Pantothenic acid, also called vitamin B5 (a B vitamin), is a water-soluble vitamin. Pantothenic acid is an essential nutrient. Animals require pantothenic acid to synthesize coenzyme-A (CoA), as well as to synthesize and metabolize proteins, carbohydrates, and fats. The anion is called pantothenate.
Pantothenic acid is the amide between pantoic acid and β-alanine. Its name derives from the Greek pantothen, meaning "from everywhere", and small quantities of pantothenic acid are found in nearly every food, with high amounts in fortified whole-grain cereals, egg yolks, liver and dried mushrooms. It is commonly found as its alcohol analog, the provitamin panthenol (pantothenol), and as calcium pantothenate.
Pantothenic acid was discovered by Roger J. Williams in 1933.
Only the dextrorotatory (D) isomer of pantothenic acid possesses biologic activity. The levorotatory (L) form may antagonize the effects of the dextrorotatory isomer.
Pantothenic acid is used in the synthesis of coenzyme A (CoA). Coenzyme A may act as an acyl group carrier to form acetyl-CoA and other related compounds; this is a way to transport carbon atoms within the cell. CoA is important in energy metabolism for pyruvate to enter the tricarboxylic acid cycle (TCA cycle) as acetyl-CoA, and for α-ketoglutarate to be transformed to succinyl-CoA in the cycle. CoA is also important in the biosynthesis of many important compounds such as fatty acids, cholesterol, and acetylcholine. CoA is incidentally also required in the formation of ACP, which is also required for fatty acid synthesis in addition to CoA.
Pantothenic acid in the form of CoA is also required for acylation and acetylation, which, for example, are involved in signal transduction and enzyme activation and deactivation, respectively.
Since pantothenic acid participates in a wide array of key biological roles, it is essential to all forms of life. As such, deficiencies in pantothenic acid may have numerous wide-ranging effects.
Content of pantothenic acid varies among manufactured and natural foods, especially fortified ready-to-eat cereals, infant formulas, energy bars and dried foods. Major food sources of pantothenic acid are dried mushrooms, liver, dried egg yolks and sunflower seeds. Whole grains are another good source of the vitamin, but milling removes much of the pantothenic acid, as it is found in the outer layers of whole grains. In animal feeds, the most important sources are alfalfa, cereal, fish meal, peanut meal, molasses, mushrooms, rice, wheat bran, and yeasts.
The derivative of pantothenic acid, pantothenol (panthenol), is a more stable form of the vitamin and is often used as a source of the vitamin in multivitamin supplements.:347 Another common supplemental form of the vitamin is calcium pantothenate. Calcium pantothenate is often used in dietary supplements because, as a salt, it is more stable than pantothenic acid. Supplementation may improve oxygen utilization efficiency and reduce lactic acid accumulation in athletes.
The Food and Nutrition Board of the U.S. Institute of Medicine updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for B vitamins in 1998. At that time there was not sufficient information to establish EARs and RDAs for pantothenic acid. In instances such as this, the Board sets Adequate Intakes (AIs), with the understanding that at some later date, AIs will be replaced by more exact information. As for safety, the FNB sets Tolerable Upper Intake Levels (known as ULs) for vitamins and minerals when evidence is sufficient. In the case of pantothenic acid there is no UL, as there is insufficient human data to identify adverse effects from high doses. The European Food Safety Authority reviewed the same safety question and also reached the conclusion that there was not sufficient evidence to set a UL for pantothenic acid. Collectively the EARs, RDAs and ULs are referred to as Dietary Reference Intakes.
For U.S. food and dietary supplement labeling purposes the amount in a serving is expressed as a percent of Daily Value (%DV). For pantothenic acid labeling purposes 100% of the Daily Value was 10 mg, but as of May 2016 it has been revised to 5 mg. A table of the pre-change adult Daily Values is provided at Reference Daily Intake. Food and supplement companies have until July 2018 to comply with the change.
Pantothenic acid in the form of 4'phosphopantetheine is considered to be the more active form of the vitamin in the body; however, any derivative must be broken down to pantothenic acid before absorption.
When found in foods, most pantothenic acid is in the form of CoA or acyl carrier protein (ACP). For the intestinal cells to absorb this vitamin, it must be converted into free pantothenic acid. Within the lumen of the intestine, CoA and ACP are hydrolyzed into 4'-phosphopantetheine. The 4'-phosphopantetheine is then