from country to country. [[Iodine]] is an important micronutrient for humans, and a [[iodine deficiency|deficiency]] of the element can cause lowered production of [[thyroxine]] ([[hypothyroidism]]) and enlargement of the thyroid gland ([[endemic goitre]]) in adults or [[cretinism]] in children.{{sfnp|Vaidya|Chakera|Pearce|2011}} Iodized salt has been used to correct these conditions since 1924{{sfnp|Markel|1987}} and consists of table salt mixed with a minute amount of [[potassium iodide]], [[sodium iodide]], or [[sodium iodate]]. A small amount of [[dextrose]] may be added to stabilize the iodine.<ref>{{cite web |url=http://extension.psu.edu/food-safety/food-preservation/faq/canning-and-pickling-salt |title=Canning and Pickling salt |publisher=Penn State University |url-status=live |archive-url=https://web.archive.org/web/20130407164426/http://extension.psu.edu/food-safety/food-preservation/faq/canning-and-pickling-salt |archive-date=7 April 2013 |df=dmy-all}}; {{cite web |url=http://www.mortonsalt.com/faqs/food-salt-faqs |publisher=Morton Salt |title=FAQs |url-status=dead |archive-url=https://web.archive.org/web/20140927063741/http://www.mortonsalt.com/faqs/food-salt-faqs |archive-date=27 September 2014 |df=dmy-all}}</ref> Iodine deficiency affects about two billion people around the world and is the leading preventable cause of [[intellectual disabilities]].<ref name="mcneil">{{cite news |url=https://www.nytimes.com/2006/12/16/health/16iodine.html |title=In Raising the World's I.Q., the Secret's in the Salt |last=McNeil |first=Donald G. Jr |date=16 December 2006 |work=[[The New York Times]] |access-date=4 December 2008 |url-status=live |archive-url=https://web.archive.org/web/20081209044238/http://www.nytimes.com/2006/12/16/health/16iodine.html |archive-date=9 December 2008 |df=dmy-all}}</ref> Iodized table salt has significantly reduced disorders of iodine deficiency in countries where it is used.<ref>{{cite web |title=Iodized salt |url=http://www.saltinstitute.org/Uses-benefits/Salt-in-Food/Essential-nutrient/Iodized-salt |publisher=Salt Institute |access-date=5 December 2010 |year=2009 |url-status=live |archive-url=https://web.archive.org/web/20130214101408/http://www.saltinstitute.org/Uses-benefits/Salt-in-Food/Essential-nutrient/Iodized-salt |archive-date=14 February 2013 |df=dmy-all}}</ref>
The amount of iodine and the specific iodine compound added to salt varies. In the [[United States]], the [[Food and Drug Administration]] (FDA) recommends 150 [[micrograms]] of iodine per day for both men and women.<ref>{{Cite web |last= |first= |date= |title=21 Code of Federal Regulations 101.9 (c)(8)(iv) |url=https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm?fr=101.9 |access-date=2021-01-30 |website=www.accessdata.fda.gov |archive-date=4 March 2021 |archive-url=https://web.archive.org/web/20210304132252/https://www.accessdata.fda.gov/scrIpts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=101.9 |url-status=live }}</ref> US iodized salt contains 46–77 ppm (parts per million), whereas in the UK the recommended iodine content of iodized salt is 10–22 ppm.<ref>{{cite web |title=Discussion Paper on the setting of maximum and minimum amounts for vitamins and minerals in foodstuffs |url=http://ec.europa.eu/food/food/labellingnutrition/supplements/documents/akj_en.pdf |publisher=Directorate-General Health & Consumers |access-date=5 December 2010 |url-status=dead |archive-url=https://web.archive.org/web/20121103050102/http://ec.europa.eu/food/food/labellingnutrition/supplements/documents/akj_en.pdf |archive-date=3 November 2012 |df=dmy-all}}</ref>
[[Sodium ferrocyanide]], yellow [[prussiate]] of soda, is sometimes added to salt as an [[anticaking agent]].<ref name="api.parliament.uk"/> Such anticaking agents have been added since at least 1911 when [[magnesium carbonate]] was first added to salt to make it flow more freely.<ref>{{cite web |title=Morton Salt FAQ |url=http://www.mortonsalt.com/faqs/general-company-faqs#q3 |access-date=12 May 2007 |url-status=live |archive-url=https://web.archive.org/web/20120119105846/http://www.mortonsalt.com/faqs/general-company-faqs#q3 |archive-date=19 January 2012 |df=dmy-all}}</ref> The safety of sodium ferrocyanide as a food additive was found to be provisionally acceptable by the [[Committee on Toxicity]] in 1988.<ref name="api.parliament.uk">[https://api.parliament.uk/historic-hansard/written-answers/1993/may/05/table-salt Discussions of the safety of sodium hexaferrocyanate in table salt] {{webarchive |url=https://web.archive.org/web/20160304090336/http://hansard.millbanksystems.com/written_answers/1993/may/05/table-salt |date=4 March 2016 }}. api.parliament.uk (5 May 1993). Retrieved 7 July 2011.</ref> Other anticaking agents sometimes used include [[tricalcium phosphate]], [[calcium carbonate|calcium]] or magnesium carbonates, [[fatty acid]] salts ([[acid salt]]s), [[magnesium oxide]], [[silicon dioxide]], [[calcium silicate]], sodium aluminosilicate and [[calcium aluminosilicate]]. Both the European Union and the United States Food and Drug Administration permitted the use of [[aluminium]] in the latter two compounds.<ref>{{cite web |first1=Wilella Daniels |last1=Burgess |first2=April C. |last2=Mason |url=http://www.ces.purdue.edu/extmedia/HE/HE-625.html |title=What Are All Those Chemicals in My Food? |publisher=School of Consumer and Family Sciences, Purdue University |access-date=27 February 2011 |url-status=dead |archive-url=https://web.archive.org/web/20060211210829/http://www.ces.purdue.edu/extmedia/HE/HE-625.html |archive-date=11 February 2006 |df=dmy-all}}</ref>
In "doubly fortified salt", both iodide and iron salts are added. The latter alleviates [[iron deficiency anaemia]], which interferes with the mental development of an estimated 40% of infants in the developing world. A typical iron source is [[Iron(II) fumarate|ferrous fumarate]].{{sfnp|Westphal|Kristen|Wegener|Ambatiello|2010}} Another additive, especially important for [[pregnancy|pregnant]] women, is [[folic acid]] (vitamin B<sub>9</sub>), which gives the table salt a yellow colour. Folic acid helps prevent [[neural tube defect]]s and anaemia, which affect young mothers, especially in developing countries.{{sfnp|Westphal|Kristen|Wegener|Ambatiello|2010}}
A lack of [[fluoride]] in the diet is the cause of a greatly increased incidence of [[dental caries]].{{sfnp|Selwitz|Ismail|Pitts|2007}} [[Fluoride]] salts can be added to table salt with the goal of reducing tooth decay, especially in countries that have not benefited from fluoridated toothpastes and fluoridated water. The practice is more common in some European countries where [[water fluoridation]] is not carried out. In [[France]], 35% of the table salt sold contains added [[sodium fluoride]].{{sfnp|Westphal|Kristen|Wegener|Ambatiello|2010}}
=== Other kinds ===
{{multiple image
| direction = horizontal
| image1 = Himalayan salt of Saúde flea market, São Paulo, Brazil.jpg
| caption1 = [[Himalayan salt]] is [[halite]] with a distinct pink colour.
