The best way is to drink milk and exercise, since Milk gives calcium and exercise helps keeps bones strong.
Foods rich in iron help you maintain healthy red blood cells. Vitamins are also needed to build healthy red blood cells. These include vitamins B-2, B-12, and B-3, found in foods such as eggs, whole grains, and bananas. Red meats , and organ meat are high in nutrition which will increase the amount of red blood cells in your body.