Biotin

Biotin, or vitamin H, is a water soluble vitamin. It is an essential coenzyme.

Biotin is synthesized by bacteria of the GI tract. Other sources include yeast, liver, egg yolks, kidneys, nuts and legumes. Both dietary sources result in urinary excretion being greater than oral intake.

Absorption takes place within the jejunum by secondary active transport along with sodium ions.

The coenzyme is involved with:

• oxaloacetic acid carboxylation reactions
• the formation of unsaturated fatty acids
• the synthesis of:
  • serine
  • threonine
  • aspartic acid

Deficiency of biotin is very rare and tends to occur under two circumstances:

• reduction of normal gut flora by antibiotic therapy
• consumption of excessive raw egg white; this contains the protein avidin which binds to biotin and prevents its absorption

Biotin deficiency may cause mental depression, muscular, pain, dermatitis, fatigue, glossitis, anorexia and nausea.