Potassium is chemically very similar to sodium, the previous element in group 1 of the periodic table. They have a similar first ionization energy, which allows for each atom to give up its sole outer electron. It was first suggested in 1702 that they were distinct elements that combine with the same anions to make similar salts,<ref name="1702Suspect" /> which was demonstrated in 1807 when elemental potassium was first isolated via electrolysis. Naturally occurring potassium is composed of three isotopes, of which [[potassium-40|Template:Chem]] is radioactive. Traces of Template:Chem are found in all potassium, and it is the most common radioisotope in the human body.
Potassium ions are vital for the functioning of all living cells. The transfer of potassium ions across nerve cell membranes is necessary for normal nerve transmission; potassium deficiency and excess can each result in numerous signs and symptoms, including an abnormal heart rhythm and various electrocardiographic abnormalities. Fresh fruits and vegetables are good dietary sources of potassium. The body responds to the influx of dietary potassium, which raises serum potassium levels, by shifting potassium from outside to inside cells and increasing potassium excretion by the kidneys.
Most industrial applications of potassium exploit the high solubility of its compounds in water, such as saltwater soap. Heavy crop production rapidly depletes the soil of potassium, and this can be remedied with agricultural fertilizers containing potassium, accounting for 95% of global potassium chemical production.<ref name="g73">Greenwood, p. 73</ref>
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The English name for the element potassium comes from the word potash,<ref>Template:Cite journal</ref> which refers to an early method of extracting various potassium salts: placing in a pot the ash of burnt wood or tree leaves, adding water, heating, and evaporating the solution. When Humphry Davy first isolated the pure element using electrolysis in 1807, he named it potassium, which he derived from the word potash.
The symbol K stems from kali, itself from the root word alkali, which in turn comes from Template:Langxal-qalyah 'plant ashes'. In 1797, the German chemist Martin Klaproth discovered "potash" in the minerals leucite and lepidolite, and realized that "potash" was not a product of plant growth but actually contained a new element, which he proposed calling kali.<ref>Klaproth, M. (1797) "Nouvelles données relatives à l'histoire naturelle de l'alcali végétal" (New data regarding the natural history of the vegetable alkali), Mémoires de l'Académie royale des sciences et belles-lettres (Berlin), pp. 9–13 ; see p. 13.Template:Webarchive From p. 13: "Cet alcali ne pouvant donc plus être envisagé comme un produit de la végétation dans les plantes, occupe une place propre dans la série des substances primitivement simples du règne minéral, &I il devient nécessaire de lui assigner un nom, qui convienne mieux à sa nature. La dénomination de Potasche (potasse) que la nouvelle nomenclature françoise a consacrée comme nom de tout le genre, ne sauroit faire fortune auprès des chimistes allemands, qui sentent à quel point la dérivation étymologique en est vicieuse. Elle est prise en effet de ce qu'anciennement on se servoit pour la calcination des lessives concentrées des cendres, de pots de fer (pott en dialecte de la Basse-Saxe) auxquels on a substitué depuis des fours à calciner. Je propose donc ici, de substituer aux mots usités jusqu'ici d'alcali des plantes, alcali végétal, potasse, &c. celui de kali, & de revenir à l'ancienne dénomination de natron, au lieu de dire alcali minéral, soude &c."
(This alkali [i.e., potash] — [which] therefore can no longer be viewed as a product of growth in plants — occupies a proper place in the originally simple series of the mineral realm, and it becomes necessary to assign it a name that is better suited to its nature.
The name of "potash" (potasse), which the new French nomenclature has bestowed as the name of the entire species [i.e., substance], would not find acceptance among German chemists, who feel to some extent [that] the etymological derivation of it is faulty. Indeed, it is taken from [the vessels] that one formerly used for the roasting of washing powder concentrated from cinders: iron pots (pott in the dialect of Lower Saxony), for which roasting ovens have been substituted since then.
