Promote healthy skin hair and nails with Natrol Biotin Plus. A member of the B vitamin family biotin is often referred to as the beauty nutrient due to its ability to promote healthy hair skin and nails. Each serving of Biotin Plus delivers a whopping 5 000 mcg of biotin as well as 10 mg of lutein a nutrient derived from marigold flowers. Lutein promotes healthy skin hydration and elasticity.