Studies with poultry and swine indicate that those species can safely tolerate dietary levels four to 10 times their nutritional requirements of biotin (NRC, 1987). In view of the rapid metabolic turnover of biotin, toxicity is unlikely to occur in livestock. Studies in humans and laboratory animals have shown a high tolerance level for oral biotin and few if any toxicity symptoms (Bonjour, 1991). Relatively high levels of supplementation have been used in humans to combat weak fingernails, dermatitis and hair loss and as a therapy for diabetes without noticeable adverse reactions (Bonjour, 1991).
