The Gut-Breast Connection: How Your Gut Microbiome Determines Breast Health

How Your Gut Microbiome Determines Breast Health | Gut-Breast Connection

If you just read the title of this blog post and furrowed your brows, I get it. A gut-breast connection might seem far-fetched. How could seemingly two unrelated parts of your body be so separate, and yet so connected? The breasts are part of the reproductive system, and your gut microbiome is part of the digestive system, right? Why would they be related at all? 

If you asked yourself any of these questions, you’re not alone. But as “ America’s Gut Doctor ,” it’s my job to educate you on all the ways that your gut health influences your overall health — breast health included. 

So this week, I’m diving into the microbiome-breast health connection and why it not only exists, it’s influencing your health right this very minute.

What does it mean to have healthy breasts?

Before we dive into the Gut-Breast Connection , let’s talk about how we define healthy breasts in the first place. As they write in a Mayo Clinic online publication , “Breast health begins with a sense of what’s normal for your breasts (breast awareness).” That means doing regular self breast exams and paying attention to how your breast structure may fluctuate during your monthly cycle, or during major hormonal transitions like puberty, menopause, and pregnancy. For example, it’s not atypical to experience changes in breast texture and experience breast pain in the second half of your menstrual cycle, but lots of pain could be a sign of estrogen dominance or fibrocystic breast disease , which is caused by the thickening of the breast tissue. 

Having healthy breasts also means keeping up with recommended screenings, like mammograms, breast ultrasounds, and clinical breast exams. So when do you know that something is up? If you have any of the following, I recommend seeing your doctor right away: 

  • Any unusual lump or mass
  • Swollen lymph nodes
  • Unexpected discharge from the nipple

Breast health is a facet of health that all women should be up-to-date on. We’ll be reminded of this over and over this month, as October is Breast Cancer Awareness Month .

The Gut-Breast Connection Explained…  gut microbiome + breast health

Although the breast tissue and the gut microbiome exist in very different parts of your body, they are surprisingly connected. For example, PMS symptoms, including breast tenderness, can be associated with an altered gut microbiome. One study showed that increased intestinal permeability — AKA, leaky gut — can affect progesterone and contribute to the severity of physical PMS symptoms, such as breast pain and tenderness. In my practice, I often find that PMS and underlying gut health conditions go hand in hand. 

A patient (let’s call her Jessica) who recently joined my Concierge Program is a case-in-point. Jessica had been suffering from severe, debilitating PMS for years. She also had a fibroid — another sign of estrogen dominance and gut imbalance —  and they were planning on removing it surgically. She had ordered a copy of my book, Happy Gut ® , thinking it was a cookbook by mistake. Low and behold she was surprised it contained an entire 28-day gut-healing program I call the HAPPY GUT ® Reboot . She followed the program, and by the end of the 28 days, the gut-wrenching period pain and breast tenderness she suffered from on a monthly basis that kept her in bed for several days disappeared completely . That is the power of gut healing!  

And the connections go far beyond PMS, too. One study showed that giving breastfeeding women a probiotic supplement reduced the occurrence of mastitis — or inflammation of the breast tissue that sometimes involves infection and pain during breastfeeding. 

And then, there are the almost endless connections between the gut microbiome and breast cancer. Most of these connections have to do with estrogen, the main female reproductive hormone, which plays a role in breast health and breast cancer. Research shows that there is a subset of the gut microbiome, called the estrobolome , that centers around estrogen metabolism. These bacteria have the ability to metabolize estrogen and control estrogen levels in the body. When these bacteria get out of whack, estrogen levels can become too high , which can increase the risk factor of breast cancer. I’m in agreement with the authors of one study who concluded that , “Future research attention should include a more extensive focus on the role of the human gut microbiota in breast cancer.” 

And then, there’s the bacteria that live within the breast tissue itself. Yep, you read that right!

Does breast tissue have its own microbiome?

When I say the word “microbiome,” there’s a great chance you immediately think about the digestive system. But the truth is, even though I’m “ America’s Gut Doctor ,” the word “microbiome” doesn’t just exist in the context of the gut. In fact, your mouth, lungs, skin — and yes, your breasts! — have their own microbiomes too. Study after study has shown that the composition of the bacteria living in and on the breast may be a risk factor for breast cancer; in fact, some scientists are wondering if it may even be a method for early detection or risk management. 

