If you're taking calcium supplements under the assumption that you're doing your nails a favor, hang on -- it's never a good idea to assume. Results of a study published in The New England Journal of Medicine suggest that calcium supplements aren't actually helpful in keeping nails strong and healthy [source: Reid]. But there are other vitamins and minerals that will give your nail health a boost. Let's look at protein, iron and the B vitamins.
Protein helps with nail growth and strength, and it's recommended that you aim to get about 10 to 35 percent of your daily calories from protein sources (that's about 46 grams for women and about 56 grams for men) [source: Centers for Disease Control and Prevention]. Iron is also important for nail health, and helps keep spoon-shaped nails from developing. And there is some evidence that biotin -- which is especially helpful in keeping horse hooves healthy and strong -- and other B vitamins may be beneficial in keeping nails in good condition, too.