Pantothenic acid/ja: Difference between revisions

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===Dietary===

===Supplements===

[[Dietary supplements]] of pantothenic acid commonly use [[pantothenol]] (or ''panthenol''), a [[Shelf-stable food|shelf-stable]] [[Functional analog (chemistry)|analog]], which is converted to pantothenic acid once consumed. Calcium pantothenate &ndash; a [[salt (chemistry)|salt]] &ndash; may be used in manufacturing because it is more resistant than pantothenic acid to factors that deteriorate stability, such as acid, [[alkali]] or heat. The amount of pantothenic acid in dietary supplement products may contain up to 1,000&nbsp;mg (200 times the Adequate Intake level for adults), without evidence that such large amounts provide any benefit. According to [[WebMD]], pantothenic acid supplements have a long list of claimed uses, but there is insufficient scientific evidence to support any of them.

As a dietary supplement, pantothenic acid is not the same as [[pantethine]], which is composed of two pantothenic acid molecules linked by a [[disulfide]] bridge. Sold as a high-dose supplement (600&nbsp;mg), pantethine may be effective for lowering blood levels of [[LDL cholesterol]] &ndash; a [[risk factor]] for cardiovascular diseases &ndash; but its long-term effects are unknown, requiring that its use be supervised by a physician. Dietary supplementation with pantothenic acid does not have the same effect on LDL.

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===Fortification===

According to the Global Fortification Data Exchange, pantothenic acid deficiency is so rare that no countries require that foods be fortified.

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==Absorption, metabolism and excretion==

When found in foods, most pantothenic acid is in the form of CoA or bound to [[acyl carrier protein]] (ACP).  For the intestinal cells to absorb this vitamin, it must be converted into free pantothenic acid.  Within the [[Lumen (anatomy)|lumen]] of the intestine, CoA and ACP are [[Hydrolysis|hydrolyzed]] into 4'-phosphopantetheine. The 4'-phosphopantetheine is then [[Dephosphorylation|dephosphorylated]] into [[pantetheine]].  [[Pantetheine hydrolase|Pantetheinase]], an intestinal enzyme, then hydrolyzes pantetheine into free pantothenic acid. Free pantothenic acid is absorbed into intestinal cells via a saturable, sodium-dependent active transport system. At high levels of intake, when this mechanism is saturated, some pantothenic acid may also be additionally absorbed via passive diffusion. As a whole, when intake increases 10-fold, absorption rate decreases to 10%.

Pantothenic acid is excreted in urine. This occurs after its release from CoA. Urinary amounts are on the order of 2.6&nbsp;mg/day, but decreased to negligible amounts when subjects in multi-week experimental situations were fed diets devoid of the vitamin.

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==Deficiency==

Pantothenic acid deficiency in humans is very rare and has not been thoroughly studied. In the few cases where deficiency has been seen (prisoners of war during World War II, victims of starvation, or limited volunteer trials), nearly all symptoms were reversed with orally administered pantothenic acid. Symptoms of deficiency are similar to other [[vitamin B]] deficiencies. There is impaired energy production, due to low CoA levels, which could cause symptoms of irritability, [[Fatigue (medical)|fatigue]], and [[apathy]]. Acetylcholine synthesis is also impaired; therefore, neurological symptoms can also appear in deficiency; they include sensation of numbness in hands and feet, [[paresthesia]] and muscle cramps. Additional symptoms could include restlessness, malaise, sleep disturbances, nausea, vomiting and abdominal cramps.

Pantothenic acid status can be assessed by measuring either whole blood concentration or 24-hour urinary excretion. In humans, whole blood values less than 1&nbsp;μmol/L are considered low, as is urinary excretion of less than 4.56&nbsp;mmol/day.

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==Animal nutrition==

[[File:Pantothenic acid biosynthesis.svg|thumb|Pantothenic acid biosynthesis]]

Calcium pantothenate and dexpanthenol (D-panthenol) are European Food Safety Authority (EFSA) approved additives to animal feed. Supplementation is on the order of 8–20&nbsp;mg/kg for pigs, 10–15&nbsp;mg/kg for poultry, 30–50&nbsp;mg/kg for fish and 8–14&nbsp;mg/kg feed for pets. These are recommended concentrations, designed to be higher than what are thought to be requirements. There is some evidence that feed supplementation increases pantothenic acid concentration in tissues, i.e., meat, consumed by humans, and also for eggs, but this raises no concerns for consumer safety.

No dietary requirement for pantothenic acid has been established in ruminant species. Synthesis of pantothenic acid by [[Rumen|ruminal]] microorganisms appears to be 20 to 30 times more than dietary amounts. Net microbial synthesis of pantothenic acid in the rumen of steer calves has been estimated to be 2.2&nbsp;mg/kg of digestible organic matter consumed per day. Supplementation of pantothenic acid at 5 to 10 times theoretical requirements did not improve growth performance of feedlot cattle.

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==Synthesis==

===Biosynthesis===

Bacteria synthesize pantothenic acid from the amino acids aspartate and a precursor to the amino acid valine. Aspartate is converted to [[β-alanine]]. The amino group of valine is replaced by a keto-[[Moiety (chemistry)|moiety]] to yield [[α-ketoisovalerate]], which, in turn, forms α-ketopantoate following transfer of a methyl group, then D-pantoate (also known as pantoic acid) following reduction. β-alanine and pantoic acid are then condensed to form pantothenic acid (see figure).

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===Industrial synthesis===

The industrial synthesis of pantothenic acid starts with the [[aldol condensation]] of [[isobutyraldehyde]] and [[formaldehyde]]. The resulting [[hydroxypivaldehyde]] is converted to its [[cyanohydrin]] derivative. which is cyclised to give [[racemic]] pantolactone. This sequence of reactions was first published in 1904.

:[[File:Pantothenic acid synthesis.svg|650px]]

Synthesis of the vitamin is completed by [[Chiral resolution|resolution]] of the lactone using [[quinine]], for example, followed by treatment with the calcium or sodium salt of β-alanine.

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==History==

{{Further|Vitamin#History}}

The term ''vitamin'' is derived from the word ''vitamine'', which was coined in 1912 by Polish biochemist [[Casimir Funk]], who isolated a complex of water-soluble micronutrients essential to life, all of which he presumed to be [[amine]]s. When this presumption was later determined not to be true, the "e" was dropped from the name, hence "vitamin". Vitamin nomenclature was alphabetical, with [[Elmer McCollum]] calling these fat-soluble A and water-soluble B. Over time, eight chemically distinct, water-soluble B vitamins were isolated and numbered, with pantothenic acid as vitamin B₅.

The essential nature of pantothenic acid was discovered by [[Roger J. Williams]] in 1933 by showing it was required for the growth of yeast. Three years later Elvehjem and Jukes demonstrated that it was a growth and anti-dermatitis factor in chickens. Williams dubbed the compound "pantothenic acid", deriving the name from the Greek word ''pantothen'', which translates as "from everywhere". His reason was that he found it to be present in almost every food he tested. Williams went on to determine the chemical structure in 1940. In 1953, [[Fritz Lipmann]] shared the [[Nobel Prize in Physiology or Medicine]] "for his discovery of co-enzyme A and its importance for intermediary metabolism", work he had published in 1946.

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