Thus I now propose to substitute for the until now common words of "plant alkali", "vegetable alkali", "potash", etc., that of kali ; and to return to the old name of natron instead of saying "mineral alkali", "soda", etc.)</ref> In 1807, Humphry Davy produced the element via electrolysis: in 1809, Ludwig Wilhelm Gilbert proposed the name Kalium for Davy's "potassium".<ref>Template:Cite journal</ref> In 1814, the Swedish chemist Berzelius advocated the name kalium for potassium, with the chemical symbol K.<ref>Berzelius, J. Jacob (1814) Försök, att, genom användandet af den electrokemiska theorien och de kemiska proportionerna, grundlägga ett rent vettenskapligt system för mineralogien [Attempt, by the use of electrochemical theory and chemical proportions, to found a pure scientific system for mineralogy]. Stockholm, Sweden: A. Gadelius., p. 87.</ref>
Potassium is the second least dense metal after lithium. It is a soft solid with a low melting point, and can be easily cut with a knife. Potassium is silvery in appearance, but it begins to tarnish toward gray immediately on exposure to air.<ref name="g76">Greenwood, p. 76</ref> In a flame test, potassium and its compounds emit a lilac color with a peak emission wavelength of 766.5 nanometers.<ref>Greenwood, p. 75</ref>
Neutral potassium atoms have 19 electrons, one more than the configuration of the noble gasargon. Because of its low first ionization energy of 418.8Template:NbspkJ/mol, the potassium atom is much more likely to lose the last electron and acquire a positive charge, although negatively charged alkalideTemplate:Chem2 ions are not impossible.<ref name="K-">Template:Cite journal</ref> In contrast, the second ionization energy is very high (3052Template:NbspkJ/mol).
Potassium reacts with oxygen, water, and carbon dioxide components in air. With oxygen it forms potassium peroxide. With water potassium forms potassium hydroxide (KOH). The reaction of potassium with water can be violently exothermic, especially since the coproduced hydrogen gas can ignite. Because of this, potassium and the liquid sodium-potassium (NaK) alloy are potent desiccants, although they are no longer used as such.<ref>Template:Cite journal</ref>
In general, potassium compounds are ionic and, owing to the high hydration energy of the Template:Chem2 ion, have excellent water solubility. The main species in water solution are the aquo complexesTemplate:Chem2 where n = 6 and 7.<ref name="Lincoln">Lincoln, S. F.; Richens, D. T. and Sykes, A. G. "Metal Aqua Ions" in J. A. McCleverty and T. J. Meyer (eds.) Comprehensive Coordination Chemistry IITemplate:Webarchive, Vol. 1, pp. 515–555, Template:ISBN.</ref>
Template:Chem occurs in natural potassium (and thus in some commercial salt substitutes) in sufficient quantity that large bags of those substitutes can be used as a radioactive source for classroom demonstrations. Template:Chem is the radioisotope with the largest abundance in the human body. In healthy animals and people, Template:Chem represents the largest source of radioactivity, greater even than [[Carbon-14|Template:Chem]]. In a human body of 70 kg, about 4,400 nuclei of Template:Chem decay per second.<ref>Template:Cite web</ref> The activity of natural potassium is 31 Bq/g.<ref>Template:Cite book</ref>
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Potash is primarily a mixture of potassium salts because plants have little or no sodium content, and the rest of a plant's major mineral content consists of calcium salts of relatively low solubility in water. While potash has been used since ancient times, its composition was not understood. Georg Ernst Stahl obtained experimental evidence that led him to suggest the fundamental difference of sodium and potassium salts in 1702,<ref name="1702Suspect">Template:Cite book</ref> and Henri Louis Duhamel du Monceau was able to prove this difference in 1736.<ref>Template:Cite journal</ref> The exact chemical composition of potassium and sodium compounds, and the status as chemical element of potassium and sodium, was not known then, and thus Antoine Lavoisier did not include the alkali in his list of chemical elements in 1789.<ref name="weeks">Template:Cite journal</ref><ref name="disco">Template:Cite journal</ref> For a long time the only significant applications for potash were the production of glass, bleach, soap and gunpowder as potassium nitrate.<ref>Template:Cite journal</ref> Potassium soaps from animal fats and vegetable oils were especially prized because they tend to be more water-soluble and of softer texture, and are therefore known as soft soaps.