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Fiber vs. Breast Cancer

Inadequate fiber intake appears to be a risk factor for breast cancer, which can explain why women eating plant-based diets may be at lower risk.

April 3, 2013 |
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Acknowledgements

Images thanks to Kelidimari via Wikimedia Commons and *Zoha.N  

Transcript

A recent editorial in the journal of the American Association for Cancer Research starts out “There are far too many breast cancer survivors,” by which she means it's great that women with breast cancer are living longer, but lamenting the fact that the number of women getting breast cancer in the first place isn't going down. 'A million women every year. As with any other epidemic, identification and aggressive reduction of any reversible risk factors must become an immediate priority. One such risk factor appears to be inadequate fiber consumption. For example, this new study out of Yale. Among pre-menopausal women, higher intake of soluble fiber (highest versus lowest quartile of intake) was associated with a significantly reduced risk of breast cancer, 62% lower odds. And when they just looked at younger women with the hardest to treat tumors, the estrogen receptor negative tumors, then those eating the most fiber appeared to have 85% lower odds of breast cancer. This is what's called case-control study, where you compare women who already have disease to those that don't and you ask both to tell you what they used to eat. And so how they get these statistics is that the breast cancer patients were significantly less likely to report eating lots of plant foods, the only natural place fiber is found. The reason it's important to understand how they arrived at their conclusion is that maybe it's not the fiber at all that's what's so protective. The reduced risk of breast cancer associated with dietary fiber intake observed in this study may in fact indirectly reflect the effects from other dietary nutrients, and thus dietary fiber here may simply act as a marker for other exposures which have been linked to a reduced risk of human cancer as well, such as folate, phytochemicals, carotenoids, vitamin C and E which are also like dietary fiber found in plant foods, such as vegetables, fruits, and pulses (legumes, beans peas lentils soy), as well as in grains. And look, if you're eating more plants, you may be eating fewer animals. An increased consumption of fiber from foods of plant origin (such as vegetables, fruits, and grains) may reflect a reduced consumption of foods of animal origin. A combined analysis of a dozen such studies published in the Journal of the National Cancer Institute show they all found pretty much the same thing, a consistent, statistically significant, association between breast cancer risk and saturated fat intake, which is mostly from cheese and chicken, and consistent protective effect for a number of markers of fruit and vegetable intake was demonstrated; such as  , which like fiber, is basically only found in plant founds.  Every 20 grams of fiber a day was associated with a 15% drop in breast cancer risk. Case control studies are susceptible to something called recall bias, though, since they rely on people's memory. If people with cancer are more likely to selectively remember all the bad things they ate, since they may be feeling responsible for their condition, it could artificially inflate the correlation; so prospective cohort studies may provide stronger evidence. That's where you take a bunch of healthy women and follow them and their diets over time to see who gets cancer and who doesn't. By 2011, 10 such studies had been done, and the same thing was found. Every 10-g/d increment in dietary fiber intake was associated with a significant 7% reduction in breast cancer risk. Pretty much the same the other studies found, remember, 15% for every 20 grams? This has important public health implications. That was 2011. By 2012 we were up to 16 prospective, or forward-looking studies on dietary fiber and breast cancer, and they found the same thing.  But for the first time it showed a nonlinear response. The more fiber you eat the more benefit you appear to get. American women eat a little under 15 grams of fiber a day, less than half the minimum daily recommendation. Maybe that's why vegetarian women may have lower breast cancer rates, more plant foods equals more fiber. But vegetarians only seem to be averaging about 20 grams a day. So one might really have to venture out into vegan territory, off the chart at 47 grams a day, or a really healthy vegan diet (59), or eat lots of vegan thai food averaging 68.7.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring watch the above video. This is just an approximation of the audio contributed by Jonathan Hodgson.

To help out on the site please email volunteer@nutritionfacts.org

Dr. Michael Greger

Doctor's Note

Yes, but how might fiber intake lower breast cancer risk? Basically the same way Fiber Lowers Cholesterol. See my video Relieving Yourself of Excess Estrogen.

Mushroom consumption (Breast Cancer vs. Mushrooms), nuts (Tree Nuts or Peanuts for Breast Cancer Prevention?), green tea and soy (Why Do Asian Women Have Less Breast Cancer?), crucifers (Broccoli Versus Breast Cancer Stem Cells), and greens (Preventing Breast Cancer By Any Greens Necessary) may be particularly protective.

The comparison of fiber intakes by diet could certainly help explain why vegans are such regular people (see the ending of Prunes vs. Metamucil vs. Vegan Diet).

