This is the striking result of a new study, published in the Journal of Urology by a team of Brady investigators including epidemiologist Bruce J. Trock, Ph.D., the Frank Hinman Jr. Professor of Urology, urologist Christian P. Pavlovich, M.D., the Bernard L. Schwartz Distinguished Professor in Urologic Oncology, and Brady resident Zhuo Tony Su, M.D.

“Diet is one of the most important factors that a man can modify to reduce his risk of prostate cancer,” says Trock. “What you eat affects multiple pathways directly related to cancer risk, including inflammation, DNA repair, and metabolic changes.”

What you eat — and don’t eat — can either give you cancer-fighting nutrients and antioxidants (from a diet rich in fruits and vegetables and lean meats), or junk (from additives such as food coloring, chemicals, fillers, sugars, and fats). In addition, food can be either soothing or inflammatory to your body. Chronic inflammation plays a role in many health conditions, including heart disease, diabetes, autoimmune disease, and cancer. Similarly, what you drink and don’t drink – particularly, alcohol, sugary drinks, and even diet drinks with various sweeteners – is important, too.

“Men managed with AS often ask whether changing their diet can reduce their risk of developing more aggressive disease,” says Pavlovich, Director of the Prostate Cancer AS Program. Until now, Pavlovich did not have hard evidence to back up what he and many investigators believed to be true: that diet can help slow the growth of prostate cancer. “Previous studies have looked at diet in men undergoing AS, but have not found a statistically significant association with disease progression,” Pavlovich says. “Most studies have evaluated specific foods or nutrients, rather than capturing the characteristics of a man’s overall diet.”

In this study, Trock, Pavlovich, and Su analyzed self-reported diet information from all the men in the AS Program, looking to correlate overall diet quality and dietary inflammatory potential with prostate cancer grade reclassification (when higher-grade cancer is found on a follow-up biopsy).

“From 2005 to 2017, 886 men with Grade Group (GG) 1 prostate cancer enrolled in the AS program,” says Trock. “They completed detailed questionnaires describing their usual dietary patterns,” from which the investigators calculated a Healthy Eating Index (HEI) score. “The HEI is a measure of overall diet quality,” Trock explains. “We also calculated each man’s Dietary Inflammatory Index (DII), a way to measure the inflammatory potential of his diet. Then we looked at whether either the HEI or DII influenced risk of grade reclassification (or upgrading) to GG2 and to GG3 (extreme grade reclassification – a condition that warrants definitive treatment) on a surveillance biopsy.”

After an average follow-up of 6.5 years, 187 men had grade reclassification to GG2 cancer, and 55 had extreme grade reclassification to GG3 or higher. But as they added diet to the equation, the investigators found something remark- able: “For each 25-point increase in the HEI, the risk of grade reclassification to GG2 decreased by 28 percent,” says Su, “and the risk of GG3 cancer decreased by 48 percent!” The investigators found no significant association with the DII.

This study is the first to demonstrate that a healthy diet is associated with a lower risk of grade reclassification, particularly for GG3 disease. Pavlovich advises his patients that what’s good for the heart is also good for the prostate. “A heart-healthy diet, or a Mediterranean diet, is a prostate-healthy diet.”