<ref name="g73" /> The discovery by Justus Liebig in 1840 that potassium is a necessary element for plants and that most types of soil lack potassium<ref>Template:Cite book</ref> caused a steep rise in demand for potassium salts. Wood-ash from fir trees was initially used as a potassium salt source for fertilizer, but, with the discovery in 1868 of mineral deposits containing potassium chloride near Staßfurt, Germany, the production of potassium-containing fertilizers began at an industrial scale.<ref>Template:Cite book</ref><ref>Template:Cite book</ref><ref>Template:Cite book</ref> Other potash deposits were discovered, and by the 1960s Canada became the dominant producer.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
Potassium metal was first isolated in 1807 by Humphry Davy, who derived it by electrolysis of molten caustic potash (KOH) with the newly discovered voltaic pile. Potassium was the first metal that was isolated by electrolysis.<ref name="Enghag2004">Template:Cite book</ref> Later in the same year, Davy reported extraction of the metal sodium from a mineral derivative (caustic soda, NaOH, or lye) rather than a plant salt, by a similar technique, demonstrating that the elements, and thus the salts, are different.<ref name="weeks" /><ref name="disco" /><ref name="Davy1807">Template:Cite journal</ref><ref name="200disco">Template:Cite journal</ref> Although the production of potassium and sodium metal should have shown that both are elements, it took some time before this view was universally accepted.<ref name="disco" />
Because of the sensitivity of potassium to water and air, air-free techniques are normally employed for handling the element. It is unreactive toward nitrogen and saturated hydrocarbons such as mineral oil or kerosene.<ref name="HollemanAF">Template:Cite book</ref> It readily dissolves in liquid ammonia, up to 480 g per 1000 g of ammonia at 0Template:Nbsp°C. Depending on the concentration, the ammonia solutions are blue to yellow, and their electrical conductivity is similar to that of liquid metals. Potassium slowly reacts with ammonia to form [[Potassium amide|Template:Chem]], but this reaction is accelerated by minute amounts of transition metal salts.<ref name="b32">Burkhardt, p. 32</ref> Because it can reduce the salts to the metal, potassium is often used as the reductant in the preparation of finely divided metals from their salts by the Rieke method.<ref>Template:Cite journal</ref> Illustrative is the preparation of magnesium:
Potassium is the 20th most abundant element in the Solar System and the 17th most abundant element by weight in the Earth. It makes up about 2.6% of the weight of the Earth's crust and is the seventh most abundant element in the crust.<ref>Greenwood, p. 69</ref> The potassium concentration in seawater is 0.39Template:Nbspg/L<ref name="seawaterconcentration" /> (0.039 wt/v%), about one twenty-seventh the concentration of sodium.<ref name="geo">Template:Cite book</ref><ref name="indus">Template:Cite book</ref>
Elemental potassium does not occur in nature because of its high reactivity. It reacts violently with water<ref name="HollemanAF" /> and also reacts with oxygen. Orthoclase (potassium feldspar) is a common rock-forming mineral. Granite for example contains 5% potassium, which is well above the average in the Earth's crust. Sylvite (KCl), carnallite (Template:Chem2), kainite (Template:Chem2) and langbeinite (Template:Chem2) are the minerals found in large evaporite deposits worldwide. The deposits often show layers starting with the least soluble at the bottom and the most soluble on top.<ref name="indus" /> Deposits of niter (potassium nitrate) are formed by decomposition of organic material in contact with atmosphere, mostly in caves; because of the good water solubility of niter the formation of larger deposits requires special environmental conditions.<ref>Template:Cite book</ref>
