Calcium and magnesium are important minerals that play roles in bone and teeth strength, muscle contractions, and metabolism of glycogen, the stored form of carbohydrates in our bodies. Dr. Sue's Cal Mag contains calcium to magnesium in a well-studied 2:1 ratio, and also contains Vitamin D3, as it is required for optimal calcium absorption. Studies have shown that calcium may be useful in preventing or treating brittle nails, high cholesterol, osteoporosis, and even PMS.