Data from the Centers for Disease Control and Prevention shows that as many as 30 million Americans suffer from a vitamin D deficiency, making it the most common nutrient deficiency in the country. There is no absolute consensus among medical professionals as to the exact amount of daily vitamin D required, but the Mayo Clinic uses the benchmark of 600 international units (IU).
But how do we get all of this vitamin D, and why is it so important to our overall health?
The body derives most of the vitamin D it needs from sunlight (good old ultraviolet B rays), but food and supplements are also common sources. Regardless of how you get your vitamin D — whether from an afternoon on the beach, a bowl of mushrooms, or a pill — the body needs to convert it into a useable substance called 25(OH)D.
After vitamin D is processed, the chemical is dispersed throughout the body, where it is “activated,” and able to perform its two main functions: managing calcium in the blood, bones, and gut; and assisting with intercellular communication. Within these two broad categories, vitamin D serves many other functions. It helps the body absorb calcium, promotes bone growth, helps fight depression, encourages weight loss, and reduces the risk of multiple sclerosis, heart disease, and the flu.
In the colder months, however, sunlight can be unreliable, with the time of day and your geographical location dramatically impacting the amount of vitamin D the body can manufacture. Getting your vitamin D through food is a more consistent and reliable solution that also avoids the risk of sunburn or skin cancer. Eating foods naturally rich in vitamin D — like certain fish and mushrooms — or foods fortified with vitamin D — such as tofu, milk, or orange juice — is an easy way to incorporate this crucial vitamin into your diet.
Holly Van Hare and Michael Serrur contributed to this article.