You Are What You Eat: Good News About Cancer Edition

Alicia: This is the Good News About Cancer. I’m Dr. Alicia Morgans. 

Chuck: And I’m Dr. Chuck Ryan.

Alicia: We're oncologists, and we've spent our careers working to understand cancer. We believe that there's more progress now in research and treatment than ever before, and we're here to share that with you.

Chuck: In each episode of this show, we talk with one of our colleagues about a promising development in oncology. We'll break down what's new, why it matters, and how it points the way forward.

Mathilde:  We are able now to quantify the proportion of our risk factors that come from nutrition, and that could lead to avoidable cancer cases.

_________________

Alicia:  Well, I can't believe I'm saying it, but spring is finally here. 

Chuck: Amen. Thank you for that. And I bet you and your family are looking forward to not only the spring, but the summer when you can get out to baseball games, soccer games, maybe some summer picnics, and of course, thinking about those types of events, one can't help but think about the great food that you get to eat at those types of things.

Alicia: Absolutely. I definitely love a good picnic, but you know, as I think about it and all of the foods that we eat, it's important for us to remember that there can be a connection between the foods that we eat, especially the ultra-processed foods – those that are preserved in special ways – and the way that those exposures, those foods that we eat, can potentially be associated with the development of cancer.

Chuck: Hugely important and I think underappreciated by the general public. We all know that smoking is associated with cancer. We're going to be having a podcast about that, of course – those rates are way down. 

But people may be a little bit less aware of how exactly the extent to which the food we eat, and what types of food we eat, may impact our risk of cancer.

Alicia: I think it's so exciting too that the science around the exposures to these different products, these different additives to our food, has really matured over the last number of years. 

Chuck: Absolutely. 

Alicia: And has given us the opportunity to not just imagine that there are connections, but to really show that with rigorous investigations. And we had the opportunity to speak with somebody about this, to understand it on a much deeper level.

Chuck: That's right. Mathilde Touvier is head of the Nutritional Epidemiology Research Team at the French National Institute for Health and Medical Research. Her work is part of the French Network for Nutrition and Cancer Research. 

Alicia: Let's talk to her.

_________________

Chuck: Dr. Mathilde Touvier thank you so much for joining us from Paris today on the Good News About Cancer podcast.

Mathilde: I'm very happy to be with you today and to talk about the research that we conduct in our laboratory.

Chuck: We wanted to focus on why we would be talking about nutritional additives and various factors that are shown to promote cancer on a podcast called the Good News About Cancer. I see it as a positive because we're learning so much, but I want you to walk us through your work, what your findings are, and how they might extend to a broader population.

Mathilde: In our laboratory, we explore all the relationships between nutrition and health, in particular cancer risk. 

And we work on all the dimension of nutrition, the dietary patterns, food additive, exposure to pesticides, or meal timing, and the way they might impact our risk of developing cancer. 

For decades now we have more and more evidence accumulating, showing that our diets have an impact on the development of cancer. This is something we ignored before because, uh, we thought that our diet only acted on obesity or cardiovascular diseases, but now we know, they are also major risk, but also protective factors for, cancer risk.

Alicia: So tell us about some of those findings. What have you and your colleagues learned about the positive and negative effects of the food we consume, particularly when it comes to cancer risk? 

Mathilde: So the elements for which we have the highest weight of evidence are regarding deleterious factors, processed meat or alcohol or obesity as such, which is caused by too much, uh, sugary drinks and so on. And obesity, as such, is a risk factor for 12 cancer locations. Alcohol of course, also part of diets, which is a big risk factor for several cancer types.

And on the contrary, we know now with strong level of evidence that diets rich in fruits and vegetables, dietary fibers, and also physical activity are really important protective factors for several cancer types.

So these are the elements for which we have dozens of epidemiological studies conducted during years and years on, uh, several hundreds of thousands of people. And also mechanistic studies coming from studies on animal models or cellular models explaining the mechanisms beyond all that. 