Please also check out my associated blog posts for some more context: Flax and Breast Cancer Prevention 

If you haven't yet, you can subscribe to my videos for free by clicking here.

  • beetsbeansbutts

    Wow, those vegan Thai people.

    The statistic on vegetarian fiber intake really surprised me. Only 20 grams!

    I think there is a correlation with my high fiber diet and farting up a storm. I know Dr. Greger addressed the gas issue. In my experience that is still a big reason why many people avoid high fiber foods.

    • b00mer

      Haha! How long have you been vegan? Or are you vegan?

      In hindsight, my gas level has actually decreased significantly since going vegan. I don’t know if it’s because I’m actually eating more of the presumably offensive foods (cabbage, cauliflower, etc) on a regular basis and have gotten more used to them, or if it’s that I’m not eating them in combination with meat left to putrefy in my gut. Don’t know, don’t really care. I guess I still toot, but it’s like it’s just air, no smell. That probably sounds like the most conceited high falootin vegan comment ever and may be tmi, sorry!

      Anyway, perhaps you’re just sensitive to certain foods? Have you tried an elimination diet experiment? Or conversely eating the crap out of the potentially offending foods to see if your body builds up a resistance of sorts? Best of luck! And at least farts are better than cancer. All the best.

    • b00mer

      One more thing: I find I can eat an unlimited amount of naturally occurring plant fiber with no ill effects, but if I eat any of the “high fiber” cereals/breakfast bar products, where they add some sort of isolated refined fiber source, instant bloat.

    • http://www.facebook.com/profile.php?id=670735069 Tan Truong

      Since going vegan, I don’t know if I have more or less gas, but I do excrete a lot more, which is expected.

  • Plantstrongdoc

    This is important info – I would like all women to know this – and take action. The answer to fighting breast cancer is not screening and early detection, but to avoid it in the first place. A lot of problems with screening programs, but that`s another issue.

    Glad that there are a lot of survivors because of advanced treatment, but there are high morbidity – lymphedema after surgery, chemotherapy-related cognitive dysfunction etc.

    “Health magazines” promote milk to women to avoid osteoporosis, popular diets are high meat protein (which probably increase the risk for osteoporosis).

    Western diet sucks…….

  • Thea

    This is a *great* presentation because it packs so much compelling information in such a short little video. Thanks!

    Rant: What hit me so strongly after watching this video is how much this video and all of the studies it references so clearly backs up/repeats what researchers learned in the China Study decades ago. And yet you still get people like a recent poster on this site who actually think the China Study has been “debunked”. Argh. In fact, study after study after study after study… continue to build upon and support the conclusions of the China Study.

    It becomes the same argument you have with people who talk about Human-Made Global Climate Change being “debunked” or President Obama being born in Kenya. People believe what they want to believe regardless of the known, sound science or facts presented. It’s exhausting thinking about the lack of education and critical thinking skills found in humanity (especially Americans?).

    OK, rant over.

    While exhausting, it does highlight why sites like NutritionFacts are
    so important. I’m grateful not only to Dr. Greger for donating his time
    for this site, but also the great posters who help answer questions
    with quality information. I hope that this site will be able to get enough donations to keep running strong.

    • Plantstrongdoc

      I find it interesting that (as I see it) the discussion (in balanced science) is whether meat is harmful or neutral, and whether vegetables, fruit and legumes are healthful or very healthful. All (sciencebased) public health authorities recommends less meat, and more fruit and vegetables. Not the other way round. Why not go all the way…..

      • Thea

        re: “Why not go all the way.” Exactly. As the graph in the video shows, you can make great strides in your diet (say getting 20 grams of fiber) relative to people who eat SAD and still not get dramatic health benefits. The health benefits / risk reductions are a sliding scale depending on how far you go. But that sliding scale is not always linear. If you really want to reduce that breast (or pick your popular ) cancer risk to practically zero, the way to do it is with a whole-plant food diet, or “go all the way”.

        re: “All (sciencebased) public health authorities recommends…” If you haven’t already read the The China Study, I highly recommend at least reading the last part of the book. You will get a huge education on the politics of nutritional science. It explains a lot on how our recommendations have traditionally been formed. Shocking stuff. (At least it was to me. Blew me away.)

      • b00mer

        Agreed! The psychology of eating is so interesting. I always say to people, hey, the majority of *everyone’s* diet should be vegan. Fruits, veggies, beans. Right? And people are forced to agree.

        And if you were to show most people a 95% plant based diet, they’ll think it’s super duper healthy, but if you go that extra five percent, they get scared.

        It’s like if someone told me that if I eat really healthy, I could probably get away with smoking a few cigarettes a day. Well fine, but no thanks. But people have a hard time believing that I don’t want the metaphorical cigarettes.

