KIN 343 - 11.27 Vitamin B7 Digestion and Absorption

Vitamin B7 (Biotin)

• Vitamin B7 is commonly referred to as biotin and is essential for various metabolic processes.

Biocitin

• Biocitin is a complex of biotin and lysine.

• Biotin can be cleaved from biocitin by enzymes called biotinidases, which are present in the small intestine.

• Bound biotin (often attached to lysine or other proteins) requires hydrolysis to be released.

Digestion and Absorption

• The hydrolysis of biocitin by biotinidases releases free biotin.

• Free biotin is then taken up by the sodium-dependent multivitamin transporter in the small intestine.

  • This transporter also facilitates the absorption of other B vitamins, including pantothenate (Vitamin B5).

• Biotin absorption is extremely efficient, approximating 100% effectiveness.

• Similar to other B vitamins, the absorption of biotin is inhibited by ethanol consumption.

Transport Mechanism

• The specific transport mechanism by which biotin is moved from enterocytes across the basolateral membrane into the bloodstream remains unknown.