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Boron Safety for Breast Cancer Survivors

Lara Pizzorno is the author of “Your Bones: How You Can Prevent Osteoporosis and Have Strong Bones for Life – Naturally” and a member of the American Medical Writers Association with over 30 years of experience specializing in bone health.

Recently, we asked Lara if she would help us provide a series of short, ongoing talks to help you (our customers and readers) stay up to date on the latest facts and science related to bone health.

Lara recently discussed whether boron is safe for breast cancer survivors who are taking aromatase inhibitors. Read the transcript below and let us know what you think in the comments. 🙂

“Hello, I’m Lara Pizzorno the author of “Your Bones” and I’m here today to share some information with you that I hope will help you have healthier bones.

So far, we’ve been talking about the importance of a trace mineral called boron for healthy bones. Today, I wanted to discuss with you whether boron is safe for breast cancer survivors who are taking aromatase inhibitors such as Arimidex.

This topic came up for me because a few months ago now because a woman wrote me to ask if taking boron was a good idea for her. She had recently been successfully treated for stage 1 ER+ breast cancer which is an estrogen positive form of breast cancer and had prescribed a drug called Arimidex which she was to take for the next 5 years to block her body’s ability to produce estrogen, in the hopes that it would protect her against developing and recurrence of her breast cancer. The drug she was prescribed called Arimidex is used in both the treatment and to help recurrence of estrogen positive breast, ovarian and also prostate cancers. It’s one of a class of drugs called aromatase inhibitors and prevents the production of estrogen by binding to and shutting down an enzyme called aromatase. This is the enzyme that is responsible for synthesizing estrogen from its precursors which are other steroid hormones called androgens. And these include DHEA and testosterone and would normally be the targets of aromatase. Arimidex inhibits estrogen synthesis by out- competing androgens’ ability to bind with aromatase. Arimidex and the other aromatase inhibitors are so effective at preventing the production of estrogen that if you are taking one of these drugs you will be producing virtually no estrogen. So boron will have no estrogen to convert to its magnesium absorbing form. And this means that taking boron is not going to have any negative effect on breast, prostate or ovarian cancer treatment if you are taking an aromatase inhibitor. But it also means that estrogen’s beneficial effects, its beneficial effects on our ability to absorb magnesium, and in our production of osteoblasts and in our activation of vitamin D are going to be lost. For these reasons, aromatase inhibitors cause substantial bone loss and increase risk of osteoporosis and fractures. Not only when used in postmenopausal women with breast or ovarian cancer but also given as androgen deprivation therapy for men with prostate cancer.

If you’ve read “Your Bones” then you know that men produce a small amount of estrogen, but that it plays a very important role in their ability to maintain healthy bones. So by preventing men from producing the small amount of estrogen, the aromatase inhibitors also cause bone loss in men and increase their risk of osteoporosis.

Well, it turns out that boron is now being used to increase and restore effectiveness of another drug that is used to treat or prevent estrogen positive cancers called tamoxifen. Even in breast cancer patients whose cancer cells who are supposedly resistant to tamoxifen, boron is changing this.

And why might this be important for your bones if you have or are recovering from an estrogen positive type of cancer?

Well, tamoxifen causes far less bone loss than the aromatase inhibitors, so it is worth looking into if you might be able to use tamoxifen rather than one of the aromatase inhibitors. Tamoxifen has long been considered the first line therapy for estrogen positive breast cancers. Most all of the estrogen positive breast cancers respond positively to tamoxifen treatment but about 8% of patients with these cancers are resistant to tamoxifen. Why? Because these patients have a slow CYP2D6 enzyme, this is the enzyme in the liver that is responsible for converting tamoxifen into its most potent forms. Two potent metabolites called 4-hydroxy tamoxifen or 4-OHT, that’s what you’ll see in the research literature and endoxifen, both of which inhibit estrogen dependent cell proliferation. There are tests that can now be run to determine if you are among these 8% of people who are resistant to tamoxifen treatment and if you are not, tamoxifen will be a much less bone destructive treatment for you than one of the aromatase inhibitors. So this is something you might want to discuss with your doctor.

Boron in addition is now being used to develop different forms of tamoxifen that are already in these two more potent forms the 4-OHT and endoxifen forms. So even people who are resistant to tamoxifen because they have a slow CYP2D6 enzyme can benefit from tamoxifen and discuss using it rather than an aromatase inhibitor their physicians.

If you need to be on an aromatase inhibitor, the good news is that not only will taking boron NOT interfere with the cancer protective effect of aromatase inhibitor therapy, but boron will lessen some of its harmful effects on your bones. Boron is still going to help you convert vitamin D into the form in which it helps absorb calcium most effectively and the latest research which I have discussed in an earlier in this series on boron is  showing us that boron plays a number of protective roles for us including greatly lessening chronic inflammation, which would otherwise excessively activate osteoclasts.

So boron can still help you maintain the health of your bones even if you need to be on an aromatase inhibitor. Next time, we will talk about how much boron you need to take and whether you can rely on dietary sources for this trace mineral or whether you should consider a bone health supplement that will provide boron for you. Thanks for tuning in, I hope this was helpful.”


Limburg C, Maxwell C, Mautner B. Prevention and treatment of bone loss in patients with nonmetastatic breast or prostate cancer who receive hormonal ablation therapy. Clin J Oncol Nurs. 2014 Apr;18(2):223-30. doi: 10.1188/14.CJON.223-230. PMID: 24675258

Decensi A, Sun Z, Guerrieri-Gonzaga A, et al. Bone mineral density and circulating biomarkers in the BIG 1-98 trial comparing adjuvant letrozole, tamoxifen and their sequences. Breast Cancer Res Treat. 2014 Apr;144(2):321-9. doi: 10.1007/s10549-014-2849-2. Epub 2014 Feb 1. PMID: 24487691

Jiang Q, Zhong Q, Zhang Q, et al. Boron-Based 4-Hydroxytamoxifen Bioisosteres for Treatment of de Novo Tamoxifen Resistant Breast Cancer. ACS Med Chem Lett. 2012 Apr 6;3(5):392-396. PMID: 23864928

Author: Lara Pizzorno, MDIV, MA, LMT

Best-selling author of “Your Bones: How You Can Prevent Osteoporosis and Have Strong Bones for Life – Naturally” and a member of the American Medical Writers Association with 30+ years of experience specializing in bone health. Lara is the Editor of Longevity Medicine Review ( as well as a Senior Medical Editor for SaluGenecists Inc., and Integrative Medicine Advisors, LLC.