Diet, Obesity, and Breast Cancer
Tracy Crane's research focuses on diet, specifically studying diet quality and cancer risk. Tracy also has more than 15 years’ experience developing nutrition plans for cancer survivors, many of them breast cancer survivors.
Listen to the podcast to hear Tracy discuss:
why obesity is linked to higher breast cancer risk
the new U.S. Department of Agriculture 2015-2020 Dietary Guidelines for Americans and what they mean for women who’ve been diagnosed with breast cancer, as well as women who want to keep their risk of the disease as low as it can be
how to make lasting changes to your diet
styles of eating that can keep your risk of breast cancer or breast cancer recurrence as low as it can be
Tracy Crane is a registered dietitian and senior research specialist at the University of Arizona Zuckerman College of Public Health.
— Last updated on June 29, 2022, 2:47 PM
Jamie DePolo: Hello, everyone, I’m Jamie DePolo. I’m the senior editor at Breastcancer.org. I’m thrilled to welcome Tracy Crane to this podcast. Tracy’s a registered dietitian and senior research specialist at the University of Arizona Zuckerman College of Public Health. Her research focuses on diet, specifically studying diet quality and cancer risk. Tracy has more than 15 years of experience developing nutrition plans for cancer survivors, many of them breast and ovarian cancer survivors.
Today, we’re going to talk about diet, obesity, and what the new U.S. Department of Agriculture 2015-2020 Dietary Guidelines for Americans mean for women who’ve been diagnosed with breast cancer, as well as women who want to keep their risk of the disease as low as it can be. Tracy, welcome to the podcast.
Tracy Crane: Thank you so much, Jamie, for having me.
Jamie DePolo: Oh, we’re thrilled. And it’s February now, so it’s relatively still a new year. There may be a lot of resolutions that people are still trying to keep out there. So let’s just get right into it. I know there’s a large body of research that’s linked obesity to higher breast cancer risk. And why is this? I know we talk about it a lot, but is it the actual number on the scale, is it the amount of body fat a woman has, is it the fat’s location? Are they all related? What’s going into that?
Tracy Crane: So I think it’s important that we think about -- with obesity, the research today is more focused on postmenopausal breast cancer risk. And so one reason is that adipose tissue, or fat tissue, is a good sources of estrogen. And before menopause, fat tissue really only is a minor contributor to estrogen levels. However, after menopause, it becomes a major player, adipose tissue does, fat tissue.
So obesity is associated with several exposures that promote cancer, and these include higher levels of insulin, inflammation, oxidative stress, just to name a couple of those. And so when you think about the number on the scale, total fat does matter, but more so it’s really the distribution of fat, and these are really highly correlated in women in the U.S. In fact, we do know that this is an elevated risk. But particularly fat that’s found around the middle section of the body, what we call central adiposity in research, or your waist circumference, this seems to be more pro-inflammatory. So when you think about inflammation, it appears to be more pro-inflammatory.
It’s difficult, though, to spot weight loss, so you can’t tell your body, well, I’m going to go do this exercise alone, and I’m going to lose just weight around my abdomen. So really, the goal with weight loss is, while if you see a reduction overall, you hope and likely will see reduction around the central part of the abdomen as well.
Jamie DePolo: Okay. Okay, that’s helpful. Now is diet a top lifestyle risk for breast cancer, or are there other things? I know smoking is a big one, alcohol’s a big one. How does diet fit into that?
Tracy Crane: So I am biased, because I’m a dietitian of course, so I have to put that disclaimer out there. But diet is a major driver in weight loss. It is important to exercise, and of course any modifiable behavior such of smoking is important. But we do see consistent evidence with diet. So beyond weight, it appears that with diet there’s this pattern. And the guidelines kind of go into this now, about overall dietary patterns. And so when you look at these large epidemiological studies like EPIC, or that was known as the European Prospective Investigation into Cancer, it really showed that eating a Mediterranean-type diet pattern reduced overall breast cancer risk.
And these key components of dietary patterns really are high vegetables, high fruit consumption. We know fiber -- I mentioned earlier in the podcast that really the adipose tissue and estrogen may be a link for that increased risk, and fiber we know can modify estrogen exposure. So I think that really thinking about the overall diet pattern is very, very important when we think about breast cancer risk. It’s not just one food, one nutrient.
