Vitamin B7 (Biotin)

Biotin is a water-soluble B vitamin that was originally discovered as part of a complex which facilitated yeast growth. Functioning as a coenzyme in the human body, biotin is involved in the synthesis of fatty acids, the process of gluconeogenesis, and the catabolism of amino acids. Widely distributed in a variety of food sources, deficiency of the vitamin is rare but excessive intake of raw egg white, which is rich in the biotin-binding protein avidin, is a known risk factor.


As a cofactor, biotin acts to transfer carbon dioxide in several carboxylase enzymes involved in fatty acid synthesis, gluconeogenesis, and branched-chain amino acid catabolism.  

Reference Intake (RI)

Whilst RI values for biotin have been published to date, dietary intakes of between 10 - 200 ug / d are agreed as safe and adequate.  

Food Sources


   Eggs (cooked)


  Salmon (cooked)

   Pork Chop (cooked)

(µg / 100 g)







   Yeast (fresh)

  Milk (whole)


   (µg / 100 g)






Deficiency / Toxicity

With the exception of patients maintained on long duration parenteral nutrition (intravenous feeding), clinical biotin deficiency is rare. Chronic egg white over-consumption has been seen to result in systemic biotin deficiency due to avidin binding with resultant symptoms including the development of dermatitis, alopecia, glossitis, nausea, halucinations and depression.