A new report from the Dana-Farber Cancer Institute found that consuming higher amounts of vitamin D, mainly from dietary sources, may help protect against developing young-onset colorectal cancer or precancerous colon polyps, according to the first study to show such an association.
The study, recently published online in the journal Gastroenterology, by scientists from Dana-Farber Cancer Institute, the Harvard T.H. Chan School of Public Health, and other institutions, could potentially lead to recommendations for higher vitamin D intake as an inexpensive complement to screening tests as a colorectal cancer prevention strategy for adults younger than age 50.
While the overall incidence of colorectal cancer has been declining, cases have been increasing in younger adults – a worrisome trend that has yet to be explained. The authors of the study, including senior co-authors Kimmie Ng of Dana-Farber, and Edward Giovannucci of the T.H. Chan School, noted that vitamin D intake from food sources such as fish, mushrooms, eggs and milk has decreased in the past several decades. There is growing evidence of an association between vitamin D and risk of colorectal cancer mortality. However, prior to the current study, no research has examined whether total vitamin D intake is associated with the risk of young-onset colorectal cancer.
“Vitamin D has known activity against colorectal cancer in laboratory studies. 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,” said Ng, director of the Young-Onset Colorectal Cancer Center at Dana-Farber. “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 percent lower risk of developing young-onset colorectal cancer.”
From 1991 to 2015, the researchers documented 111 cases of young-onset colorectal cancer and 3,317 colorectal polyps. Analysis showed that higher total vitamin D intake was associated with a significantly reduced risk of early-onset colorectal cancer. The same link was found between higher vitamin D intake and risk of colon polyps detected before age 50.
The association was stronger for dietary vitamin D, principally from dairy products, than from vitamin D supplements. The study authors said that finding could be due to chance or to unknown factors that are not yet understood.
