Higher levels of dietary vitamin D may help protect patients against developing young-onset colorectal cancer or precancerous colon polyps, according to a study published in Gastroenterology. The study could potentially lead to recommendations of higher vitamin D intake as a colorectal cancer prevention strategy for adults under 50 years of age.
The overall incidence rate for colorectal cancer has been declining, but cases in younger adults have been increasing without explanation, according to the investigators. They noted that vitamin D intake from food sources—including fish, mushrooms, eggs, and milk—has decreased over the past several decades and there is growing evidence of an association between vitamin D and the risk of colorectal cancer mortality.
“Vitamin D has known activity against colorectal cancer in laboratory studies,” said Kimmie Ng, MD, MPH, director of the Young-Onset Colorectal Cancer Center at Dana-Farber, in a press release. “Because vitamin D deficiency has been steadily increasing over the past few years, we wondered whether this could be contributing to the rising rates of colorectal cancer in young individuals. We found that total vitamin D intake of 300 IU per day or more—roughly equivalent to three 8-oz. glasses of milk—was associated with an approximately 50% lower risk of developing young-onset colorectal cancer.”
The study examined data from 94,205 women participating in the Nurses’ Health Study 2 (NHS 2) and calculated the total vitamin D intake of each participant, both from dietary sources and supplements. Between 1991 and 2015, the investigators documented 111 cases of young-onset colorectal cancer and 3317 colorectal polyps.
Analysis demonstrated an association between higher total vitamin D intake and a significant reduction in the risk of early-onset colorectal cancer. This association was stronger for dietary vitamin D than for vitamin D supplements. According to the investigators, this is either due to chance or unknown factors that have yet to be understood.
“Our results further support that vitamin D may be important in younger adults for health and possibly colorectal cancer prevention,” Ng said in the release. “It is critical to understand the risk factors that are associated with young-onset colorectal cancer so that we can make informed recommendations about diet and lifestyle, as well as identify high risk individuals to target for earlier screening.”
The study did not find an association between vitamin D intake and a decreased risk of colorectal cancer in patients over 50 years of age. The cause for this inconsistency is uncertain and further research with a larger sample of patients will be necessary to determine whether the protective effect of vitamin D is actually stronger in young-onset colorectal cancer, according to the investigators.
Vitamin D may protect against young-onset colorectal cancer [news release]. EurekAlert; August 17, 2021. Accessed August 17, 2021. https://www.eurekalert.org/news-releases/925198