Vitamin D3 functions as a hormone, a chemical messenger with widespread effects in the human body. It is important for optimal bone, cardiovascular, neuromuscular, and immune health. Adequate calcium and vitamin D3 throughout life, as part of a well-balanced diet, may reduce the risk of osteoporosis. Supplementation with vitamin D may be necessary to meet daily needs, since obtaining sufficient vitamin D3 from natural food sources and sun exposure alone can be difficult. Research shows that vitamin D3 (cholecalciferol) is approximately 87% more potent than vitamin D2 for raising and maintaining vitamin D blood levels.