The Breast, its Microbiome and Ways to Improve It

by | Jun 16, 2021 | Breast Microbiome | 8 comments


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The Breast, its Microbiome and Ways to Improve It

by | Jun 16, 2021 | Breast Microbiome | 8 comments

The Breast, its Microbiome and Ways to Improve It

There is a dynamic relationship between a human host and its microbiota, the collection of microorganisms, both beneficial and pathogenic, that live in a particular environment in the body. We hear and read much about the gut and its microbiome, but did you know that the breast has a microbiome as well?

A number of studies have shown that this is indeed the case. Since the breast is comprised of a lot of fatty tissue, vasculature and lymph nodes, and is exposed to the outside environment through the nipple, it only stands to reason that it may be a favorable environment in which bacteria can thrive.

In fact, bacteria found in the breast is quite unique and distinct from that found anywhere else on/in the body. [1]

I first became aware of the possible association between pathogenic bacteria in the breast and breast cancer when I was studying aromatherapy and essential oils for breast health. What I observed was that every single one of the essential oils that had research showing its anti-cancer activity also had direct action against pathogenic bacteria. I found that very interesting and thought at the time there must be a correlation.

And indeed it seems that may be the case. When I delved into the studies that have been done, they investigated the role of bacteria in the breast as a risk factor in breast cancer occurrence; the proposed mechanisms of interaction between the microbiome and genes known to be involved in breast cancer; the impact of alterations in the breast microbiome and how these alterations may cause cancerous or non-cancerous breast lesions.

How the Breast Microbiome is Acquired and/or Altered

The breast microbiome is thought to be populated through several different routes including the overlying skin, breast feeding, sexual activity, and/or through bacteria transferred from the gut. The types of bacteria present in the breast vary from person to person (of course) but also country to country. [2]

We have known from studies done in the 1960s that breast-feeding is associated with a reduced risk of breast cancer. More recent studies suggest that this may be because breast milk supports the growth of beneficial bacteria in the breast, and this contributes to the health of the breast.

On the other hand, when pathogenic bacteria get into the breast, this can lead to conditions such as chronic inflammation, mastitis and other breast diseases, including cancer.

The Research

Although a number of journal articles state that there is insufficient evidence to say that there is a bacterial link to breast cancer, I found several studies with something quite different to say.

One 2018 review of medical studies [3] stated that it has been noted that reduced quantities of beneficial bacteria which exert a protective effect against carcinogenesis (development of cancer) and increased quantities of pathogenic bacteria in the breast can contribute to the development of cancer.

A 2014 study [4] and a 2020 review of medical studies [5] both stated there was definitely a link between dysbiosis (a reduction in the diversity of beneficial microbes, and an increase in pathogenic microbes) and breast cancer.

One 2016 study [6] found that there was a significant difference in the microbiome of malignant compared to benign breast tissue samples.

Interestingly, bacterial dysbiosis may also be linked to breast cancer recurrence, especially in women undergoing breast reconstruction, or in those who develop post-surgical infections. [7] But fear not! I have some remedies for you, read on.

One study [8] discussed the pathogens Escherichia coli (aka E coli) and Staphylococcus sp in particular. These are common hospital-borne pathogenic bacteria, and they appear to have multiple links to breast cancer. There are many more – I won’t list all of the types of bacteria that have been found in malignant breast samples – you can read the studies for that information if you are sufficiently interested.

I also found it intriguing that one study [9] discovered that the microbiomes of women with hormone positive breast cancers tended to vary from those with triple negative breast cancer.

How Do Bacteria Cause Cancer?

What are the mechanisms of action? According to a 2020 review of medical studies [4] on the breast microbiome and breast cancer, bacteria and their metabolites have the ability to:
(a) manipulate genetic signaling pathways
(b) cause DNA double-strand breaks
(c) promote apoptosis (cell death)
(d) alter cell differentiation
(e) interact with receptors in the innate immune system to trigger inflammatory pathways

This interaction between the breast microbiome and cancer is referred to as the “oncobiome”. There is a huge amount of evidence that shows these microorganisms are able to regulate the tumor microenvironment. [5]

Further, healthy bacteria in the breast are significantly altered by things like the taking of antibiotics, diet (the plant-based diet is protective), chemotherapy and radiation. Two studies [10] [11] found that taking antibiotics intermittently increases the probability of dysbiosis and lowers the bacterial diversity. This is not new, we know this about our gut microbiome, but we probably didn’t realize that the taking of antibiotics might possibly be putting us at a higher risk for breast cancer as well.

