Adding fish oil supplements to your diet can help lower breast cancer risk

WINSTON-SALEM, N.C. — Although people typically take dietary supplements for their gut health, a new study finds one popular supplement may be very beneficial to breast health as well. Researchers from Wake Forest School of Medicine say fish oil supplements appear to alter the breast microbiome and reduce cancer risk.

Many dieters and people taking probiotics are probably familiar with the gut microbiome. This collection of billions of microorganisms living in the intestines plays a vital role in maintaining balance and health within every person. However, study authors say there is also a breast microbiome which regulates breast tissue health and determines tumor development risk.

In 2018, scientists from Wake Forest Baptist Health discovered that a person’s diet can impact this microbiome, just like the one in the gut. Now, study authors have zeroed in on fish oil as a particularly healthy substance that can alter breast cancer tumors.

Any contact with a high-fat diet can increase cancer risk

To study the effect of diet on breast cancer risk, researchers conducted three separate experiments involving both human and animal cancer patients. Specifically, scientists examined the relationship between cancer development and the consumption of a high-fat diet.

Obesity, typically associated with a high-fat diet consumption, is a well-known risk factor in postmenopausal breast cancer,” says Katherine L. Cook, Ph.D., assistant professor in the surgery – hypertension and cancer biology departments, in a media release. “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.”

In the first study, researchers fed mice susceptible to breast cancer either a high-fat or low-fat diet. Results revealed mice on the high-fat diet developed more tumors, which were also larger and grew more quickly.

In the next experiment, the team performed a series of fecal transplants between these two groups of mice. Study authors transplanted the microbiome of high-fat diet mice into the low-fat group and vice-versa. To their surprise, researchers discovered low-fat diet mice receiving a transplant from high-fat diet mice developed just as many cancerous breast tumors as those actually consuming the fatty foods.

“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 adds. “These results highlight the link between the microbiome and breast health.”

So how does fish oil help prevent this?

The final phase of the study involved human breast cancer patients in a double-blind placebo-controlled clinical trial. Patients consumed either a placebo or fish oil supplements for two to four weeks before undergoing a lumpectomy or mastectomy.

The results reveal adding fish oil to a patient’s diet changes the microbiome in both non-cancerous and malignant breast tissue. Researchers discovered those taking the supplements for four weeks had more Lactobacillus in the normal tissue surrounding a tumor.

Lactobacillus is a type of bacteria scientists say can decrease breast cancer tumor growth. The team also found fewer Bacteroidales and Ruminococcus microbes in the group’s breast tumors. The significance of this change, however, is still unclear.

“This study provides additional evidence that diet plays a critical role in shaping the gut and breast microbiomes,” Cook concludes. “Ultimately, our study highlights that potential dietary interventions might reduce breast cancer risk.”

Cook’s team is now looking into whether probiotics have a similar impact on breast health and tumor development risk.

The study appears in the journal Cancer Research.