August 8/Chicago/CBS News -- New research finds a simple modification may make a cancer drug three times more powerful without the side effects a higher dose would likely cause. All it takes is a glass of grapefruit juice.

In the preliminary study published in the August issue of Clinical Cancer Research, scientists at the University of Chicago set out to analyze how certain foods would affect metabolism of the anti-cancer drug called sirolimus, which is an FDA-approved drug to prevent rejection of a kidney transplant and has been seen to help some people with cancer.