Adults younger than 50 who consume higher amounts of vitamin D may lower their risk for colorectal cancer, according to research recently published in Gastroenterology.
While the overall numbers of people diagnosed with colorectal cancer have been declining, cases are on the rise among younger adults — a trend that prompted the research.
"Vitamin D has known activity against colorectal cancer in laboratory studies," said Kimmie Ng, MD, study coauthor and oncologist at Boston-based Dana Farber Cancer Institute. "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 adults."
For the study, Dr. Ng and team calculated the total vitamin D intake from both supplements and dietary sources. The study included 94,205 women participating in the Nurses' Health Study, which began in 1989 and included women aged 25 to 49. Researchers followed up with the women every two years through questionnaires.
From 1991 to 2015, researchers identified 111 cases of young-onset colorectal cancer and 3,317 colorectal polyps. A higher intake of vitamin D, mostly from food sources such as fish, mushrooms, eggs and milk, was associated with a significantly lower risk of early-onset colorectal cancer, as well as for precancerous colon polyps.
"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," Dr. Ng. said.
Among those older than 50, researchers did not observe the same association between total vitamin D intake and risk of colorectal cancer, the July 6 findings said. The study could not explain the inconsistency and said additional research is needed to determine whether the protective effect is in fact stronger among younger adults.
To view the full findings, click here.