Biotin (vitamin H)

by MedlinePlus

Biotin is an essential water-soluble B vitamin. Biotin is required by the body in order for four specific enzymes to function in metabolism: propionyl coenzyme A carboxylase (PCC), pyruvate carboxylase (PC), beta-methylcrotonyl coenzyme A carboxylase (β-MCC), and acetyl coenzyme A carboxylase (ACC). Without biotin, these enzymes do not work properly, and various complications can occur involving the skin, intestinal tract, and nervous system. Metabolic problems including very low blood sugars between meals, high blood ammonia, or acidic blood (acidosis) can occur. Death is theoretically possible, although no clear cases have been reported. Recent studies suggest that biotin is also necessary for processes on the genetic level in cells (DNA replication and gene expression).

Biotin deficiency is extremely rare. This is because daily biotin requirements are relatively small, biotin is found in many foods, and the body is able to recycle much of the biotin it has already used. Bacteria which normally live in the human gut (flora) are able to make biotin, although it is not known if humans are able to use this source of biotin. No significant toxicity has been reported with biotin intake.

The name biotin is taken from the Greek word bios meaning "life." Biotin was discovered to be an essential vitamin in the 1930s through rat experiments. In these studies, large amounts of raw egg-whites fed to rats caused toxicity which was cured with biotin-containing foods. It was found that the egg-whites contained a chemical (glycoprotein) called avidin which prevents the body from absorbing biotin from food. Avidin attaches itself to biotin to form a "biotin-avidin complex" which cannot be broken down in the gut for absorption. This problem is prevented by cooking eggs, which destroys avidin's ability to bind biotin.

Synonyms

ARP [N-(Aminooxyacetyl)-N¡-(D-biotinoyl) hydrazine], biocytin, biotin-alkaline phosphate, biotin cadaverine, biotin NTA (nitrilotriacetic acid), biotin-PEO4-amine, Biotin-PEO2-PPO2-amine, biotin-PEO3-maleimide, biotin-PEO4-propionate succinimidyl ester, biotinidase, coenzyme R, D-biotincis-hexahydro-2-oxo-1H-thieno[3,4-d]-imidazole-4-valeric acid, dUTP biotin, factor alpha, tripotassium salt (BNTA), vitamin Bw, vitamin H, W factor.

Selected products: Appearex, Arbum, Biotin Forte, Carotin, D-Biotin, Deacura, Diathynil, Doctodermis, Forcapil, Gabunat, Herbavit, Lacerdermol, Medebiotin, Medobiotin, Meribin, Merzbiotin, Natuderm, Nebiotin, Sonnenbraun, Tersoderm Anticaspa, Zeniac.

Note: This review does not cover the use of biotin in radioimmunotherapy (radioactive therapy), or radio-labeling for diagnostic procedures.

Evidence

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Uses based on scientific evidence

Biotin deficiency

Biotin deficiency is extremely rare. This is because daily biotin requirements are relatively small, biotin is found in many foods, and the body is able to recycle much of the biotin it has already used. Bacteria which normally live in the human gut (flora) are able to make biotin, although it is not known if humans are able to use of this source of biotin.Potential causes: Long-term use of certain anti-seizure medications (phenytoin [Dilantin], primidone [Mysoline], carbamazepine [Tegretol], phenobarbital [Solfoton], and possibly valproic acid); prolonged oral antibiotic use (due to changes in intestinal bacteria/flora); intestinal malabsorption (for example short gut syndrome); intravenous feeding (total parenteral nutrition/TPN) without added biotin; and eating raw egg whites on a regular basis.Effects: Without biotin, four enzymes which are necessary for normal metabolism cannot function properly (propionyl coenzyme A carboxylase [PCC], pyruvate carboxylase [PC], beta-methylcrotonyl coenzyme A carboxylase [β-MCC], and acetyl coenzyme A carboxylase [ACC]). Various complications can occur involving the skin (red scaly face rash around the eyes, nose, mouth, and ears; dry skin; seborrheic dermatitis; brittle hair/hair loss; conjunctivitis; vulnerability to skin fungal infections), intestinal tract (nausea; vomiting; appetite loss; weight loss), and nervous system (confusion; hallucinations; fatigue; tiredness; mild depression; muscle aches; numbness/tingling; increased sensitivity to touch [hyperesthesia]). Death is theoretically possible, although no clear cases have been reported.PCC is required for breaking down amino acids, and β-MCC is required to break down the amino acid leucine. Without the proper function of these enzymes, severe metabolic complications can occur including low blood glucose, high blood ammonia, acidic blood (acidosis), coma, or death. ACC is necessary for making fatty acids. PC is required for the body to make sugar from its stored energy sources (gluconeogenesis), and without PC blood sugar levels between meals can become dangerously low.Tests: Biotin levels in the blood or urine can be measured. Urine organic acids can be evaluated, including measurement of beta-hydroxyisovalerate.Treatment: Should be under strict medical supervision. There is disagreement among experts about the proper biotin dose. In adults, intramuscular doses as low as 150-300mcg daily have been suggested. Higher doses between 10-40mg of biotin daily have also been recommended (given orally, intramuscularly, or intravenously). Higher doses may lead to faster improvement. In children, doses as high as 6-30mg daily have been recommended, either orally, intramuscularly, or intravenously (although lower doses can also be considered). Dosing should be selected and adjusted depending on the duration and severity of the deficiency. Symptoms generally improve within 3-5 days, and completely resolve after several months. The cause of the deficiency should be addressed, and supportive care should be provided as appropriate.

Biotin-responsive inborn errors of metabolism

There are several inborn errors of metabolism that cause a "functional" biotin deficiency, leading to much greater biotin needs than normal in order to activate biotin-dependent enzymes. These disorders include: multiple carboxylase deficiency, holocarboxylase synthetase deficiency, biotidinase deficiency, and propionic-coenzyme A carboxylase deficiency (common among Innuit people in Greenland). Severe metabolic complications and death can occur from these disorders unless treated. High-dose biotin is used to treat these disorders. Management should be under strict medical supervision.

Brittle fingernails

Biotin has been suggested as a treatment for brittle fingernails, particularly in women. There is not sufficient scientific evidence to form a clear conclusion.

Diabetes mellitus (type 2)

In preliminary research, biotin has been reported to decrease insulin resistance and improve glucose tolerance - both properties which may be beneficial in patients with types 2 (adult-onset) diabetes. However, there is not sufficient human evidence to form a clear conclusion in this area.

Pregnancy supplementation

Marginal biotin deficiency has been found to commonly occur during pregnancy. Serious concern has been focused on this finding, because biotin deficiency is teratogenic (causes birth defects) in many animals. It has been suggested by some experts that biotin supplements should be considered for widespread use in pregnant women, although as of 2004 the scientific evidence is not generally considered conclusive enough to make this recommendation. Biotin supplementation during pregnancy in not currently standard practice, and prenatal vitamins generally do not contain biotin. However, individual patients may be considered for biotin supplementation by health care practitioners on a case-by-case basis.

Total parenteral nutrition (TPN)

Intravenous feeding solutions (TPN) should contain biotin, in order to avoid biotin deficiency in recipient patients. This applies for patients in whom TPN is the sole source of nutrition.

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Alopecia areata, antioxidant, basal ganglia disease, cancer, Crohn's disease, exercise capacity improvement, glucose intolerance, gray hair, hair loss, hyperlipidemia, Parkinson's disease, peripheral neuropathy, Rett syndrome, seborrheic dermatitis, uncombable hair syndrome, vaginal candidiasis.

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