Do Vitamin D Supplements Improve GI Cancer Survival?

Translational evidence suggests vitamin D has antineoplastic effects, and observational studies have shown an inverse association between serum vitamin D levels and colorectal cancer risk. But clinical trials of vitamin D for cancer chemoprevention have had conflicting results. This video abstract summarizes findings from two clinical trials investigating whether vitamin D supplementation improves outcomes for patients with colorectal, gastric, and esophageal cancer. Both trials showed no overall benefit but hinted that vitamin D supplementation in different doses and duration might benefit some patient subgroups. Learn more at