What Is Vitamin D?
Highlights The Basics Vitamin D is a fat-soluble vitamin that also functions as a hormone in our bodies. It plays a critical role in building and maintaining skeletal health, since it helps the body absorb calcium and maintain appropriate concentrations of calcium and phosphorus, two of the primary minerals in bone. It’s also important for muscle function, helping nerves carry signals throughout the body and supporting the immune system. Vitamin D’s effect on preventing and treating a variety of health conditions is being actively studied, though no benefits have emerged as strongly as its role in preventing osteoporosis, osteomalacia and rickets (see “Vitamin D and Health,” below). Humans can get vitamin D in three ways: eating certain foods, taking dietary supplements and making it in our skin after sun exposure. When ultraviolet (UV) light from the sun comes in contact with the skin, vitamin D synthesis is triggered. However, this form of vitamin D is inactive and needs to undergo two activation steps before being used by the body. The amount of active vitamin D in our body is tightly regulated, so blood measurements of vitamin D status often measure the concentration of a form of inactive vitamin D known as 25(OH)D. The amount of 25(OH)D in the blood accounts for vitamin D consumed through foods and supplements as well as vitamin D made in the skin. Vitamin D and Health There is conclusive evidence that vitamin D plays an indispensable role in bone health. Long-term vitamin D deficiency leads to bone softening, known as rickets in children and osteomalacia in adults. Insufficient vitamin D can also contribute to osteoporosis, a loss in bone density that results in brittle bones that are prone to breaking. Because it is involved in so many systems in the human body, vitamin D continues […]
article