It is involved in the production of amino acid proteins and fatty acids, aids in the synthesis of hormones and cholesterol, and contributes to the growth of healthy skin and hair follicles. In addition to being produced naturally by the body, biotin can be found in a number of food sources. Raw egg whites, for instance, bind biotin and make it unavailable for absorption. Alcohol and tobacco also decrease biotin absorption. Biotin deficiency may lead to dermatitis, brittle nails and hair loss.
Severe deficiency can lead to high blood cholesterol levels and heart problems.
There is no evidence of toxicity with biotin. Because it is water-soluble and is not stored in the body, the chances of enough biotin building up to toxic levels are highly unlikely. Most people taking multivitamins with high levels of biotin or eating foods rich in amounts of biotin need not worry about toxicity. Vitamins, carotenoids and phytochemicals. Feinstein A. Prevention's Healing with Vitamins.