Human requirement and food sources of biotin
Because the combined urinary and fecal losses of biotin usually exceed the daily intake, much of the fecal biotin is assumed to be of microbial origin. The obliga tory urinary loss has been estimated to be less than 50 mcg per day; excretion increases at higher levels of intake. As the contribution by the intestinal synthesis is unknown, and the availability of biotin from foods is highly variable, no recommended allowance has been established. However, estimates of daily intakes suggest that 100 mcg is more than adequate for adults; thus the Food and Nutrition Board recommends a daily intake of100 mcg to 200 mcg as safe and adequate. Recommendations for infants and children are estimated on the basis of 50 mcg per 1000 kcal.
Few foods have been analyzed for this factor. It is abundant in liver and other organs, in mushrooms, and in peanuts. Lesser amounts occur in milk, eggs, and certain vegetables and fruits.
