History
In the 1920s and 1930s researchers saw that rats fed large amounts of raw egg white lost fur and developed dermatitis, dubbed "egg-white injury." In 1936 Germany's Fritz Kögl crystallized a yeast growth factor from 250 kg of egg yolk and named it biotin; it proved identical to "vitamin H," named for protecting the skin (German Haut). Researchers also learned that avidin in raw egg white binds biotin tightly and blocks its absorption.
What the evidence says
Gut bacteria make biotin, and egg yolk, liver, nuts, legumes and sweet potatoes supply it, so deficiency is rare. It occurs with inherited enzyme defects, long-term raw egg-white intake and some anticonvulsants, causing hair loss, facial rash and brittle nails. A 2017 review found that every case of hair improvement involved deficiency or a specific disorder; there is no evidence it helps hair or nails in healthy people. For hair loss, checking iron, zinc and thyroid function is more useful.
Caution: lab-test interference
Biotin is water-soluble and rarely toxic, but the 5,000–10,000 μg doses common in hair supplements disrupt blood tests that use biotin-streptavidin chemistry. In 2017 the US FDA warned of a death after falsely low troponin delayed a heart-attack diagnosis, and thyroid tests can falsely suggest hyperthyroidism. Stop biotin a few days before blood tests and tell your clinician you take it.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- Will biotin make my hair grow?
- Only if you are deficient; there is no evidence it helps hair loss in healthy people.
- How much biotin do I need?
- The adult adequate intake is 30 μg, easily met by a normal diet.
Sources reviewed: 2026-10-26
References
- Kögl, F., & Tönnis, B. (1936). Über das Bios-Problem. Darstellung von krystallisiertem Biotin aus Eigelb. Hoppe-Seyler's Zeitschrift für physiologische Chemie, 242, 43–73.
- U.S. Food and Drug Administration. (2019). Biotin (Vitamin B7): Safety Communication — May Interfere with Lab Tests.
- Patel, D. P., Swink, S. M., & Castelo-Soccio, L. (2017). A review of the use of biotin for hair loss. Skin Appendage Disorders, 3(3), 166–169.