        • Plantstrongdoc

          Good point

        • Meditating

          These naysayers aren’t scared. They just don’t want to give up their irresponsible behavior and “debunking” science is what they must do to justify their actions. Otherwise they have to admit their choices are stupid.

          I have been this person. It is hard to give up foods you enjoy, especially when high doses of salt, sugar, and fat cause your brain to fire off dopamine. For many, our unhealthy choices catch up with us and we make changes out of desperation.

          • Plantstrongdoc

            Yes, now and then, a study shows that there are no healthbenefits from eating fruit and vegetables – and everybody is happy and continue with SAD – but when you examine the study just a little, you find that one group was eating SAD + 2 servings of fruit or vegetables and the other group was eating SAD + 4 servings of fruit or vegetables (and ketchup was counting as a vegetable) – of course there is no difference in such a stupid study, but is shows what people want to hear, and it hits the newspapers.

          • Meditating

            Dr. Michael Klaper with True North Health lectures that people are always eager to accept good news about their bad habits but quick to reject anything they don’t want to hear.

            I was amazed to read the press release issued by the Spanish government regarding their recent study on the “benefits” of olive oil. The press release reported the study was stopped early for ethical reasons because the olive oil benefits were so prevalent.

            What they did not mention is that there was a third group in the study where most of the olive oil was replaced by nuts and seeds as a source of fats. Those whole foods significantly outperformed the olive oil (something like a five-fold increase) while the olive oil only benefited cardiovascular health by a tiny margin.

            I suspect the study was stopped and the third group ignored because it actually proved olive oil is a bad health choice, unless perhaps you are substituting it for animal fat. What else can you expect when the study is done by a government with such a clear conflict of interest. I only read one report which stated that Spain had engineered and financed the study.

          • b00mer

            I guess everyone’s reactions are different. I do actually remember a somewhat fearful feeling when I first decided to go vegan, because at that point in time I wasn’t aware of all the wonderful foods I would be adding to my diet. I was only thinking “I can’t eat this, I can’t eat that…”

            And we should remember that there are still people out there who genuinely think we eat nothing but lettuce and tofu, and that this is no doubt playing a role in their aversion to our diet.

            I personally think one of the best forms of outreach is showing people your food! I do believe I see a twinkle of jealousy in the eyes of those eating their greasy cafeteria sandwiches and Lean Cuisines at work.

            My MIL also seemed absolutely enamored when she saw my bean rice veggie bowl the last time we were over. I was just putting together the scraps I could find, but she thought it was just the most creative and delicious looking thing ever. They’re very meat n potatoes type.

            Bottom line we should never underestimate anyone’s potential to go vegan! Sometimes people really just need exposure to it.

          • Meditating

            I agree that exposure to veganism educates people and anyone can go vegan. But my comment was directed at why people ultimately debunk a history of scientific evidence.

            When you talk to those who dispute that a plant-based diet will radically change one’s health, careful examination reveals they just don’t want to change their behavior because they believe it will be less pleasurable or inconvenient. This includes thinking you will not enjoy a vegan diet.

            While some people yield immediately to the scientific data, it is difficult for most people to change their behavior based on the degree of pleasure or convenience they perceive in their current choices when compared to alternatives.

            Greed and/or fear of loss are two instinctual motivators. These traits are a survival mechanism. They are become a character flaw when we do not change our behavior when the behavior has negative ramifications. Such circumstances tend to occur in situations where modern man has altered the terrain of his day-to-day life like diet or energy use.

            I initially thought recycling and paying attention to my carbon footprint would create many inconveniences but it wasn’t a bother at all. I found changing to a vegan diet to be a much harder and longer process (12 years). I always accepted the nutritional science but, like most people, still founds ways to justify my continued intake of meat and dairy because it pleased me and I was reluctant to change. Eventually poor health caught up with me and I had to change. It also became difficult to ignore my role in the horrific abuse of so many animals.

          • Thea

            Meditating: I’m sorry you have experienced health problems. Good for you, though, in doing something about it. I personally know people who would rather die than change their eating habits. And I agree with you that some people simply do not believe that eating healthy can equal eating delicious.

            One of the things that I often tell people, and which I think you would agree, is that it is important to educate oneself on the ethical side of eating. That’s because most people have at least a basic level of compassion for animals and other people and care about the future of the planet. It is quite common for people to believe with all of their mind that healthy eating = plant based eating. But they still can’t motivate themselves to change until they take the time to learn about the ethical/emotional side of their choices. Being healthy is as much about motivation (including overcoming fear) as it is about nutritional education. (*Not* that nutritional education is unimportant.)

