Encouraged by prior research revealing a link between plant-based diets and improved prostate cancer outcomes, professor of urology Stacy Loeb, MD, has led several recent studies reinforcing the benefits of diet in both mitigating cancer risk and enhancing overall health. These insights inspired her to pursue an additional board certification in lifestyle medicine.
Here, Dr. Loeb shares her findings—and what she now tells patients about plant-based eating.
Physician Focus: Dr. Loeb, do you recall the specific study that inspired you to research plant-based diets in prostate cancer?
Dr. Loeb: I read about an early randomized trial from 2005 showing that patients with prostate cancer who engaged in a lifestyle intervention—including a vegan diet, physical activity, and stress reduction—experienced less disease progression compared with those who did not. Given how often I treat prostate cancer, I began educating myself further in this area and found that the research was compelling.
“I wanted to be in a position to advise my patients if this is something that can help them.”
Stacy Loeb, MD
Though traditional medical school training has not placed sufficient emphasis on nutrition as a complementary therapeutic approach, the benefits of plant-based eating overall are well documented. I wanted to be in a position to advise my patients if this is something that can help them. My interest led me to obtain an additional board certification in lifestyle medicine in 2023.
Physician Focus: What are some of your own findings around plant-based diets and their benefits for patients with prostate cancer?
Dr. Loeb: We have found that a plant-based diet is associated with both a lower risk of developing aggressive forms of prostate cancer and a reduction in disease progression among those diagnosed with the condition. We use a plant-based diet index (PDI) to measure adherence to plant consumption, with positive marks for plant foods and negative marks for animal-derived foods.
In these studies, males who consumed plant-based diets were found to have a 19 percent lower risk of diagnosis with fatal prostate cancer, while those scoring in the highest quintile of PDI had a 47 percent lower risk of progression.
While those findings are encouraging enough, we’ve also found an association between plant-based eating with better quality of life among prostate cancer survivors. Among patients treated for prostate cancer, we reported higher quality-of-life scores for sexual function, urinary function, and hormonal vitality among those eating the most plant-based and the least animal-based food.
In my own practice, I have seen patients experience weight loss, improve blood pressure control, and no longer needing medication for their erectile dysfunction or urinary symptoms after adopting a plant-based diet.
Physician Focus: What is your working theory of why a plant-based diet may be so beneficial in prostate cancer, specifically?
Dr. Loeb: We know on a basic level that plant-based diets are the source of beneficial components such as fiber and antioxidants while eliminating processed and red meats, which are classified as carcinogens by the World Health Organization.
We also know that plant-based diets improve cardiovascular health. Erectile dysfunction is often found to be the “canary in the coal mine,” an early-warning sign of problems with the vascular system. In fact, a diagnosis of erectile dysfunction has been found to precede cardiovascular events by approximately five years in some patients.
This connection is reinforced by our observations of better erectile function when patients with prostate cancer eat more plant-based food. Anything that can help improve cardiovascular health—diet included—will likely also benefit the vascular system throughout the body.
Physician Focus: How have your findings impacted the advice you give patients who are at risk for or have developed prostate cancer? Are patients receptive to your counsel when it comes to diet?
Dr. Loeb: This research has significantly influenced my approach to patient care. I now routinely emphasize the benefits of plant-based eating as part of a comprehensive management plan for prostate cancer.
While I do point out that many of these studies are observational in nature, it’s also true that there’s no evidence of harm in adopting a plant-based diet; in fact, the opposite is true. Patients treated for early-stage prostate cancer are then most likely to die from cardiovascular disease, so a diet that supports heart health is a win all around.
“When patients are diagnosed, they want to know what they can do to improve their outcome. I pursued this research so that I could develop a truly informed answer to that question: that a plant-based diet is unlikely to hurt and likely to help.”
I find most patients are amenable to making this diet change. And many report positive outcomes. For instance, Gabe Canales and Brian Jones, who have publicly shared their journeys, demonstrate how adopting a plant-based diet can have a profound impact on managing prostate cancer.
When patients are diagnosed, they want to know what they can do to improve their outcome. I pursued this research so that I could develop a truly informed answer to that question: that a plant-based diet is unlikely to hurt and likely to help. The teachable moment here is to encourage patients to adopt healthy lifestyle changes that can improve their quality of life and overall health.
