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What is biotin? Uses and health benefits of vitamin B7
Written bySanjana Bhatt
Reviewed byHeeral Tomlinson
Biotin has a reputation in haircare – so let’s comb through the details. We’ll explore what biotin does and learn how much you need in our ultimate guide
Summary
1What is biotin?
Biotin, also called vitamin B7, is part of the B vitamin family. It contributes to the maintenance of normal skin and hair.
2What foods contain biotin?
You can find biotin in beef liver, eggs, salmon, sunflower seeds, sweet potatoes and almonds.
3What are biotin supplements used for?
While biotin plays an important role in healthy hair, you don’t need any extra biotin if you already get enough.
Biotin is one of beauty’s favourite nutrients – maybe you’ve seen gummies alluding to shinier hair or stronger nails. But is it truly all it seems? With advice from H&B nutritionist Sanjana Bhatt, we’ll explore the science behind this hard-working B vitamin, how to get biotin in your diet plus what makes it so unique...
What is biotin and what does it do?
Biotin, also called vitamin B7, is part of the B vitamin family. “It contributes to normal energy-yielding metabolism (turning the food you eat into usable energy) and the maintenance of normal skin and hair,” says Sanjana. As well as this, biotin helps the body make fatty acids and supports normal psychological function.1,2
Our gut bacteria actually produces some biotin and according to the NHS it’s not actually clear whether we need to get more from our diet.1 But a balanced diet including foods like eggs, meat and fish, nuts and seeds will provide biotin.3
What foods contain biotin?
The highest sources of biotin are beef liver, eggs and salmon – an 85g serving of liver provides over 100% of your daily reference intake, while an egg provides about 33%.3 Egg whites must be cooked to count as a source of biotin though, as they contain a protein that prevents absorption when raw.3 Don’t worry if you’re vegetarian or vegan, as sunflower seeds, sweet potatoes and almonds are good sources of biotin too.3
Biotin deficiency is rare because biotin is widely available in foods and only small amounts are needed. Gut bacteria may also contribute some biotin, although the extent of this contribution is unclear. So, while it’s a good idea to eat a balanced diet and include biotin food sources where possible, most people don’t need to worry about their biotin intake.3
How much biotin do you need per day?
There isn’t a recommended dietary allowance (RDA) for biotin, since researchers don’t know exactly how much we need and deficiency is rare. Instead, the European Food Safety Authority (EFSA) suggests an adequate intake (AI) of: 4
- adults, including during pregnancy: 40µg per day
- if you’re breastfeeding: 45µg per day
- infants aged six to 12 months: 6µg per day
- children aged one to three: 20µg per day
- children aged four to 10: 25µg per day
- older children and teenagers: 35µg per day
According to the NHS, taking 0.9mg or less a day of biotin supplements is unlikely to cause any harm.1 “It’s a water-soluble vitamin,” Sanjana adds, “which means your body will use what it needs and excrete the rest as it's not stored in large amounts.”3
What are biotin supplements used for?
Most people won’t need a biotin supplement if they’re generally healthy and eat a balanced diet. However, some medications or health conditions (like colitis) may prevent your body from absorbing nutrients effectively.6 If so, talk to your doctor to see if a biotin supplement might be right for you.
You might have seen biotin tablets and gummies advertised to support hair and nail health. While biotin plays an important role in healthy hair, you don’t need any extra biotin if you already get enough. As Sanjana says, “some symptoms of deficiency include fatigue or hair thinning.3 However, supplements are mostly effective if you have a diagnosed biotin deficiency. Additionally, there are many factors to hair growth, so it’s important to consider overall diet and lifestyle too.”
Biotin FAQs
There’s no set time for biotin supplements to ‘work’, as effects depend on you and on the strength and type of supplement you’re taking. As with many supplements, any noticeable effects are unlikely to be immediate and may take several weeks or months of consistent use.
Biotin deficiency is rare, so you might not always see significant effects from biotin supplements if you already have normal levels. Biotin deficiency symptoms can include thinning hair, red rashes around the eyes and mouth, conjunctivitis and neurological changes (including depression, lethargy and hallucinations).3 If you think you might have a biotin deficiency, speak to your doctor. They can give you a urine test and recommend supplements if needed.
High-dose biotin supplements can interfere with certain laboratory tests. potentially leading to inaccurate results.7 Always tell your doctor if you’re taking biotin supplements before having blood tests.
If you have an existing biotin deficiency, getting more biotin may help your hair growth and thickness return to normal. But it’s unlikely that biotin will make your hair thicker or longer than usual if you already have enough in your diet.
The final say
Whether you’re chasing shinier strands or just want to get all the nutrients you need, biotin certainly knows how to stay in the spotlight. While biotin plays a role in maintaining normal hair, it’s far from a miracle cure. The best approach? A balanced diet, realistic expectations and giving your body the nutrients it needs to thrive from root to tip. If you’re still curious, learn how to protect your hair and scalp from the sun or shop our top hair oil picks...
Disclaimer – This article provides informational advice and is not a substitute for medical care. Working with experts for accuracy, we take great care to ensure the information is up-to-date and relevant. However, you should always consult your GP or healthcare professional before using supplements or alternative products, particularly if you have medical conditions or are under supervision.
1. NHS. B vitamins and folic acid [Internet]. NHS [reviewed 2020 Aug 3; cited 2026 Jun 12]. Available from: https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-b/
2. European Commission. Characteristics [Internet]. European Commission [cited 2026 Jun 12]. Available from: https://ec.europa.eu/food/food-feed-portal/screen/health-claims/eu-register/details/POL-HC-6336
3. National Institutes of Health (NIH). Biotin – Fact Sheet for Health Professionals [Internet]. NIH [reviewed 2022 Jan 10; cited 2026 Jun 12]. Available from: https://ods.od.nih.gov/factsheets/biotin-healthprofessional/
4. European Food Safety Authority (EFSA). Draft Scientific Opinion – Scientific Opinion on Dietary Reference Values for Biotin [Internet]. EFSA [cited 2026 Jun 12]. Available from: https://www.efsa.europa.eu/sites/default/files/consultation/131104.pdf
5. Crohn’s & Colitis UK. Food [Internet]. Crohn’s & Colitis UK [reviewed 2023 Feb; cited 2026 Jun 12]. Available from: https://www.crohnsandcolitis.org.uk/info-support/information-about-crohns-and-colitis/all-information-about-crohns-and-colitis/living-with-crohns-or-colitis/food
6. Patel DP, Swink SM, Castelo-Soccio L. A Review of the Use of Biotin for Hair Loss. Skin Appendage Disord [Internet]. 2017 Apr 27 [cited 2026 Jun 12]; 3(3): 166-69. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC5582478/
7. NHS Barnsley Hospital. Drugs and other substances that can interfere with biochemistry tests [Internet]. NHS Barnsley Hospital [cited 2026 Jun 12]. Available from: https://www.barnsleyhospital.nhs.uk/pathology/drugs-and-other-substances-can-interfere-biochemistry-tests
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