Jamie DePolo: Okay. And as you said, one food doesn’t lead to an increase in cancer risk; similarly no one food is going to prevent cancer risk or lower it. And you’ve kind of just alluded to this with the Mediterranean diet. On our site, we tell women to eat a diet that’s rich in fresh, nutrient-dense foods and low in processed foods and foods with added sugar. Is that similar to what you talk to your clients about?
Tracy Crane: So with our clients we really try to focus on, again, the overall pattern and the quality of the diet. And I think it’s important, as you begin to think about changing your lifestyle, to pick one thing at a time, focus in on that, and see how that really starts to incorporate. I often tell my clients that many people can do anything for 3 days, right? You could ask somebody to eat nothing but carrots for 3 days, and they can probably do it. Likewise, they can probably even, with the right incentive, do it for 3 weeks.
But when we’re talking about a long-term change in your overall diet pattern or diet quality, it’s got to be something that’s sustainable and that’s doable. And I can write you a prescription, but if that prescription doesn’t fit into your everyday life, the odds of you continuing to do it are really not very good. So it is important to think about, globally and holistically, what does your lifestyle look like? Give it some thought. Pick one thing at a time. But we really do encourage a heavily plant-based diet, because it covers many of those things. It’s high in fiber chemicals, in antioxidants, it’s high in fiber, if you focus on a plant-based diet.
So that is really, if I had to pick one targeted area that we really try for, this is the first place. Now, if you came to me and said, “I hate vegetables,” I may try someplace else first. So again, it goes back to this very tailored approach of thinking about your life, and where can you start? And it’s important to remember, too, to enjoy your food, I think. I mean, I think oftentimes we get caught up in trying so hard to do everything right that we forget that food is meant to be enjoyed. So, finding that balance is really important.
Jamie DePolo: Okay. And I know, kind of going along with that, a lot of people say they do great when they’re at home but then when they go out it becomes an issue, because you may go to, I don’t know, a specific type of restaurant, whether it’s a food ethnicity, Italian, whatever, and they don’t feel like there’s anything there that’s appropriate for them to eat. Do you have advice for people who travel a lot, or for business or work or whatever, have to eat out a lot?
Tracy Crane: So what I tend to tell clients is that humans are creatures of habit for the most part. And so, if you’re flying on a regular basis, or you’re traveling, or you are going to work, and you usually have a set set of restaurants that you’re going to gravitate towards. And planning is your best friend. And I know it takes time out of your day, but if you could spend 15 minutes, every restaurant has a website where you can look up the food ahead of time, in advance.
And I oftentimes find if people can spend a little bit of time thinking about things ahead of time, it can really help you versus you’re starving and you go up to the food counter, “Oh my gosh, I’m so hungry. What can I get? The plane is boarding, I don’t have time to think.” And so when you can give it some thought ahead of time, you can make these better food choices.
And back to a previous comment that I made, with the plant-based diet you probably never are going to go wrong if it’s predominantly vegetables. A salad is usually good. Little tips of portion control with the dressing, thinking about eating a sandwich with lean proteins, turkey versus something that’s fried, a fried chicken sandwich.
So there are things you can do. And again, I think if you can give it some thought ahead of time then you’re not in the pressure of the moment to think about, “what can I eat,” and that can be very successful for people, is kind of pre-planning.
Jamie DePolo: Okay. That makes great sense. Now, talking specifically about the guidelines, I read the new ones. I found the way they were presented a little confusing online, and was fairly familiar with the old ones. Now to me they look really similar. I’m not an expert. They seem very similar, except that it was really, to me, more what they didn’t talk about. So they don’t talk about limiting cholesterol any more. So, what does that mean? We’ve all been told for so long, cholesterol leads to heart disease, and then studies have come out showing, no, there’s really not that association, it’s okay to eat eggs. As a professional, what are you telling your clients about that?
Tracy Crane: So -- they did take out the specific guidelines around cholesterol. However the three Ss are there, right: so watching your salt intake, the new added sugar, and your saturated fat. And we know that saturated fat is a very large driver of cholesterol. So I don’t think it’s really gone per se, they’re still targeting it with the saturated fat recommendations. And I really think that, again, it goes back to this overall pattern of a diet. You don’t want to have a diet that’s very, very high in any one thing, for that matter, whether it’s processed food or high in meat intake.