Potassium salts such as carnallite, langbeinite, polyhalite, and sylvite form extensive evaporite deposits in ancient lake bottoms and seabeds,<ref name="geo" /> making extraction of potassium salts in these environments commercially viable. The principal source of potassium – potash – is mined in Canada, Russia, Belarus, Kazakhstan, Germany, Israel, the U.S., Jordan, and other places around the world.<ref>Template:Cite book</ref><ref name="USGSCS2008">Template:Cite web</ref><ref name="USGSYB2006">Template:Cite web</ref> The first mined deposits were located near Staßfurt, Germany, but the deposits span from Great Britain over Germany into Poland. They are located in the Zechstein and were deposited in the Middle to Late Permian. The largest deposits ever found lie Template:Convert below the surface of the Canadian province of Saskatchewan. The deposits are located in the Elk Point Group produced in the Middle Devonian. Saskatchewan, where several large mines have operated since the 1960s pioneered the technique of freezing of wet sands (the Blairmore formation) to drive mine shafts through them. The main potash mining company in Saskatchewan until its merge was the Potash Corporation of Saskatchewan, now Nutrien.<ref>Template:Cite book</ref> The water of the Dead Sea is used by Israel and Jordan as a source of potash, while the concentration in normal oceans is too low for commercial production at current prices.<ref name="USGSCS2008" /><ref name="USGSYB2006" />
Several methods are used to separate potassium salts from sodium and magnesium compounds. The most-used method is fractional precipitation using the solubility differences of the salts. Electrostatic separation of the ground salt mixture is also used in some mines. The resulting sodium and magnesium waste is either stored underground or piled up in slag heaps. Most of the mined potassium mineral ends up as potassium chloride after processing. The mineral industry refers to potassium chloride either as potash, muriate of potash, or simply MOP.<ref name="indus" />
Pure potassium metal can be isolated by electrolysis of its hydroxide in a process that has changed little since it was first used by Humphry Davy in 1807. Although the electrolysis process was developed and used in industrial scale in the 1920s, the thermal method by reacting sodium with potassium chloride in a chemical equilibrium reaction became the dominant method in the 1950s.
Na + KCl → NaCl + K
The production of sodium potassium alloys is accomplished by changing the reaction time and the amount of sodium used in the reaction. The Griesheimer process employing the reaction of potassium fluoride with calcium carbide was also used to produce potassium.<ref name="indus" /><ref>Template:Cite book</ref>
Reagent-grade potassium metal costs about $10.00/pound ($22/kg) in 2010 when purchased by the tonne. Lower purity metal is considerably cheaper. The market is volatile because long-term storage of the metal is difficult. It must be stored in a dry inert gas atmosphere or anhydrousmineral oil to prevent the formation of a surface layer of potassium superoxide, a pressure-sensitive explosive that detonates when scratched. The resulting explosion often starts a fire difficult to extinguish.<ref>Burkhardt, p. 34</ref><ref name="fire">Template:Cite journal</ref>
Potassium ions are an essential component of plant nutrition and are found in most soil types.<ref name="g73" /> They are used as a fertilizer in agriculture, horticulture, and hydroponic culture in the form of chloride (KCl), sulfate (Template:Chem2), or nitrate (Template:Chem2), representing the 'K' in 'NPK'. Agricultural fertilizers consume 95% of global potassium chemical production, and about 90% of this potassium is supplied as KCl.<ref name="g73" /> The potassium content of most plants ranges from 0.5% to 2% of the harvested weight of crops, conventionally expressed as amount of Template:Chem2. Modern high-yield agriculture depends upon fertilizers to replace the potassium lost at harvest. Most agricultural fertilizers contain potassium chloride, while potassium sulfate is used for chloride-sensitive crops or crops needing higher sulfur content. The sulfate is produced mostly by decomposition of the complex minerals kainite (Template:Chem2) and langbeinite (Template:Chem2). Only a very few fertilizers contain potassium nitrate.<ref name="Kent">Template:Cite book</ref> In 2005, about 93% of world potassium production was consumed by the fertilizer industry.<ref name="USGSYB2006" /> Furthermore, potassium can play a key role in nutrient cycling by controlling litter composition.<ref>Template:Cite journal</ref>
Major potassium chemicals are potassium hydroxide, potassium carbonate, potassium sulfate, and potassium chloride. Megatons of these compounds are produced annually.<ref>Schultz</ref>
KOH is a strong base, which is used in industry to neutralize strong and weak acids, to control pH and to manufacture potassium salts. It is also used to saponify fats and oils, in industrial cleaners, and in hydrolysis reactions, for example of esters.<ref>Template:Cite book</ref><ref>Schultz, p. 95</ref>
