Calcium, Magnesium, Zinc and Vitamin D3 tablets offer a unique bone health formula that provides the correct amount of the key nutrients to keep your bones strong and healthy. ... Calcium and vitamin D3 are essential nutrients for the prevention and treatment of osteoporosis.This combination medication is used to prevent or treat low blood calcium levels in people who do not get enough calcium from their diets. ... If there is not enough calcium in the blood, then the body will take calcium from bones, thereby weakening bones. Vitamin D helps your body absorb calcium and phosphorus.Magnesium assists in the activation of vitamin D, which helps regulate calcium and phosphate homeostasis to influence the growth and maintenance of bones. All of the enzymes that metabolize vitamin D seem to require magnesium, which acts as a cofactor in the enzymatic reactions in the liver and kidneys.take as directed by physician.