Answer
Over the decades, people have always looked for an easy way to strengthen the natural nail plate. Nails are made of protein called keratin, and a deficiency of protein can show up as soft, fragile, or brittle nails. Since gelatin is a form of protein, the logic is that the protein would help strengthen nails. It has never been proven in a controlled and scientific fashion that gelatin does anything to strengthen nails. Nails also contain no calcium so there is no rationale for taking calcium to strengthen nails. Several studies have been done with the vitamin biotin that showed some usefulness in making nails stronger.