There are thousands of uses of various potassium compounds. One example is potassium superoxide, Template:Chem2, an orange solid that acts as a portable source of oxygen and a carbon dioxide absorber. It is widely used in respiration systems in mines, submarines and spacecraft as it takes less volume than the gaseous oxygen.<ref>Greenwood, p. 74</ref><ref>Template:Cite book</ref>
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Potassium is the eighth or ninth most common element by mass (0.2%) in the human body, so that a 60Template:Nbspkg adult contains a total of about 120Template:Nbspg of potassium.<ref>Template:Cite journal</ref> The body has about as much potassium as sulfur and chlorine, and only calcium and phosphorus are more abundant (with the exception of the ubiquitous CHON elements).<ref>Template:Cite book</ref> Potassium ions are present in a wide variety of proteins and enzymes.<ref>Template:Cite book</ref> Potassium is largely intracellular.<ref>Template:Cite journal</ref>
resting cellular-membrane potential and the propagation of action potentials in neuronal, muscular, and cardiac tissue. Due to the electrostatic and chemical properties, Template:Chem2 ions are larger than Template:Chem2 ions, and ion channels and pumps in cell membranes can differentiate between the two ions, actively pumping or passively passing one of the two ions while blocking the other.<ref>Template:Cite journal</ref>
hormone secretion and action
vascular tone
systemic blood pressure control
gastrointestinal motility
acid–base homeostasis
glucose and insulin metabolism
mineralocorticoid action
renal concentrating ability
fluid and electrolyte balance
local cortical monoaminergic norepinephrine, serotonin, and dopamine levels, and through them, sleep/wake balance, and spontaneous activity.<ref name="Dietz Weikop Hauglund Andersen 2023 p.">Template:Cite journal</ref>
Potassium homeostasis denotes the maintenance of the total body potassium content, plasma potassium level, and the ratio of the intracellular to extracellular potassium concentrations within narrow limits, in the face of pulsatile intake (meals), obligatory renal excretion, and shifts between intracellular and extracellular compartments.
Plasma potassium is normally kept at 3.5 to 5.5 millimoles (mmol) [or milliequivalents (mEq)] per liter by multiple mechanisms.<ref name="Wei Gritter Vogt de Borst 2020 pp. 952–968">Template:Cite journal</ref> Levels outside this range are associated with an increasing rate of death from multiple causes,<ref>Template:Cite journal</ref> and some cardiac, kidney,<ref>Template:Cite journal</ref> and lung diseases progress more rapidly if serum potassium levels are not maintained within the normal range.
An average meal of 40–50Template:Nbspmmol presents the body with more potassium than is present in all plasma (20–25Template:Nbspmmol). This surge causes the plasma potassium to rise up to 10% before clearance by renal and extrarenal mechanisms.<ref>Template:Cite journal</ref>
Collectively, the first three are sometimes termed the "external potassium homeostasis system";<ref>Template:Cite journal</ref> and the first two, the "reactive potassium homeostasis system".
The reactive negative-feedback system refers to the system that induces renal secretion of potassium in response to a rise in the plasma potassium (potassium ingestion, shift out of cells, or intravenous infusion.)
The reactive feed-forward system refers to an incompletely understood system that induces renal potassium secretion in response to potassium ingestion prior to any rise in the plasma potassium. This is probably initiated by gut cell potassium receptors that detect ingested potassium and trigger vagalafferent signals to the pituitary gland.
The predictive or circadian system increases renal secretion of potassium during mealtime hours (e.g. daytime for humans, nighttime for rodents) independent of the presence, amount, or absence of potassium ingestion. It is mediated by a circadian oscillator in the suprachiasmatic nucleus of the brain (central clock), which causes the kidney (peripheral clock) to secrete potassium in this rhythmic circadian fashion.File:Scheme sodium-potassium pump-en.svgThe action of the sodium-potassium pump is an example of primary active transport. The two carrier proteins embedded in the cell membrane on the left are using ATP to move sodium out of the cell against the concentration gradient; The two proteins on the right are using secondary active transport to move potassium into the cell. This process results in reconstitution of ATP.
