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VITAMIN B5
Pantothenic acid, also called vitamin B5, is a water-soluble vitamin required to sustain life. Pantothenic acid is needed to form coenzyme-A (CoA), and is thus critical in the metabolism and synthesis of carbohydrates, proteins, and fats. Its name is derived from the Greek pantothen 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. The dimeric form 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.
Biologic Role
Pantothenic acid is a precursor to cortisone and is required to sustain life since it is a component of coenzyme-A.
Coenzyme A is synthesised in a five step process from pantothenate; first phosphorylated to 4'-phosphopantothenate by the enzyme pantothenate kinase, next a cysteine is added to form (R)-4'-phospho-N-pantothenoylcysteine (PPC), which then is decarboxylated to 4'-phosphopantetheine.
4'-phosphopantetheine is finally converted to Coenzyme A by the enzymes 4'-phosphopantetheine adenylyltransferase and dephospho-CoA kinase.
This makes pantothenic acid necessary in the synthesis of fats, steroids and steroid derivatives (such as cholesterols), proteins, and the neurotransmitter acetylcholine.
Sources
Small quantities of pantothenic acid are found in most foods [1], with high quantities found in whole grain and eggs. Pantothenic acid can also be found in many dietary supplements (as calcium-D-pantothenate), and some energy drink companies are now adding pantothenic acid to their beverages.
A recent study also suggests that gut bacteria in humans can generate pantothenic acid[1].
Daily Requirement
US RDA 10 mg
UK RDA 6mg
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 insuffiency and hepatic encephalopathy.
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.
Acne
Following from the 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 the study, published in 1997 by Dr. Lit-Hung Leung, 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.
Today, many companies offer Vitamin B5 supplements aimed at reducing acne. The recommend treatment course, however, is difficult and expensive to maintain. Many sites suggest starting off the first three days with 5g and then moving up to 10g a day for three months. Since the largest pill available is 500mg (a 1g pill of B5 has been made, but is extremely difficult to swallow), this can result in as many as 20 pills a day. The average cost for a bottle of 200 B5 500mg tablets is $10, so the cost can be steep. However, after three months many users suggest decreasing to 3-5g a day, with some claiming 1 g/day is sufficient.
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.
Synonyms
- pantothenate
- vitamin B5
- Vilantae-a brand name for the supplement when used to treat acne.
Enzymes
References
- ^ Said H, Ortiz A, McCloud E, Dyer D, Moyer M, Rubin S (1998). "Biotin uptake by human colonic epithelial NCM460 cells: a carrier-mediated process shared with pantothenic acid.". Am J Physiol 275 (5 Pt 1): C1365-71. PMID 9814986.
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