Preventing disease through lifestyle medicine is the cornerstone of Dr. Dean Ornish’s work. As founder & CEO, Ornish Lifestyle Medicine and Clinical Professor of Medicine, University of California, San Francisco, Ornish, through his research, finds that a whole-food plant-based diet, exercise, sleep, meditation, and other approaches benefit longevity.
At DOC 2025, Ornish spoke about how lifestyle changes address the root cause of illness rather than just managing symptoms, allowing the body to begin healing. As he said on stage, “The whole approach is to turn off the faucet instead of just mopping up the floor.”
We caught up with him this summer to ask about updates to his own research — and new findings that resonate with his own approach.
DOC: In 2024, you published a randomized controlled trial that showed cognitive improvement in early-stage Alzheimer’s from lifestyle changes. What were the key details?
Ornish: In 2024, using one of the key measures of cognition and function, the Clinical Global Impression of Change, we found that 42 percent of patients showed significant improvement in cognition, and 71 percent stopped deterioration in cognition or showed improvement after 20 weeks. In contrast, in the usual care randomized control group, none showed improvement: 32 percent were unchanged, and 68 percent worsened cognition.
Have you continued to track this cohort? Are there new updates?
We’re about to report our findings after 40 weeks, showing that the lifestyle intervention group, overall has more improvement after 40 weeks compared to after 20 weeks. After 20 weeks, the usual-care control group crossed over and received the same lifestyle medicine intervention. They then showed similar improvements, adding evidence to what we found.
You mentioned your telomere research as the first to show how lifestyle changes could lengthen them. Has anything in the longevity science field changed how you interpret this, or surprised you?
In 2013, my colleagues and I, including Nobel Laureate Elizabeth Blackburn, published in The Lancet Oncology the first controlled human intervention study to show that any intervention — in this case, comprehensive lifestyle changes — was associated with significant telomere lengthening over time.
In contrast, the 2025 VITAL telomere study found that vitamin D3 at 2,000 IU/day for four years reduced leukocyte telomere attrition by about 140 base pairs, while omega-3 did not show the same benefit in that analysis. This is a large randomized trial and therefore important. But the result is best described as reduced shortening, not definite lengthening.
What does this say to you about single interventions compared to broader changes?
To me, this indicates that a comprehensive lifestyle intervention is more effective than looking for one intervention (e.g., vitamin D3) as there is often synergy between diet, stress management, exercise, and social support.
Is there one message you’d want the DOC community to walk away thinking about this year?
There is a growing awareness that lifestyle medicine works not only as well as drugs and surgery to increase longevity, but often even better. For example, only three drugs have been approved for treating Alzheimer’s disease in the past 20 years. All three only slow down the rate of getting worse, and not even by very much; they are very expensive and often have significant side effects, such as bleeding in the brain.
In contrast, 71 percent of the randomized lifestyle medicine intervention group we ran stopped or reversed the progression of dementia due to early-stage Alzheimer’s disease, which I noted.
As Dr. Eric Verdin (CEO of the Buck Institute for Research on Aging) posted recently, “The irony of spending a career searching for the longevity pill is that evidence keeps pointing back to the same boring, available, inexpensive behaviors that humans have always known matter. I just needed 30 years of research to believe it.”
You can watch Ornish’s original talk at DOC 2025 below to hear more, or read our lightly edited transcript.
TRANSCRIPT:
Ornish: I want to talk today about the transformative power of lifestyle medicine and lifestyle. Medicine is, I feel that I helped create, which is using lifestyle changes to not only treat disease to prevent disease, but to treat and often reverse it. And I love this quote from Nelson Mandela, “It’s always seems impossible until it’s done.” And the reason why I spend so much of my time doing research is that properly done, working with the best collaborator is published in the leading peer review journals can often redefine what’s possible, and by doing so, can give many people new hope and new choices that they didn’t have before.
These studies were published, in all the leading, peer reviewed medical and scientific journals. And the other quote that I like so much is, “If you can’t explain it simply, you don’t understand it well enough.” And so to reduce it to its essence, lifestyle medicine is eat well, move more, stress less, and love more. Eat well a whole foods plant based diet that’s low in fat and sugar and refined carbs and processed foods, meditation and other yoga based stress management techniques, as well as sleep, exercise, both aerobic and, resistance training. And the Love More part is really about social connection that we’ve been hearing so much about in these in the previous panels, a panel of experts has rated what they call the order side as number one for heart health for 12 years, which is a nice endorsement. And the whole approach of this is to turn off the faucet instead of just mopping up the floor.