The ion transport system moves potassium across the cell membrane using two mechanisms. One is active and pumps sodium out of, and potassium into, the cell. The other is passive and allows potassium to leak out of the cell. Potassium and sodium cations influence fluid distribution between intracellular and extracellular compartments by osmotic forces. The movement of potassium and sodium through the cell membrane is mediated by the Na⁺/K⁺-ATPase pump.<ref>Template:Cite book</ref> This ion pump uses ATP to pump three sodium ions out of the cell and two potassium ions into the cell, creating an electrochemical gradient and electromotive force across the cell membrane. The highly selective potassium ion channels (which are tetramers) are crucial for hyperpolarization inside neurons after an action potential is triggered, to cite one example. The most recently discovered potassium ion channel is KirBac3.1, which makes a total of five potassium ion channels (KcsA, KirBac1.1, KirBac3.1, KvAP, and MthK) with a determined structure. All five are from prokaryotic species.<ref name="pmid16253415">Template:Cite journal</ref>
Sodium is reabsorbed to maintain extracellular volume, osmotic pressure, and serum sodium concentration within narrow limits. Potassium is reabsorbed to maintain serum potassium concentration within narrow limits.<ref>Template:Cite journal</ref> Sodium pumps in the renal tubules operate to reabsorb sodium. Potassium must be conserved, but because the amount of potassium in the blood plasma is very small and the pool of potassium in the cells is about 30 times as large, the situation is not so critical for potassium. Since potassium is moved passively<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> in counter flow to sodium in response to an apparent (but not actual) Donnan equilibrium,<ref>Template:Cite book</ref> the urine can never sink below the concentration of potassium in serum except sometimes by actively excreting water at the end of the processing. Potassium is excreted twice and reabsorbed three times before the urine reaches the collecting tubules.<ref>Template:Cite journal</ref> At that point, urine usually has about the same potassium concentration as plasma. At the end of the processing, potassium is secreted one more time if the serum levels are too high.Template:Citation needed
With no potassium intake, it is excreted at about 200Template:Nbspmg per day until, in about a week, potassium in the serum declines to a mildly deficient level of 3.0–3.5Template:Nbspmmol/L.<ref>Template:Cite journal</ref> If potassium is still withheld, the concentration continues to fall until a severe deficiency causes eventual death.<ref>Template:Cite book</ref>
The potassium moves passively through pores in the cell membrane. When ions move through ion transporters (pumps) there is a gate in the pumps on both sides of the cell membrane and only one gate can be open at once. As a result, approximately 100 ions are forced through per second. Ion channels have only one gate, and there only one kind of ion can stream through, at 10 million to 100 million ions per second.<ref>Template:Cite journal; for a diagram of the potassium pores are viewed, see Template:Cite journal</ref> Calcium is required to open the pores,<ref>Template:Cite journal</ref> although calcium may work in reverse by blocking at least one of the pores.<ref>Template:Cite journal includes a detailed picture of atoms in the pump.</ref> Carbonyl groups inside the pore on the amino acids mimic the water hydration that takes place in water solution<ref>Template:Cite journal</ref> by the nature of the electrostatic charges on four carbonyl groups inside the pore.<ref>Template:Cite journal</ref>
The U.S. National Academy of Medicine (NAM), on behalf of both the U.S. and Canada, sets Dietary Reference Intakes, including Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs), or Adequate Intakes (AIs) for when there is not sufficient information to set EARs and RDAs.
For both males and females under 9 years of age, the AIs for potassium are: 400Template:Nbspmg of potassium for 0 to 6-month-old infants, 860Template:Nbspmg of potassium for 7 to 12-month-old infants, 2,000Template:Nbspmg of potassium for 1 to 3-year-old children, and 2,300Template:Nbspmg of potassium for 4 to 8-year-old children.