| width1 = 130
| image2 = DeadSeaIsrael5.jpg
| caption2 = Salt deposits beside the [[Dead Sea]], Israel
| width2 = 170
}}
Unrefined [[sea salt]] contains small amounts of [[magnesium]] and [[calcium]] [[halides]] and [[sulfate]]s, traces of [[algae|algal products]], salt-resistant bacteria and sediment particles. The calcium and magnesium salts confer a faintly bitter overtone, and they make unrefined sea salt [[hygroscopic]] (i.e., it gradually absorbs moisture from air if stored uncovered). Algal products contribute a mildly "fishy" or "sea-air" odour, the latter from [[Organobromine compound#Organobromine compounds in nature|organobromine compounds]]. Sediments, the proportion of which varies with the source, give the salt a dull grey appearance. Since taste and aroma compounds are often detectable by humans in minute concentrations, sea salt may have a more complex flavour than pure sodium chloride when sprinkled on top of food. When salt is added during cooking however, these flavours would likely be overwhelmed by those of the food ingredients.{{sfnp|McGee|2004|p=642}} The refined salt industry cites scientific studies saying that raw sea and rock salts do not contain enough [[iodine]] salts to prevent [[Iodine deficiency|iodine deficiency diseases]].<ref>{{cite web |title=References on food salt & health issues |url=http://www.saltinstitute.org/Articles-references/References-on-salt-issues/References-on-salt-issues/References-on-food-salt-health-issues |publisher=Salt Institute |access-date=5 December 2010 |year=2009 |url-status=dead |archive-url=https://web.archive.org/web/20100919163713/http://www.saltinstitute.org/Articles-references/References-on-salt-issues/References-on-salt-issues/References-on-food-salt-health-issues |archive-date=19 September 2010 |df=dmy-all}}</ref>
Salts have diverse [[Minerality#I–P|mineralities]] depending on their source, giving each a unique flavour. [[Fleur de sel]], a natural sea salt from the surface of evaporating brine in salt pans, has a distinctive flavour varying with its source. In traditional [[Korean cuisine]], so-called "[[jugyeom|bamboo salt]]" is prepared by roasting salt{{sfnp|Livingston|2005|p=45}} in a [[bamboo]] container plugged with mud at both ends. This product absorbs minerals from the bamboo and the mud, and has been claimed to increase the [[clastogen|anticlastogenic]] and [[mutagen|antimutagenic]] properties of [[doenjang]] (a fermented bean paste).{{sfnp|Shahidi|Shi|Ho|2005|p=575}} [[Kosher salt|Kosher or kitchen salt]] has a larger grain size than table salt and is used in cooking. It can be useful for [[brining]], in bread or [[pretzel]] making, and as a scrubbing agent when combined with oil.<ref>{{cite web |url=http://www.saltworks.us/salt_info/kosher-salt.asp |title=Kosher Salt Guide |publisher=SaltWorks |year=2010 |url-status=live |archive-url=https://web.archive.org/web/20101224110615/http://saltworks.us/salt_info/kosher-salt.asp |archive-date=24 December 2010 |df=dmy-all}}</ref>
=== Salt in food ===
Salt is present in most [[food]]s, but in naturally occurring foodstuffs such as meats, vegetables and fruit, it is present in very small quantities. It is often added to processed foods (such as [[canning|canned foods]] and especially [[salting (food)|salted foods]], [[pickling|pickled foods]], and [[snack food]]s or other [[convenience food]]s), where it functions as both a [[preservative]] and a [[flavoring|flavouring]]. [[Dairy salt]] is used in the preparation of butter and cheese products.<ref>{{cite book |last1=Pieters |first1=A.J. |last2=Flint |first2=D. |last3=Garriott |first3=E.B. |last4=Wickson |first4=E.J. |last5=Lamson-Scribner |first5=F. |last6=Brackett |first6=G.B. |last7=Atwater |first7=H.W. |last8=Alvord |first8=H.E. |last9=Withcombe |first9=J. |last10=Howard |first10=L.O. |display-authors=5 |title=Experiment Station Work |publisher=U.S. Department of Agriculture |series=Bread and the Principles of Bread Making |year=1899 |url=https://books.google.com/books?id=l85CAQAAMAAJ&pg=RA5-PA28 |access-date=17 November 2015 |pages=28–30 |url-status=live |archive-url=https://web.archive.org/web/20160616193742/https://books.google.com/books?id=l85CAQAAMAAJ&pg=RA5-PA28 |archive-date=16 June 2016 |df=dmy-all}}</ref> As a flavouring, salt enhances the taste of other foods by suppressing the bitterness of those foods making them more palatable and relatively sweeter.<ref>{{cite journal |last1=Breslin |first1=P. A. S. |last2=Beauchamp |first2=G. K. |title=Salt enhances flavour by suppressing bitterness |journal=Nature |date=5 June 1997 |volume=387 |issue=6633 |pages=563 |doi=10.1038/42388 |pmid=9177340 |bibcode=1997Natur.387..563B |s2cid=205030709|doi-access=free }}</ref>
Before the advent of electrically powered [[refrigeration]], salting was one of the main methods of [[food preservation]]. Thus, [[herring]] contains 67 mg sodium per 100 g, while [[kipper]], its preserved form, contains 990 mg. Similarly, [[pork]] typically contains 63 mg while [[bacon]] contains 1,480 mg, and [[potato]]es contain 7 mg but [[potato crisp]]s 800 mg per 100 g.<ref name=HMSO /> Salt is used extensively in [[cooking]] as a flavouring, and in cooking techniques such as with [[salt crust]]s and [[brining]]. The main sources of salt in the Western diet, apart from direct use, are bread and cereals, meat, and dairy products.<ref name=HMSO>{{cite book |last1=Buss |first1=David |last2=Robertson |first2=Jean |title=Manual of Nutrition |year=1973 |publisher=Her Majesty's Stationery Office |isbn=978-0-11-241112-3 |pages=37–38}}</ref>
