Can a healthy diet reverse thin nails?

Health and nail/skin: Genetic plays a major role in the health and appearance of your skin/nails/hair. If you experienced a significant, prolonged illness, the nails do become "sick" too and so won't be as healthy. So once you recovered and maintain a healthy lifestyle, your nails should be back to normal. If you were born with not so good nails, likely they will remain so. So live healthy. Consult doc. Good luck.