So again, it comes back to that overall quality. But you’re right, things don’t look too different, other than the cholesterol. But I think it’s still in there. I think that they are coming at it from really a saturated fat standpoint. But again, I think it’s important to look at the quality, and what type of fat are you eating? So it comes down to the different types of fats.
Jamie DePolo: Okay. Okay, that’s helpful. Now you’ve very much emphasized a plant-based diet. If I’m a diagnosed woman, I’m out of treatment. It’s in my rearview mirror. I want to keep my risk of recurrence as low as I can. Is there a best way for me to eat, and is that different or the same than for, say, a high-risk woman who hasn’t been diagnosed, but also wants to keep her risk low? I guess I’m wondering if there are any differences between those groups.
Tracy Crane: So I think, what I tell women regardless of whether they want to prevent the risk of recurrence of disease or prevent the risk of an initial breast cancer, or any type of cancer, for that matter, really it boils down to, again, it’s a lot of high vegetable consumption, higher in fiber, lower in fat. I do think there’s evidence supporting a lower-fat diet, particularly for breast cancer risk, in both the primary prevention as well as the recurrent risk. Again, I think I’d go back to sustainability for both of these women that are looking at breast cancer in different places, whether it’s prevention of recurrence or prevention of initial disease.
And again, it’s got to be something you can sustain, because we know that long-term, changing it overall is the best. So thinking about your lifestyle individually, or maybe, really, looking at it globally. Where could I maybe fit in another serving of vegetables? And I also find it’s easier for people to think about behavior change when they look at it from the standpoint of adding something. So it’s easier to add than it is to take away. So I often will challenge people to think about adding some vegetables to their lifestyle, to their diet, versus taking something out. And oftentimes that’s pretty successful.
Jamie DePolo: Well, that makes sense, because then you’re not deprived, in air quotes, you’re adding things.
Tracy Crane: That’s right. So again, I think the takeaway message is trying to reduce your intake of processed foods as much as possible, because it does usually have higher levels of saturated fat, higher levels of added sugar, and really replacing those things with more wholesome vegetables, whole grains, and that sort of thing.
Jamie DePolo: Okay. Now, I want to go back to red meat and processed meat. There was a study that came out last year, it was slightly controversial because of the way it was conducted -- should somebody who’s been diagnosed or somebody who’s really trying hard to keep their risk low avoid either one of those groups? I mean, just from my limited knowledge it seems like processed meats would have more strikes against it than just red meat. If you have a good, high-quality red meat there may not be anything wrong with that. But certainly you are the expert.
Tracy Crane: So the evidence supporting the association between red meats is highest with colorectal cancer. There is evidence with breast cancer, an associated risk. Eating processed food in general, I think, is not ideal for anybody, regardless if they’re a cancer survivor or not.
However, again, I go back to enjoying your food. And if something you have always loved is eating a steak perhaps, once in a while, a high-quality cut of meat, and it’s not a routine occurrence but maybe on a special occasion, maybe it’s something that you have a tradition around. Again, you’ve got to go back to quality of life, also. And if that’s something you really enjoy, once in a while, I think it’s acceptable to have that nice meal and share it with somebody, or even just for yourself.
But on a regular basis, I think that people should consider limiting their intake of processed meats, particularly, and red meats, yes.
Jamie DePolo: Okay. And just to clarify, because I know people have asked me this, when you say processed foods, what does that mean?
Tracy Crane: What does that mean to me? So to me, that means that things that have had preservatives added. Let’s just think about the context of the study that came out, the one that you spoke about, with processed meats. And processed meat’s one that has been cured with nitrates or nitrites, and those we certainly see an association with cancer risk with things that have been cured or preserved…
Jamie DePolo: So then it’s like lunch meat, bacon…
Tracy Crane: Lunch meat, bacon…
Jamie DePolo: …cold cuts, all those things.
Tracy Crane: Yes. You can oftentimes find things that are nitrate-free or nitrite-free, but those additives seem to have an increased association with risk.
Jamie DePolo: Okay. And one sort of ruler, I guess, I used for that is, I look at it. Is it a packaged food, does it have more than two or three ingredients? Does that sound fair?
