Vitamin D has long been known to be a key player in the health of your bones, but in recent years research has also uncovered some of the other ways vitamin D affects your body. For example, vitamin D seems to play a significant role in the functioning of the immune system and there are some indications that it may have roles in the brain and heart. A new study published this week has added support to a growing base of data that vitamin D may also play as one of the body’s defenders against cancerous growth.

What is vitamin D?
Vitamin D is a vitamin made by your body with the help of sunlight. Its building blocks are made in your skin, where sunlight helps perform a needed step to turn those precursors together into a preliminary version of vitamin D. Unfortunately, that initial form isn’t ready to be used by the body. Instead, it circulates through the blood and is modified first by the liver and then by the kidneys. Once converted to its active form (called 1,25 dihydroxy vitamin D or calcitriol), it can circulate to the bones, kidneys, and various other organs where it’s needed for healthy function. Vitamin D is uncommon in food, but can be found in fatty fish, beef liver, cheese, and egg yolks.