In many East Asian cultures, salt is not traditionally used as a condiment.<ref>{{cite web |url=https://archive.seattletimes.com/archive/20010729/pfish29/the-salt-of-southeast-asia |work=The Seattle Times |title=The Salt of Southeast Asia |access-date=7 July 2011 |year=2001 |url-status=live |archive-url=https://web.archive.org/web/20160303223708/http://community.seattletimes.nwsource.com/archive/?date=20010729&slug=pfish29 |archive-date=3 March 2016 |df=dmy-all}}</ref> In its place, condiments such as [[soy sauce]], [[fish sauce]] and [[oyster sauce]] tend to have a high sodium content and fill a similar role to table salt in western cultures. They are most often used for cooking rather than as table condiments.<ref>{{cite web |url=http://www.diet.com/g/asian-diet |title=Asian diet |publisher=Diet.com |access-date=7 July 2013 |url-status=live |archive-url=https://web.archive.org/web/20160611091524/http://www.diet.com/g/asian-diet |archive-date=11 June 2016 |df=dmy-all}}</ref>
=== Biology of salt taste ===
{{See also|Taste receptor#Salt|Taste#Saltiness}}
Human salt [[taste]] is detected by sodium [[taste receptor]]s present in taste bud cells on the tongue.<ref>{{Cite book |last1=Intake |first1=Institute of Medicine (US) Committee on Strategies to Reduce Sodium |url=https://www.ncbi.nlm.nih.gov/books/NBK50958/ |title=Taste and Flavor Roles of Sodium in Foods: A Unique Challenge to Reducing Sodium Intake |last2=Henney |first2=Jane E. |last3=Taylor |first3=Christine L. |last4=Boon |first4=Caitlin S. |date=2010 |publisher=National Academies Press (US) |language=en |access-date=4 April 2021 |archive-date=9 May 2021 |archive-url=https://web.archive.org/web/20210509080305/https://www.ncbi.nlm.nih.gov/books/NBK50958/ |url-status=live }}</ref> Human sensory taste testing studies have shown that [[Proteolysis|proteolyzed]] forms of [[epithelial sodium channel]] (ENaC) function as the human salt taste receptor.<ref>{{Cite journal |last1=Shekdar |first1=Kambiz |last2=Langer |first2=Jessica |last3=Venkatachalan |first3=Srinivasan |last4=Schmid |first4=Lori |last5=Anobile |first5=Jonathan |last6=Shah |first6=Purvi |last7=Lancaster |first7=Amy |last8=Babich |first8=Olga |last9=Dedova |first9=Olga |last10=Sawchuk |first10=Dennis |display-authors=5 |date=2021-03-08 |title=Cell engineering method using fluorogenic oligonucleotide signaling probes and flow cytometry |url= |journal=Biotechnology Letters |volume=43 |issue=5 |pages=949–958 |doi=10.1007/s10529-021-03101-5 |issn=1573-6776 |pmc=7937778 |pmid=33683511}}</ref>
===
{{Main|Health effects of salt}}
Table salt is made up of just under 40% sodium by weight, so a 6{{nbsp}}g serving (1{{nbsp}}teaspoon) contains about 2,400{{nbsp}}mg of sodium.<ref name="USDA">{{cite web |url=https://ndb.nal.usda.gov/ndb/foods/show?ndbno=02047 |title=National Nutrient Database for Standard Reference, Basic Report: 02047, Salt, table |publisher=[[United States Department of Agriculture]] |work=Agricultural Research Service, National Nutrient Database for Standard Reference |access-date=21 July 2018 |url-status=dead |archive-url=https://web.archive.org/web/20160426013021/https://ndb.nal.usda.gov/ndb/foods/show/277 |archive-date=26 April 2016 |df=dmy-all}}</ref> Sodium serves a vital purpose in the human body: via its role as an electrolyte, it helps nerves and muscles to function correctly, and it is one factor involved in the [[autoregulation|osmotic regulation]] of water content in body organs ([[fluid balance]]).<ref>{{cite web |url=https://www.medlineplus.gov/sodium.html |title=Dietary sodium |publisher=MedLinePlus |access-date=17 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20131019134642/http://www.nlm.nih.gov/medlineplus/dietarysodium.html |archive-date=19 October 2013 |df=dmy-all}}</ref> Most of the sodium in the [[Western diet]] comes from salt.<ref name=CDC>{{cite web |url=https://www.cdc.gov/salt/ |title=Most Americans should consume less sodium |work=Salt |publisher=Centers for Disease Control and Prevention |access-date=17 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20131019175037/http://www.cdc.gov/salt/ |archive-date=19 October 2013 |df=dmy-all}}</ref> The habitual salt intake in many Western countries is about 10 g per day, and it is higher than that in many countries in Eastern Europe and Asia.<ref name=Strazzullo/> The high level of sodium in many processed foods has a major impact on the total amount consumed.<ref>{{cite web |url=https://www.nice.org.uk/guidance/ph25/resources/guidance-prevention-of-cardiovascular-disease-pdf |title=Prevention of cardiovascular disease |date=1 June 2010 |publisher=National Institute for Health and Clinical Excellence |access-date=5 May 2015 |url-status=dead |archive-url=https://web.archive.org/web/20150518063044/https://www.nice.org.uk/guidance/ph25/resources/guidance-prevention-of-cardiovascular-disease-pdf |archive-date=18 May 2015 |df=dmy-all}}</ref> In the United States, 75% of the sodium eaten comes from processed and restaurant foods, 11% from cooking and table use and the rest from what is found naturally in foodstuffs.<ref>{{cite web |url=https://www.cdc.gov/salt/food.htm |title=Sodium and food sources |work=Salt |publisher=Centers for Disease Control and Prevention |access-date=17 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20131019175038/http://www.cdc.gov/salt/food.htm |archive-date=19 October 2013 |df=dmy-all}}</ref>