And so we are able now to quantify the proportion of our risk factors that come from nutrition, and that could lead to avoidable cancer cases. And, the good news, if you put it that way, is that yes, we could avoid, the exposure to these factors, because we can choose the food that we, we eat and we can influence policy makers to have better food offer to prevent cancer.

Alicia:  I'd really like to hear more about exactly how you're studying the elements of our diet and how they can impact cancer risk.

I know you've been working on a cohort study, which is an important way to investigate these kinds of questions where we follow a large number of people over time. Can you explain what you've been doing and how this study operates? 

Mathilde: We are leading a big cohort study called Nutrinet Santé, which gathers more than 182,000 participants. It's a cohort which started in 2009, and people regularly fill dietary records in which they declare all the foods, the beverages, that they consume. They also declare the commercial brands of food products.

The strength of the cohort study of Nutrinet Santé is that we collect a very detailed information on our daily diet and nutritional exposures. Where other cohort studies on nutrition will use, for instance, frequency questionnaires. They will ask people, okay: How many times, during the last month or last week, did you, uh, drink a soda or did you eat a chocolate cookie for instance? We really have a higher level of detail in Nutrinet Santé, because we really record every food, and beverage consumed, their commercial names and brands. 

So you have all the ingredient list, the presence of food additives. So we have a huge amount of information about what they eat on a daily basis.

And we also have lots of questionnaires in between, in which we ask questions about their consumption of organic food, dietary supplements, the way they cook their food. Do they use, for instance, the, the, the, their ready-made meals in plastic trays and put them in a microwave with the risk of contaminants coming from packaging and so on?

So we have many, many information on all these factors, and we follow participant in time, and record the appearance of cancer cases and other chronic diseases.

We have a physician in the team who validates the declared health events, cancers and so on, with medical records and things like that. And we also have a linkage with the medical administrative databases to retrieve also other health information. 

And this allows us as epidemiologists to study whether the fact of eating more or less dietary fibers or aspartame or other food additives is associated with a higher risk or lower risk of cancer or other chronic diseases. 

So it's a very powerful tool. It's public research and every citizen who has at least 15 is aged at least 15, and with an access to the internet can participate to the study.

Alicia: That's wonderful. So people could even participate after they listen to this podcast, which I think is very, very exciting. 

I wonder if you could walk us through one of the evaluations and one of the findings that you had within this cohort so that people can get a sense of how, how this information actually leads to the findings that you ultimately have.

Mathilde: Yes. So when participants will declare, okay, I drank one bottle or one can of this type of soda, specific with a specific brand. We retrieve the information about, okay, in this beverage you ate aspartame, acesulfame potassium, citric acid, the caramel dye and so on. 

And we also made, laboratories analyze the content in terms of food additives to have specific doses of food additives, which are not labeled on the packaging. So we were able to quantify the, the daily exposure. And this was used to, correlate the level of exposure to these food additives, to the risk of cancer, for instance. 

We showed association for several cancer types. So overall are breast cancer, prostate cancer, depending on the food additive studied. For nitrites, artificial sweeteners and more specifically aspartame and acesulfame potassium, which are the two most frequently used, artificial sweeteners in France.

We also had several, showed several results on um emulsifiers. So carbonate cellulose or mono and di glycerides of fatty acids, carrageenan that we find in yogurts or fresh cream and things like that. Um, and also several associations with cancer types. And we are now studying food additive colors, dyes, and also the mixtures of food additives. We've published a first paper on type two diabetes risk. We are studying other outcomes, such as cancer, currently. 

This is what we do in terms of observational epidemiology in the Nutrinet Santé study.

Chuck: As I was reading through your work, I was struck by some of the relationships between food and cancer that weren't obvious.

Processed meats I would think might be a little bit more obvious to many people, but there are certain additives and whatnot that might appear in foods that otherwise might appear healthy, but might be surprisingly linked to various cancers. Can you tell us a little bit about that?

Mathilde:  Yes, indeed. When we think about ultra-processed food, sometimes we think about junk food, sodas or hamburgers and things like that, but in fact, even foods with a relatively healthy nutritional profile, such as some yogurts for instance, or crispbreads, whole grain cereals, or some types of fruits or vegetable-based preparations. 

