Vitamin D3

Vitamin D3, also known as cholecalciferol, is synthesized in the skin upon exposure to sunlight and can also be obtained through diet and supplements. It plays a critical role in maintaining calcium and phosphate balance, which is vital for healthy bones and teeth. Deficiency in vitamin D3 can lead to bone disorders such as rickets in children and osteomalacia in adults. Beyond bone health, vitamin D3 modulates immune responses, reducing the risk of infections and autoimmune diseases. Emerging research suggests it may also influence mood and cognitive function. Because natural dietary sources are limited, supplementation is often recommended, especially in regions with low sunlight exposure.

Vitamin D3 is converted in the liver to 25-hydroxyvitamin D, the main circulating form, and then activated in the kidneys to calcitriol, which acts as a hormone. Calcitriol binds to vitamin D receptors in various tissues, regulating gene expression related to calcium and phosphate metabolism. This mechanism enhances intestinal absorption of calcium and phosphate, essential for bone mineralization. Additionally, vitamin D receptors in immune cells help modulate innate and adaptive immune responses, contributing to its role in infection prevention and immune regulation.