The Gut Microbiome-Breast Cancer Connection

October is Breast Cancer Awareness Month, so we’re honoring women’s wellness this month by first taking a closer look at how the gut microbiome and breast cancer may be linked in surprising ways, and then looking at some of the top anti-cancer foods you can start incorporating into your daily diet right away.

Did you know 1 in 8 women will get breast cancer at some point in their lifetime? Odds are you know someone who is a breast cancer survivor. Maybe you are. Or you may have lost someone to breast cancer.

If this is you, then keep reading, because this blog post is especially for you.

About 5 to 10 percent of breast cancer cases are genetic, which means that if your mom or grandmother had breast cancer, your risk for developing it will be higher.

But here’s the good news:

The vast majority of breast cancer cases are influenced by the food and lifestyle choices you make every day.

This is called “epigenetics.” In other words, when you eat the right foods (more on those in a minute), exercise regularly, detoxify your body properly, avoid smoking and excess alcohol, take care of your gut health, and manage stress, you can reduce your overall risk of developing breast cancer.

This week, in honor of Breast Cancer Awareness Month, I want to focus on the one thing often missing in the conversation about breast health — the health of your gut.

Long-Term Breast Health Starts in the Gut

Like all diseases, there is almost always more than one factor involved in breast cancer. That said, when it comes to laying a foundation for healthy breasts (and hormones) in the long-term, gut health is something that can’t be ignored. If you’re been a long-time Happy Gut reader, this won’t come as a huge surprise. After all, supporting the gut microbiome – that diverse ecosystem living inside you comprising trillions of symbiotic bacteria – impacts nearly every system in your body. The breasts and your hormones are no exception. In fact, your breasts actually have their own specific microbiome. And while we’re still understanding how this works, specific bacteria in the breast microbiome can support healthy breast tissue, while imbalances in the make-up of that bacteria can increase your risk of breast cancer .

Today, though, we’ll be focusing on the gut microbiome, which we know plays many roles in the body. Some important ones that are relevant to breast health include:

• Supporting immune system development and maintenance, which is key in cancer prevention and recovery.
• Fermenting  indigestible fibers into short-chain fatty acids (SCFAs), which have been shown to have anti-cancer properties.
• Producing essential amino acids that are key to a healthy immune system.
• Producing vitamins, including B vitamins and vitamin K, which have a protective effect against breast cancer.
• Increasing the absorption of minerals that can prevent key nutrient deficiencies that may put you at higher risk for diseases of all kinds.
• Supporting regular elimination, which allows estrogen and other hormone metabolites to be excreted from the body efficiently
• Deactivating toxins and carcinogens that are linked to increased breast cancer risk.

Looking at this list, you can see right away how absolutely critical a healthy gut microbiome is to breast cancer prevention. This is particularly true for the last bullet point because…

It’s suspected that gut bacteria play an important role in our ability to deactivate or detoxify the nearly constant onslaught of toxins that we encounter daily.

Knowing this, it’s not surprising that newer research is showing that a compromised gut can impact the risk of breast cancer.

The Gut Health-Immune System Connection You Should Know About

The delicate balance maintained by the trillions of microorganisms influences so many aspects of our health. For example, when your gut microbes are in harmony, you maintain a healthy weight, you feel great, and you keep disease at bay. Unfortunately, when that delicately orchestrated ecosystem inside your gut loses its state of harmony — as so frequently happens in our modern world — it can have serious consequences.

This loss of harmony is called dysbiosis, which literally means “living out of harmony with,” In dysbiosis, bad gut bacteria take over and throw an unwelcome party in your gut, crowding out beneficial bacteria and disrupting nutrient absorption, perhaps creating constipation, and sabotaging the healthy elimination of excess hormones and toxins. This sounds bad but dysbiosis is usually subtle. It evolves over time and can exist in the background for months or years.

Among many things, dysbiosis causes a domino effect that can lead to leaky gut syndrome and disruptions in the ability of your immune system to fight infections and keep cancer cells in check. Eventually, this can lower the effectiveness of certain immune cells, such as lymphocytes, while increasing others, like neutrophils. Animal studies have found that gut microbiome alterations lead to the development of breast tumors. Researchers have also found that imbalances in the gut microbiome can even affect the survival of patients with breast cancer.