Because consuming too much sodium increases risk of [[cardiovascular disease]]s,<ref name=CDC/> health organizations generally recommend that people reduce their dietary intake of salt.<ref name=CDC/><ref name=WHO2013/><ref name=He2013/><ref name="aha">{{cite web |url=http://www.heart.org/HEARTORG/HealthyLiving/HealthyEating/Nutrition/Sodium-and-Salt_UCM_303290_Article.jsp#.V1jHedQrJkg |title=Sodium and salt |publisher=American Heart Association |date=2016 |access-date=8 June 2016 |url-status=live |archive-url=https://web.archive.org/web/20160817025149/http://www.heart.org/HEARTORG/HealthyLiving/HealthyEating/Nutrition/Sodium-and-Salt_UCM_303290_Article.jsp#.V1jHedQrJkg |archive-date=17 August 2016 |df=dmy-all}}</ref> High sodium intake is associated with a greater risk of [[stroke]], total cardiovascular disease and [[kidney disease]].<ref name=IOM2013/><ref name=Strazzullo>{{cite journal |last1=Strazzullo |first1=Pasquale |last2=D'Elia |first2=Lanfranco |last3=Kandala |first3=Ngianga-Bakwin |last4=Cappuccio |first4=Francesco P. |year=2009 |title=Salt intake, stroke, and cardiovascular disease: meta-analysis of prospective studies |journal=British Medical Journal |volume=339 |issue=b4567 |pages=b4567 |doi=10.1136/bmj.b4567 |pmc=2782060 |pmid=19934192}}</ref> A reduction in sodium intake by 1,000 mg per day may reduce cardiovascular disease by about 30 percent.<ref name=USDA2015>{{cite book |title=Scientific Report of the 2015 Dietary Guidelines Advisory Committee |date=2015 |publisher=US Department of Agriculture |page=7 |url=http://www.health.gov/dietaryguidelines/2015-scientific-report/PDFs/Scientific-Report-of-the-2015-Dietary-Guidelines-Advisory-Committee.pdf |url-status=live |archive-url=https://web.archive.org/web/20160418002033/http://health.gov/dietaryguidelines/2015-scientific-report/PDFs/Scientific-Report-of-the-2015-Dietary-Guidelines-Advisory-Committee.pdf |archive-date=18 April 2016 |df=dmy-all}}</ref><ref name=CDC/> In adults and children with no acute illness, a decrease in the intake of sodium from the typical high levels reduces blood pressure.<ref name=He2013>{{cite journal |last1=He |first1=F.J. |last2=Li |first2=J. |last3=Macgregor |first3=G.A. |title=Effect of longer term modest salt reduction on blood pressure: Cochrane systematic review and meta-analysis of randomised trials. |journal=BMJ (Clinical Research Ed.) |date=3 April 2013 |volume=346 |pages=f1325 |pmid=23558162 |doi=10.1136/bmj.f1325 |doi-access=free}}</ref><ref name=Abur2013>{{cite journal |last1=Aburto |first1=Nancy J. |last2=Ziolkovska |first2=Anna |last3=Hooper |first3=Lee |last4=Elliott |first4=Paul |last5=Cappuccio |first5=Francesco P. |last6=Meerpohl |first6=Joerg J. |display-authors=3 |year=2013 |title=Effect of lower sodium intake on health: systematic review and meta-analyses |journal=British Medical Journal |volume=346 |issue=f1326 |pages=f1326 |doi=10.1136/bmj.f1326 |pmid=23558163 |pmc=4816261}}</ref> A low sodium diet results in a greater improvement in blood pressure in people with [[hypertension]].<ref>{{Cite journal |last1=Graudal |first1=N iels Albert |last2=Hubeck-Graudal |first2=Thorbjorn |last3=Jurgens |first3=Gesche |date=April 9, 2017 |title=Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride |journal=The Cochrane Database of Systematic Reviews |volume=4 |issue=4 |pages=CD004022 |doi=10.1002/14651858.CD004022.pub4 |issn=1469-493X |pmc=6478144 |pmid=28391629}}</ref><ref>{{cite journal |last1=Adler |first1=A. J. |last2=Taylor |first2=F. |last3=Martin |first3=N. |last4=Gottlieb |first4=S. |last5=Taylor |first5=R.S. |last6=Ebrahim |first6=S. |title=Reduced dietary salt for the prevention of cardiovascular disease |journal=The Cochrane Database of Systematic Reviews |date=18 December 2014 |volume=12 |issue=12 |pages=CD009217 |pmid=25519688 |pmc=6483405 |doi=10.1002/14651858.CD009217.pub3}}</ref>
The [[World Health Organization]] recommends that adults should consume less than 2,000 mg of sodium (which is contained in 5{{nbsp}}g of salt) per day.<ref name=WHO2013>{{cite web |url=https://www.who.int/mediacentre/news/notes/2013/salt_potassium_20130131/en/ |title=WHO issues new guidance on dietary salt and potassium |date=31 January 2013 |publisher=World Health Organization |access-date=17 October 2013 |url-status=dead |archive-url=https://web.archive.org/web/20160720052736/http://www.who.int/mediacentre/news/notes/2013/salt_potassium_20130131/en/ |archive-date=20 July 2016 |df=dmy-all}}</ref> Guidelines by the United States recommend that people with hypertension, African Americans, and middle-aged and older adults should limit consumption to no more than 1,500 mg of sodium per day and meet the potassium recommendation of 4,700 mg/day with a healthy diet of fruits and vegetables.<ref name=CDC/><ref name=Health.gov2010>{{cite book |title=Dietary Guidelines for Americans |date=2010 |publisher=U.S. Department of Agriculture & U.S. Department of Health and Human Services |page=24 |url=http://www.health.gov/dietaryguidelines/dga2010/DietaryGuidelines2010.pdf |access-date=29 April 2015 |quote=African Americans, individuals with hypertension, diabetes, or chronic kidney disease and individuals ages 51 and older, comprise about half of the U.S. population ages 2 and older. While nearly everyone benefits from reducing their sodium intake, the blood pressure of these individuals tends to be even more responsive to the blood pressure-raising effects of sodium than others; therefore, they should reduce their intake to 1,500 mg per day. |url-status=live |archive-url=https://web.archive.org/web/20160901170759/https://health.gov/dietaryguidelines/dga2010/dietaryguidelines2010.pdf |archive-date=1 September 2016 |df=dmy-all}}</ref>