For males 9 years of age and older, the AIs for potassium are: 2,500Template:Nbspmg of potassium for 9 to 13-year-old males, 3,000Template:Nbspmg of potassium for 14 to 18-year-old males, and 3,400Template:Nbspmg for males that are 19 years of age and older.
For females 9 years of age and older, the AIs for potassium are: 2,300Template:Nbspmg of potassium for 9 to 18-year-old females, and 2,600Template:Nbspmg of potassium for females that are 19 years of age and older.
For pregnant and lactating females, the AIs for potassium are: 2,600Template:Nbspmg of potassium for 14 to 18-year-old pregnant females, 2,900Template:Nbspmg for pregnant females that are 19 years of age and older; furthermore, 2,500Template:Nbspmg of potassium for 14 to 18-year-old lactating females, and 2,800Template:Nbspmg for lactating females that are 19 years of age and older. As for safety, the NAM also sets tolerable upper intake levels (ULs) for vitamins and minerals, but for potassium the evidence was insufficient, so no UL was established.<ref>Template:Cite book</ref><ref>Template:Cite book</ref>
Likewise, in the European Union, in particular in Germany, and Italy, insufficient potassium intake is somewhat common.<ref>Template:Cite journal</ref>
The National Health Service in the United Kingdom recommends a similar intake, saying that "adults (19 to 64 years) need Template:Val per day" and that excess amounts may cause health problems such as stomach pain and diarrhea.<ref>Template:Cite web</ref>
Supplements of potassium are most widely used in conjunction with diuretics that block reabsorption of sodium and water upstream from the distal tubule (thiazides and loop diuretics), because this promotes increased distal tubular potassium secretion, with resultant increased potassium excretion.<ref>Template:Cite journal</ref> A variety of prescription and over-the counter supplements are available.<ref>Template:Cite web</ref> Potassium chloride may be dissolved in water, but the salty/bitter taste makes liquid supplements unpalatable.<ref name="bitter" /><ref>Template:Cite journal</ref> Potassium is also available in tablets or capsules, which are formulated to allow potassium to leach slowly out of a matrix, since very high concentrations of potassium ion that occur adjacent to a solid tablet can injure the gastric or intestinal mucosa.<ref name=BNF69/><ref>Template:Cite journal</ref> For this reason, non-prescription potassium pills are limited by law in the US to a maximum of 99Template:Nbspmg of potassium.<ref>Template:Cite web</ref>
Potassium supplementation can also be combined with other metabolites, such as citrate or chloride, to achieve specific clinical effects.<ref name="pmid38333496">Template:Cite journal</ref>
Potassium supplements may be employed to mitigate the impact of hypertension, thereby reducing cardiovascular risk.<ref>Template:Cite journal</ref> Potassium chloride and potassium bicarbonate may be useful to control mild hypertension.<ref>Template:Cite journal</ref> In 2020, potassium was the 33rd most commonly prescribed medication in the U.S., with more than 17Template:Nbspmillion prescriptions.<ref>Template:Cite web</ref><ref>Template:Cite web</ref> Potassium supplementation has been shown to reduce both systolic and diastolic blood pressure in individuals with essential hypertension.<ref name="pmid38333496"/>
Additionally, potassium supplements may be employed with the aim of preventing the formation of kidney stones, a condition that can lead to renal complications if left untreated. Low potassium levels can lead to decreased calcium reabsorption in the kidneys, increasing the risk of elevated urine calcium and the formation of kidney stones. By maintaining adequate potassium levels, this risk can be reduced.<ref name="pmid38333496"/>
The mechanism of action of potassium involves various types of transporters and channels that facilitate its movement across cell membranes. This process can lead to an increase in the pumping of hydrogen ions. This, in turn, can escalate the production of gastric acid, potentially contributing to the development of gastric ulcers.<ref name="pmid38333496"/>
Potassium has a role in bone health. It contributes to the acid-base equilibrium in the body and helps protect bone tissue. Potassium salts produce an alkaline component that can aid in maintaining bone health.<ref name="pmid38333496"/>
