A recent study showed that there may be a protective role of Vitamin D against colorectal development in women. Vitamin D levels below 30 nmol/L were associated with an increased colorectal cancer risk of 31%. On the flip side, an increase of Vitamin D levels by 25 nmol/L reduces the risk of colorectal cancer in women by 19%. For example, Vitamin D levels of 75 – 87.5 nmol/L reduced the female risk of colorectal cancer by 19%, and levels of 87.5 < 100 nmol/L reduced their risk by 27%. However, once Vitamin D levels reached 100 nmol/L and above, the benefit of Vitamin D did not increase. This association proved to only be true in women.
It is important to note that vitamin D is a fat-soluble vitamin and therefore, taking too much can cause toxicity. We think levels of greater than 100 nmol/L sounds too high. It also is reassuring that there was no benefit from this super high level. It is important to consult your doctor before taking large amounts of vitamin D. Currently our patients in our clinic are encouraged to take Vitamin D supplements to maintain levels >30 nmol/L and perhaps closer to 50. But we will be exploring this low target range and seeing whether greater levels in higher risk individuals (i.e. those with a personal history of polyps, or family history colon cancer) would benefit from higher target levels.
Author Kelsey Zuckerman Patient Care Coordinator