Men with early stage prostate cancer are often advised to increase their intake of vegetables to lower the risk for progression to more serious disease. But now a randomized trial has found that vegetables, whatever other health benefits they may confer, have no discernible effect on prostate cancer progression.
In a two-year study published in JAMA, researchers randomly divided 478 patients with biopsy-confirmed early stage prostate cancer into two groups. Men in the first group were enrolled in a behavioral counseling program, with each assigned a counselor who, with repeated telephone calls, encouraged them to eat at least seven daily servings of fruits and vegetables. The second were simply given written information about diet and prostate cancer.
Diet interviews and blood tests for carotenoid concentrations showed that compared with the controls, the intervention group consumed significantly more vegetables. They also ate less red meat and less fat.
But there was no difference between the groups in time to progression to higher grade tumors as measured by increases in prostate specific antigen levels or by repeated biopsy.
The lead author, Dr. J. Kellogg Parsons, a professor of urology at the University of California, San Diego, said that improved diet has been shown to be helpful in previous epidemiological studies, but “unfortunately that isn’t the case, probably because cancer is a very complex disease, and the answer is not as simple as eating more vegetables.”
“The study doesn’t give license for folks to not eat a healthy diet,” he added. “Lots of other research in prostate and other cancers has shown that men who are more robust and healthier in general tolerate their treatment much better.”
