Vitamin D and Greater Colon Protection

Vitamin D is probably most known for its association with bone health, but a recent study suggests higher levels of vitamin D in the bloodstream may have a protective role against colorectal malignancy. In this study, the people who had lower levels of vitamin D had a 31 percent higher risk of colorectal malignancy, and those with higher levels of circulating 25(OH)D  had a 22 percent lower risk.

The study included 17 cohorts, comprised of 5706 colorectal cancer patients and 7107 control subjects, all with a wide range of circulating 25(OH)D levels. The varying vitamin D levels were categorized based on what is currently recommended by the Institute of Medicine (IOM), based on bone health.

“Compared with the lower range of sufficiency for bone health (50–<62.5 nmol/L), deficient 25(OH)D (<30 nmol/L) was associated with 31% higher colorectal cancer risk (RR = 1.31, 95% confidence interval [CI] = 1.05 to 1.62); 25(OH)D above sufficiency (75–<87.5 and 87.5–<100 nmol/L) was associated with 19% higher colorectal cancer risk (RR = 0.81, 95% CI = 0.67 to 0.99) and 27% (RR = 0.73, 95% CI = 0.59 to 0.91) lower risk, respectively. Associations were minimally affected when adjusting for body mass index, physical activity, or other risk factors.  

In conclusion, for each 25 nmol/L increments of circulating 25(OH)D, colorectal cancer risk was decreased 19% in women (RR = 0.81, 95% CI = 0.75 to 0.87) and 7% in men (RR = 0.93, 95% CI = 0.86 to 1.00). It appears that the optimal 25(OH)D concentrations associated with reducing colorectal cancer risk would be 75-100 nmol/L, higher than what is currently recommended by IOM for bone health.