            You are on a great path now. Congratulations.

          • Meditating

            I have to agree with you about the ethics of eating animals. I just posted something on that to another comment here.

            It is amazing to me how growing, handling, preparing and eating foods which have not been molested or processed profoundly grounds and reconnects you to the physical world. It is truly wonderful and I dare say it seems to have some type of “spiritual” component for lack of a better definition. I can’t exactly explain it and try to dissect what is happening to me on a regular basis so hopefully I will have an epiphany on the subject. It is sad most of us are raised without this experience in the modern world.

      • HemoDynamic, M.D.

        Great to see you back brother!! Plant strong all the way!! At McDougalls again. Wish you could be here. Someday soon.

  • http://www.facebook.com/darryl.roy.752 Darryl Roy

    As its flax week, even videos with no mention of flax will be entitled “Flax vs. [insert disease]“.

    I guess it shorter than “Oatmeal, oat cereal, lentils, apples, oranges, pears, oat bran, strawberries, nuts, flaxseeds, beans, dried peas, blueberries,cucumbers, celery, and carrots vs. Breast Cancer” (all good sources of soluable fiber).

    • http://www.facebook.com/darryl.roy.752 Darryl Roy

      Oops, that was me. For some reason I’m seeing “flax” everywhere this week.

  • http://www.facebook.com/darryl.roy.752 Darryl Roy

    It’s worth looking also at Aune et al.’s dose response curve for fiber and colorectal cancer from their prior study, figure 2 in: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3213242/pdf/bmj.d6617.pdf

    Aune et al (I’d prefer calling him Dagfinn) found a linear response, but just as strong, probably hitting negligible risk for the Thai vegans.

  • Alastair

    Dr Greger what is the nutritional and health difference between soluble and insoluble fibre. Doug Grahame advocates for soluble fibre in “The 80/10/10 Diet” found in fruits. He says that’s the fibre that buffers fructose so that blood sugar levels don’t spike when eating high carb meals of all fruit. All lot of people seem to confuse dietary fibre with dietary roughage. Care to comment?

    • Toxins

      Insoluble fiber promotes fecal bulking and helps allow stools to pass easily, insoluble fiber ferments and allow the gut flora to flourish. All plant foods have a mix of these 2 fibers and I know of no evidence showing that we should try to focus on any specific portion of the fiber.

  • http://www.facebook.com/dan.lundeen Dan Lundeen

    That last article cited for high vegan fiber intakes is a paper on mineral deficiencies and says “phytate and fiber are known to have a profound deleterious effect on mineral aborption.” Should this be a concern for vegans like it is for my fiber-avoiding paleobuds?

    • Toxins

      I am not sure if fiber is the true culprit in mineral absorption, as I have not seen evidence supporting this. Phytates, on the other hand, are contingent with fiber so this may be what they are referring to. Phytates have the ability to bind up calcium and zinc, but they also double as a potent antioxidant. Regardless of this, cooking or soaking eliminates phytates so this is really not an issue. If one is consuming a healthful, unrefined vegan diet comprised of whole plant foods, then these “antinutrients” are not issues at all.

      • http://www.facebook.com/dan.lundeen Dan Lundeen

        Well, Toxins, that was my take too, thanks. Also looking at the stoichiometry there’s simply not enough phytate to bind more minerals than those present in the grains, assuming the multiple binding sites on phytate are not that strong after the first complex is formed.

  • frnkbnhm

    This chart is BS. I am assuming the dashed lines are the data that the curve is extrapolated from. Why does the curve continue downward when at around 35g/day the data has a distinct up swing?

    • ted

      I don’t know for a fact, but the solid line probably represents a curve drawn through the actual data and the dashed lines represent “error bars” associated with the solid line. So there’s no up-swing in the actual data, just less confidence associated with the curve around 35g/day, and that’s probably because there are less data at this level (smaller n) because so few people get 35g of fiber per day.

      • frnkbnhm

        Which is fine, but if there is “less confidence associated with the curve around 35g/day” why does the video mention the benefits of 50+ g/day?
        My point is that showing the chart with the error bars, but not explaining it is bad science and bad journalism. Conjecture on the effects of what might happen if you go off the chart is simply living in the land of make believe…

  • HemoDynamic, M.D.

    Awesome compilation!!

  • John

    Its also well known now that Asian people do not drink Milk as in the Western countries. Milk is another risk factor towards Breast cancer, as it contains cows hormones and it also increases the release of IGF-1 from the Liver.

    A nice video to emphasize this point would be nice Michael :)