Pantothenic acid

Pantothenic acid
IUPAC name	3-[(2,4-dihydroxy-3, 3-dimethyl-1-oxobutyl) amino]propanoic acid
Identifiers
CAS number	137-08-6
PubChem	988
SMILES	CC(C)(CO)C(C(=O)NCCC(=O)O)O
Properties
Molecular formula	C9H17NO5
Molar mass	219.235
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references

Pantothenic acid, also called vitamin B₅ (a B vitamin), is a water-soluble vitamin required to sustain life (essential nutrient). Pantothenic acid is needed to form coenzyme-A (CoA), and is critical in the metabolism and synthesis of carbohydrates, proteins, and fats. In chemical structure, it is the amide between D-pantoate and beta-alanine. Its name is derived from the Greek pantothen (παντόθεν) meaning "from everywhere" and small quantities of pantothenic acid are found in nearly every food, with high amounts in whole-grain cereals, legumes, eggs, meat, and royal jelly. It is commonly found as its alcohol analog, the provitamin panthenol, and as calcium pantothenate.

Biological role

Only the dextrorotatory (D) isomer of pantothenic acid possesses biologic activity.^[1] The levorotatory (L) form may antagonize the effects of the dextrorotatory isomer.^[2]

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. The transfer of carbon atoms by coenzyme A is important in cellular respiration, as well as the biosynthesis of many important compounds such as fatty acids, cholesterol, and acetylcholine.

Acetyl-CoA is used in the condensation of oxaloacetate to citrate at the initiation of the TCA cycle. From the TCA cycle, acetyl-CoA can also initiate the fatty acid synthesis pathway ^[3]

Since pantothenic acid participates in a wide array of key biological roles, it is considered essential to all forms of life.^[4] As such, deficiencies in pantothenic acid may have numerous wide-ranging effects, as discussed below.

Pantothenic acid is vital for a healthy pregnancy.

Sources

Dietary

Small quantities of pantothenic acid are found in most foods.^[5] The major food sources of pantothenic acid are meats, although the concentration found in food animals' muscles is only about half that in humans' muscles. [2] Some vegetables are also good sources, as well as whole grains, but a large amount of pantothenic acid is found in the outer layers of the whole grains, so the milling process removes a majority of the vitamin. In animal feeds, the most important sources of the vitamin are rice, wheat brans, alfalfa, peanut meal, molasses, yeasts, and condensed fish solutions. The most significant source of pantothenic acid in nature are coldwater fish ovaries and royal jelly.^[6]

A recent study also suggests that gut bacteria in humans can generate pantothenic acid.^[7]

Supplementation

The derivative of pantothenic acid, pantothenol, is a more stable form of the vitamin and is often used as a source of the vitamin in multivitamin supplements.^[8] 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 in the digestive tract allowing for better absorption.

Possible benefits of supplementation: Doses of 2g/day of calcium pantothenate may reduce the duration of morning stiffness, degree of disability, and pain severity in rheumatoid arthritis patients. Although the results are inconsistent, supplementation may improve oxygen utilization efficiency and reduce lactic acid accumulation in athletes. ^[9]

Daily requirement

Pantothenate in the form of pantethine is considered to be the more active form of the vitamin in the body, but is unstable at high temperatures or when stored for long periods, so calcium pantothenate is the more usual form of vitamin B5 when it is sold as a dietary supplement. Ten mg of calcium pantothenate is equivalent to 9.2 mg of pantothenic acid.

• United Kingdom RDA: 6 mg/day

Absorption

Within most foods, pantothenic acid is in the form of CoA or Acyl Carrier Protein (ACP). In order 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 degraded from the food into 4'-phosphopantetheine. This form is then dephosphorylated into pantetheine that is then acted upon by the intestinal enzyme, pantetheinase, to yield 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 absorbed via passive diffusion.^[10]

Deficiency

Pantothenic acid deficiency is exceptionally rare and has not been thoroughly studied. In the few cases where deficiency has been seen (victims of starvation and limited volunteer trials), nearly all symptoms can be reversed with the return of pantothenic acid.

