Any member of a group of vitamers that belong to the chemical structural class called biotins that exhibit biological activity against vitamin B7 deficiency. Vitamin B7 deficiency is very rare in individuals who take a normal balanced diet. Foods rich in biotin are egg yolk, liver, cereals, vegetables (spinach, mushrooms) and rice. Symptoms associated with vitamin B7 deficiency include thinning hair, scaly skin rashes around eyes, nose and mouth, and brittle nails. The vitamers include biotin and its ionized and salt forms.