A study of more than 2,000 men with localized prostate cancer found that eating a primarily plant-based diet was associated with a 47% lower risk that their cancer would progress, compared with those who consumed the most animal products.

This amounted to eating just one or two more servings per day of healthy foods, particularly vegetables, fruits, and whole grains, while eating fewer animal products, like dairy and meat. The study followed the men, whose median age was 65 years old, over time to see how dietary factors affected the progression of their cancer.

Plant-based diets include fruits, vegetables, whole grains, nuts, legumes, vegetable oils, tea and coffee. The researchers measured consumption using a plant-based index and compared the men who scored in the highest 20% to those who scored in the lowest 20%.

“These results could guide people to make better, more healthful choices across their whole diet, rather than adding or removing select foods,” said Vivian N. Liu, formerly lead clinical research coordinator at the UCSF Osher Center for Integrative Health and first author of the study, which appears in JAMA Network Open.

“Progressing to advanced disease is one of many pivotal concerns among patients with prostate cancer, their family, caregivers and physicians,” she said. “This adds to numerous other health benefits associated with consuming a primarily plant-based diet, such as a reduction in diabetes, cardiovascular disease and overall mortality.”

Antioxidants and anti-inflammatory compounds

Plant-based diets are becoming increasingly popular in the United States, and evidence is accumulating that they can be beneficial to patients with prostate cancer, the most common cancer among men in the country after non-melanoma skin cancer.

Fruits and vegetables contain antioxidants, as well as anti-inflammatory compounds that have been shown to protect against prostate cancer, and prior research has consistently demonstrated the importance of dietary factors to overall health and well-being.

“Making small changes in one’s diet each day is beneficial,” said senior author Stacey A. Kenfield, ScD, a UCSF professor of urology and the Helen Diller Family Chair in Population Science for Urologic Cancer. “Greater consumption of plant-based food after a prostate cancer diagnosis has also recently been associated with better quality of life, including sexual function, urinary function and vitality, so it’s a win-win on both levels.”

Coauthors: From UCSF, other authors are Erin L. Van Blarigan, ScD; Li Zhang, PhD; Rebecca E. Graff, ScD; Crystal S. Langlais, PhD; Janet E. Cowan, MA; Peter R. Carroll, MD, MPH; and June M. Chan, ScD.