This connection is further proven by what we’ve learned about antibiotics in recent years. Antibiotics, which are often overprescribed, impact the biodiversity and abundance of some bacterial communities and disrupt the balance of the gut microbiome, increasing the risk of diseases, including cancer .

How the Microbiome, Inflammation, and Cancer Are Linked

As it turns out, dysbiosis can play a role in many types of cancer, including breast cancer. In fact, scientists have coined a word, “oncobiome,” to describe the interaction between the gut microbiome and cancer. The microbiome influences the development of cancer formation in several ways:

• It stimulates cells to increase in number or self-destruct 
• It regulates the immune response
• It metabolizes indigestible dietary components, medications, and other xenobiotics or foreign substances in the body
• It reduces inflammation in the gut and the entire body 

This has inspired an increase in research about the gut microbiome — breast cancer connection. For instance, one study found that the microbe composition of women with breast cancer differs from that of healthy women . The authors wrote that specific bacteria are able to produce estrogen-metabolizing enzymes, that the gut microbiota is capable of modulating estrogen serum levels, and that estrogen-like compounds in the gut may support the growth of certain types of bacteria. In other words, there’s a LOT of interplay between the gut microbiota and estrogen — a hormone that plays an extremely important role in the development of breast cancer.

From that understanding, we are now exploring how certain bacteria, like the Firmicutes population and Akkermansia muciniphila , could play a part in the development of cancer .

Gut inflammation is another huge driver for cancer, since the inflammation that starts in the gut can eventually impact the entire body.  I mentioned antibiotics as a primary driver of dysbiosis, which can lead to leaky gut and a host of gut problems. In one study, when mice were given antibiotics, their guts became unhealthy and inflamed from the microbe imbalances. With the gut environment messed up, researchers proposed breast cancer could become more invasive and spread faster throughout the body.

Another study looked at a possible link between prolonged gut inflammation and breast cancer. The researchers discovered that mammary carcinoma (a type of cancer that can start in cells that make up the skin) developed within four to six weeks in mice that acquired an infection with Helicobacter hepaticus , a gut-associated pathogen. Mice mature about 25 times faster than humans, so we can’t take the results of this study and directly apply them to you or me, but this study does provide helpful hints as to how specific gut bacteria may create conditions that increase the risk of breast cancer in humans. Studies like these show that specific species of bacteria should be on our radar when looking for the underlying causes of cancer.

But research, without practical, clear actions you can take creates more angst than helps. That said, what can you do if you are worried your gut is imbalanced? What if you’ve been on multiple rounds of antibiotics? What if you suffer from bloating and constipation?

Or you’re simply worried you might be one of the every eight women who is at risk for breast cancer in your lifetime?

Reduce Your Risk of Breast Cancer, One Bite at a Time

As I mentioned earlier, most breast cancer cases are not caused by genetics, but by lifestyle and environmental factors. What this means is you have A LOT of power when it comes to reducing your risk of breast cancer and maintaining breast health throughout your life.

The best place to start is with what’s at the end of your fork, because what you eat can alter the gut flora, for better or worse.

I talk about the seven worst foods for gut health you should avoid in a blog I wrote for mindbodygreen . When you remove these foods, which are “toxic” to your body because they activate your immune response, it initiates the process that allows your microbiome to become more balanced.

But when I tell my patients what they can’t eat, they’re often baffled and ask, “What’s left to eat? Seriously, what should I eat?” So, let’s focus on the positive — what foods are BEST for preventing breast cancer. And that means nutrient-dense, colorful plant foods that contain important nutrients for supporting overall gut health and detoxification.

The Top Breast Cancer-Fighting Foods

1. Broccoli

Studies have shown that higher intakes of cruciferous vegetables like broccoli, kale, cabbage, and cauliflower are associated with reduced breast cancer risk , especially in premenopausal women. I suggest opting for broccoli because it’s the only cruciferous vegetable to pack meaningful amounts of sulforaphane, an antioxidant which has demonstrated anti-breast cancer activity. Broccoli is an all-around nutrient superstar that makes a great side dish, easily sauteed in coconut oil and garlic. This Creamy Broccoli Soup also makes a warming, savory starter for the cold months ahead!