To compound matters further, a 2016 study [12] found that certain strains of bacteria, namely species such as Clostridium and Escherichia, had the ability to increase circulating estrogen levels, thereby associating these bacterial strains with an increased risk of breast cancer.

Now, on to the good stuff.

Five Tips for Promoting Good Bacteria and Reducing Pathogenic Bacteria

1. Probiotics

Several studies have investigated the effect of probiotics on breast cancer, and these are outlined in the study review at [5]. The taking of probiotics significantly inhibits cell proliferation (rapid growth), promotes induction of apoptosis (planned cell death, absent in cancer cells), and cell cycle arrest, as well as a number of other anti-cancer actions.

Specifically Lactobacillus acidophilus, a well-known probiotic, can reach the breast and has a number of anti-cancer effects. This strain of beneficial bacteria has been found to be more common in healthy breast tissue than in cancerous tissue, and is thought to have a role in breast cancer prevention. [13]

Probiotics also have beneficial effects for the immune system, 70-80% of which is located in the gut.

2. Beneficial Fats

One study [14] with both animals and breast cancer patients had interesting findings. First, the researchers fed mice that were susceptible to breast cancer either a high fat or a low fat diet. The mice receiving the high-fat diet had more tumors which were larger and developed more quickly than the tumors in the mice receiving the low fat diet.

Secondly, the researchers performed fecal transplants in order to study the microbiome of the mice. The mice eating the low fat diet received a microbiome transplant from the mice eating the high fat diet, and the mice eating the high fat diet received a transplant of the microbiome from those eating the low fat diet. The result was that the mice that had the low fat diet and received the microbiome of those eating the high fat diet had just as many breast tumors as the mice that had eaten the high fat diet.

Lastly, these researchers conducted a double-blind placebo-controlled clinical trial with actual breast cancer patients. The patients received either fish oil supplements or a placebo for about 2-4 weeks prior to undergoing lumpectomy or mastectomy. The results clearly showed that taking fish oils had a significant beneficial effect on the breast microbiome in both cancerous and non-cancerous breasts.

My tweak would be not to take fish oils because I believe they are too polluted from our oceans these days, but rather to take organic flaxseed oil with lignans – both are known to be hugely protective against breast cancer [15] [16] [17].

3. Anti-Inflammatory Diet

Because pathogenic bacteria are associated with inflammation, include plenty of anti-inflammatory foods in your diet such as carrots, sweet potatoes, mangoes, papayas, hempseed, walnuts, garlic, berries, ginger, greens like spinach, rocket, kale and chard, pineapple, flaxseed (mentioned in tip 2 above), turmeric, and superfoods such as goji, amla, acai, maqui and noni.

4. Essential Oils

As a breast cancer patient, I used essential oils extensively after my lumpectomy surgery and breast reconstruction in 2004 (along with quite a few other things). I did this because I knew that essential oils would help to protect surgical wounds from infection. I continue to use them daily all these years later to help keep breast tissue healthy. As a breast cancer coach, I recommend this course of action to all of my clients.

As I mentioned before, I have delved deeply into the research on essential oils and have found a number of studies that show these essential oils clearly have anti-cancer and antibacterial activity. However, due to governmental restrictions, I am not actually allowed to make any claims about that. I do have plenty of research on this subject and if you’d like to see some of it, I am more than happy to share it. Be warned, though, there’s a prodigious amount of it. My list of the best essential oils to use appears on this page of my website.

I have a very specific protocol. I massage two different essential oils into the breasts for three days, and then switch to a different pair after those three days. Each oil works in different ways to keep us healthy, so by switching frequently you are getting a wide array of beautiful plant-based phytochemicals that help to keep the breast microbiome nice and healthy.

5. Bioenergetic Device

This is brand new cutting-edge technology using age-old wisdom. It is a wearable frequency therapy device with a quantum sensor which is able to balance and support the body’s bioenergetic field. As you are no doubt aware, we are comprised of energy – our cells, our bodies, the Universe. There is a frequency to everything in the Universe, including our cells. This energetic field can get out of balance for many different reasons, and this device has the ability to scan and analyze your individual energy field, and pick up any imbalances in not only the physical level, but also the mental and emotional levels. Better yet, it can deliver the right frequencies to you – customized and specific to you – to help you to repair any imbalances it picks up. I’m not saying we can heal anything with this device, but it stands to reason that if we are nourishing the cells of our body with the frequencies they need to be able to thrive, this just makes sense. This is not a new idea or concept but for those who don’t work with energy, it can be a difficult concept to grasp. If you need more information about this, just contact me.

There you have it – my best 5 tips for keeping the breast microbiome at its happiest and best. Hope you enjoyed this article.


