Biotin (vitamin H, vitamin B7)

Biotin, also known as vitamin H, is of great importance for the biochemistry of the human organism. Biotin is involved in carbon dioxide transfer and therefore essential to the metabolism of carbohydrate and fat. A balanced diet usually contains enough biotin. Biotin is essential for metabolic reactions involving carbohydrates and fats. Biotin is absorbed by facilitated transport (low concentrations) and passive diffusion (high concentrations) in the upper part of the small intestine. As a prosthetic group of mitochondrial enzymes (carboylases), biotin plays a central role as a CO2-carrier in important metabolic reactions such as gluconeogenesis, synthesis of fatty acids and metabolism of amino acids.

Biotin is excreted in the urine. Biotin is relatively stable in heat, light, and oxygen. Biotin is typically found in liver, egg yolk, cereals, legumes and nuts. Intestinal bacteria produce a small amount of biotin, which may be absorbed and contribute to daily needs.

Biotin helps in the synthesis of fatty acids, in energy metabolism, and in the synthesis of amino acids and glucose. Biotin is used for the breakdown and utilization by the body of food and is part of the B vitamin complex. Biotin serves as an essential coenzyme for four carboxylase enzymes, each of which is important in metabolism. Biotin is an important vitamin for helping certain enzymes in the body.

Enzymes are natural substances that speed up chemical reactions. Biotin promotes normal health of sweat glands, bone marrow, male gonads, blood cells, nerve tissue, skin, hair. In the body, biotin is found in low concentrations in the brain, liver and muscle tissue. Biotin is utilized to synthesize intracellular carboxylase enzymes and is essential for normal skin and hair growth.

Biotin (vitamin H, vitamin B7) functions, uses, and health benefits

The primary role of biotin is in the metabolism of fats, proteins and carbohydrates. Biotin functions as a critical component of several enzymes (where it functions as a coenzyme) involved in energy metabolism (such as pyruvate carboxylase). Biotin helps in the synthesis of fatty acids, in energy metabolism, and in the synthesis of amino acids and glucose. Biotin is also involved in making glucose, some amino acids and in energy production.

Vitamin H plays a special role in enabling the body to use blood sugar (glucose), a major source of energy for body fluids. Biotin supplements may improve thin, splitting, or brittle toe and fingernails as well as hair health. Biotin has also been used to combat alopecia (partial or complete loss of hair) in both children and adults. Biotin is typically included in most multi-vitamin supplements.

Biotin is used to treat the biotin-responsive inborn errors of metabolism holocarboxylase synthetase deficiency and biotinidase deficiency. Large doses of biotin may be given to babies with a condition called infantile seborrhea or to patients with genetic abnormalities in biotin metabolism. Biotin supplements are sometimes given to help reduce blood sugar in diabetic patients. People with type 2 diabetes often have low levels of biotin. The major benefit of biotin as a dietary supplement is in strengthening hair and nails.

Biotin supplements may improve thin or splitting toenails or fingernails and improve hair health. Some skin disorders, such as "cradle cap," improve with biotin supplements. Biotin has also been used to combat premature graying of hair, though it is likely to be useful only for those with a low biotin level. Biotin has been used for people in weight loss programs to help them metabolize fat more efficiently.

Biotin (vitamin H, vitamin B7) dosage, intake, recommended daily allowance (RDA)

An adequate amount of biotin is about 30 to 100 mcg daily. The U.S. RDA for biotin, the value used for nutritional supplement and food labeling purposes, is 30 micrograms/day. Doses of up to 2,500 mcg have been used safely to treat hair and nail problems. Higher intakes have been recommended for reducing blood sugar levels in diabetics (5-15 mg/d). Vitamin H works best when combined with B-vitamins. Biotin is available in multivitamin and multivitamin/multimineral products as well as in single ingredient products. In single ingredient products, biotin is available as lozenges, tablets and capsules.