Even more interesting, studies show that factors like obesity and a poor diet can influence the breast and gut microbiomes in ways that increase or decrease a person’s risk for disease. See how almost every health issue can be traced back to diet and gut health? Even after years of practicing medicine and reading studies just like this, I still find this absolutely fascinating! A world we cannot see with the naked eye has a huge impact on the health of its host — the human body.

What are the foundations of breast health?

As I mentioned earlier, keeping up with screening and being aware of what’s “normal” for you are the keys to breast health. Beyond that, I recommend following the Happy Gut ® Principles from my book Happy Gut ® for overall health to optimize breast health. These principles include: 

  1. Eat nutrient-rich foods
  2. Exercise regularly
  3. Maintain a healthy weight
  4. Manage stress levels
  5. Get high-quality sleep
  6. Limit exposure to environmental toxins

There are also steps you can take to specifically optimize the gut microbiome-breast health connection.

The Gut-Breast Connection: 5 Foods for Better Breast Health

Fatty Fish

1. Fatty Fish

The omega-3 fatty acids found in fatty fish like wild or sockeye salmon are one of the most important foods to include in your diet if you want to optimize breast health. For example, a study from the Wake Forest School of Medicine showed that diet — especially fish oil supplements — can not only alter the breast microbiome, it can alter breast tumors themselves.  Pretty fascinating, isn’t it?

Cruciferous Vegetables

2. Cruciferous Vegetables

If you want to bring balance to estrogen, cruciferous veggies are one food group to love eating on a regular basis. This class of vegetables include: 

  • Arugula 
  • Bok choy  
  • Broccoli 
  • Brussels sprouts
  • Cabbage 
  • Cauliflower 
  • Collard greens
  • Horseradish
  • Kale  
  • Radishes
  • Rutabaga
  • Turnips
  • Watercress
  • Wasabi

Cruciferous vegetables contain a compound called DIM , which works to bring balance to estrogen levels. One study showed that women who eat more cruciferous vegetables have a lower risk of developing breast cancer.

Fermented Foods

3. Fermented Foods

Thanks to the overprescribing of antibiotics, the overuse of pesticides spilling chemicals into our food and water, and the over-the-counter and prescription medications many of us have taken in the past, our beneficial gut bacteria are often not only depleted, but the diversity of our gut microbiomes has been decimated. Luckily, fermented foods are the best way to re-inoculate your gut and improve microbial diversity scores. In fact, a fermented food-rich diet may just be the best diet for gut health, according to a recent study that I wrote about in a recent blog . Check out my guide to fermentation to get started with ferments.


4. Seeds

Seeds are one of the underappreciated superfoods for women’s health. For example, pumpkin seeds contain phytoestrogens, a type of plant compound that mimics estrogen. And while that might sound strange, consuming pumpkin seeds has been linked to a decreased risk for breast cancer. In my practice I often recommend regular consumption of sprouted (thus, more rich in bioavailable nutrients) pumpkin seed to my patients looking to bring more balance to their estrogen and progesterone levels.


5. Berries

Have you ever heard the popular nutrition advice “Eat the rainbow”? That’s because berries contain polyphenols and antioxidants, which are known anti-cancer compounds. Studies have shown that women who eat more berries are less likely to be diagnosed with estrogen-positive breast cancer — talk about gut-breast connection! Berries are also one of the lowest sugar fruits, which means they will be a sweet treat, but not feed bad gut bugs, like high-sugar fruits, that would allow sugar-eating bacteria and yeast to overgrow.

When it comes to breast health, it’s important to take a holistic approach; one that involves proper screening, self-awareness, and of course, a healthy diet and a Happy Gut. 

By the way, if you’re worried about your breast health and hormone balance, we’re here to help. The HAPPY GUT ® Reset is a quick detox to rebalance your gut microbiome and leverage the gut-breast connection to create hormone harmony in 7 days or less, without feeling like you’re starving.

HAPPY GUT® 7-Day Detox

Patients who have completed the RESET often say:

My weight has dropped (15 pounds) and so did my sugar cravings. No need for coffee to boost energy and I love the increased mental clarity. I have followed this detox program twice now. Both times successfully. I suggest this program to anyone needing to take off the last 10 lbs or just a quick reset, it works!”



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