Healthvit Vitamin D3 20000 IU Maximum Strength | 60 Tablets Vitamin D3 plays a key role in the proper absorption of calcium for strong bones and teeth. This important vitamin also enhances immune system strength in adults. Vitamin D3 can be taken as a supplement to improve overall health or used to treat osteoporosis. Vitamin D is normally obtained from the diet or produced by the skin from the ultraviolet energy of the sun. However, it is not abundant in food. As more people avoid sun exposure, Vitamin D supplementation becomes even more necessary to ensure that your body receives an adequate supply. The amount of vitamin D3 can assist in correcting deficiencies in people who don’t get adequate sun exposure and/or dietary sources of these vitamins. It can also be used to treat conditions in which vitamin D3 levels may be low, such as in people who have underactive parathyroid glands, low levels of phosphate in the blood, or hereditary conditions in which the body doesn’t respond to the parathyroid hormone.