Red Clover Controversy – Safe For Breast Cancer Or Not?

Photo courtesy of and micromoth
Photo courtesy of and micromoth

Red Clover Controversy – Safe For Breast Cancer Or Not?

As a natural therapist I have always considered red clover to have some wonderful healing qualities and any studies I did on red clover appeared to confirm this. I never considered that it might have potential harmful effects until I was faced with breast cancer and began to hear lots of conflicting advice about it.

Red clover has long been considered an anti-cancer herb.  After all, it is one of the constituents of the Hoxsey formula, Jason Winters Tea and in some formulations of Essiac tea, although not the original formulation.

Red Clover’s Benefits

Red clover has been used for centuries for its blood cleansing and anti-cancer properties, it has also been used as a natural diuretic, nerve tonic, expectorant, demulcent, mild laxative, gentle antispasmodic, and it is a natural blood thinner (so should not be used by anyone on blood thinning medication).

The wide range of benefits discovered over the centuries for red clover is most likely due in part to the nutrients found within it which include vitamin C, magnesium, calcium, chromium, niacin, thiamin, phosphorus and potassium.  Probably the most important constituents, however, of red clover are the isoflavones, which are polyphenolic compounds capable of exerting estrogen-like effects.  And it’s that last bit that is causing all the controversy.

Phytoestrogens Are Misunderstood!

Phytoestrogens, literally “plant estrogens” mimic the hormone estrogen.  Many doctors will warn you against them if you have breast cancer, their reasoning being that phytoestrogens may increase the amount of estrogens in your body and if you have hormone-dependent cancer, is something you should avoid.

While I was doing the research for this article, I came across a lot of websites that warned against phytoestrogens for breast cancer.  The American Cancer Society stated on their website “Women who have had estrogen receptor-positive cancers or who are pregnant or breastfeeding should not use this herb.”   The National Center for Complementary and Alternative Medicine stated on their website: “It is unclear whether red clover is safe for women who are pregnant or breastfeeding, or who have breast cancer or other hormone-sensitive cancers.”  The webMD website stated: “Red clover might act like estrogen. If you have any condition that might be made worse by exposure to estrogen, don’t use red clover.”  Okay, that’s the anti-phytoestrogen stance.

Here’s some research for you which indicates they could all be wrong.  The June 2004 edition of Breast Cancer Research states that “red clover does not cause any estrogenic increase in breast density, while human and synthetic estrogen does.  An increase in density is associated with a higher risk of breast cancer, inferring that taking red clover could prove to be preventative.”

The most interesting research I found was done in 2008.  This large study, Red Clover Isoflavones Are Safe And Well Tolerated In Women With A Family History of Breast Cancer was done at the Royal Marsden Hospital and the University Hospital of South Manchester, England.  The lead investigator for the study, Professor Trevor Powles, a well respected oncologist and breast cancer expert, said “Reassuringly for women, this study shows that these phytoestrogens do not cause any oestrogenic increase in breast density in women who have a family history of breast cancer. This would indicate that they are unlikely to cause an increased risk of breast cancer. This 3-year study confirms similar findings from previous, shorter-term studies.”

Let’s Clear Up This Controversy

Most herbalists agree: phytoestrogens are much weaker than the body’s own estrogens. They DO NOT promote cancer, in fact, quite the opposite.  Because of their extremely gentle nature they hardly exert any estrogenic effect on the body. 

How they work is to occupy estrogen receptors on cells, preventing stronger estrogens from the body, together with  xenoestrogens (environmental estrogens), from having any effect.

Through this mechanism they may help to prevent cancer growth and have a balancing effect on the hormonal system. This is why so many of the herbs used to treat cancer are rich in phytoestrogens.

Professor Trevor Powles has renamed phytoestrogens “anti-estrogens”, because of how they are capable of blocking the action of human estrogens in the cancer process.  He believes that phytoestrogens have the ability both to block the receptor sites to which human estrogens attach, and also in some cases to even denature aggressive human estrogens.

Red Clover Also Useful For Increasing Bone Density

In addition, I found some research which indicated that phytoestrogens increase bone density, which is a considerable concern to women who are on post-breast-cancer hormonal therapies as bone loss is one of the side effects of these drugs.  At the University of Bari in Italy, this interesting study indicated that phytoestrogens found in red clover can actually increase bone density, making it a helpful herb for the treatment of osteoporosis.

One last thing to note.  The University of Maryland advised against taking red clover at the same time as tamoxifen because it could interfere with its action.  Indeed — it may even act much in the same way as tamoxifen by blocking the estrogen receptor sites!  I know which one I would rather take.

I hope this article helps to clear the controversy surrounding red clover and phytoestrogens.

