Pantothenic acid
Pantothenic acid (vitamin B5) is a B vitamin and an essential nutrient.[6] All animals need pantothenic acid in order to synthesize coenzyme A (CoA), which is essential for cellular energy production and for the synthesis and degradation of proteins, carbohydrates, and fats.[6][7]
Not to be confused with pantethine.Pantothenic acid is the combination of pantoic acid and β-alanine. Its name comes from the Greek πάντοθεν pantothen, meaning "from everywhere", because pantothenic acid, at least in small amounts, is in almost all foods.[6][8][7] Deficiency of pantothenic acid is very rare in humans.[6][7] In dietary supplements and animal feed, the form commonly used is calcium pantothenate, because chemically it is more stable, and hence makes for longer product shelf-life, than sodium pantothenate and free pantothenic acid.[1]
Sources[edit]
Dietary[edit]
Food sources of pantothenic acid include animal-sourced foods, including dairy foods and eggs.[6][8] Potatoes, tomato products, oat-cereals, sunflower seeds, avocado are good plant sources. Mushrooms are good sources, too. Whole grains are another source of the vitamin, but milling to make white rice or white flour removes much of the pantothenic acid, as it is found in the outer layers of whole grains.[6][10] In animal feeds, the most important sources are alfalfa, cereal, fish meal, peanut meal, molasses, rice bran, wheat bran, and yeasts.[26]
Supplements[edit]
Dietary supplements of pantothenic acid commonly use pantothenol (or panthenol), a shelf-stable analog, which is converted to pantothenic acid once consumed.[7] Calcium pantothenate – a salt – may be used in manufacturing because it is more resistant than pantothenic acid to factors that deteriorate stability, such as acid, alkali or heat.[9][26] The amount of pantothenic acid in dietary supplement products may contain up to 1,000 mg (200 times the Adequate Intake level for adults), without evidence that such large amounts provide any benefit.[7][6] According to WebMD, pantothenic acid supplements have a long list of claimed uses, but there is insufficient scientific evidence to support any of them.[27]
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.[7] Sold as a high-dose supplement (600 mg), pantethine may be effective for lowering blood levels of LDL cholesterol – a risk factor for cardiovascular diseases – but its long-term effects are unknown, so use should be supervised by a physician.[7] Dietary supplementation with pantothenic acid does not have the cholesterol-lowering effect as pantethine.[9]
Absorption, metabolism and excretion[edit]
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 of the intestine, CoA and ACP are hydrolyzed into 4'-phosphopantetheine. The 4'-phosphopantetheine is then dephosphorylated into pantetheine. Pantetheinase, an intestinal enzyme, then hydrolyzes pantetheine into free pantothenic acid.[29] Free pantothenic acid is absorbed into intestinal cells via a saturable, sodium-dependent active transport system.[14] At high levels of intake, when this mechanism is saturated, some pantothenic acid may also be additionally absorbed via passive diffusion.[26] As a whole, when intake increases 10-fold, absorption rate decreases to 10%.[14]
Pantothenic acid is excreted in urine. This occurs after its release from CoA. Urinary amounts are on the order of 2.6 mg/day, but decreased to negligible amounts when subjects in multi-week experimental situations were fed diets devoid of the vitamin.[10]
Deficiency[edit]
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.[14][9] 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, and apathy.[14] Acetylcholine synthesis is also impaired; therefore, neurological symptoms can also appear in deficiency;[30] 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.[30]
In animals, symptoms include disorders of the nervous, gastrointestinal, and immune systems, reduced growth rate, decreased food intake, skin lesions and changes in hair coat, and alterations in lipid and carbohydrate metabolism.[31] In rodents, there can be loss of hair color, which led to marketing of pantothenic acid as a dietary supplement which could prevent or treat graying of hair in humans (despite the lack of any human trial evidence).[9]
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 μmol/L are considered low, as is urinary excretion of less than 4.56 mmol/day.[9]
Animal nutrition[edit]
Calcium pantothenate and dexpanthenol (D-panthenol) are European Food Safety Authority (EFSA) approved additives to animal feed.[1] Supplementation is on the order of 8–20 mg/kg for pigs, 10–15 mg/kg for poultry, 30–50 mg/kg for fish and 8–14 mg/kg feed for pets. These are recommended concentrations, designed to be higher than what are thought to be requirements.[1] 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.[1]
No dietary requirement for pantothenic acid has been established in ruminant species. Synthesis of pantothenic acid by ruminal microorganisms appears to be 20 to 30 times more than dietary amounts.[32] Net microbial synthesis of pantothenic acid in the rumen of steer calves has been estimated to be 2.2 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.[33]