Air Date: Week of January 24, 2025

Scientists globally are studying the impact eating organic may have on cancer risk, and have found eating organic may help decrease an individual’s risk for several cancers. But the few published epidemiology studies so far do not have enough data to draw more than limited and sometimes conflicting conclusions. (Photo: Steve Loya, Flickr, CC BY-NC-ND 2.0)

A number of pesticides have been linked to cancer, but there are challenges to studying whether eating organic food grown without these toxins would help reduce your risk. Dr. Mary Beth Terry of the Silent Spring Institute joins Host Steve Curwood to explain the mixed results of some studies on organic food and cancer and offer a variety of ways that people can reduce their cancer risk.

Transcript

CURWOOD: A number of pesticides have been linked to cancer, so one might think that eating organic food, grown without these toxins, would help reduce your risk. In fact, studies of animals exposed in the lab to pesticides have demonstrated correlation between these chemicals and cancer. But people don’t live in labs, don’t always remember accurately what they eat and can change their diets over time, so studies of humans and the impact of eating organic have major limitations. That said, a large study from France published in 2018 found eating organic food was correlated with a reduced risk of breast cancer and lymphomas. More recently, a Danish health study found a decrease of stomach cancers in participants who reported eating more organic food compared to those who ate less. But the same study found an increase in non-Hodgkin lymphoma among those organic eaters. For insight into these confusing results, we turn now to Columbia University Professor Mary Beth Terry of the Silent Spring Institute. Dr. Terry, welcome to Living on Earth!

TERRY: Thank you so much!

CURWOOD: So, what can we say about any links between eating organic food and the incidence of cancer? What do studies tell us? There was a study published by the Journal of American Medical Association from France almost a decade ago, and more recently, from Denmark.

TERRY: What we have evidence on that is very compelling, is the evidence between pesticides and cancer risk. Many of these studies that are conducted in humans have been conducted by using what we call biomarkers, which is measures of the pesticides from your blood. They're looking at these measures in bio specimens, which is often more accurate than questionnaire data. What's new now with looking at organic food specifically, is a study, as you mentioned, from Denmark, looking at a variety of different cancers and self-reported use of organic food. And so, within that study, they did find a very strong reduced risk of stomach cancer. The study was equivocal on a number of other cancers and actually showed an increased risk with non-Hodgkin’s lymphoma. So, I think what we can say, which is very related to organic food consumption, is that many pesticides are known carcinogens. Since organic food do not contain the pesticides that you would see in some other foods, eating organic would be preferable if you can reduce your exposures to pesticides.

CURWOOD: This is a difficult topic to actually drill down on, right? You have this sort of strange result that people who ate organic had actually a larger incidence of non-Hodgkin’s lymphoma. I mean, how do you get a result like that?

TERRY: Yeah, that's a great question, and I think this is what can be very frustrating to most people when they hear about epidemiology results. Until you have a large body of data, no one study is conclusive, because of all the challenges of measuring things in humans and all of the other factors that may be related. With diet, again, people can change their diets over their lifetime. Often do. People may not know what's in the foods that they eat, so it can just be a very hard thing to measure reliably. So that's why we would want to see a lot of studies on this. That being said, I know just from my own experience and reading the literature on nutrition and cancer, many of the older cohorts in this country didn't ask specifically about organic food consumption. So even though there's a lot of studies and cancer cohorts that we use for all different exposures, there's really a much smaller percentage of studies that even ask people about organic food consumption. And that's why you may see, for example, in the Jama study, one cancer being lower and one cancer being higher in this newer study. And so, until there's additional studies, it's hard to know if this is just statistical variation or not.

CURWOOD: Dr Terry, there are pesticides around us much of the time. You walk into a building, they have vermin that they're spraying for, a field nearby that has crops or a golf course, those things get sprayed with pesticides. How can we tell that if someone gets cancer that is maybe linked to pesticide that they got it from eating, as opposed to these other exposures?

TERRY: Unfortunately, for any one individual who gets cancer, we don't know what their source of exposure is and so what we can tell, though, at a population level, is that when you introduce certain exposures into a population and the cancers increase, then that's a strong signal of a causal signal between those whether or not that chemical came from the water or came from the apple or came from the lawn. There is no way to distinguish between all of that. So, all we know is that you can reduce your exposures, and when people do reduce their exposures, they can reduce their risk.

CURWOOD: How safe is it to say that if people eat organic, they are reducing, at least to some extent, their risk of cancer?

TERRY: I think that's a very fair statement to make, we all have different ways we can reduce our cancer risk throughout our life, and I think the focus should be on reducing the risk rather than prevention, because cancer can occur also just from random mutations as one ages. An important way to think about it is each and every person, regardless of their history, can reduce their risk, their exposures today and going forward, if that is by eating organic or eating fruits and vegetables in general, is a good thing. We do have decades worth of research showing that having fruits and vegetables on a daily basis helps reduce the risk of many different types of cancer.

