I learned about biotin believe it or not from owning horses and the farrier informed me of the magic it produces for weak hoofs. He recommended it for their hoofs and hair. OK it worked. So then came an aging aunt that had very bad weak nails from "old age" (afterall she is 93). So I put her on the Parm Assure Biotin caplets to see what it would do if anything. Worked like magic. She claims it has made such a difference in her nails no more splitting and horizontal ridges. She happy - I'm HAPPY!