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Biotin is a water-soluble member of the B group of vitamins, sometimes known as vitamin B7. It is involved in several processes in the body, such as the metabolism of fatty acids and production of glucose, and is needed for the growth and repair of skin, hair and nails.
There are authorised health claims that biotin contributes to:
Biotin supplements can increase nail plate thickness by 25 per cent in women with brittle nails.1
Studies also found that biotin supplements improved nail firmness and hardness after 6 months of treatment.2
Cauliflower is a good source of biotin to include in your diet.
Biotin is found in meat, liver, oily fish and egg yolks as well as in wholegrains, nuts and legumes such as soybeans and lentils. Vegetarian sources include vegetables such as spinach, cauliflower and mushrooms, as well as yeast extract.
The recommended daily intake for biotin is 50mcg.
To maintain healthy skin, hair and nails, however, higher doses of a biotin supplement around 1mg can be taken daily. Two out of three people respond, with nails growing significantly thicker.3
Biotin is relatively non-toxic as excess is excreted in the urine. No serious biotin side effects have been reported.
Daily intakes of up to 1mg daily appear to be safe.
As biotin is widely found in food, and is also made by bacteria in the gut, dietary deficiency is rare.
An estimated one in every 120 people inherits an error of biotin metabolism, however, which is believed to affect their immunity against yeast infections. In such cases, high-dose biotin supplements will help if biotin deficiency is to blame.
Deficiency can also occur in those taking long-term antibiotics, although taking a probiotic supplement containing friendly digestive bacteria will help to overcome this effect.
Biotin deficiency is occasionally seen in people who eat large amounts of raw egg white over a long period. Raw (but not cooked) egg white contains a protein called avidin that binds to biotin in the gut and prevents its absorption.
Symptoms that may be due to biotin deficiency include:
Dr Sarah Brewer is Healthspan's Medical Director and holds degrees in Natural Sciences, Surgery and Medicine from the University of Cambridge. Having worked as a GP and hospital doctor, Dr Sarah now holds an MSc in Nutritional Medicine from the University of Surrey and specialises in nutrition. She is also an award-winning writer and author.
Nothing beats a healthy, balanced diet to provide all the nutrients we need. But when this isn't possible, supplements can help. This article isn't intended to replace medical advice. Please consult your healthcare professional before trying supplements or herbal medicines.
1Hochman, L. G., Scher, R. K., & Meyerson, M. S. (1993). Brittle nails: response to daily biotin supplementation, Cutis 51(4), 303-305.
2 Floersheim G. L. (1989). Behandlung brüchiger Fingernägel mit Biotin [Treatment of brittle fingernails with biotin], Zeitschrift fur Hautkrankheiten 64(1), 41-48.
3Hochman, L. G., Scher, R. K., & Meyerson, M. S. (1993). Brittle nails: response to daily biotin supplementation, Cutis 51(4), 303-305.