We so often we just spend so much time with very high tech ways of mopping up the floor without really treating the underlying causes. The idea is that if we can treat the cause, which more often than not, are the lifestyle choices we make, that our bodies often have this remarkable capacity to begin healing and much more quickly than we had once thought. With all this interest in personalization, which is important, we found these same lifestyle changes could reverse so many different diseases. Why is that?
I was trained like most doctors, to view these as being fundamentally different, but they all share the same many of the same underlying biological mechanisms. Things like chronic inflammation, overstimulation of the sympathetic nervous system, changes in the microbiome and angiogenesis, the ptosis, changes in gene expression and telomeres and, immune function, which, all turned on or turned off very quickly, these are very dynamic by what we eat, how we respond to stress, how much exercise we get, and how much love and social support we have. And these affect all of these different diseases heart disease, prostate cancer, type two diabetes, and others that I’ll be describing with you. When we can treat the root causes, in this case, literally all these different diseases in the branches are mediated and begin to heal, through these mechanisms in ways that, we’ve been able to document.
We started by showing that in a series of studies, culminating in what was called the Lifestyle Heart trial, that it was thought at the time that once you had heart disease, the best you could do was slow down the rate at which we got worse. We found if you make a lot of changes that are bigger at the same time, that instead of getting worse and worse, which is shown in the red line, the usual care randomized control group, the arteries got more and more clogged from baseline to one year to five years. They actually started getting less clogged after one year, which we published in The Lancet. And even more improvement after five years, which we published in Jama.
This is a representative patient showing the narrowing in the upper left if the beginning is less clogged after a year, but the PET scans or a fourth power function, blood flow is a fourth power function of the ratio. So even a small increase in the blockage and the decrease in the blockage can cause an exponential improvement in blood flow, which we could measure. You can see on the pet scan in the same patient in the lower left. The beginning, blue and black is no blood flow. And the lower right, orange and white is maximal.
In 99% of the patients stopped to reverse the progression of the disease as measured by PET, and only 5% of the usual care control group got better. We then found these same lifestyle changes cut off and slow, stop and even reverse the progression of men with early stage prostate cancer. And what’s true for prostate cancer will likely be true for women with breast cancer. This was done in collaboration with the Chair of Urology at UCSF, Peter Carroll, where I’m a professor, and the then Chair of Urology at Sloan-Kettering in New York. Bill Belfair.
We found that the tumor activity began to diminish. You can see here shown in the red. When we added the serum of patients who made his lifestyle changes to a standard line of prostate tumor cells growing in tissue culture, the tumor growth was inhibited 70% versus only 9% of the control group in a dose response effect. The more people change their lifestyle, the more it actually affected the tumor from growing and we published that in the Journal of Urology. So we wonder what some of the mechanisms might be. And we found that when you change your lifestyle, a change of genes, and in fact, turning on the genes that are beneficial and downregulated are turning off the genes that that regulate these biological mechanisms.
We’ve been talking about chronic inflammation, oxidative stress, and so on. And we did that with, Craig Venter. And then with Liz Blackburn and Elissa Epel, we published the first study showing that any intervention could actually lengthen telomeres, the ends of our chromosomes that regulate cellular aging. Elissa and Dr. Blackburn had shown that people who smoke or overeat or, are sedentary or in junk food, their telomeres got shorter, faster. I thought, well, if bad things make them shorter, maybe good things make them longer. Sure enough, we found for the first time that any intervention can actually lengthen telomeres shown in green, whereas they got shorter in the usual care group. And when your telomeres get shorter, your life gets shorter, and the risk of all these, chronic diseases goes up proportionate. When we published that, The Lancet editors called it the first studies showing that lifestyle changes may reverse aging on a cellular level after many years.
When we published our studies, I thought this will really change medical practice and to some degree, but not nearly as much as I hoped. I realized that if you change reimbursement, then you change medical practice. It took 16 years. But Medicare ultimately created a new benefit category to cover our program, first in hospitals and clinics and more recently, when done at home via Zoom. Now we can reach people everywhere.
The most recent and probably the most important study we’ve done because nothing else works, was these same lifestyle changes in a randomized controlled trial published last summer could actually improve cognition in people who have early stage Alzheimer’s disease. Only three drugs have been approved in the last 20 years. They just slow down the rate at which we get worse. We found that people could often get better, and then three of the four measures showed improvement. The one that I liked the best called, the Clinical Global Impression of Change. I like it because they interview the patient’s spouse or caregiver as well, and they really know what’s going on. We found that 42% of the patients got better and 71% stopped to reverse the progression of the disease, whereas in the usual care group, none got better, a third were unchanged and two thirds got worse. Sanjay Gupta from CNN filmed the first group of patients and then came back five years later and filmed them again. I’m going to just show a two minute video because it gives a really good idea of what we actually did, as well as what happened.
