An intensive lifestyle program may slow or even halt the progression of early, low-grade prostate cancer in men, according to data presented at the International Conference on Nutrition in Medicine (ICNM), held in Washington, DC, August 14-16, 2025.
Dean Ornish, MD, clinical professor of medicine, University of California, San Francisco (UCSF), in San Francisco, and president and founder of the nonprofit Preventive Medicine Research Institute in Sausalito, California, described his research, which he placed within the broader context of research he has conducted on other diseases and conditions.
“The program we studied for prostate cancer, is similar to the program we developed that has been proven effective in reversing heart disease and Alzheimer disease,” Dr Ornish explained (interview at ICNM; August 2025). “We’ve been researching the impact of this program on these conditions for 47 years. After decades of studies, I have arrived at a unifying theory, which is that these seemingly disparate conditions share many of the same underlying biologic mechanisms, such as chronic inflammation, oxidative stress, and angiogenesis, and all are influenced by how we eat, how we respond to stress, how much we exercise, and how much love and social support we have.”
Lifestyle Intervention Superior to Usual Care
To investigate the impact of an intensive lifestyle intervention on prostate cancer, Dr Ornish teamed up with Peter R. Carroll, MD, MPH, professor of urology and Ken and Donna Derr-Chevron Distinguished Professor in Prostate Cancer, UCSF School of Medicine, to focus on a cohort of Dr Carroll’s patients with early low-grade prostate cancer who had opted not to undergo conventional treatment.1
The patients (n=93), all of whom had serum prostate-specific antigen (PSA) scores ranging between 4 and 10 ng/ml, Gleason score less than 7, and stage T1 or T2 disease, were randomly assigned to either an experimental group that received the intensive lifestyle intervention or to a control group that received usual care.1
“These patients had opted for what used to be called ‘watchful waiting,’ but is now called ‘active surveillance,’ in which they’re monitored carefully because they don’t need surgery, radiation, or chemotherapy immediately,” Dr Ornish commented.
Active surveillance refers to repeat monitoring of the patient for signs of disease progression through conducting regular PSA screening, prostate examinations, multiparametric MRI, and periodic biopsies.2 The goal is to mitigate “common adverse effects associated with treatment, such as urinary incontinence, urinary irritative symptoms, and erectile or bowel dysfunction.”2 In fact, active surveillance is currently the “preferred management for low-grade prostate cancer.”2
Dr Carroll, who presented together with Dr Ornish on the panel at ICNM about prostate cancer, said that the patients in the study were regarded as having “low-risk disease — meaning that their disease would generally appear to be indolent, slowly progressive, and the hypothesis being tested was to decide whether the lifestyle [intervention] changed the outcome of those patients” (interview at ICNM; August 2025).
The intervention the experimental group followed consisted of a vegan diet supplemented daily with soy (1 serving of tofu plus 58 gm of a fortified soy protein powdered beverage), fish oil (3 gm), vitamin E (400 IU), selenium (200 mcg), and vitamin C (2 gm); moderate aerobic exercise (walking for 30 minutes 6 days a week); stress management techniques (gentle yoga-based stretching, breathing, meditation, imagery, and progressive relaxation); and participation in a weekly 1-hour support group. A registered dietitian was available for nutritional education and counseling.1
Serum PSA was measured at baseline and then at 1 year. LNCaP [lymph node carcinoma of the prostate] cells were grown and also measured. LNCaP cells model critical stages of prostate cancer progression, shedding light on prostate tumorigenesis, metastasis, and treatment response.3
None of the participants in the intervention group needed to undergo conventional treatment due to an increase in PSA and/or disease progression (as determined by MRI imaging), whereas 6 patients in the control group underwent conventional treatment for these reasons. PSA decreased by 4% in the intervention group vs an increase of 6% in the control group (P =.016).1 Moreover, LNCaP cell growth was inhibited by serum from the intervention group almost eight times more than serum from the control group (70% vs 9%; P <.001).1
Patients in the intervention group reported improved quality of life, significant decreases in body weight, and improvements in lipid profile, compared with those in the control group. “This lifestyle intervention therefore had beneficial effects beyond its impact on prostate cancer,” Dr Ornish commented.
