Among the many causes of yellow nails is a rare disease known as yellow nail syndrome. The cause of yellow nail syndrome is unknown, though patients often have problems with their lymphatic systems and, less commonly, problems with their respiratory systems. Yellow nail syndrome can dramatically affect the nails' appearance, turning them a golden yellow and causing them to separate from the nail bed.
While the change in appearance is often permanent, some patients have found success taking zinc supplements. Over the course of several years, one Australian patient reversed the yellowing by regularly taking zinc orally [source: Arroyo and Cohen]. While zinc's effectiveness for treating yellow nails is up in the air, popping enough of the element has other benefits, such as preventing infection and helping night vision.
If you're looking for a treatment with some positive side effects, read on.