[1] The Microbiome of Aseptically Collected Human Breast Tissue in Benign and Malignant Disease –
[2] Microbiota of Human Breast Tissue –
[3] Resident bacteria in breast cancer tissue: pathogenic agents or harmless commensals? –
[4] Microbial Dysbiosis Is Associated with Human Breast Cancer –
[5] Microbiome and Breast Cancer: New Role for an Ancient Population –
[6] The Microbiome of Aseptically Collected Human Breast Tissue in Benign and Malignant Disease –
[7] The Breast Microbiome: A Role for Probiotics in Breast Cancer Prevention –
[8] The Breast Microbiome: A Role for Probiotics in Breast Cancer Prevention –
[9] Distinct microbiological signatures associated with triple negative breast cancer –
[10] The role of the microbiome in cancer development and therapy –
[11] Does antibacterial treatment for urinary tract infection contribute to the risk of breast cancer? –
[12] The Intestinal Microbiome and Estrogen Receptor–Positive Female Breast Cancer –
[13] Oral Administration of Lactobacillus Strains Isolated from Breast Milk as an Alternative for the Treatment of Infectious Mastitis during Lactation –
[14] Diet alters entero-mammary signaling to regulate the breast microbiome and tumorigenesis –
[15] Consumption of flaxseed, a rich source of lignans, is associated with reduced breast cancer risk —
[16] Flaxseed and its lignan and oil components: can they play a role in reducing the risk of and improving the treatment of breast cancer —
[17] Flax and Breast Cancer: A Systematic Review —


  1. Kathy

    Hi Marnie,
    I am newly diagnosed with metastatic breast cancer, hormonal cancer.. whatever that means. I am about to start treatment, not chemo based but hormonal based and a monthly dose of X-Geva. It’s all been overwhelming and I’m trying my hardest to stay strong and keeping my faith. With that said I certainly have my moments.
    My doctor said that I do not have the markers for immunotherapy and that I will be taking the “gold standard treatment”. As I read about the side effects, they are terrifying.
    I’ve heard a lot about Ayuravedics, clean eating and most of what I see on this sight. It’s just overwhelming and I don’t know where to begin:( American standard of medicine is all about the “science”.
    My question is, will eating healthy, cutting out red meat, processed sugar, dairy, and grains help? My doctors say everything in moderation. I find that hard to believe and what does that really mean? When I mentioned herbal supplements, they said to be careful because may cause harmful interaction with treatment.
    I feel like I’m just babbling and all over the place, honestly that’s how I feel at times.
    Any thoughts?

    • Marnie

      Hi Kathy,
      I just sent you an email in response to your questions. Lots of love and I hope to be of help to you in your healing journey.
      Warmest regards,

  2. Cindy Morris

    Hi Marnie! I recently found your website. I’m in the last week of radiation therapy. I’ve only required 20 treatments as the tumor was found early at stage 0. I feel blessed. My Lord is good!
    #1 I’m interested in more info on the bioenergetic device. Sounds interesting.
    #2 would juicing help at this point? I’ll need to invest in a good juicer. I have a Vitamix for making smoothies and love them!
    #3 Any other advice will be greatly appreciated. I’m also 72 and over weight by about 30 lbs.
    I’m so glad I found you first on YouTube!

    • Marnie

      Hi Cindy,
      Thanks for your message. I have responded to you via private email.
      Warmest regards,

  3. Robin

    Hi Marnie,
    I am definitely interested in the Bioenergetic Device. I have been using 4 different essential oils on my breast skin and am happy to learn of more for ER+PR+ Her2- breast cancer. Thank you for your time and all you do.

    • Marnie

      Hi Robin,
      I just sent the info you’re interested in.
      Warmest regards,

  4. bonnie Ann laing

    please send me more information on the bioenergetic device, not sure if what i have is what you are talking about, thank you for all your advice, love the essential oil research you have done, that too can be so confusing..

    • Marnie

      Hi Bonnie
      Info on its way. Thanks for your message.
      Warmest regards,


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About Marnie Clark

marnie clark breast cancer coach

Hi I’m Marnie Clark, breast cancer survivor turned coach. I have 20 years of experience in natural medicine.  In 2004/05 I battled breast cancer myself. You can see more about my journey on my page Breast Cancer Diary.

I’ve been healthy and recurrence-free since 2004 and in 2012 I became a Breast Cancer Coach because I became aware of the fact that whilst there is now a wealth of information on the Internet, much of it is confusing, conflicting, and sometimes just wrong!

So it is my duty to help you unconfuse and untangle all that information, and find what works for YOU.

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