12 Foods for Stronger Nails and Thicker Hair

Eggs are a good source of protein and contain some vitamin D, and they also have biotin. “Biotin, a B-complex vitamin, may play a role in the development of keratin,” says Dr. Zeichner, who explains that patients with biotin deficiency often have weak hair and nails.

Note: If you have a major nail concerns, you may want to consider a biotin supplement. A daily dose of 2.5 milligrams may strengthen brittle nails, says a Journal of Drugs in Dermatology review, and that’s too much to get from food (you’d need to eat over 300 eggs, in fact).