What is Vitamin D? Do You Need a Supplement?
Vitamin D is a fat-soluble vitamin that plays a crucial role in maintaining overall health. Unlike most vitamins, it functions more like a hormone in the body, and nearly every cell has a receptor for it.
It exists in several forms, but vitamin D3, also known as cholecalciferol, is the most important. Once in the body, D3 undergoes changes—first in the liver and then in the kidneys—to become its fully active form called calcitriol.
Your body is capable of producing its own vitamin D by converting a cholesterol precursor into it, but that requires exposure to UVB radiation on your skin. You can also get it through diet from a few foods including eggs, oily fish, and mushrooms—but it’s unlikely to be as much as you need.
What Happens When You Don’t Get Enough Vitamin D?
Vitamin D’s best-known role is helping the body use calcium. It promotes the absorption of calcium from the gut, ensuring an adequate level in the blood for building bones. Deficiency can lead to decreased bone density, bone pain, muscle weakness, and an increased risk of fractures. In children, severe deficiency can cause rickets; in adults, it may lead to osteomalacia.