Symptoms of deficiency are similar to other vitamin B deficiencies. Most are minor, including fatigue, allergies, nausea, and abdominal pain. In a few rare circumstances more serious (but reversible) conditions have been seen, such as adrenal insufficiency and hepatic encephalopathy.

It has been noted that painful burning sensations of the feet were reported in tests conducted on volunteers. Deficiency of pantothenic acid may explain similar sensations reported in malnourished prisoners of war.^[4]

Deficiency symptoms in other non-ruminant animals include disorders of the nervous, gastrointestinal, and immune systems, reduced growth rate, decreased food intake, skin lesions and changes in hair coat, alterations in lipid and carbohydrate metabolism.^[11]

Toxicity

Toxicity of pantothenic acid is unlikely. Large doses of the vitamin, when ingested, have no reported side effects and massive doses (e.g. 10 g/day) may only yield mild intestinal distress and diarrhea at worst. There are also no adverse reactions known following parenteral or topical application of the vitamin.^[12]

Disputed uses

Given pantothenic acid's prevalence among living things and the limited body of studies in deficiency, many "alternative" uses of pantothenic acid have been devised.

Hair care

Mouse models identified skin irritation and loss of hair color as possible results of severe pantothenic acid deficiency. As a result, the cosmetic industry began adding pantothenic acid to various cosmetic products, including shampoo. These products, however, showed no benefits in human trials. Despite this, many cosmetic products still advertise pantothenic acid additives. ^{[13][14][15][16][17][18]}

Acne

Following from discoveries in mouse trials, in the late 1990s a small study was published promoting the use of pantothenic acid to treat acne vulgaris.

According to a study published in 1995 by Dr. Lit-Hung Leung,^[19] high doses of Vitamin B₅ resolved acne and decreased pore size. Dr. Leung also proposes a mechanism, stating that CoA regulates both hormones and fatty-acids, and without sufficient quantities of pantothenic acid, CoA will preferentially produce androgens. This causes fatty acids to build up and be excreted through sebaceous glands, causing acne. Leung's study gave 45 Asian males and 55 Asian females varying doses of 10-20g of pantothenic acid (100,000%-200,000% of the US Daily Value), 80% orally and 20% through topical cream. Leung noted improvement of acne within one week to one month of the start of the treatment.

Critics are quick to point out the flaws in Dr. Leung's study, however. Dr. Leung's study was not a double-blind placebo controlled trial. To date, the only study looking at the effect of Vitamin B₅ on acne is Dr. Leung's, and few if any dermatologists prescribe high-dose pantothenic acid. Furthermore, there is no evidence documenting acetyl-CoA regulation of androgens instead of fatty acids in times of stress or limited availability, since fatty acids are also necessary for life.^[20][21][22]

Diabetic peripheral polyneuropathy

28 out of 33 patients (84,8%) previously treated with alpha-lipoic acid for peripheral polyneuropathy reported further improvement after combination with pantothenic acid. The theoretical basis for this is that both substances intervene at different sites in pyruvate metabolism and are thus more effective than one substance alone. Additional clinical findings indicated that diabetic neuropathy may occur in association with a latent prediabetic metabolic disturbance, and that the symptoms of neuropathy can be favourably influenced by the described combination therapy, even in poorly controlled diabetes.^[23]

Dream Stimulant

Taken before bedtime can increase the likeliness of having/remembering dreams with elevated vividness.

Ruminant Nutrition

No dietary requirement for pantothenic acid has been established as synthesis of pantothenic acid by 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 mg/kg of digestible organic matter consumed per day. The degradation of dietary intake of pantothenic acid is considered to be 78 percent. Supplementation of pantothenic acid at 5 to 10 times theoretic requirements did not improve performance of feedlot cattle ^[24]

Synonyms

• Pantothenate
• Vitamin B5

See also

• Coenzyme A
• Panthenol
• Roger J. Williams (discoverer of pantothenic acid)

Enzymes

• Ketopantoate hydroxymethyltransferase

References

External links

• PDRhealth.com - Pantothenic acid
• Pantothenate at Klotho
• Reference link to Coenzyme-A and acne