If you would like my help with getting through breast cancer in an inspiring and ultra-healthy way, please sign up for my free e-newsletters and e-book on the right, and/or “like” me on Facebook (  It is my honor and my goal to help you through this so that you emerge from breast cancer feeling better than before, thriving!

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18 thoughts on “Red Clover Controversy – Safe For Breast Cancer Or Not?

  1. Hi! What do you know about red clover as an aromatase inhibitor? I have high estradiol and low testosterone, but I am scared of taking the letrizole they are trying to prescribe me because it suppresses estrogen too low . I am trying to find a natural substance which will suppress the estrogen to a normal level while taking testosterone replacement therapy. In men simply adding testosterone doesn’t work – it just gives the aromatase more to feed on and increases the estrogen levels, hence the need for an aromatase inhibitor.

    You appear to be knowledgeable in the subject and you made a whole lot mor sense out of the NIMH article than I did so I hope you can advise me on this. Thanks! **** Jeremiah Price

    1. Hi Jeremiah,
      Thanks for your message. I decided to answer you privately via email, and I hope that you find the information helpful and useful.
      Warmest regards,

  2. Thanks, Marnie, for clearing this up. My wife has stage IV breast cancer and had 13 weeks of taxol. Now she is on Exemestane and Xgiva “to protect her bones”.I’ve been giving her many natural supplements, herbs, minerals etc. I’ve wanted to use red clover in Hoxsey’s tincture formula but was afraid to use it due to her being 95% Estrogen and
    Progesterone positive!

    1. Hi, thanks for your message. I’m glad to be of assistance to you. I hope that you have signed up for my free newsletters and e-books? They are full of my best information on healing from breast cancer and preventing recurrences. You can do that from any page on this website. I wish both of you the best and if I can assist you further, please let me know.
      Warmest regards,
      Marnie Clark

  3. I am now cleansing my lympth nodes . My tumor is gone and I am planning to
    use red clover , dandelion and pau d’arco to cleanse along with my juicing
    vegan diet lots of water and exercise and trampoline exercise to circulate my
    lympth nodes. Note: So many pro and cons for red clover, although there are
    good and bad estrogens.

    1. Hi Elizabeth,
      I apologize for the delay in responding to you. I had a landslide of emails over the weekend. Congrats on the disappearance of the tumor! Your wellness plan sounds pretty good. Your last statement about there being good and bad estrogens, though, has me forwarding you one of my articles. Please read this and especially the article that I link to – because even that is being debated (the good/bad estrogen argument): If you would like some help with your wellness regimen, you might like to subscribe to my free newsletters where I offer lots of advice about healing from and preventing breast cancer. You can do that from any page (right hand side). Thanks for your comment, and I wish you much healing.
      Warmest regards,
      Marnie Clark

  4. Hi Marnie,
    I found this article on red clover very informative. I was diagnosed with breast cancer over six years ago. I have treated it using natural alternatives. The cancer has not metastasized, but I don’t seem to be able to get rid of it. I’ve just recently started talking red clover, and I’m praying that I’ll have some positive results. I would appreciate any advice that you can offer.

  5. Thank you Marnie for a very informative article. I have been a bit hesitant to take red clover, because of the worry of getting cancer due to the way red clover works. I feel more confident now about taking it after finding your article, thank you so much, kind regards, Julie.

    1. Hi Julie,
      I apologize for the delay in responding to you. I have been away for a quick break and got such a deluge of emails! I’m glad you found the article helpful. You might also enjoy receiving my free e-newsletters – I share loads of helpful tips and information in my newsletter series. You can sign up for them on any page of my website.
      Warmest regards,
      Marnie Clark

  6. Thank you for this article. I am taking exemestane and having side effects. I think I will try red clover after reading your post.

  7. Thanks for help clearing this up. I’m taking Hoxsey formula which is high in red clover and was quite confused. I have an early stage of estrogen pos cancer, which I am taking responsibility for healing. I’m learning so much and appreciate your articles.

    1. Tara,
      Thanks for your comment. I’m glad to have been of help to you. You might also consider subscribing to my newsletters. They are full of my best information on healing from breast cancer and avoiding recurrences and I have just updated them with the latest info and research. You can sign up from any page on my site, if you haven’t already done so.
      Warmest regards,
      Marnie Clark

  8. Marnie,
    my radionics testing shows that my body wants or needs red clover. My herbalist has sent me the remedy but I am afraid to take this due to the controversy. I have had Her2 positive seven years ago. Would like a second opinion on the use of this remedy.
    Thank you!

  9. I very much appreciate the information I have found at this site. I have a large breast tumor that I have been trying to treat for a year now using Budwig as my main course of treatment. I need help in adding further natural aides of which red clover might be one. Please let me know what I can do to increase the effectiveness of my protocal.

  10. Thank you for clearing up the red clover leaf. I was afraid of using a shampoo that contains it during my short TC chemo regimen.

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