Taking vitamin D3 supplements lowers the risk for rickets, a disease characterized by bone-weakening, and other chronic diseases, such as osteoporosis and heart disease, states Harvard School of Public Health. Vitamin D is needed for optimum calcium and phosphorus absorption and the proper functioning of organs with vitamin D receptors.
The human body can easily manufacture vitamin D from cholesterol and exposure to sunlight, mentions Harvard School of Public Health. But many people, such as those having dark skin, the elderly, the overweight and those who use sunscreen, still lack vitamin D because of lack of sunlight exposure. Taking supplements with at least 1,000 IU of vitamin D helps to address the deficiency.