Does Vitamin D Reduce Risk for Colorectal Cancer?

High vitamin D levels have been associated with reduced risk for colorectal cancer (CRC), although recent trials have shown that vitamin D supplementation does not prevent development of colorectal neoplasia.

Given that vitamin D regulates immune function, investigators conducted a nested, case–control trial within the two large cohort studies (the Nurses' Health Study and the Health Professionals Follow-up Study) to determine whether vitamin D plays a greater protective role in tumors with a prominent immune response. The researchers measured plasma 25-hydroxyvitamin D levels in 318 CRC patients and 624 healthy matched controls.

High vitamin D levels were associated with a lower risk for tumors with high-level immune responses, but not for t…