Vitamin D is often called the sunshine vitamin because our bodies manufacture it in response to our skins exposure to sunlight. Vitamin D is absolutely necessary for your body to absorb calcium properly. During times in our lives when women need extra calcium for the formation of strong healthy bones, such as pregnancy and menopause, vitamin D taken along with calcium supplements is often recommended. Vitamin D plays a role in proper immune system function, as well. Vitamin D may be depleted by certain medications such as barbiturates, cimetidine, cholestyramine, cholestipol, corticosteroids, isoniazid, mineral oil, ranitidine, and carbamazepine, and phenytoin. 1000IU. 100 Tablets.