Vitamin D‚ an essential nutrient that participates in a wide range of critical biological processes that allow your body to function properly. Despite its classification as a vitamin‚ vitamin D often acts like a regulatory hormone for calcium and bone metabolism. Sufficient intake of vitamin D is vital to insure that your body can absorb normal amounts of calcium and maintain healthy levels of calcium in the plasma. Studies also show that when vitamin D‚ it may help obstruct the growth of some cancer cells.