Sources of biotin (vitamin H, vitamin B7)

Biotin can be found in beans, breads, brewer's yeast, cauliflower, chocolate, egg yolks, fish, kidney, legumes, liver, meat, molasses, dairy products, nuts, oatmeal, oysters, peanut butter, poultry, wheat germ, and whole grains. Good dietary sources of biotin include organ meats, oatmeal, egg yolk, soy, mushrooms, bananas, peanuts, and brewer's yeast. Egg whites contain a chemical that binds to biotin very strongly and prevents it being absorbed into the blood from the intestines. Food-processing techniques can destroy biotin. Less-processed versions of the foods listed above will contain more biotin. In the intestines, bacteria produce a small amount of biotin, which may be absorbed and contribute to daily needs. This vitamin supplement is available in tablet form in doses of 10 mcg, 50 mcg, and 100 mcg.

Biotin is found in many foods, but generally in lower amounts than other water-soluble vitamins. Natural sources of biotin include egg yolk, liver, kidney, cooked oats, soybeans, unpolished rice, brewer's yeast, nuts and milk. Egg whites contain a chemical that binds to biotin very strongly and prevents it being absorbed into the blood from the intestines. Organ meats such as liver and kidney are the best dietary sources of biotin. Some other foods, such as wheat, contain considerable amounts of biotin but with very low bioavailability.

Other meats, vegetables, and fruits usually contain low amounts of biotin. The bacteria that normally colonize the colon (large intestine) are capable of making their own biotin. Biotin is widely distributed in food stuffs, but the amounts are small relative to other vitamins. Biotin is available within multivitamins and B-vitamin complexes, and as individual supplements. Biotin content of food is reduced by cooking and preserving.

Biotin (vitamin H, vitamin B7) deficiency

Biotin deficiency can be induced in humans by feeding them raw egg whites, which contain a protein that binds biotin and prevents its absorption. Long-term antibiotic use can interfere with biotin production in the intestine and increase the risk of deficiency symptoms, such as dermatitis, depression, hair loss, anemia, and nausea. Long-term use of anti-seizure medications may also lead to biotin deficiency. Biotin deficiency results in fatigue, depression, nausea, muscle pains, hair loss, and anemia. Biotin is necessary for both metabolism and growth in humans, particularly with reference to production of fatty acids, antibodies, digestive enzymes, and in niacin (vitamin B3) metabolism.

Biotin is required in a number of enzymatic reactions in the body, particularly in the production of energy from carbohydrates and fats. Neurologic symptoms in adults have included depression, lethargy, hallucination, and numbness and tingling of the extremities. Individuals with hereditary disorders of biotin metabolism resulting in functional biotin deficiency have evidence of impaired immune system function, including increased susceptibility to bacterial and fungal infections.

Alcoholics, people with inflammatory bowel disease, and those with diseases of the stomach have been reported to show evidence of poor biotin status. Diabetics may have a deficiency of certain enzymes in the body (biotin-dependant enzymes), which may lead to a biotin deficiency and possible problems in the nervous system. A number of drugs deplete biotin levels, such as antibiotics (tetracycline, sulfonamides, trimethoprim, penicillin, macrolides, fluoroquinolones and cephalosporins) and sedative and anti-epileptic drugs (phenytoin, barbiturates, carbamazepine, phenobarbitol and primidone).

People with type 2 diabetes often have low levels of biotin. Biotin may be involved in the synthesis and release of insulin. Preliminary studies in both animals and people suggest that biotin may help improve blood sugar control in those with diabetes, particularly type 2 diabetes. More research in this area would be helpful.

Symptoms of a biotin deficiency include hair loss, a dry, scaly rash around the eyes, nose, mouth, and genital area, decreased appetite, nausea and vomiting and failure to thrive in children. Neurologic symptoms in adults have included depression, lethargy, hallucination, and numbness and tingling of the extremities. Individuals with hereditary disorders of biotin metabolism resulting in functional biotin deficiency have evidence of impaired immune system function, including increased susceptibility to bacterial and fungal infections. Infants deficient in biotin often develop this scaly scalp condition. Some infants may respond to biotin supplementation either through formulas or breast milk.