Vegetable Consumption Does Not Decrease Prostate Cancer Progression

Patients with prostate cancer assigned to eat seven or more servings of vegetables and fruits daily did not experience decreased risk for progression of their disease, according to phase 3 study findings published in JAMA.

“The most common question I receive from men on active surveillance is, ‘Can I decrease the chances that I will need treatment for prostate cancer by changing my diet?’ We now have good evidence that a diet rich in fruits and vegetables and light on red meat is not likely to impact need for treatment,” co-author of the study, Dr. James Mohler, a professor of oncology with Roswell Park’s department of urology, said in a press release. “But this study does not provide justification for eating anything you want, either. The overall health benefits of a diet that’s relatively low in fat and rich in fruits, vegetables and healthy grains are well-established.”

Clinical guidelines for prostate cancer have promoted diets high in micronutrient-enriched vegetables. However, evidence does not support whether this type of diet decreases prostate cancer progression or death.

In the Men’s Eating and Living (MEAL) study, 478 men diagnosed with early-stage prostate adenocarcinoma, aged 50 to 80 years, were enrolled across 91 sites in an active surveillance program. The program was comprised of patients who deferred immediate treatment until their disease advanced.

In the study, patients were randomized to a control group that received written information about diet and prostate cancer or to a telephone counseling behavioral intervention program that encouraged participants to eat foods high in carotenoids. Such foods include leafy greens, carrots and tomatoes, and cruciferous vegetables such as broccoli and cabbage.

“We designed a simple and inexpensive program that proved we could change people’s diets for the better. We hoped that through nutrition we could alter disease outcomes and then use those data to build a network of diet counselors to help men with prostate cancer eat more vegetables,” lead study investigator Dr. J. Kellogg Parsons, from the University of California San Diego School of Medicine and Moores Cancer Center professor of urology, said in a press release.

After being monitored for two years, there were 245 progression events (124 in the intervention arm and 121 in the control arm) and four deaths during the study (one and three patients, respectively).

There was no difference between arms in time to progression or in the total number of patients who pursued active treatment.

“These data indicate that, despite prevailing scientific and public opinion, eating more vegetables will not alter the course of prostate cancer. It will not, to the best of our knowledge, suppress or cure it,” Parsons said in the release. “However, while eating a healthy diet rich in fruits and vegetables and getting more exercise may not cure cancer, it may keep the body stronger and healthier, which may help patients tolerate cancer treatments.”