While reduction of sodium intake to less than 2,300 mg per day is recommended by developed countries,<ref name=CDC/> one review recommended that sodium intake be reduced to at least 1,200 mg (contained in 3{{nbsp}}g of salt) per day, as a further reduction in salt intake led to a greater fall in systolic blood pressure for all age groups and ethnicities.<ref name=He2013/> Another review indicated that there is inconsistent/insufficient evidence to conclude that reducing sodium intake to lower than 2,300 mg per day is either beneficial or harmful.<ref>{{Cite book |url=https://www.nap.edu/read/18311/chapter/7#122 |title=5 Findings and Conclusions {{!}} Sodium Intake in Populations: Assessment of Evidence |publisher=The National Academies Press|language=en |doi=10.17226/18311|pmid=24851297 |url-status=live |archive-url=https://web.archive.org/web/20170516040201/https://www.nap.edu/read/18311/chapter/7#122 |archive-date=16 May 2017|df=dmy-all|year=2013 |isbn=978-0-309-28295-6 |author1=Committee on the Consequences of Sodium Reduction in Populations |last2=Food Nutrition |first2=Board |author3=Board on Population Health Public Health Practice |last4=Institute Of |first4=Medicine |last5=Strom |first5=B. L. |last6=Yaktine |first6=A. L. |last7=Oria |first7=M. }}</ref>
Evidence shows a more complicated relationship between salt and cardiovascular disease. "The association between sodium consumption and cardiovascular disease or mortality is U-shaped, with increased risk at both high and low sodium intake."<ref name="clinicalkey.com">{{cite journal |doi=10.1016/S0140-6736(16)30467-6 |pmid=27216139 |title=Associations of urinary sodium excretion with cardiovascular events in individuals with and without hypertension: A pooled analysis of data from four studies |journal=The Lancet |volume=388 |issue=10043 |pages=465–475 |year=2016 |last1=Mente |first1=Andrew |last2=O'Donnell |first2=Martin |last3=Rangarajan |first3=Sumathy |last4=Dagenais |first4=Gilles |last5=Lear |first5=Scott |last6=McQueen |first6=Matthew |last7=Diaz |first7=Rafael |last8=Avezum |first8=Alvaro |last9=Lopez-Jaramillo |first9=Patricio |last10=Lanas |first10=Fernando |last11=Li |first11=Wei |last12=Lu |first12=Yin |last13=Yi |first13=Sun |last14=Rensheng |first14=Lei |last15=Iqbal |first15=Romaina |last16=Mony |first16=Prem |last17=Yusuf |first17=Rita |last18=Yusoff |first18=Khalid |last19=Szuba |first19=Andrzej |last20=Oguz |first20=Aytekin |last21=Rosengren |first21=Annika |last22=Bahonar |first22=Ahmad |last23=Yusufali |first23=Afzalhussein |last24=Schutte |first24=Aletta Elisabeth |last25=Chifamba |first25=Jephat |last26=Mann |first26=Johannes F E. |last27=Anand |first27=Sonia S. |last28=Teo |first28=Koon |last29=Yusuf |first29=S. |display-authors=5 |s2cid=44581906 |url=https://www.researchgate.net/publication/303462194 |hdl=10379/16625 |hdl-access=free |access-date=3 October 2020 |archive-date=9 January 2022 |archive-url=https://web.archive.org/web/20220109063636/https://www.researchgate.net/publication/303462194_Associations_of_urinary_sodium_excretion_with_cardiovascular_events_in_individuals_with_and_without_hypertension_A_pooled_analysis_of_data_from_four_studies |url-status=live }}</ref> The findings showed that increased mortality from excessive salt intake was primarily associated with individuals with hypertension. The levels of increased mortality among those with restricted salt intake appeared to be similar regardless of blood pressure. This evidence shows that while those with hypertension should primarily focus on reducing sodium to recommended levels, all groups should seek to maintain a healthy level of sodium intake of between 4 and 5 grams (equivalent to 10–13 g salt) a day.<ref name="clinicalkey.com"/>
One of the two most prominent dietary risks for disability in the world are diets high in sodium.<ref>{{Cite journal |last1=Lim |first1=Stephen S. |last2=Vos |first2=Theo |last3=Flaxman |first3=Abraham D. |last4=Danaei |first4=Goodarz |last5=Shibuya |first5=Kenji |last6=Adair-Rohani |first6=Heather |last7=Amann |first7=Markus |last8=Anderson |first8=H. Ross |last9=Andrews |first9=Kathryn G. |date=15 December 2012 |title=A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010 |journal=[[The Lancet]] |volume=380 |issue=9859 |pages=2224–2260 |doi=10.1016/S0140-6736(12)61766-8 |pmc=4156511 |pmid=23245609}}</ref>
==Non-dietary uses==
{{Main|Sodium chloride}}
Only a small percentage of the salt manufactured in the world is used in food. The remainder is used in agriculture, water treatment, chemical production, de-icing, and other industrial use cases.{{sfnp|Westphal|Kristen|Wegener|Ambatiello|2010}} In the practice of watering plants with salt as a fertilizer, applying a moderate concentration helps avoid potential toxicity; typically, {{convert|1|-|3|g}} per liter is considered safe and effective for most plants.