The Benefits of a Plant-Based Diet to Reduce Prostate Cancer Risk

In this podcast episode, Stacy Loeb, MD, MSc, PhD (hon), discusses the association between a plant-based diet and prostate cancer risk, how the diet is beneficial in reducing the risk of fatal prostate cancer in men, and what is next for research on the topic of diet and prostate cancer.

Additional Resource:

• Loeb S, Fu B, Bauer SR, et al. Association of plant-based diet index with prostate cancer risk. Am J Clin Nutr. 2022;115(3):662-670. doi:10.1093/ajcn/nqab365

Stacy Loeb, MD, MSc, PhD (hon), is a urologist and population scientist at New York University Langone Health and the Manhattan Veterans Affairs Medical Center, and the host of the "Men's Health Show" on SiriusXM radio (New York, NY)

TRANSCRIPTION:

Jessica Ganga: Hello everyone, and welcome to another installment of Podcast360, your go-to resource for medical news and clinical updates. I'm your moderator, Jessica Ganga with Consultant360, a multi-disciplinary medical information network.

About one in eight men will be diagnosed with prostate cancer in his lifetime, and there were more than 250,000 estimated new cases of prostate cancer in the United States in 2022, according to the American Cancer Society.

Dr Stacy Loeb is here to speak with us today about the benefits of a plant-based diet to reduce the risk of prostate cancer in men. Dr Loeb is a urologist and population scientist at New York University and the Manhattan Veterans Affairs and the host of the "Men's Health Show" on SiriusXM radio. 

Thank you so much for joining us today, Dr Loeb. Please provide an overview of your article, "Association of plant-based diet index with prostate cancer risk."

Stacy Loeb, MD: This is a research study that we did in the health professionals follow-up study. It's a really big study out of Harvard University where they followed these individuals over many decades and gave them food frequency questionnaires and a lot of other questionnaires, and then were able to observe over time who developed cancer and other health conditions. And so it gave a really great picture of the relationship between a lot of lifestyle factors and the risk of disease. So in this particular study, we used the food frequency questionnaires that the participants completed about their nutritional patterns and observed who developed prostate cancer and especially fatal prostate cancer over the course of the study and was there any difference in the men who consume more plant-based foods.

And what we found is that consuming more plant-based foods was associated with a lower risk of fatal prostate cancer. So this is good news because we want to have modifiable factors that patients can do to  reduce their risk of developing a common cancer like prostate cancer. We know that prostate cancer has a large genetic component. People who have family members with prostate cancer or other cancers are at higher risk, but it only accounts for about half of prostate cancer risk. So that's good because it does leave that other half for things that we can potentially do in our own lives to lower that risk.

Jessica Ganga: What led you and your team to research the association of plant-based diets and prostate cancer risk?

Dr Loeb: Well, plant-based diets are really just becoming increasingly popular due to their really well studied benefits for a lot of different health conditions, especially things like heart disease, lowering the risk of diabetes, also environmental benefits. A lot of environmental organizations and the United Nations have discussed the importance of more plant-based diets to reduce climate change. It saves a lot of land and water use and things like that. So really for both health and environmental reasons, there's a big push towards more plant-based diets.

Now, prostate cancer is the number one cancer in men in the US and so it's a very common cancer and it's important for us to understand how eating a plant-based diet might impact that risk. And is it also beneficial for prostate cancer as it is for heart disease and diabetes and other things, or is there any difference? And really it's nice to see that everything aligns. It's not like there's one diet that's good for one thing and another diet that's good for something else. It's actually much easier and simpler for public health recommendations when in fact the same diet is really just kind of beneficial for everything.

Jessica Ganga: That's a good lead into my next question. Why is a plant-based diet beneficial for reducing the risk of prostate cancer?