For individuals with diabetes, potassium supplementation may be necessary, particularly for those with type 2 diabetes. Potassium is essential for the secretion of insulin by pancreatic beta cells, which helps regulate glucose levels. Without sufficient potassium, insulin secretion is compromised, leading to hyperglycemia and worsening diabetes.<ref name="pmid38333496"/>
Excessive potassium intake can have adverse effects, such as gastrointestinal discomfort and disturbances in heart rhythm.<ref name="pmid38333496"/>
Potassium supplementation can have side effects on ulceration, particularly in relation to peptic ulcer disease. Potassium channels have the potential to increase gastric acid secretion, which can lead to an increased risk of ulcerations. Medications used for peptic ulcer disease, known as "proton pump inhibitors", work by inhibiting potassium pumps that activate the H/K ATPase. This inhibition helps to reduce the secretion of hydrochloric acid into the parietal cell, thereby decreasing acidic synthesis and lowering the risk of ulcers. Nicorandil, a drug used for the treatment of ischemic heart disease, can stimulate nitrate and potassium ATP channels, and as a result, it has been associated with side effects such as GI, oral, and anal ulcers. Potassium chloride tablets are specifically associated with pill esophagitis.<ref>Template:Cite journal</ref> Prolonged and chronic use of potassium supplements has been linked to more severe side effects, including ulcers outside of the gastrointestinal (GI) tract. Close monitoring is necessary for patients who are also taking angiotensinogen-converting enzyme inhibitors, angiotensin receptor blockers, or potassium-sparing diuretics.<ref name="pmid38333496"/>
Potassium can be detected by taste because it triggers three of the five types of taste sensations, according to concentration. Dilute solutions of potassium ions taste sweet, allowing moderate concentrations in milk and juices, while higher concentrations become increasingly bitter/alkaline, and finally also salty to the taste. The combined bitterness and saltiness of high-potassium solutions makes high-dose potassium supplementation by liquid drinks a palatability challenge.<ref name="bitter">Template:Cite book</ref><ref>Template:Cite book</ref> As a food additive, potassium chloride has a salty taste. People wishing to increase their potassium intake or to decrease their sodium intake, after checking with a health professional that it is safe to do so, can substitute potassium chloride for some or all of the sodium chloride (table salt) used in cooking and at the table.<ref>Template:Cite journal</ref>
This reaction is exothermic and releases sufficient heat to ignite the resulting hydrogen in the presence of oxygen. Finely powdered potassium ignites in air at room temperature. The bulk metal ignites in air if heated. Because its density is 0.89Template:Nbspg/cm3, burning potassium floats in water that exposes it to atmospheric oxygen. Many common fire extinguishing agents, including water, either are ineffective or make a potassium fire worse. Nitrogen, argon, sodium chloride (table salt), sodium carbonate (soda ash), and silicon dioxide (sand) are effective if they are dry. Some Class D dry powder extinguishers designed for metal fires are also effective. These agents deprive the fire of oxygen and cool the potassium metal.<ref>Template:Cite book</ref>
During storage, potassium forms peroxides and superoxides. These peroxides may react violently with organic compounds such as oils. Both peroxides and superoxides may react explosively with metallic potassium.<ref>Template:Cite web</ref>
Because potassium reacts with water vapor in the air, it is usually stored under anhydrous mineral oil or kerosene. Unlike lithium and sodium, potassium should not be stored under oil for longer than six months, unless in an inert (oxygen-free) atmosphere, or under vacuum. After prolonged storage in air dangerous shock-sensitive peroxides can form on the metal and under the lid of the container, and can detonate upon opening.<ref>Template:Cite web</ref>
Ingestion of large amounts of potassium compounds, certain drugs, and homeostatic failure, can lead to hyperkalemia, leading to a variety of brady- and tachy-arrhythmias that can be fatal.<ref name="hyper">Template:Cite book</ref><ref>Template:Cite book</ref><ref>Template:Cite journal</ref> Potassium chloride is used in the U.S. for lethal injection executions.<ref name="hyper" />
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