Ouch! I broke a nail....again....

I have thick strong nails myself. But my cousin's were really brittle and thin. She was told by her college professor to take biotin 2.5mg. She did and it only seemed a few weeks before her nails were growing and looking better. She just took it and a multivitamin. Many times it's just missing nutrients that make nails brittle. Hope this helps. She still takes it and her nails are great.