Dr Loeb: So I think that there's sort of two sides to this. It's like there's benefits to some of the plant-based foods themselves, and then it's also the lowering of the consumption of animal foods when you have a more plant-based diet. So there's the inherent benefits of the plant-based foods. So we've known, for example, for a long time that certain plant-based foods are really good for the prostate, and that includes things like cooked tomato products, which have lycopene, which is beneficial for the prostate. It includes cruciferous vegetables, which are known to be beneficial for the prostate. Nuts are also beneficial, and all of these plant-based foods have fiber and antioxidants, which are all very important in terms of cancer prevention. Then on the flip side, it's the reduction or elimination of the harmful animal-based foods. So we know that, for instance, when you cook meat at high temperatures, there are these heterocyclic amines that are released, which are related to cancer.

Processed meat is considered a group one carcinogen by the World Health Organization. That's things like bacon, hot dogs, deli meats, that's considered, known to cause cancer in humans. It's actually in the same category as asbestos or cigarettes. So it's already known that processed meats cause cancer. Red meats, things like beef, pork, these are considered group two carcinogens by the World Health Organization, which means probably causes cancer in humans. And that's the same group as DDT and mustard gas. So there's already quite a lot of research related to some of the cancer risk associated with meats. Many of those studies have been in terms of colorectal cancer risk, but there are studies in prostate cancer as well. And so bottom line, lowering the consumption or eliminating the consumption of these meat products that have been associated with cancer risk and in place of that, having more of these beneficial plant-based substances seems to be the reason behind this.

Jessica Ganga: Did the age of the participants play a role in your study and how so?

Dr Loeb: It did, and that's something that we see in a lot of nutritional research because these cancers develop over a really long period of time. It's not just instantaneous for a cancer to develop. And so what we see in a lot of these nutritional studies is that dietary consumption at a younger age can have a bigger impact. So here the people who consume more plant-based food before age 65 had the most bang for their buck. That's where we saw the greatest reductions in terms of aggressive, lethal and fatal prostate cancer.

So it's tough because prostate cancer occurs in older men and maybe some younger men aren't worried about it quite yet or don't know about the problem. But it really is important for younger men to consume more plant-based foods and actually not just for prostate cancer risk. We have another study in this same population looking at the risk of erectile dysfunction, and there we see this sort of situation as well where consuming more plant-based food was beneficial in terms of reducing the risk of erectile dysfunction. So I think it's just something to think about that what you do across your lifespan can really have a big impact even on these things that occur later in life.

Jessica Ganga: How do your findings impact clinical practice?

Dr Loeb: Well, I think it's important. There's a lot of men with prostate cancer, about three million survivors living in our country with this condition, and a lot of people are worried about it. So I think it's important for healthcare providers to talk to patients about nutrition. A lot of patients ask about these things, what can I do to reduce my risk? And it's nice to have something to tell them. And like I said before, even better when it's also something that's good for your heart, reduces the risk of diabetes, and other cancers. So I think that healthcare providers should be counseling patients to eat more plant-based food. And for people who are listening to this in the general public, just to be aware that what you eat really can make a difference and fueling your body with healthy plant-based food is a great way to reduce the risk of prostate cancer and some of these other really common and morbid conditions.

Jessica Ganga: What would you say is next for research on this topic?

Dr Loeb: I think just how to roll this out and into clinical practice more. A lot of physicians don't receive much nutrition education in medical schools, so how do we increase that? So even just some of the gaps in terms of helping to roll this out, it's not an aspirational diet to have. There's some studies of men with prostate cancer who adopted a strict vegan diet along with physical activity and mindfulness training, and actually the study went on for about a year, but like 98% of the people were continuing to do the lifestyle afterwards. So people are able to do it and stick to it if they learn how to do it, but that education piece really has to be there.

Jessica Ganga: What would you say are the overall take home messages from our conversation today?

Dr Loeb: I think the take home message is just that eating more healthy plant-based foods is good for your prostate and also good for the heart, general health, and the environment. Our study specifically showing that consuming more plant-based food was associated with the lower risk of fatal prostate cancer. So I think this is really good news. We really want to find more things that are easy for people to do to reduce their risk. Prostate cancer is a leading cause of cancer death in this country, and anything that we can find to help to save lives is really important.

Jessica Ganga: Well, thank you so much Dr Loeb for joining us today. We appreciate you taking the time out of your day to speak with us.

Dr Loeb: Thank you so much for having me.