New Delhi, Oct. 4 -- Fingernails protect the skin underneath from injury and can be useful for scratching an itch or peeling a fruit. But they can also reveal clues about your health. There are many old beliefs about what nails indicate. For example, some say white spots on nails-called leukonychia-mean a calcium deficiency. But is this really true?

Nails are an extension of the skin and are made of keratin, a strong protein that protects your fingers and toes from damage. The half-moon shape at the base, called the lunula, is the nail's "growth centre," producing cells that harden into the nail. Just above it is the cuticle, a layer of dead cells connecting the nail to the skin. The cuticle acts as a guard, keeping bacteria, fungi, and ...