Vitamin B7 (Biotin / Vitamin H)

Direct Answer

Vitamin B7 is an essential sulfur-containing water-soluble vitamin serving as a prosthetic group for five carboxylase enzymes in gluconeogenesis, lipogenesis, and branched-chain amino acid catabolism. Adequate Intake (AI) is 30 µg/day (no Upper Limit established).

Source: NIH ODS / EFSA · Last reviewed Aug 28, 2026

Specs

Nutrient Type	Water-Soluble Ureido-Tetrahydrothiophene Vitamin
Adult Adequate Intake (AI)	30 µg / day (35 µg during lactation)
Tolerable Upper Limit (UL)	None Established (No adverse effects recorded)
Chemical Forms	D-Biotin (Biologically active isomer), Biocytin (Biotinyl-lysine)
Primary Biological Function	Prosthetic group for Pyruvate Carboxylase (Gluconeogenesis), Acetyl-CoA Carboxylase (Fatty acid synthesis), Propionyl-CoA Carboxylase, Histone biotinylation
Deficiency Condition	Alopecia (Hair loss), Erythematous scaly periorofacial rash, Brittle nails, Neurological depression / hallucinations
Top Whole Food Sources	Egg Yolk, Beef Liver, Salmon, Pork Chop, Sunflower Seeds, Almonds, Sweet Potatoes
Raw Egg White (Avidin) Interaction	Raw egg albumen contains avidin glycoprotein which binds biotin with Kd ~10^-15 M (the strongest non-covalent bond known), completely blocking absorption unless cooked

Avidin Thermal Inactivation

Cooking egg whites above 85°C denatures avidin's quaternary beta-barrel structure, eliminating its biotin-binding capacity and unlocking 100% of yolk biotin for intestinal enterocyte absorption.