Your breast microbiome and breast cancer risk

By now you’re probably familiar with your gut microbiome, a collection of microorganisms that help maintain a balanced environment in your gut. But you may not be as aware that other parts of the body have their own microbiomes that are just as important to your health.

One such environment that researchers have been taking a close look at in recent years is the breast microbiome. Investigators have found that certain changes in the breast microbiome — such as lower levels of the friendly bacteria Lactobacillus — can increase the risk of breast cancer.

We previously wrote about a 2018 Wake Forest University study that showed the difference diet can make in your breast microbiome. Now, new research by Wake Forest scientists has uncovered even more evidence of the connections between diet, breast microbiome and breast cancer risk…

How microbiome influences breast cancer

The most recent multi-pronged study, which involved animal models and breast cancer patients, found diet and certain supplements can alter both the breast microbiome and breast cancer tumors.

“Obesity, typically associated with a high-fat diet consumption, is a well-known risk factor in postmenopausal breast cancer,” says Dr. Katherine Cook, assistant professor in the surgery – hypertension and cancer biology departments at Wake Forest School of Medicine. “But there’s still a lot we don’t know about the obesity link to microbiomes and the impact on breast cancer and patient outcomes.”

Results of the first part of the study showed mice susceptible to breast cancer that were fed a high-fat diet had more tumors than the same type of mice receiving a low-fat diet. And the tumors in the high-fat diet mice were larger and developed more quickly.

To study the microbiome of the mice, researchers performed fecal transplants. Mice consuming the low-fat diet received the high-fat diet microbiome transplant, and vice-versa.

“Simply replacing the low-fat diet gut microbiome to the microbiome of high-fat diet consuming animals was enough to increase breast cancer risk in our models,” Cook says. “These results highlight the link between the microbiome and breast health.”

Things really got interesting with what the researchers did next, to see the significance of changes to the breast microbiome of breast cancer patients…

In a double-blind placebo-controlled clinical trial, they gave breast cancer patients either fish oil supplements or a placebo for two to four weeks before their lumpectomy or mastectomy.

According to the results, supplementing with fish oil significantly changed the microbiome throughout the breast, in both the non-cancerous and malignant breast tissue. For instance, scientists found that those who took fish oil supplements for four weeks had an increase in the amount of Lactobacillus in the normal breast tissue adjacent to the tumor. Previous preclinical studies have shown Lactobacillus can decrease breast cancer tumor growth.

The scientists also discovered a decrease in abundance of Bacteroidales and Ruminococcus microbes in the breast tumors of patients taking the fish oil supplements, although the significance of these changes is not yet known.

The study clearly highlights the central role diet plays in shaping the breast microbiome and indicates certain specific dietary interventions may help reduce breast cancer risk. The Wake Forest research team is conducting further studies to determine whether probiotic supplements can influence microbiome populations in mammary glands and in breast tumors.

Supporting good breast health through diet

Even if you’re not at high risk of breast cancer, adding a fish oil supplement to your daily regimen is a good idea. The omega-3 fatty acids in fish oil help combat inflammation and support a healthy heart and brain.

We’ve written in the past about how to choose the best fish oil supplements, as well as the similar benefits offered by krill oil supplements. Whichever you choose, make sure the oil is truly sourced from fish or krill and that it’s free from toxins.

Aside from these supplements, we’ve often touted the health benefits of the Mediterranean diet. It’s good for your heart, prostate and gut, helps you manage stress and maintain weight loss and promotes healthy aging.

And research shows eating like they do in the Mediterranean also promotes good breast health. In fact, the 2018 Wake Forest study found that macaques eating a Mediterranean diet had 10 times more Lactobacillus in their breasts than macaques fed a Western diet.

The Mediterranean diet tends to include lots of fish, poultry, whole grains, fruits and vegetables, olive oil, nuts and beans and legumes. Try to keep your consumption of eggs, cheese and dairy to a minimum, limit alcohol to a glass of red wine with dinner and make sweets an occasional treat.

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Researchers find evidence that diet can alter the microbiome to affect breast cancer risk — EurekAlert!

Carolyn Gretton

By Carolyn Gretton

Carolyn Gretton is a freelance writer based in New Haven, CT who specializes in all aspects of health and wellness and is passionate about discovering the latest health breakthroughs and sharing them with others. She has worked with a wide range of companies in the alternative health space and has written for online and print publications like Dow Jones Newswires and the Philadelphia Inquirer.