Vitamin D Insufficiency

Vitamin D is a fat-soluble vitamin that has several important roles in our bodies. It is produced in our skin cells in response to exposure to the ultraviolet (UV) rays in sunlight. Given enough sun exposure, our bodies will make all the vitamin D we need. However, most of us don’t get enough sun exposure to maintain adequate levels of vitamin D in the body. Our diets don’t provide enough vitamin D either. There are few foods that naturally contain meaningful amounts of vitamin D. Drinking a quart of fortified milk (to which vitamin D has been added) each day delivers only about 400 IU, which is much lower than the amount needed to ensure ideal blood levels of vitamin D.

It is estimated that about one-third of Americans may have insufficient vitamin D levels due to lack of sunlight exposure, increased sunscreen use, less efficient vitamin D production and metabolism with older age, increased obesity rates, and decreased intake of vitamin D from foods. To achieve desirable vitamin D levels, most adults need to take a vitamin D supplement.