Tracy Crane: Yes, I think that’s fair. And I also think it’s important to remember that the food labels are your friends. Look at the food label. The food labels give you ingredients, and they are listed in order of quantity. So if there are three or four things that you cannot pronounce on that food label and they are very high up on the list, it’s probably not as good of a selection as something else that has what I call clean ingredients, things you know, things you’re familiar with, and that you would want to put in your body.
Jamie DePolo: Okay. Okay. Now, do you think that most people are going to change the way they eat because of these new guidelines? I can’t even say that without laughing.
Tracy Crane: So I would love to say that, yes, everybody’s going to read these. First of all, that everybody’s going to read them. Second of all, that yes, I would love to say that people are really going to change. But do I think… I think it takes more effort and more intervention throughout this country, and policy change, to really help people change the way that they’re eating and really interpret these. I read a recent study that you have to put things into perspective for people. This particular study I was looking at put the calorie content of different foods in a fast food restaurant.
And they wanted to see, if people could see the calorie content, would they make different choices? It turns out they didn’t. But when they went back a few weeks later and they put up how much time they would have to exercise, that changed their behaviors. And it’s because people don’t know what they don’t know. And so we can’t expect people to, say -- make a recommendation that you to need to limit your added sugar. Well, what does that mean exactly?
So I think we have to put it into a context for people that is meaningful and understandable.
Jamie DePolo: Okay. I was going to ask you about alcohol. Now I thought it was interesting that the guidelines actually, my understanding is, they allow more alcohol than what a lot of research has shown for breast cancer risk. Do you have any insight into that, how that came about, or, I guess, what is your position on alcohol?
Tracy Crane: So my position on alcohol with cancer survivors is that if you do not currently drink alcohol on a regular basis, there is no evidence to suggest you should start drinking alcohol. If you do enjoy an alcoholic beverage on an occasional basis, I think there’s nothing wrong with that. Meaning one drink per day, maybe two, usually one drink per day of an alcoholic beverage. I think moderation is key.
There’s nothing to say you should start drinking it for the health benefits. However, again, I go back to that comment on quality of life. And if you can unwind at the end of the day, let your stress go, and you do that with a glass of wine, as long as it’s an appropriate serving size -- I think it’s important for people to recognize serving size -- I think that that can be something that can be worked into your everyday life.
Jamie DePolo: Okay. Perfect. And then one last question. The guidelines also, much like the previous ones did, also say now, everybody should follow the exercise requirements. I don’t remember the official name. And everybody clearly has to move along with eating well. And are there any studies or any evidence showing which percentage of which, whether it’s diet or exercise, goes into weight and weight loss? Because I know people have asked me that, I’m like, “I really have no idea.”
Tracy Crane: So traditionally, people lose more weight initially with the diet component. But for weight maintenance, you really do need that exercise component to maintain the weight loss long-term. So I think the two go hand in hand. There have not been enough studies in cancer survivors that have had weight loss as the outcome that have been a combined exercise and diet research project.
I think there are some large studies in the works that are coming down the pipeline -- I don’t want to speak too much about them yet because I’m not for certain -- but I think that that is a definite gap that we have in cancer prevention right now, is that there’s not been well-designed trials that really combine the two and look at outcome and weight loss.
So to answer your question, I think they go hand in hand. I think that most people and most researchers would tell you that initially the diet is really an important component to weight loss, but you do need the physical activity to maintain that long-term weight loss, it appears. I would also say that, women will often ask me, they’ll say, “Well, which one should I do? Which one is the best?”
Jamie DePolo: Which one meaning, which diet, or which…
Tracy Crane: Well, any of it, but I’m thinking more specifically about exercise. “Which exercise should I do? I’ll do it.” And really, I tell people, “The one you’ll do.” It doesn’t matter which one. And I think it’s important if you’re not feeling good, particularly depending upon where you are in treatment, if you’re recently out, if fatigue is a problem, lymphedema can be a problem, just reducing the time that you’re sitting can be effective.
I’ve had clients who have told me that they put on music and dance around the house for 10 or 15 minutes. That’s perfect! It’s not structured, but it’s what that person enjoys doing. So I think that’s an important point, that there’s no one prescription for everybody. You really need to think about it in the context of your lifestyle and what works for you. There’s hundreds of different vegetables out there to choose from, there’s lots of different exercises, pick one that works for you.
Jamie DePolo: Great. Tracy Crane, thank you so much. This has been so helpful.
Tracy Crane: All right, thanks so much.