Nails are largely composed of protein and sulfur, much like hair. Some abnormalities, such as vertical ridges or white spots, are harmless. Others, such as discolored, weak, or misshapen nails, can indicate nutrient deficiencies or other internal health problems. Fungal and bacterial infections, particularly on the toenails, can cause unsightly irregularities as well.

Beneficial Foods

Hemp Strengthens nails.
Horsetail Especially high in silicon, which strengthens nails.
Nettles Strengthen nails.

Beneficial Nutrients

Calcium A deficiency can cause dry or brittle nails.
Omega-3 Fatty Acids A deficiency can lead to brittle nails.
Protein/Amino Acids A deficiency can lead to brittle, concave, or ridged nails. Can also cause white bands across nails.
Silicon Strengthens nails and gives them a healthier appearance.
Sulfur Brings strength and shine to nails.
Vitamin A A deficiency can cause nails to peel.
Vitamin B12 A deficiency can lead to dark nails that are flat or thin.