7 times our feet reveal hidden diseases and vitamin deficiencies

Toenails that split, break easily, or develop strange ridges often mirror nutritional gaps. Low zinc, biotin, or iron can make nails thin, soft, or brittle.

​Research in dermatology also links deficiencies of Vitamins A, D, and the B-complex to various nail abnormalities. Because nails grow slowly, these changes may surface before other more obvious symptoms.