Flax and Breast Cancer Survival

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Flax & Breast Cancer Survival

 A randomized, double-blind, placebo-controlled clinical trial of flaxseeds in breast cancer patients found that flaxseeds appear to have the potential to reduce tumor growth in just a matter of weeks. Scientists believe this is due to a class of phytonutrients known as lignans, which are present in flaxseeds at levels up to 800 times other plant foods.

Lignans can be thought of as the Western equivalent of the isoflavone phytoestrogens found in soy foods popular in traditional Asian diets, as they share many purported anti-cancer mechanisms. Since soy food consumption is associated with both preventing breast cancer and prolonging breast cancer survival, one might expect the same to be found for lignans. In Flaxseeds & Breast Cancer Prevention I covered the population-based, in-vitro, and clinical evidence supporting prevention, but what about for women already diagnosed with the dreaded disease?

Three studies were recently published that followed a total of thousands of women diagnosed with breast cancer. The first study from New York reported substantially reduced risks of overall mortality and especially breast cancer mortality associated with higher lignan intakes in postmenopausal women.

The next population study was out of Italy. At surgery, when the women were getting their primary breast tumors removed, they had some blood drawn; within 5 years those who had lower circulating levels of lignans were significantly more likely to die from their cancer coming back than those with more lignans in their bloodstream. The researchers concluded “Lignans might play an important role in reducing all-cause and cancer-specific mortality of the patients operated on for breast cancer.”

The latest and largest study to date was performed in Germany. Postmenopausal patients with breast cancer who had high blood lignan levels appeared to have better survival, and the higher the better. You can see the survival curve in my 3-min video Flaxseeds and Breast Cancer Survival: Epidemiological Evidence. Those who had the most lignans in their blood lived the longest and tended to live the longest disease free.

The population data looked so promising that researchers decided to put lignans to the test by feeding women flaxseeds, the most concentrated source of lignans, to see what would happen.

One of the ways the chemotherapy drug tamoxifen works is by boosting the levels of angiogenesis inhibitors like endostatin, which is a protein the body makes to try to starve tumors of their blood supply. Using a technique called microdialysis, you can stick a catheter into a woman’s breast and suck out some of the fluid bathing the breast cells. If you give women tamoxifen for 6 weeks, the levels of endostatin within the breast tend to go up, and the same thing happens when you instead add three and a half tablespoons of ground flaxseeds to their daily diet. As you can see in my video Flaxseeds and Breast Cancer Survival: Epidemiological Evidence, the flaxseed doesn’t seem as powerful as the chemo, but the results were so exciting that researchers undertook a randomized, double-blind, placebo-controlled, clinical trial of flaxseeds in breast cancer patients.

Breast cancer patients were randomized into either the treatment or the placebo group; either a flaxseed-containing muffin or a control placebo muffin every day between the time of their first biopsy and surgery. Researchers then had tumor samples before and after about a month of flaxseeds or no flaxseeds. Those lucky enough to be randomized into the flax group saw, on average, their tumor cell proliferation go down, cancer cell death go up, and their c-erbB2 score go down (a marker of cancer aggressiveness and potential for forming metastases and spreading).

The researchers concluded: “Dietary flaxseed has the potential to reduce tumor growth in patients with breast cancer. If the therapeutic index seen in this short-term study can be sustained over a long-term period, flaxseed, which is inexpensive and readily available, may be a potential dietary alternative or adjunct to currently used breast cancer drugs.”

For more on breast cancer survival, see:

What about the role of flaxseeds in preventing breast cancer in the first place? See my video Flaxseeds & Breast Cancer Prevention.

A study similar to this was also carried out in prostate cancer patients: Flaxseed vs. Prostate Cancer.

See Anti-Angiogenesis: Cutting Off Tumor Supply Lines for more on the role diet plays in angiogenesis, the formation of new blood vessels to enable tumors to grow. I also have touched on briefly in Cancer as an Autoimmune Disease and How Tumors Use Meat to Grow: Xeno-Autoantibodies.

This is the final installment of my latest video series on flax. Feel free to check out the role flaxseeds may play in helping diabetes and sensitive skin.

-Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

18 responses to “Flax & Breast Cancer Survival

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  1. Yes, Flax. It seems to work wonders for some women. I just wish (be careful what you wish for) my body didn’t react so poorly/adversely to flax. But speaking of cancer,food, and women, do you have any thoughts on whether or not it is safe to eat olives? Most olives are soaked in salt/brine. There have been issues raised about olives in regards to acrylamide content, as well as olives that have been salted/brined sharing some of negatives of smoked food products and certain fermented veggies (kimchi). Anyone have any thoughts on olives being OK or NOT in a health vegan diet?

  2. Are flax seeds beneficial If the breast cancer is estrogen, progesterone and HER2/neu negative, which means the tumor cells are aggressive?

    1. I just realized this question was address by Toxins and Darryl in great detail and expertise about a month ago. The links were very informative. Please forgive the repetition–and again, “thanks”.

  3. I would love to know what adverse affects Nelsie blanche has to fresly ground flax seeds. I have used it for years and avised others to its use and have never received an adverse
    JB teacher

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    1. how did he cure you? is it a long process or something easy to use the method? did you go to the dr.’s to check his methods and how did they work for you?

  6. Dr. Gregor,I was diagnosed with cancer brest the 3-rd grade and triple negative in 13 june this year. When I asked my oncologist what I need to do with my life? What type of food do I need? Which vitamins do I need? I had 22 questions on my list, but his answers disappointed me…He didn’t give me any information how I can help myself. His answers were given : 1.You can have everything but not have a blue cheese and yogurt with bifidobacterium. 2. You can have all vitamins. Do you know what, I was really upset after the conversation with him.I was reading a lot of articles and I’m happy to found you. Thank you very much your advices . I have 1 teaspoon Flaxseed oil the morning and 1 tablespoon Milled Flexseed I put in my soup or muesli. I hope it will help me.

    1. Yana Northen: I’m glad you found this site also. In case you hadn’t seen it yet, NutritionFacts has a topic/overview page on breast cancer: http://nutritionfacts.org/topics/breast-cancer/ Also, Dr. Greger’s book, How Not To Die has an entire chapter on breast cancer, plus several other chapters on other cancers which might also have some relevant information.

      Best of luck to you!

  7. I recently had a benign cyst in my breast and my breasts have scattered fibroglandular density. Reading through internet it is scary. I am only 36 years old with small children. Trying to keep my healthy in good shape from this day and do whatever it takes for good breast and overall health. I have been reading contradicting information about flax seeds for breast health. Even the research in these videos are done on postmenopausal women whose estrogen is already at lower rates I assume.
    So is consuming flax seeds in our diet good for women who are not postmenopausal who are in age group 35-50? Please let me know.

  8. Hello sati. Thanks a lot for your question and I really understand your concern, as there are many misinformation about certain foods and health outcomes.

    I found a recent review on PubMed, which will be very helpful for you:

    The Effect of Flaxseed in Breast Cancer: A Literature Review >>> https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5808339/
    Although many of the studies reported in this paper concluded that flaxseed intake may be related to the decreased risk of breast cancer and also to the reduction of the tumor’s growth and size, some studies including premenopausal and postmenopausal women did not show the same results.

    Consumption of flaxseed, a rich source of lignans, is associated with reduced breast cancer risk >>> https://www.ncbi.nlm.nih.gov/pubmed/23354422/
    This Canadian study is, to our knowledge, the first to report on the association between flaxseed alone and breast cancer risk and has found that flaxseed intake is associated with a reduction in breast cancer risk. As dietary intake of flaxseed is modifiable, this finding may be of public health importance with respect to breast cancer prevention.

    And you cal also check all Dr. Greger’s video about flax here >> https://nutritionfacts.org/topics/flax-seeds/

    Hope it helps!

    1. I was told by my functional medicine doctor that flax and soy are estrogenic. I am two years out of breast cancer that was estrogen/progesterone receptor positive, HER2-Negative and I take Arimidex. I have stayed away from flax, soy and have been wondering about pumpkin seeds which I eat regularly, in moderation. I have been trying to stay away from estrogenic food. Now I am completely confused!

      1. I’m confused as well. Why do my doctors all say to stay away from Flax and that it’s bad for estrogen positive cancer ? I had chemo, lumpectomy surgery and radiation for breast cancer and I do NOT want to take hormone therapy. My doctors act like I’m going to die if I don’t take it and that this is the only way to be sure it may not come back(I’m 46) .I don’t know what to do ? I was hoping flax would be just the thing to keep it away along with diet and exercise. Please if you see this Doctor can you reply ?

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