Using feeding studies with dried egg white, Boas first described in 1927 that mammals require the water soluble vitamin biotin.
Biotin is a bicyclic compound; one of the rings contains an ureido group and the other contains sulfur in a tetrahydrothiophene ring with a valeric acid side chain. It is an imidazole derivative with chemical structure C10H16N2O3S1.
Like other B vitamins, biotin acts as coenzymes in dozens of reactions. Among these reactions are amino acid metabolism, including the conversion of amino acids to glucose; fatty acid synthesis; release of energy from fatty acids and DNA synthesis.
Novel roles for biotin in cell signaling, epigenetic control of gene expression and chromatin structure have also been discovered.
In food, mostly meats and protein, biotin is found both free and bound to protein. The protein bound form can liberated via proteases yielding free biotin forms, predominantly biotin and secondary biocytin.
Good sources of biotin include cauliflower liver, peanuts and cheeses. Egg yolks are also a good source of biotin but a protein called avidin in raw egg whites bonds biotin and prevents its absorption from raw eggs.
Biotin deficiency leads to impairment of gluconeogenesis and fat metabolism.
Biotin deficiencies can also induce severe metabolic acidosis. The first manifestation of biotin deficiency is a depressed biotin level in urine. Subsequently, the following clinical signs may develop: dermatitis, conjunctivitis, alopecia and central nervous system abnormalities.
Vitamin B7 or biotin