<ref>{{cite journal|doi=10.1093/aob/mcu217|date=1 December 2014 |title=Sodium chloride toxicity and the cellular basis of salt tolerance in halophytes |last1=Flowers |first1=Timothy J. |last2=Munns |first2=Rana |last3=Colmer |first3=Timothy D. |journal=Annals of Botany |volume=115 |issue=3 |pages=419–431 |pmid=25466549 |pmc=4332607 }}</ref><ref>{{cite journal|doi=10.1093/jxb/ert326|date=22 October 2013 |title=Sodium in plants: Perception, signalling, and regulation of sodium fluxes |last1=Maathuis |first1=Frans J. M. |journal=Journal of Experimental Botany |volume=65 |issue=3 |pages=849–858 |pmid=24151301 }}</ref><ref>{{cite journal |doi=10.21273/HORTSCI.43.6.1888 |title=Sodium Chloride Effects on Growth, Morphology, and Physiology of Chrysanthemum (Chrysanthemum ×morifolium) |date=2008 |last1=Lee |first1=M. Kate |last2=Van Iersel |first2=Marc W. |journal=HortScience |volume=43 |issue=6 |pages=1888–1891 |doi-access=free }}</ref> Sodium chloride is one of the most widely used inorganic raw materials. It is a [[Raw material|feedstock]] in the production of [[caustic soda]] and [[chlorine]]. These are used in the manufacture of [[PVC]], [[paper pulp]] and many other inorganic and organic compounds. Salt is used as a [[Flux (metallurgy)|flux]] in the production of [[aluminium]]. For this purpose, a layer of melted salt floats on top of the molten metal and removes iron and other metal contaminants. It is used in the manufacture of [[soap]]s and [[glycerine]], where it is used to [[Saponification|saponify]] fats. As an emulsifier, salt is used in the manufacture of [[synthetic rubber]], and another use is in the firing of [[pottery]], when salt added to the furnace vaporises before condensing onto the surface of the ceramic material, forming a strong [[Ceramic glaze|glaze]].<ref name=WASG>{{cite web |url=http://www.wasalt.com.au/SaltUses.html |title=Salt uses |publisher=WA Salt Group |access-date=10 October 2013 |archive-url=https://web.archive.org/web/20131011054052/http://www.wasalt.com.au/SaltUses.html |archive-date=11 October 2013}}</ref>
When drilling through loose materials such as sand or gravel, salt may be added to the [[drilling fluid]] to provide a stable "wall" to prevent the hole collapsing. There are many other processes in which salt is involved. These include its use as a [[mordant]] in [[textile]] dying, to regenerate [[resin]]s in water softening, for the [[Tanning (leather)|tanning]] of hides, the preservation of meat and fish and the [[canning]] of meat and vegetables.<ref name=WASG/><ref name=IHS>{{cite web |url=http://www.ihs.com/products/chemical/planning/ceh/sodium-chloride.aspx |title=Sodium chloride |date=1 December 2008 |publisher=IHS Chemical |access-date=12 March 2013 |url-status=live |archive-url=https://web.archive.org/web/20130325193515/http://www.ihs.com/products/chemical/planning/ceh/sodium-chloride.aspx |archive-date=25 March 2013 |df=dmy-all}}</ref>{{sfnp|Kostick|2011}}
==
{{See also|List of countries by salt production}}
[[file:2018-07-19 037 Sifto Salt Mine, Goderich ON Canada.jpg |thumb| upright 1.5 |Sifto Canada salt mine and processing plant at the harbor in [[Goderich, Ontario]], Canada]]
Food-grade salt accounts for only a small part of salt production in [[Developed country|industrialized countries]] (7% in Europe),<ref>{{cite web |url=http://eusalt.com/salt-uses |title=Salt Uses |publisher=European Salt Producers' Association |access-date=5 May 2015 |url-status=live |archive-url=https://web.archive.org/web/20150212060035/http://eusalt.com/salt-uses |archive-date=12 February 2015 |df=dmy-all}}</ref> although worldwide, food uses account for 17.5% of total production.<ref>{{cite web |url=http://www.roskill.com/reports/salt |title=Roskill Information Services |publisher=Roskill.com |date=30 March 2011 |access-date=7 July 2011 |url-status=dead |archive-url=https://web.archive.org/web/20030618234222/http://www.roskill.com/reports/salt |archive-date=18 June 2003 |df=dmy-all}}</ref>
In 2018, total world production of salt was 300 million [[tonne]]s, the top six producers being China (68 million), the United States (42 million), India (29 million), Germany (13 million), Canada (13 million) and Australia (12 million).<ref>{{cite report |last1=Bolen |first1=Wallace P.|chapter-url=https://prd-wret.s3-us-west-2.amazonaws.com/assets/palladium/production/atoms/files/mcs-2019-salt.pdf |chapter=Salt |title=US Geological Survey, Mineral Commodity Summaries |publisher=US Geological Survey |date=February 2019 |url-status=live |archive-url=https://web.archive.org/web/20190731194635/https://prd-wret.s3-us-west-2.amazonaws.com/assets/palladium/production/atoms/files/mcs-2019-salt.pdf |archive-date=31 July 2019 |df=dmy-all}}</ref>
The manufacture of salt is one of the oldest chemical industries.<ref>{{cite web |url=http://www.salt.org.il/arch.html |title=Salt made the world go round |work=Salt.org.il |date=1 September 1997 |access-date=7 July 2011 |url-status=live |archive-url=https://web.archive.org/web/20160405130434/http://www.salt.org.il/arch.html |archive-date=5 April 2016 |df=dmy-all}}</ref> A major source of salt is seawater, which has a [[salinity]] of approximately 3.5%.{{sfnp|Westphal|Kristen|Wegener|Ambatiello|2010}} This means that there are about {{cvt|35|g|oz}} of [[sea salt|dissolved salts]], predominantly [[sodium]] ({{chem|Na||+}}) and [[chloride]] ({{chem|Cl||-}}) [[ions]], per kilogram (2.2 lbs) of water.{{sfnp|Millero|Feistel|Wright|McDougall|2008}} The world's oceans are a virtually inexhaustible source of salt, and this abundance of supply means that reserves have not been calculated.<ref name=IHS/> The evaporation of seawater is the production method of choice in marine countries with high evaporation and low precipitation rates. [[Salt evaporation pond]]s are filled from the ocean and salt crystals can be harvested as the water dries up. Sometimes these ponds have vivid colours, as some species of algae and other micro-organisms thrive in conditions of high salinity.<ref>{{cite web |url=http://visibleearth.nasa.gov/view.php?id=2631 |title=Salt Ponds, South San Francisco Bay |work=NASA Visible Earth |publisher=NASA |access-date=5 May 2015 |url-status=live |archive-url=https://web.archive.org/web/20160715085242/http://visibleearth.nasa.gov/view.php?id=2631 |archive-date=15 July 2016 |df=dmy-all |date=2009-08-11}}</ref>
