Nail care starts with good nutrition. Lack of Vitamin A and Calcium can cause dryness and brittleness in nails. B vitamin deficiency causes fragility in the ridges of the nails. B12 deficiency leads to rounded and curved nails. Lack of protein, folic acid, and Vitamin C causes hangnails.
Zinc deficiency can cause misshapen nails.
Proteins are found in meats, eggs, and milk, or combinations of certain vegetables. Many people supplement 1 packet of Knox gelatin, a protein source, in water daily which over the course of some months helps the nails. Hydrochloric acid deficiency contributes to splitting nails. Betaine HCL with Pepsin can solve this problem. Iron Picolinate may be useful.