Biotin

Studies in people

• Open question

  Skin, hair and nail health²

  Scientists do not yet know whether biotin supplements help skin, hair or nails, because too few large studies exist.

• Open question

  Hair and skin health³

  Studies of biotin for skin, hair and nerve diseases have not found enough evidence.

• No harm found

  Hair loss in women⁴

  In women with hair loss, biotin levels in blood and urine were no different from women without it.

• No harm found

  Hair loss after weight-loss surgery⁵

  In people who had weight-loss surgery, taking biotin made little difference to hair loss.

• Open question

  Gut bacteria and obesity⁶

  In people, severe obesity came with fewer gut bacteria that make biotin, and lower biotin levels in the blood.

• Open question

  Thyroid test results⁷

  In people, biotin in over-the-counter supplements led to wrong thyroid test results and confused diagnoses.

• Open question

  Blood fat levels⁸

  In people, biotin supplements changed blood fat levels early on, but scientists do not yet know what this means.

Animal and lab studies only

• Open question

  Allergy and lab test results¹²

  In lab studies, biotin can interfere with allergy blood tests, causing false positive or false negative results.

• Benefit

  Gut inflammation in mice¹³

  In mice with gut inflammation, biotin in drinking water helped heal the gut lining and calm swelling.

How it’s made and used

• Infant formula nutrition gaps⁹

  Babies with milk allergies fed amino acid or hydrolyzed formulas had low biotin, which biotin supplements quickly fixed.

• Vitamin levels in vegans¹⁰

  People eating vegan diets had more biotin in their urine than those eating meat and dairy.

• Gut absorption of vitamins¹¹

  Biotin is taken up in the small intestine and colon by a carrier shared with pantothenic acid.

The signal at the top counts the findings in people and in animal and lab studies. A concern in studies of people outranks animal and lab studies, and “No concerns” needs at least one finding in people. When most findings in people point one way, the page leans that way (“Mostly”), and every finding is still shown. Findings whose study type is not stated are shown but not counted. This page is a reference, not medical advice. It describes what regulators and published research say. Talk to a doctor or dietitian about your own diet.