What does biotin do?

Biotin, a water-soluble B vitamin, acts as a coenzyme during the metabolism of protein, fats, and carbohydrates.

Where is biotin found?

Good dietary sources of biotin include organ meats, oatmeal, egg yolk, soy, mushrooms, bananas, peanuts, and brewer’s yeast. Bacteria in the intestine produce significant amounts of biotin, which is probably available for absorption and use by the body.

Who is likely to be biotin deficient?

Certain rare inborn diseases can leave people with depletion of biotin due to the inability to metabolize the vitamin normally. A dietary deficiency of biotin, however, is quite uncommon, even in those consuming a diet low in this B vitamin. Nonetheless, if someone eats large quantities of raw egg whites, a biotin deficiency can develop, because a protein in the raw egg white inhibits the absorption of biotin. Cooked eggs do not present this problem. 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. Alcoholics, people with inflammatory bowel disease, and those with diseases of the stomach have been reported to show evidence of poor biotin status; however, the usefulness of biotin supplements for these individuals remains unclear. In animals, biotin deficiency can cause birth defects.

How much biotin is usually taken?

The ideal intake of biotin is unknown; however, the amount of biotin found in most diets, combined with intestinal production, appears to be adequate for preventing deficiency symptoms. Researchers have estimated that 30 mcg per day appears to be an adequate intake for adults. Typically, consumption from a Western diet has been estimated to be 30–70 mcg per day. Larger amounts of biotin (8–16 mg per day) may be supportive for diabetics by lowering blood glucose levels and preventing diabetic neuropathy. Biotin in the amount of 2.5 mg per day strengthened the fingernails of two-thirds of the individuals with brittle nails, according to one clinical trial.

Are there any side effects or interactions?

Excess intake of biotin is excreted in the urine; no toxicity symptoms have been reported.

Biotin works with some other B vitamins, such as folic acid, pantothenic acid (also known as vitamin B5), and vitamin B12; however, no solid evidence indicates that people supplementing with biotin need to also take these other vitamins. Symptoms of pantothenic acid or zinc deficiency have been reported to be lessened with biotin, though people with these deficiencies should supplement with the nutrients they are deficient in. Researchers have speculated that biotin and alpha lipoic acid may compete with each other for absorption or uptake into cells; but little is known about the importance of these interactions in humans.