- Biotin, also known as vitamin B7 or vitamin H, is a water-soluble member of the B-complex group of vitamins that plays a crucial role in energy metabolism and various cellular processes.
- It functions primarily as a coenzyme for carboxylase enzymes, which are involved in critical metabolic pathways such as the synthesis of fatty acids, gluconeogenesis (the production of glucose from non-carbohydrate sources), and the breakdown of amino acids and branched-chain fatty acids. By supporting these pathways, biotin contributes significantly to the production of ATP—the body’s primary energy source—and to the maintenance of healthy skin, hair, nails, and nervous system function.
- Biotin is widely available in foods, both in free form and bound to proteins. Rich dietary sources include egg yolks, liver, nuts, seeds, salmon, sweet potatoes, and whole grains. Additionally, biotin is synthesized by gut microbiota in the colon, although the extent to which this contributes to human biotin status remains uncertain. Biotin is stable to heat and light, but it can be lost during food processing, especially in the presence of sulfites.
- Biotin deficiency is rare in healthy individuals due to its presence in a wide variety of foods and endogenous production by intestinal bacteria. However, certain conditions and behaviors can lead to deficiency. These include prolonged consumption of raw egg whites (which contain avidin, a protein that binds biotin and prevents its absorption), chronic alcohol use, long-term antibiotic therapy (which disrupts gut flora), and genetic disorders such as biotinidase deficiency—a condition that impairs the body’s ability to recycle biotin. Deficiency symptoms may include hair thinning or hair loss, scaly red rash (especially around the eyes, nose, and mouth), brittle nails, conjunctivitis, fatigue, depression, hallucinations, and neurological symptoms like numbness and tingling in the extremities.
- Biotin is often marketed in supplements for hair, skin, and nail health, and while severe deficiency does lead to problems in these areas, evidence supporting the benefits of high-dose biotin supplementation in people without deficiency is limited. Most individuals obtain sufficient biotin from their diets, and excess intake is typically excreted in urine. Biotin has a very low toxicity risk, and no upper intake level (UL) has been established. However, high doses can interfere with laboratory tests, particularly certain hormone assays and markers for cardiac health (e.g., troponin levels), potentially leading to false results.
