A water-soluble B vitamin found in eggs, nuts and seeds.
Why it’s used: Contributes to the maintenance of normal hair and normal skin.
Biotin, sometimes called vitamin B7, is a water-soluble B vitamin needed in very small amounts to help the body make fatty acids. It is found in a wide range of foods, including eggs, nuts and seeds, but usually only at low levels. The bacteria that live naturally in the bowel can also make biotin, so it is not clear whether you need any additional biotin from the diet.
Biotin contributes to the maintenance of normal hair and normal skin. That is why it is one of the most familiar ingredients in hair, skin and nail formulas, even though most people already get enough from food.
On labels it is usually listed simply as biotin, with amounts shown in micrograms (µg). You will find it in multivitamins, B-complex products, supplements containing biotin alone and dedicated hair and skin formulas, some of which provide much larger amounts than the others. Large amounts matter for one practical reason in particular: biotin can affect the results of some blood tests, so it is worth knowing how much you are taking.
3 findings behind this ingredient. Hover a card for the detail and the source.
A double-blind trial randomised 105 adults to placebo, 1.25 mg biotin from a plant extract, or biotin with silica for 90 days. Both biotin groups showed less hair fall, faster hair growth and smoother nails, with no adverse events reported.
A literature review found 18 published cases of biotin use for hair and nail changes, all in people with an underlying condition, and all showed clinical improvement. The authors found insufficient evidence for supplementation in healthy people.
Scanning electron microscopy compared nail clippings from 32 people. In eight people with brittle nails measured before and after biotin, nail thickness increased by 25% and splitting was reduced.
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Biotin contributes to the maintenance of normal hair and normal skin, which is its authorised role. Most people already get enough from their diet and from bowel bacteria, so it is best thought of as one part of a balanced routine rather than a standalone answer.
Yes. Biotin above recommended amounts can cause false results in some lab tests, including those that measure thyroid hormone. If you take a biotin or hair supplement, tell your doctor or the person taking your blood so the results can be read correctly.
The NHS says 0.9mg (900 micrograms) or less a day of biotin from supplements is unlikely to cause any harm. No UK daily requirement has been set, as bowel bacteria make some biotin and it is found in many foods.
Information only, not medical advice. If you take medication, are pregnant or breastfeeding, speak to your GP or pharmacist first.
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