Away from the sea, salt is extracted from the vast sedimentary deposits which have been laid down over the millennia from the evaporation of seas and lakes. These sources are either [[salt mine|mined]] directly, producing rock salt, or are extracted by pumping water into the deposit. In either case, the salt may be purified by mechanical evaporation of brine. Traditionally, purification was achieved in [[Open pan salt making|shallow open pans]] that were heated to accelerate evaporation. [[Vacuum]]-based methods are also employed.{{sfnp|Kostick|2011}} The raw salt is refined by treatment with chemicals that precipitate most impurities (largely magnesium and calcium salts). Multiple stages of evaporation are then applied.<ref>[https://web.archive.org/web/20090409144219/http://www.saltsense.co.uk/aboutsalt-prod02.htm About salt: Production]. The Salt Manufacturers Association</ref> Some salt is produced using the [[Alberger process]], which involves vacuum pan evaporation combined with the seeding of the solution with cubic crystals, and produces a grainy-type flake.<ref>{{cite encyclopedia |url=http://www.britannica.com/EBchecked/topic/12642/Alberger-process |title=Alberger process |encyclopedia=Manufacture of salt: Uses of artificial heat |publisher=Encyclopædia Britannica online |access-date=9 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20110223025143/http://www.britannica.com/EBchecked/topic/12642/Alberger-process |archive-date=23 February 2011 |df=dmy-all}}</ref> The [[Ayoreo people|Ayoreo]], an indigenous group from the Paraguayan [[Gran Chaco people|Chaco]], obtain their salt from the ash produced by burning the timber of the Indian salt tree (''[[Maytenus vitis-idaea]]'') and other trees.{{sfnp|Schmeda-Hirschmann|1994}}
The largest mine operated by underground workings in the world is the Sifto mine, located mostly 550 meters below Lake Huron, in Goderich, Ontario (Canada). About seven million tons of salt are extracted from it annually.<ref>{{Cite book |last1=Calvo |first1=Miguel |title=Una pizca de sal |last2=Calvo |first2=Guiomar |publisher=Prames |year=2023 |isbn=978-84-8321-582-1 |___location=Zaragoza, Spain |pages=114–115 |language=es |trans-title=A pinch of salt}}</ref> The [[Khewra Salt Mine]] in Pakistan has nineteen storeys, eleven of which are underground, and {{cvt|400|km}} of passages. The salt is dug out by the [[room and pillar]] method, where about half the material is left in place to support the upper levels. Extraction of [[Himalayan salt]] is expected to last 350 years at the present rate of extraction of around 385,000 tons per annum.The mine is also a major tourist attraction, receiving around a quarter of a million visitors a year.<ref name="The Seattle Times">{{cite news |last=Pennington |first=Matthew |title=Pakistan salt mined old-fashioned way mine |url=http://seattletimes.nwsource.com/html/nationworld/2002159747_saltmine25.html |access-date=11 October 2013 |newspaper=The Seattle Times |date=25 January 2005 |url-status=live |archive-url=https://web.archive.org/web/20120725072022/http://seattletimes.nwsource.com/html/nationworld/2002159747_saltmine25.html |archive-date=25 July 2012 |df=dmy-all}}</ref>
<gallery class=center mode=nolines widths=220 caption=Artisanal production>
File:Bo Kluea 01.jpg|[[Brine]] from [[salt wells]] is boiled to produce salt at [[Nan Province]], Thailand
File:Piles of Salt Salar de Uyuni Bolivia Luca Galuzzi 2006 a.jpg|Salt mounds in [[Salar de Uyuni]], Bolivia
File:Marakkanam Salt Pans.JPG|Sea-salt pans in [[Tamil Nadu]], India
File:Chad Creating salt balls near Tigui DSC0596.jpg|Salt balls in [[Borkou (region of Chad)|Borkou province]], Chad
</gallery>
== In religion ==
[[File:Russian bread and salt.jpg|thumb|[[Bread and salt]] at a Russian wedding ceremony]]
Salt has long held an important place in religion and culture. At the time of [[Historical Vedic religion|Brahmanic]] sacrifices, in [[Hittites|Hittite]] rituals and during festivals held by [[Semitic people|Semites]] and Greeks at the time of the [[new moon]], salt was thrown into a fire where it produced crackling noises.<ref>{{cite book |chapter-url=http://www.bookrags.com/research/salt-eorl-12/ |chapter=Research article: Salt |title=Encyclopedia of Religion |access-date=13 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20160304050505/http://www.bookrags.com/research/salt-eorl-12/ |archive-date=4 March 2016 |df=dmy-all}}</ref> The ancient Egyptians, Greeks and Romans invoked their gods with offerings of salt and water and some people think this to be the origin of [[Holy Water]] in the Christian faith.<ref name="ReferenceA">{{cite journal |year=2006 |title=10+1 Things you may not know about Salt |url=http://www.epikouria.com/issue3/article6-things.php |url-status=dead |journal=Epikouria |volume=Fall/Winter |issue=3 |archive-url=https://web.archive.org/web/20080704055740/http://www.epikouria.com/issue3/article6-things.php |archive-date=4 July 2008}}</ref> In [[Judaism]], it is recommended to have either a salty bread or to add salt to the bread if this bread is unsalted when doing [[Kiddush]] for [[Shabbat]]. It is customary to spread some salt over the bread or dip it in a little salt when passing it around the table after the Kiddush.