2. Avocado

This delicious fruit is loaded with fiber and important nutrients, like potassium. They are also an excellent source of omega-3 fatty acids, which can lower inflammation and support bothe gut and breast health. This Happy Gut Omelet combines creamy avocado with another cancer-fighting cruciferous rockstar — Brussels sprouts. This is my go-to recipe for a quick, delicious brunch or lunch.

3. Purple Cabbage

The bold color makes this type of cabbage more nutrient-rich. Purple cabbage contains two cancer-fighting compounds — sulforaphane and anthocyanins. My Happy Gut® Slaw combines purple cabbage with other cancer-fighting, gut-healing foods, such as garlic and turmeric kraut. It’s also fermented, which doubles the benefits for breast health. Emerging evidence is showing that the probiotics in fermented foods can protect against breast cancer . We are still learning about specific strains, dosage, and regimen. What we’re seeing is promising, though:

• One study found that the probiotic Lactobacillus reuteri, a specific strain of bacteria found in dairy ferments, could inhibit early-stage breast cancer and improve breast cell sensitivity to apoptosis.
• Metabolites of the lactic acid bacteria found in lacto ferments are jumpstart specific receptors in the body, like the hydroxycarboxylic acid receptor 3 , that activate the immune system and help keep chronic inflammation under control.

Learn more about fermented foods, including all types of delicious lacto ferments, here .

4. Blueberries

Organic blueberries are packed with nutrients and fiber as well as antioxidants that can prevent DNA damage. My Wild Blueberry Breakfast Muffins combine blueberries with avocado oil and almond butter in a delicious, easy-to-make snack or breakfast. Because environmental toxins can play a big role in the development of cancer, I strongly encourage you to choose organic produce whenever possible. Learn more about your best choices and more ways to minimize that toxic impact here .

5. Cauliflower

Besides also being a cruciferous veggie, cauliflower is also high in fiber, which is critical to breast cancer prevention. Why? Fiber is your gut’s best friend. Previously, I mentioned how gut bacteria turn fiber into short-chain fatty acids (SCFAs). There are other benefits of eating high-fiber foods.

• Fiber binds to hormones such as estrogen to prevent those hormones from entering the circulation and creating havoc. In my next blog, I’ll talk more about this and how not managing estrogen levels can lead to a condition called estrogen dominance.
• Researchers found that premenopausal women who ate over 30 grams of fiber daily could lower their risk of breast cancer.
• Eating raw vegetables can lower your risk of breast cancer by 34 percent .
• Fiber can help restore gut bacteria, increasing healthy Bifidobacterium and Faecalibacterium prausnitzii , which offer anti-inflammatory and anti-tumor benefits.

Sometimes I tell patients to avoid anything white, such as sugar or flour. But there’s an exception to every rule, and cauliflower is that exception. This cruciferous veggie gets spiced up in this very flavorful Curry Cauliflower Rice recipe.

In all fairness, there are a lot of great foods that you can choose among to stay healthy, support gut health, and reduce your risk of breast cancer. Narrowing them down to five was tough. From these favorites, I shared a couple of delicious Happy Gut-approved recipes that you’ll love.

Right now, we have fewer studies on the gut microbiome and breast cancer than with other cancers. But luckily, that’s changing! One current clinical trial is determining whether the gut microbiome plays a role in fighting advanced breast cancer by impacting how immune cells work.

I’m confident that emerging studies will continue to show that supporting the gut impacts many conditions, including breast cancer. But you don’t have to wait for science to catch up. The foundation of great health is in your gut! When you love your gut with healthy food and lifestyle choices, you’re taking a big step towards supporting breast health and reducing your risk of breast cancer.

With school back in session and everyone “falling” back into a routine, you may not always have time to prepare extravagant meals filled with these cancer-fighting foods above. That’s why I love smoothies — they provide fast, filling nourishment and are absolutely jam-packed with nutrients. To inspire you to eat the breast cancer-fighting foods above in the quickest and most delicious way possible, I created this 7 Breast Health-Supporting Smoothie Recipes download. These smoothies make taking care of your breast and hormone health easy and delicious.

CLICK HERE to Download the Free Recipes Today!