Editor’s note: This blog was guest-written by Dr. Micah Olson from our medical staff.
Vitamin D has been in the news quite a bit lately. Several recent studies have reported high rates of vitamin D deficiency among U.S. children.
Although we have known that a lack of vitamin D can cause a disorder of the bones called rickets, we are now learning that mild forms of vitamin D deficiency may also have adverse effects that we did not know about before.
For example, studies have shown links between low vitamin D levels and various cancers (such as breast, colon and prostate cancer), autoimmune disorders (such as multiple sclerosis and type 1 diabetes), cardiovascular disease, and type 2 diabetes.
What does vitamin D do?
You may not know this, but vitamin D is a hormone produced by our skin when we are exposed to UV-B radiation from the sun.
Vitamin D acts in our intestines to increase absorption of calcium and phosphorus. Calcium and phosphorus are the two most abundant minerals in bone. Vitamin D also acts directly on bones to help them grow stronger. Studies have shown the importance of vitamin D’s role in regulating calcium levels and helping bones grow stronger, but more recently vitamin D has been discovered to have important effects in many other parts of the body as well. For example, vitamin D plays a role in the pancreas, the immune system and the brain.
For most people, more than 90 percent of their vitamin D comes from exposure to sunlight. This is also the best and easiest form of vitamin D, and we should all make the effort to get the Vitamin D from exposure to the sun. However, we can also get vitamin D from our diet. Fatty fish, such as salmon, are good sources of vitamin D. Milk, and some breakfast cereals, are fortified with vitamin D. The recommended daily intake of vitamin D is 400 IU/day for all infants and children.
Factors affecting your vitamin D levels
Where you live and what time of year it is can affect how much sunlight exposure you get, such as amount of cloud cover, air pollution, and your use of sunscreen. Other factors that influence how much vitamin D you get after sunlight exposure include skin pigmentation (darker-skinned individuals produce less vitamin D than lighter-skinned people).