<ref>Naftali Silberberg [http://www.chabad.org/library/article_cdo/aid/484194/jewish/Why-dip-in-salt.htm Why is the Challah dipped in salt before it is eaten?] {{webarchive|url=https://web.archive.org/web/20120120034528/http://www.chabad.org/library/article_cdo/aid/484194/jewish/Why-dip-in-salt.htm|date=20 January 2012}}, Chabad.org</ref> To preserve the covenant between their people and God, Jews dip the [[Sabbath]] bread in salt.<ref name="ReferenceA"/> Salt plays a role within different Christian traditions. It is mandatory in the rite of the [[Tridentine Mass]].<ref name="CE">[[s:Catholic Encyclopedia (1913)/Salt]]</ref> Salt is used in the third item (which includes an [[Exorcism]]) of the Celtic Consecration (''cf.'' [[Gallican Rite]]) that is employed in the consecration of a church, and it is permitted to be added to the water "where it is customary" in the Roman Catholic rite of Holy water.<ref name="CE"/> The [[Bible]] makes [[Salt in the Bible|multiple mentions of salt]], both of the mineral itself and as a metaphor. Uses include the tale of how [[Lot's wife]] is turned into a pillar of salt when looking back at the cities of [[Sodom and Gomorrah]] as they are destroyed. In the [[New Testament]], [[Jesus]] refers to his followers as the "[[Salt and Light|salt of the earth]]".<ref name="McKenzie 1995">{{cite dictionary |last=McKenzie |first=John L. |chapter=Salt |title=Dictionary of the Bible |publisher=[[Simon & Schuster]] |year=1995 |isbn=0-684-81913-9 |pages=759–760}}</ref>
In [[Aztec]] mythology, [[Huixtocihuatl]] was a fertility goddess who presided over salt and salt water.<ref>{{cite web |url=http://www.amoxtli.org/cuezali/festivals.html |title=The Aztec Festivals: Toxcatl (Dryness) |last=Quipoloa |first=J. |year=2007 |work=The Aztec Gateway |access-date=18 March 2013 |url-status=usurped |archive-url=https://web.archive.org/web/20150916191933/http://www.amoxtli.org/cuezali/festivals.html |archive-date=16 September 2015 |df=dmy-all}}</ref> Salt is an auspicious substance in [[Hinduism]] and is used in ceremonies like house-warmings and weddings.<ref name="Gray">{{cite news |title=What Lies Beneath |last=Gray |first=Steven |url=http://www.time.com/time/magazine/article/0,9171,2001007,00.html |newspaper=Time Magazine |date=7 December 2010 |access-date=13 March 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130817090849/http://www.time.com/time/magazine/article/0%2C9171%2C2001007%2C00.html |archive-date=17 August 2013 |df=dmy-all}}</ref> In [[Jainism]], devotees lay an offering of raw rice with a pinch of salt before a deity to signify their devotion and salt is sprinkled on a person's cremated remains before the ashes are buried.<ref>{{cite web |url=http://www.finaljourneyseminars.com/?page_id=472 |title=The Final Journey: What to do when your loved one passes away |access-date=12 March 2013 |url-status=live |archive-url=https://web.archive.org/web/20160306031827/http://www.finaljourneyseminars.com/?page_id=472 |archive-date=6 March 2016 |df=dmy-all}}</ref> Salt is believed to ward off evil spirits in [[Mahayana Buddhism|Mahayana Buddhist]] tradition. When returning home from a [[funeral]], a pinch of salt is thrown over the left shoulder as this prevents evil spirits from entering the house.<ref>{{cite web |url=http://www.cargill.com/salt/about/historyofsalt/religion/ |title=Religion: Chasing away evil spirits |work=History of salt |publisher=Cagill |access-date=13 October 2013 |url-status=dead |archive-url=https://web.archive.org/web/20140314070618/http://www.cargill.com/salt/about/historyofsalt/religion/ |archive-date=14 March 2014 |df=dmy-all}}</ref> In [[Shinto]], {{nihongo|''Shio''|[[wikt:塩|塩]], lit. "salt"}} is used for [[ritual purification]] of locations and people (''[[harae]]'', specifically ''shubatsu''), and small piles of salt are placed in dishes by entrances to ward off evil and to attract patrons.<ref>{{cite web |title=Harae - purification rites |url=https://www.bbc.co.uk/religion/religions/shinto/ritesrituals/harae.shtml |publisher=BBC |access-date=25 November 2024 |date=16 September 2009}}</ref>
== References ==
{{Reflist}}
=== Sources ===
{{Refbegin |40em|indent=yes}}
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* {{cite journal |journal=Deep Sea Research Part I: Oceanographic Research Papers |publisher=Elsevier |volume=55 |issue=1 |date=January 2008 |pages=50–72 |title=The composition of Standard Seawater and the definition of the Reference-Composition Salinity Scale |first1=Frank J. |last1=Millero |first2=Rainer |last2=Feistel |first3=Daniel |last3=Wright |first4=Trevor J. |last4=McDougall |doi=10.1016/j.dsr.2007.10.001|bibcode=2008DSRI...55...50M }}
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* {{cite journal |title=Treatment for primary hypothyroidism: current approaches and future possibilities. |doi=10.2147/DDDT.S12894 |first2=Ali J |last2= Chakera |first3=Simon HS |last3=Pearce |first1=Bijay |last1=Vaidya |date=2011 |journal=Drug Design, Development and Therapy |volume=6|pages=1–11 |doi-access=free |pmid=22291465 |pmc=3267517 }}
{{Refend}}
{{Sister project links|wikt=salt|commons=Salt|b=Cookbook:Salt|s=Littell's Living Age/Volume 4/Issue 34/Salt in Abyssinia|v=Extra info on food consumption#Salt/potassium intake|n=no|q=no}}
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