At 2 years of follow-up, 27% of those in the control group and 5% of those in the intervention group had undergone conventional prostate cancer treatment (radical prostatectomy, radiotherapy, or androgen deprivation therapy; P <.05).4 Of the treated control patients, 3 had a PSA level of 10 ng/mL or higher and 1 had a PSA velocity of more than 2 ng/mL/y before treatment, compared with none of the treated patients in the intervention group for both markers.4
“The results of this study extended our earlier findings to show that measurable benefits by making changes in diet and lifestyle, in the form of fewer prostate cancer-related clinical events, were evident 2 years after study entry,” Dr Ornish said.
More Recent Research
Dr Carroll cited additional research suggesting that consuming diets that are richer in plant-based foods is beneficial for men with prostate cancer. For example, Dr Carroll and his colleagues studied 2062 men with nonmetastatic prostate cancer, drawn from the Cancer of the Prostate Strategic Urologic Research Endeavor (CaPSURE) — a longitudinal observational study.5,6 Participants completed a comprehensive diet and lifestyle questionnaire that included a validated food frequency questionnaire. The researchers used the overall plant-based diet index (PDI) and the healthful plant-based diet index (hPDI) scores to assess the dietary patterns of the participants.5
During a median follow-up of 6.5 years (range, 1.3 to 12.8 years) after participants completed the questionnaire, 190 progression events and 61 prostate cancer-specific mortality events occurred. Men who scored in the highest quintile of PDI had a 47% lower risk of progression, compared to those in the lowest quintile (P for trend =.003). The researchers concluded that a higher intake of plant foods was associated with lower risk of cancer progression.5
Dr Carroll also pointed to a prospective study of more than 3500 men with prostate cancer who had participated in the Health Professionals Follow-Up Study (1986-2016).7 A higher PDI was associated with modestly better scores for sexual function, urinary irritation/obstruction, urinary incontinence, and hormonal/vitality.
Nutritional Guidance for Patients With Prostate Cancer
Dr Carroll presented nutritional guidance for patients with prostate cancer, noting that the same recommendations may also be helpful in patients with other types of cancers, as well as patients with heart disease.
Vegetables and fruits are recommended for all conditions — especially a variety of plant-based foods — with an emphasis on raw and cruciferous vegetables and cooked tomatoes for lethal prostate cancer. Fiber and whole grains; healthy plant-based proteins (eg, beans and nuts), fish, seafood, low-fat or fat-free dairy, and skinless protein; and liquid, nontropical plant oils are also recommended.8,9
Foods to avoid include saturated fat (eg, high-fat dairy, butter, animal fat, tropical oils), trans fat (eg, partially hydrogenated fat, animal fat); beverages with added sugar or sugar-sweetened drinks; processed and red meat; highly processed foods/refined grains; and alcohol, which should be consumed in moderation if at all.8,9
The diet participants in Dr Ornish’s study followed was vegan, consisting predominantly of fruits, vegetables, whole grains (complex carbohydrates), legumes, and soy products and was low in simple carbohydrates. Only approximately 10% of calories came from fat.1 A similar dietary regimen was investigated in his study on lifestyle changes in Alzheimer disease10 and his research into heart disease.11 The diet, in conjunction with the other interventions, contributed to reversal of the conditions.
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The results of this study extended our earlier findings to show that measurable benefits by making changes in diet and lifestyle, in the form of fewer prostate cancer-related clinical events, were evident 2 years after study entry.
Today, Dr Ornish’s program is regarded as robustly evidence-based. It is covered by Medicare and a number of other insurance companies. Some insurers also cover the program for patients with early-stage Alzheimer disease. Dr Ornish describes his unifying theory at length in the book Undo It! How Simple Lifestyle Changes Can Reverse Most Chronic Diseases (Ballantine Books; 2019).
“It’s been said that what’s good for the heart is good for the brain,” Dr Ornish concluded. “I can add that what’s good for the heart and brain is also good for the prostate. And the only ‘side effects’ are beneficial ones.”
Dr Carroll believes that active surveillance should be offered to all men with low-risk disease and many with intermediate-risk disease, and that lifestyle modifications “should be offered to all patients as primary or complementary care.” In addition, resources for healthful eating, exercise, and other lifestyle recommendations from the Department of Urology at UCSF are available here.