Vitamin D functions like a hormone, and every single cell in the body has a receptor for it. The human body makes it from cholesterol when your skin is exposed to sunlight, but sunscreen, protective clothing, limited exposure to sunlight, dark skin, and age may prevent getting enough vitamin D from the sun. It's also found in certain foods such as fatty fish and fortified dairy products, though it's very difficult to get enough from diet alone. The recommended daily intake (NRV) is usually around 400–800 IU, but many experts say you should get even more than that. Vitamin D deficiency is very common, especially in northern countries.
Vitamin D3 contributes to:
- Normal absorption/utilization of calcium and phosphorus
- Normal blood calcium levels
- The normal function of the immune system
- Maintenance of normal bones
- Maintenance of normal muscle function
- Maintenance of normal teeth
Vitamin D has a role in the process of cell division.
