One of the keys for how to strengthen nails is maintaining a healthy diet. Foods like blueberries that are full of antioxidants help protect your body’s cells from free radical damage, while leafy greens provide the iron you need for nail strength. Magnesium-rich almonds are great for smoothing your nails’ vertical ridges found a study published in the Austin Journal of Nutrition and Food Sciences. Any nutritional deficiency could potentially affect the health of your nails so eat a wide variety of fruits, vegetables, whole grains and lean proteins.