Grapes contain many important nutrients. When you bite into a grape, you get more of a batch of sweetness. Eat grapes for a healthier heart. Polyphenols found in grapes can help prevent cardiovascular disease. Grapes may soon take their place as the best food for healthy eyes. Grapes are a good source of vitamin K. Vitamin K helps the blood to clot. Vitamin K deficiency puts you at risk of bleeding. It can also increase the risk of developing osteoporosis, although more studies are needed.