SAN DIEGO — When it comes to prostate cancer, an apple a day apparently won’t keep the doctor away. Researchers at the University of California, San Diego say that prostate cancer patients who were told to eat seven or more servings of vegetables and fruits each day saw no subsequent improvements in their condition, or additional protection from the cancer.
“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,” says J. Kellogg Parsons, MD, University of California San Diego School of Medicine and Moores Cancer Center professor of urology and study lead investigator, in a 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.”
In total, 478 men from all over the United States, aged between 50-80 years old, took part in the research. All of these men had been diagnosed with early-stage prostate adenocarcinoma, and then placed in an active surveillance program, meaning their condition was monitored but treatment was deferred until the cancer progressed further.
All the participants were randomly separated into two groups: a control group that simply received written information on healthy dietary choices for prostate cancer patients, or a second group that included a telephone counseling program that encouraged listeners to eat lots of fruits and vegetables, specifically produce high in carotenoids such as carrots and tomatoes. Participants across both groups were then tracked for two full years.
“Patients assigned to the intervention increased their intake of fruits and vegetables to a statistically significant degree, and significantly more than control patients did. These findings were supported by significant changes in the blood carotenoid levels of patients. Nonetheless, these data fail to support prevailing assertions in clinical guidelines and the popular media that diets high in micronutrient-rich vegetables improve cancer-specific outcomes among prostate cancer survivors,” says co-senior author James Marshall, PhD, Distinguished Professor with the Department of Cancer Prevention and Population Sciences at Roswell Park.
This study is the first ever to perform a randomized clinical trial testing the influence of diet on prostate cancer. Researchers say they were inspired to investigate this topic because of preliminary scientific data that suggested more produce may help fight prostate cancer, as well as multiple inquiries from patients wondering if changing up their diet would help their condition.
“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,” comments co-author James Mohler, MD, professor of oncology with Roswell Park’s department of urology. “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.”
The study is published in the Journal of the American Medical Association.