Nature's Bounty Vitamin D3 is a simple and effective way to show your immune system some love. As a more potent form of Vitamin D, Vitamin D3 is an essential nutrient for immune support that may assist the immune system by helping to regulate T and B-lymphocytes (cells that major components of your immune response). While Vitamin D is known as the sunshine vitamin, many people dont get enough of it due to working and living indoors. Nature's Bounty Vitamin D3 provides 125 mc (5,000 IU) of Vitamin D per serving in one easy-to-take rapid-release softgel. Nature's Bounty Vitamin D3 also helps maintain healthy bones in adults, as Vitamin D3 assists the body with calcium absorption.