– Vitamin D is produced naturally by the body in response to sunlight and found in certain dietary sources such as oily fish, mushrooms and eggs. How Important Is Vitamin D3?. – Getting enough Vitamin D is essential for our health as scientific studies indicate that it plays an important role in the process of cell division, in normal absorption of calcium and phosphorus, and in maintaining normal blood calcium levels for healthy bones and teeth (claims are backed up by EFSA).