CURWOOD: One of the things that seems rather confusing about looking at this arena is the risk that is sometimes imposed by plastics when food is sold in plastic packaging, which, over the years, has had things like estrogenic chemicals in the actual plastic, and people could get exposed that way. What about plastic packaging and concerns about cancer in our diets, whether it's organic or not?

TERRY: You are aware, I'm sure that the UN plastics treaty just folded without reaching negotiation in Korea, and some of the scientists at Silent Spring over a few years ago published some really interesting work on the impact of plastic packaging on cancer risk. And then we do know, just through recent analyzes, that there's a lot of chemicals that are in plastics. In fact, well over 400 chemicals that are in these plastics we use every day that are breast cancer carcinogens, so either through, as you say, endocrine disrupting chemicals, or also by directing and damaging DNA. I think, how we eat food, how much food we eat, and how we store our food, should be emphasized a lot more than about specific components.

CURWOOD: Now, of course, science has connected a wide variety of other factors to cancer risk. There's everything from genetics, there's smoking, there's obesity, based on what we know, how important is organic food consumption in comparison to these other factors, do you think?

TERRY: Again, the data on organic food consumption is pretty limited compared to some of these other exposures. So smoking, we've known for 80 years almost now. One of the things that's very challenging when people ask the question is it sometimes does depend on how we measure these. So, for example, smoking is much easier to measure than most other things. Most people remember when they had their first cigarette. Most people remember if they smoke a pack a day or a half a pack a day, where it's harder to remember how much broccoli you eat or where you got your broccoli from. So, I think what has happened over time is once you look at these younger cohorts of individuals, we have an epidemic of early onset cancer. Now these are cohorts that are not smoking, and they're still getting a lot of cancer. So, this is telling us, too, as a piece of evidence that it's not just smoking, that when we take smoking out of the equation, cancer still are increasing.

CURWOOD: Why are people getting cancer at younger ages, do you think?

TERRY: So that's the million-dollar question. And there's a lot of research going into this. So, I do think a lot more research needs to focus on measuring and measuring, well, environmental chemicals, particularly for breast cancer. And you know, there's other research looking into differences in the microbiome. So again, kind of a combination of the food that we eat plus our microbiome that can be very much affected by use of antibiotics and other things. So, I think diet is very interesting because it does interact with everything, like environmental chemicals with pesticides or antibiotics and things like that. But it's, I think, going to be a combination of these things, not just one.

CURWOOD: And when you say microbiome, are you referring to what's in our intestinal tract?

TERRY: Yes, yes. And actually, some of the cancers that are increasing for early onset cancers are GI related cancers.

CURWOOD: Dr. Terry, if you were conducting these studies, what would you want to add? What do you think is missing from them?

TERRY: The first thing I would really want to look at is to look at whether or not there are differences by age of onset for some of these cancers, because, as I mentioned before, you can get a lot of changes later in life when most cancer is diagnosed that may not be attributed to the exposure as much as it's attributed to the process of aging. So, I would really wanna look at whether or not having an organic diet could prevent, for example, early onset colorectal cancer or something like that.

CURWOOD: So, Dr. Terry, we can't know everything, can we? But what are some practical things do you think people should do in their lives when it comes to things that they consume, things that can end up in their bodies, to lower the risk of cancer?

TERRY: (Laugh) I hate to make a cliche about it, but I always think like, What did my grandmother do? So, my grandmother never used plastic. We never had plastics in our school lunches. We didn't eat out at restaurants. All of these sort of things were just part of the life of most people, so to speak. But I think it's more important for people to do what's realistic within their life. And so obviously, the big ones are, try to vaccinate when you can. The two cancer vaccines that everyone should be aware of is the human papillomavirus vaccine and also the hepatitis B vaccine. Those are very effective cancer vaccines, and there may be more to come. Fruits and vegetables, lower meat intake, lower alcohol intake, all of those are things that are directly related to a number of different cancers. Alcohol has been causally linked to seven different cancers. So, you know, I think the healthy diet, the physical activity, those both prevent against many different chronic diseases, but are something that you can do at any time and definitely has a positive effect on many different cancers.

CURWOOD: Dr. Mary Beth Terry is the executive director of the Silent Spring Institute and is a professor of epidemiology and Environmental Sciences at Columbia University. Thank you so much for taking the time with us today.

TERRY: Well, thank you so much. I enjoyed our conversation.

 

Links

Read the 2018 JAMA Article, “Association of Frequency of Organic Food Consumption With Cancer Risk”

Read the 2023 European Journal of Epidemiology Study, “Organic Food Consumption and the Incidence of Cancer in the Danish Diet, Cancer and Health Cohort”

Nature Reviews | “Is Early-Onset Cancer an Emerging Global Epidemic? Current Evidence and Future Implications”

Environmental Health News | “Nearly 200 Compounds Linked to Breast Cancer Found in Food Packaging, Tableware: Study”

Frontiers in Cancer Control and Society | “Comprehensive Assessment of Pesticide Use Patterns and Increased Cancer Risk”