A daily vitamin D supplement may quietly supercharge chemotherapy. In a small study, women who took low doses alongside treatment were far more likely to see their cancer vanish than those who didn’t. Since vitamin D also supports immune function—and many patients are deficient—it could be playing a bigger role than expected. Scientists say this affordable approach deserves much deeper investigation.

A daily vitamin D supplement may quietly supercharge chemotherapy. In a small study, women who took low doses alongside treatment were far more likely to see their cancer vanish than those who didn’t. Since vitamin D also supports immune function—and many patients are deficient—it could be playing a bigger role than expected. Scientists say this affordable approach deserves much deeper investigation.