Biotin is a member of the B vitamin group of vitamins. The essentiality of biotin has been evidenced in all mammals. A deficiency of biotin results in a scaly dermatitis, and neurological symptoms, both of which are characteristics seen with deficiencies of most of the B vitamins (the three D’s: dermatitis, dementia and diarrhea). In animal experiments the symptoms of biotin deficiency can be induced by feeding raw eggs whites to the animals, as a protein within the eggs whites, avidin, can bind biotin tightly and prevent its absorption. While biotin is an essential dietary component, as with other B vitamins, biotin is synthesised by the bacteria in the gut, and this bacterially synthesised biotin is absorbed from the colon and contributes to the daily requirement in humans and other mammals. Because the contribution of gut bacteria to total biotin requirement is not known, and because biotin deficiency appears rare, it has been argued that biotin is not a priority in term of its nutritional importance.
However, while clinical deficiency of biotin is rare, the long term effects of a chronically low intakes of biotin are not known. In addition, it is unclear as to the factors that might alter the biotin requirements of individuals. The function of biotin in biochemistry is that of a co-factor with a number of difference carboxylase enzymes, and these enzymes are generally involved in important metabolic pathways. Use of biochemical parameters from metabolic pathways allows estimates as to the adequacy of biotin intakes, as changes to metabolic pathways indicate shifts in metabolism caused by changing biotin intakes. Based on these tests, evidence suggests that marginal biotin deficiency is in fact a normal occurrence in human pregnancy, although the deficiency appears to be asymptomatic. As more is learnt about biotin nutrition it may become possible to more easily observe biotin deficiency symptoms and this may allow a more detailed picture to be created as to the long term effects of differing biotin intakes.
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