Um, also some – I think you have them also in the US – there is a big trend currently trying to replace meat products, which indeed should be limited in our diet by alternatives, with some very good alternatives based on legumes and so on. But also other ones which are just mixtures of food additives, emulsifiers, and so on.

And people who consume these products think that they are healthy because okay, they don't have so much salt, sugar et cetera in them. But in fact, they are full of potentially hazardous food additives. So yes, it's not just junk food as we usually figure it.

Chuck: You know, we know with smoking, for example, that we talk about lifetime pack years. It's chronic exposure, duration of exposure, that leads, for example, to a greater risk of lung or bladder cancer. 

The question I guess I would have was somebody in their fifties or forties or thirties, they're hearing this data and we're finding out this news about nutrition and various food additives and cancer risk.Is changing nutrition and removing these additives and changing your diet always going to be associated with a reduction in the risk of cancer? Or is there a lifetime dose, if you will, like we see with smoking?

Mathilde: This is a very good question and, unfortunately for the moment, we don't have the data to support exactly, the windows of exposure that are, very important or for instance, for tobacco. There are many studies that say: okay, after years without smoking, you are now in the same level of risk as if you had never smoked and things like that. Because we have many, many epidemiological studies about tobacco and cancer risk. 

For food additives, Nutrinet is the first epidemiological study published. So we definitely need other types of studies like that to be able to answer this very important question, but probably what we see in nutrition and cancer more broadly is that yes, it's never too late to start to eat correctly, and if you reduce little by little your exposure to these food or food additives, probably you will already see benefit. And so yeah, don't, don't think it's too late. 

Alicia: I love that within the Nutrinet Santé cohort, you are not just studying the association between exposures to different, to different items, different ultra-processed things, et cetera. You are also looking for mechanism, as you said, and mechanism is really the reason, the biology underneath why there might be this association. 

Which is so important in science because if we understand the reason why something is happening on the very basic science level, we can have more control perhaps on intervening even in ways that, of course involve diet changes, but also even more than that, and it helps us understand the cancer better too, which is I think really important from a just general cancer standpoint.

Can you tell us how you came up with this idea and how you were able to support the scientists that really investigate the mechanism or the reason why these different chemicals, preservatives, and other things might be associated with different cancers?

Mathilde: Yes, this is a very important aspect. When we want to reach a strong level of evidence saying: okay, tobacco gives lung cancer, and we would like to say, okay: ultra-processed food gives some types of cancer. 

We need to associate many types of studies. So the observational cohort study showing long-term association is very important, such as what we do in Nutrinet. The mechanistic epidemiology with doses of biomarkers and, showing the pathways of, mechanism action, it's very important too. 

And the work that our colleagues do also in terms of toxicology or experimental research, working on the laboratory analysis in cellular models or animal models are very important too. In Nutrinet Santé something, for instance, we work with colleagues who take the results from Nutrinet. They say, okay, we see that in real life participants eat these type of food additive mixtures with this type of doses. 

And they translate these exposures in animal models to test many things that of course we are not allowed to do in human participants. And it really brings additional information regarding the causal mechanisms beyond all that.

And with all these types of studies published together, this is how we do to build a strong level of evidence and to really understand causal associations and causal mechanisms. 

Alicia: It is so important because with that, we not only understand why something's happening, it really cements our understanding that it is happening because associations that we can see with these different exposures are only part of the story. They tell us what we should be putting our interest into. And it's really understanding, as you said, the dose response, how much exposure you have and how likely you are to get a certain cancer. That's a piece. And then also understanding just the basic science: How did exposure to aspartame cause this particular cancer? So, so interesting.

One other thing that I really wanted to bring out from what you've been talking about is that this information that you're able to discover allows us to modify that risk factor. I think we've heard about modifiable risk factors in what you've said and what Chuck said

And that means that we as individuals have agency, have the power to affect our exposure to these things, and then have the power to hopefully reduce our risk of cancer, which is really the good news here. Understanding the cause, and understanding how we can affect it and reduce that risk is so powerful. 

