Biotin (vitamin B7) acts as a coenzyme for carboxylase enzymes that support fatty-acid synthesis, gluconeogenesis, and amino-acid metabolism, helping convert food into usable energy. It contributes to healthy hair, skin, and nails and supports normal embryonic growth during pregnancy. Deficiency is uncommon but can cause hair thinning, skin rash, and neurological symptoms; supplementation is sometimes used when needs are increased.

Get biotin naturally by eating a varied diet: cooked egg yolks, liver and other organ meats, fatty fish, nuts and seeds (almonds, walnuts, peanuts), legumes and soy, whole grains, dairy, mushrooms, cauliflower, avocados and bananas. A healthy gut microbiome also contributes small amounts. Avoid raw egg whites (they bind biotin) and see a clinician if you suspect deficiency.

Vitamin B7 (biotin) taken daily at recommended amounts is generally safe. Adults’ typical adequate intake is about 30 mcg/day; many supplements deliver higher doses (often 5,000 mcg) that are usually well tolerated. Very high doses have low toxicity but can interfere with blood tests (e.g., thyroid, troponin). Check with your clinician before high-dose use, during pregnancy, or if taking medications.

Biotin (vitamin B7) helps hair growth only when a true deficiency exists—treating deficiency can improve thinning. For people with normal biotin levels, evidence that extra biotin boosts hair growth is weak or lacking. High-dose supplements are often unnecessary and can interfere with lab tests. Check with a healthcare professional before starting biotin for hair concerns.

Most adults need about 30 micrograms (mcg) of biotin (vitamin B7) daily. Biotin deficiency can affect hair, but evidence that higher doses boost hair growth in people without deficiency is limited. Some hair/nail studies use 2,500–10,000 mcg (2.5–10 mg). Talk with a clinician before high-dose biotin — it can interfere with certain lab tests and isn’t routinely recommended.

Biotin (vitamin B7) is usually well tolerated; side effects are uncommon but can include mild gastrointestinal upset (nausea, cramping), skin reactions such as acne or rashes, and rare allergic responses. High-dose biotin can interfere with certain laboratory tests (notably thyroid and cardiac troponin assays) and may interact with some medications. Report any new symptoms to your healthcare provider.