Active Calcium Chewable^TM The teenage years are a critical stage of development. USANA formulated Active Calcium Chewable to ensure that your teens are getting enough calcium in their diet. Because of limited time in the sun and an inadequate amount in the average diet, there is growing concern that North Americans are not meeting the recommended amount of vitamin D. It's important for your body's structure and the integrity of your bones to absorb the right levels of calcium and magnesium, and vitamin D helps this process. With this chewable Active Calcium supplement, you and your teens can get the calcium and Vitamin D that you need to keep your bones healthy and strong.