Can you, you speak to, a little bit, how this might happen in real life? What does a person do with all of the information that you've come up with when they're trying to just start their day, reducing their risk from these cancers?

Mathilde: So, in, in the practical way, for every citizen, the thing would be when you choose a food for your health to prevent cancer and other chronic diseases, first thing, look at the nutritional profile.

This is why, in France, for instance, and in eight countries, we created the Nutriscore, which provides the information of a nutritional profile of food, even for products sold in the US. And so, here it's a summary of salt, saturated fat, salt, sugar fibers and so on. So, with a better Nutriscore, you will lower the risk to be exposed to, to these high fat, high salt, high sugar products. 

The second point is look at the ingredient list. If you are in the, supermarket and you see in the same. type of, shelves of supermarkets, two products, one with a very long list of many additives that you don't have in your kitchen.

You don't exactly know, why they are here. And after that, in the site you have the same type of product with a very shorter list. And no food additives prefer this one. It does not mean that all food additives will cause cancer, but as a precautionary principle and given all the signals that are accumulating, it'll be preferable to do that.

And so this is also very important for our policymakers to change the environment in which we evolve. To make those products nutritionally healthy, low to minimally processed, and organic products, the most, more affordable and the more accessible to everybody. And also to regulate the advertisement, the marketing, of products for children, which are very much the target of, aggressive marketing for these ultra processed food, foods with, full of additives and so on. Also this regulation of all that is very important and not just put all the pressure on consumers and patients for their own health. It's, we, we have to do both things, I think.

Alicia: Well, thank you so much for your time today. I think this really reinforces our understanding of what different preservatives, additives, and food types can actually do in terms of our risk of cancer. And the good news here is one that we should definitely take to heart.

We have the power to make these decisions, and we also have the power to talk with our policy makers to try to make sure that everyone will have the ability to do what they can to reduce their risk of cancer, to seize this good news by seizing their nutrition. 

Mathilde: Thank you very much for having me today. I was really happy to be with you.

______________

Chuck:  You know, I want to make a point that many may not realize about the importance of epidemiology and epidemiologists in our field and in the overall progress we're making against cancer. Can't be understated. 

Alicia: I agree. I think we can consider epidemiologists when we think about exposure to infectious disease. And many of us remember how we learned about epidemiology in the context of the COVID pandemic. But epidemiologists investigate all kinds of things, including how exposures to things like preservatives and other highly processed ingredients can affect our risk of cancer. 

Chuck: So much of the information that we can get out there today in the world comes from, let's just say, less reliable sources, or sources where the data has been collected with less scientific rigor. And so you can pick up your phone, you can look at any social media, and you’ll get some recommendation about how you should be eating or not be eating today. 

But folks like Dr. Touvier and her colleagues, by looking at huge numbers, by applying the mathematical and statistical rigor, are I think the definitive types of sources, and I think, have the authority to speak with confidence about the associations between diet, ultra-processed foods, et cetera, and cancer outcomes. 

Alicia: I agree. And as Mathilde said, we could make small changes, and even with those small changes, we can positively impact our risk for cancer. And I'm just glad that we had the opportunity to learn more about this innovative and incredibly important work.

Chuck: And I can't wait to hear about your family picnics. 

Alicia: I'll keep you posted. 

Chuck: Well, thank you for listening to the Good News about Cancer. I'm Dr. Chuck Ryan at Memorial Sloan Kettering Cancer Center in New York. 

Alicia: And I'm Dr. Alicia Morgans at Dana-Farber Cancer Institute in Boston. The views we express on this show are our own and do not represent the views or opinions of the institutions where we work. 

Chuck: Thanks to Lilly for support of the show. Our production partner for this series is CitizenRacecar. This episode was produced by Anna Van Dine with post-production by Alex Brouwer. 

Alicia: And there's a whole lot more good news to talk about. So make sure you subscribe to this wherever you listen to your podcasts. And if you like the show, share it with someone you think might find it interesting. 

Chuck: And we'll be back again soon with some more good news about cancer.