Biotin
Essential B vitamin, cofactor for carboxylase enzymes in metabolism.
Biotin, also known as vitamin B7 and vitamin H, is one of the B vitamins, a group of essential dietary micronutrients. Present in every living cell, it serves as a cofactor for enzymes in numerous metabolic processes in humans and other organisms, primarily related to the biochemistry of fats, carbohydrates, and amino acids. When isolated, biotin is a white, needle-like crystalline solid, obtained from foods such as meats and liver, and sold as a dietary supplement.
- chemical_class
- Heterocyclic compound with a sulfur-containing tetrahydrothiophene ring fused to a ureido group
- dietary_reference
- Adequate intake (AI) for adults: 30 μg/day (US), 40 μg/day (EFSA)
- deficiency_status
- Rare; subclinical deficiency may cause hair thinning, brittle nails, or skin rash
- upper_limit
- None established; adverse effects of high intake not determined
- food_sources
- Meats, liver; stable at room temperature, not destroyed by cooking
Lore & Background
Biotin is classified as a heterocyclic compound, with a sulfur-containing tetrahydrothiophene ring fused to a ureido group, and a C5-carboxylic acid side chain. The ureido ring serves as the carbon dioxide carrier in carboxylation reactions. Biotin is a coenzyme for five carboxylase enzymes involved in catabolism of amino acids and fatty acids, synthesis of fatty acids, and gluconeogenesis. Biotinylation of histone proteins in nuclear chromatin plays a role in chromatin stability and gene expression.
Reader's Guide
Biotin is a water-soluble B vitamin essential for metabolic processes in humans and other organisms. Its primary biochemical role is as a cofactor for five carboxylase enzymes, including acetyl-CoA carboxylase and pyruvate carboxylase, which are critical for fatty acid synthesis, gluconeogenesis, and amino acid metabolism. Dietary biotin is obtained from foods like meats and liver, and deficiency is rare due to its wide availability. The US National Academy of Medicine and the European Food Safety Authority have established adequate intakes rather than recommended dietary allowances due to insufficient data for more precise requirements. No upper limit for biotin intake has been set, as adverse effects from high intake have not been determined. Biotin is stable during cooking and is absorbed efficiently from the small intestine, with the large intestine microbiota also synthesizing biotin. Factors such as chronic alcohol use, certain anti-epilepsy drugs, and pregnancy may increase biotin requirements. Biotin deficiency, though rare, can result from genetic disorders like biotinidase deficiency, which is screened for at birth in many countries and treated with lifelong biotin supplementation.
Did You Know?
- Biotin is also known as vitamin B7 and vitamin H.
- The name biotin derives from the Ancient Greek word βίοτος (bíotos; 'life') and the suffix '-in'.
- Biotin is a coenzyme for five carboxylase enzymes involved in metabolism.
- No countries require foods to be fortified with biotin due to the rarity of deficiency.
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