It’s been clear for many years that vitamin D helps keep bones strong, but studies have been inconclusive and conflicting about the vitamin’s value in protecting against certain cancers, including colorectal cancer.
Now a large international study provides the strongest evidence yet that vitamin D may indeed be protective against colorectal cancer and that a deficiency may increase the risk of this cancer. The findings appear Thursday in the Journal of the National Cancer Institute.
“For both men and women, deficient levels of vitamin D were associated with a 30 percent increased risk of colorectal cancer,” says Marji McCullough, a nutritional epidemiologist with the American Cancer Society and study co-author. People who had higher circulating blood levels of vitamin D, above the range deemed “sufficient,” had a 22 percent lower risk, she says.
The study pooled findings from 17 previous studies that included 12,813 adults in the U.S., Europe and Asia. Those studies collectively looked at 5,706 people with colorectal cancer and 7,107 people of a similar age and race who didn’t have cancer. Women’s menopausal status was also taken into account.