Transcript from VIDEO: I’ve made my way to Sausalito, California. I’m going to spend time here with this world renowned doctor who believes he’s figured out a way not just to prevent Alzheimer’s, but to reverse it. And I got a really detailed look at the Ornish Lifestyle Intervention program, the exercise, the yoga and the meditation regimen socially sitting in on their support groups and eating the provided plant-based meals. That meeting in Sausalito was five years ago. Seemingly a lifetime has passed since then. It is the first randomized, controlled clinical trial showing that some Alzheimer’s patients could experience cognitive improvement in just five months, with intensive lifestyle changes alone rising up into the middle back. And importantly, those who did not make any changes in the trial worsened a big commitment, but also doable. Chichi did it and now I wanted to see how she was doing. It has been five years since she first joined that study. I’m good. I’m better now. Yes, I’m all the oh, it’s good to see you. Same here in five years. I can’t believe it. Cheech is doing very well. She goes out in the morning, she’ll go for a walk almost every morning. She was for a walk. I think she’s doing very well. Does it surprise you? Yes. After seeing her mother and grandmother? Yes, because I was figuring by this time she have been a home or some teacher. Chichi, I remember when we spoke back in 2019, you were very clear with me that one of your greatest fears was going through the same thing you had seen with your mom and your grandma. Do you still fear that? No, I think I passed that a long time ago. That’s kind of incredible. Yeah. And here I am. Here you are here. How are you doing now do you think as compared to five years ago. Much better, much better. Did this help reverse some of the symptoms of Alzheimer’s? Yes, yes, I guess the question is why? Right. What do you attribute this to? The program, the meditation, the diet, the exercise. My choice of a meal before this was a breaded veal cutlet. I haven’t had one in 5 years.
Ornish: We were used to thinking of advances in medicine as something really high tech and expensive. I think our unique contribution has been using these very high tech, state of the art scientific measures to prove how powerful these very simple and low tech and low cost interventions can be. Thank you.
John Battelle: If anyone has a question for them, we can do one. But I don’t want you to do I. Sorry I was held up. If there’s. Oh, there’s one question over here from Jamie.
Audience Member: So, I remember when you and I were in your office and you first had the telomere data. My reply to you then was, this is quite remarkable. You said, well, no, I think we’ve shown you reversed aging and said, no, you’ve convinced me that telomeres are a useful biomarker. The point I want to make is, and I think that this is something where we get a little caught in our molecular sort of obsessions, says the guy that’s the most molecular in my room.
I think it builds on what was just talked about in the panel before, what I love about your work and I think the leadership opportunity here is that it’s it’s not a question of whether or not you make people healthier by verifying it in the things that you measure. We know you make people healthier. It’s a question about whether other things we do actually match the level of health improvement that you’ve accomplished. And I think that that one of the hopeful things about this recent study in Alzheimer’s is this idea that maybe we can really establish that there is a Dean, I talk about this, a Dean Index, which is how much better can lifestyle make you. And by the way, if your drug doesn’t show up and be the Dean and go pound and and I think there’s a little bit of a need to really establish that. And I think you are the first person that’s really done that. So I, I validate the biomarkers that I think work by looking at what they do in the people you treat. Not that I think that the biomarkers indicate that doing so you’re doing actually work well.
Ornish: Thank you. And just to comment quickly, I think the work you’re doing with using those biomarkers and finding those correlations is giving us tremendous new insights. But I think in the case of Alzheimer’s, those differences really become clear. You know, as I mentioned, only three drugs have been approved in the last 20 years.
All three just slow down the rate at which you get worse, but getting worse more slowly is still getting worse. The suicide rate is seven times higher when people get diagnosed because they take their hope away. Get your affairs in order. Give us your keys. Don’t wander off. It’s devastating. When you lose your memories, you lose everything. For the first time, we can give people hope. But why is it the lifestyle works even better than drugs? Because the drugs move their monoclonal antibodies that move amyloid out of your brain. The amyloid is just one of many factors that affects them. The Alzheimer’s ones we talked about all along, whereas the lifestyle changes also move the amyloid out of the brain.
The a-beta 40 to 40 ratio, which is a measure of amyloid, also improved. But we’re also making these other lifestyle changes which affect these other mechanisms. So the the paradox is that the lifestyle changes work better than drugs because you’re not just focusing on one thing. So thank you.
Battelle: Thank you very much, Doctor Ornish.