Can plant-based diet protect against prostate cancer progression?

For more than 10 years we’ve been posting blogs on the merits of healthy diet to lower prostate cancer risk. We’ve focused on non-inflammatory diets like the Mediterranean diet and the DASH diet. We’re following the growing number of studies that specifically point to the importance of reducing animal protein and increasing plant-sourced protein for protection against prostate cancer.

Two years ago, we blogged about actor Harrison Ford’s gradual conversion away from meat and dairy, to a diet now focused on vegetables and fruit (with a side of fish). As of this writing, he is 84. While he’s only a sample of one person, it’s interesting that he’s never been diagnosed with prostate cancer.

During the same period, the Prostate Cancer Foundation posted an article, “Eat Your Beans and Greens: Benefits of a Plant-Based Diet.” It reported a May 2024 published study on 2062 patients who had been diagnosed with localized prostate cancer. They were followed for up to 20 years, and the findings showed that those who ate a primarily plant-based diet had the lowest rate of prostate cancer becoming more aggressive. In fact, we updated a 2022 blog of ours with that very study!

What does the latest study show about plant-based diet and disease progression?

Now I’m writing to tell you about a talk given at the May 2026 annual meeting of the American Urological Association in Washington DC, where two researchers from the Johns Hopkins Brady Urological Institute presented their analysis of 862 patients on Active Surveillance for grade group 1 prostate cancer.

According to a Sep. 25, 2026 ASCO Post newsletter, the duo demonstrated that “… greater adherence to a plant-based dietary pattern was associated with a lower risk of grade progression. In particular, the researchers found that consuming primarily a plant-based diet was associated with a significantly lower risk of progression to grade group 3 or worse disease during surveillance.”

The article notes that when an Active Surveillance patient’s cancer progresses to grade group 3, he is advised to seek surgery or radiation. Since the point of going on Active Surveillance is to avoid treatment (with its urinary and sexual risks) as long as possible, swapping meat for plants seems like a great trade! Not to mention the total health benefits of choosing a diet heavy in vegetables, grains, nuts, and fruit.

Is there a study that gives a biological explanation?

All of this evidence bears out the phenomenal 2008 study by Ornish, et al. in which 3 months of healthy lifestyle changes resulted in biological changes at the level of gene expression. 30 patients on Active Surveillance for low-risk prostate cancer participated for 3 months in an intensive program that included plant-based diet, regular exercise, stress management, and social support. At the end of the program, genes that suppress tumor growth had been “switched on” while those that promote tumor growth had been “switched off.”

The authors concluded that their study result “suggests that intensive nutrition and lifestyle changes may modulate gene expression in the prostate. Understanding the mechanisms of how comprehensive lifestyle changes affect transcriptional regulation may strengthen efforts to develop effective prevention and treatment strategies for prostate cancer.”^[i]

Can a plant-based diet support the results of focal therapy?

All the studies cited in this blog were done with low-risk patients on Active Surveillance. While Active Surveillance is frequently recommended for newly diagnosed low-risk patients, many are anxious at the idea of living with cancer growing in their body.

For these patients, if they choose a focal therapy for which they are qualified, they gain the peace of mind that comes from knowing their cancer is destroyed with minimal risk to their urinary and sexual function. In other words, focal therapy provides the benefits of treating the cancer while preserving the same quality of life they would have with Active Surveillance.

At our Center, we encourage men to follow focal therapy with embracing a plant-based or plant-forward diet because it supports the results of this treatment. Given the increasing research into plant-based protection against prostate cancer risk, we believe this dietary choice adds a sort of “insurance” against recurrence in the untreated portion of the gland. Of course, there are no guarantees, but the evidence from the Ornish study of changes at the level of gene expression seems very compelling. Add to their genomic analysis the real-life experience of low-risk patients whose prostate health seems to thrive on plants, and we can only believe that your prostate is happy when you eat plants.

Is it time for you to hop on the plant-wagon?

NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.

References

[i] Ornish D, Magbanua MJ, Weidner G, Weinberg V, et al. Changes in prostate gene expression in men undergoing an intensive nutrition and lifestyle intervention. Proc Natl Acad Sci U S A. 2008 Jun 17;105(24):8369-74.