Biotin is a water-soluble vitamin whose primary function is as a coenzyme in carbohydrate, amino acid, and lipid metabolism. Biotin is essential for cell growth and replication through its role in the manufacturing of DNA and RNA. Biotin has been shown to improve blood glucose control in diabetes by enhancing insulin sensitivity and increasing the activity of glucokinase, the enzyme responsible for the first step in the utilization of glucose by the liver. Studies have observed improvements with doses from 9 mcg to 16 mcg. High doses of biotin may also be useful in the treatment of diabetic neuropathy. Healthy hair and nails require biotin. Supplementation (up to 2,500 mcg/day) has been effective in treating frail, splitting, or thin toenails or fingernails and in improving hair health (through its action on the metabolism of scalp oils). Biotin has also been used to combat premature graying of hair, though it's likely to be useful only for those with a biotin deficiency.

Biotin is synthesized in the intestinal microflora. For this reason, deficiency states are rare. A vegetarian diet enhances the synthesis and absorption of biotin. Those at risk for biotin deficiency include infants with inherited deficiency disorders, babies fed biotin-deficient formula, people who eat large amounts of raw egg whites, which inactivate biotin, and people who are fed intravenously. Symptoms include hair loss, a dry, scaly dermatitis, anorexia, nausea, and depression. Biotin deficiency can exacerbate seborrheic dermatitis (cradle cap) in infants. Several case histories reveal the successful treatment of cradle cap in infants with biotin through direct supplementation to either the infant or the mother if she is breast-feeding. In adults with seborrheic dermatitis, biotin supplementation in conjunction with vitamin B–complex supplementation is necessary. Biotin deficiency also impacts the immune system.

• Liver
• Nuts
• Kidney
• Egg yolks
• Brewer's yeast
• Chocolate
• Whole grains and whole grain breads
• Beans
• Fish

Food-processing techniques can destroy biotin, therefore less processed products will have a greater percentage of their biotin intact.

Biotin is available as isolated biotin or as biocytin, a complex in brewer's yeast, composed of 65.6% biotin.

Biotin is available in multivitamin and vitamin B complexes, and in individual supplements.

Standard preparations are available in 10 mcg, 50 mcg, 100 mcg, and 500 mcg tablets.

Biotin can be used to treat:

• Infants with a potentially fatal genetic abnormality, which leads to an inability to utilize biotin
• Some skin disorders, such as seborrheic dermatitis (cradle cap)
• Blood glucose control in diabetics
• Diabetic neuropathy
• Frail, splitting, or thin nails
• Hair loss due to deficiency
• Gray hair (in some instances)
• Metabolic abnormalities in Duchenne muscular dystrophy
• Fat metabolism in weight-loss programs (normalizes)
• Intestinal candidiasis

Due to biotin's synthesis in the gut, an RDA has not been set. The adequate intake for biotin has been estimated at 30 to 100 mcg per day. Average daily biotin intake in the American diet has been estimated to be 28 to 42 mcg.

There have been no reported toxic effects, even at high doses.

No contraindications have been identified.

No clinically significant interactions between biotin and conventional medications are known to have been reported in the literature to date.

Bendich A, Deckelbaum R. Preventive Nutrition: The Comprehensive Guide for Health Professionals. Totowa, NJ: Humana Press; 1997.

Houchman LG, et al. Brittle nails: response to biotin supplementation. Cutis. 1993;51:303-307.

Jung U, Helbich-Endermann M, Bitsch R, et al. Are patients with chronic renal failure (CRF) deficient in biotin and is regular biotin supplementation required? Z Ernahrungswiss. 1998;37:363-367.

Koutsikos D, Agroyannis B, Tzanatos-Exarchou H. Biotin for diabetic peripheral neuropathy. Biomed Pharmacother. 1990;44:511-514.

Koutsikos D, Fourtounas C, Kapetanaki A, et al. Oral glucose tolerance test after high-dose i.v. biotin administration in normoglucemic hemodialysis patients. Ren Fail. 1996;18:131-137.

Messina M. The Dietitian's Guide to Vegetarian Diets: Issues and Applications. Gaithersburg, Md: Aspen Publishers, Inc; 1996.

Murray M. Encyclopedia of Nutritional Supplements. Rocklin, Calif: Prima Publishing; 1997.

Reavley N. Vitamins etc. Melbourne, Australia: Bookman Press; 1998.

Ringer DL. Physicians' Guide to Nutraceuticals. Omaha, Neb: Nutritional Data Resources; 1998.

Schulpis KH, Nyalala JO, Papakonstantinou ED, et al. Biotin recycling impairment in phenylketonuric children with seborrheic dermatitis. Int J Dermatol. 1998;37:918-921.

Zempleni J, Mock DM. Advanced analysis of biotin metabolites in body fluids allows a more accurate measurement of biotin bioavailability and metabolism in humans. J Nutr. 1999;129:494-497.