Vitamins—we all need them to grow and develop normally. We can usually obtain them through a balanced diet. Vitamin A, for example, can help prevent night blindness and is found in everything from carrots to milk. Vitamin D, found in egg yolks and liver, helps stave off rickets—the softening of bones. If your diet isn't vitamin-rich, your healthcare professional may recommend a supplement. Also see multivitamins.