Compounds in certain plant-based foods have been linked to breast cancer outcomes, which may impact the dietary choices of survivors and patients. A new study investigated this further, aiming to identify beneficial compounds and whether or not their impacts are better when a patient was already consuming them before diagnosis. They also tried to pinpoint the best dosage. The findings highlighted a few possible compounds that may lower the chances of cancer returning.
Researchers from Johns Hopkins Kimmel Cancer Center analyzed 22 observational studies on how breast cancer recurrence and mortality may be impacted by compounds in soybeans, nuts and seeds, certain vegetables, and green tea. Their findings, published in JNCI Cancer Spectrum, showed that the consumption of soy isoflavones may be beneficial. They were linked with a 26% lower risk of recurrence, with the strongest benefits found in postmenopausal women with estrogen receptor positive breast cancer. The ideal daily consumption for this protective benefit was 60 mg, or two to three servings of a soy-based food. The mortality benefit wasn’t quite as high, at 12%, with the ideal daily dosage for that at between 20 and 40 mg.
For stage I and II patients who were drinking green tea before diagnosis, meanwhile, there was a 44% lower risk of recurrence, while cruciferous vegetables weren’t linked with significant protection.
Another compound found to be protective is actually produced by the digestive system in response to consuming another compound involved in the study. Enterolactone is produced in the gut after the consumption of lignans, which are found in a variety of foods, including nuts and seeds. Past research has actually found that lignans in flaxseeds may change the gut in such a way that reduces breast cancer risk.
In this study, enterolactone was found to lower the risk of breast cancer mortality by 28% and all-cause mortality by 31%, particularly in postmenopausal women. The ideal dosage wasn’t determined, however, because each individual’s gut microbiome impacts how lignans are metabolized.
Dr. Channing Paller, senior author and director of prostate cancer clinical research at Johns Hopkins, says, “This research highlights the need for more robust studies in this area looking at the most effective dosages of these compounds, and whether starting to consume them after diagnosis has the same effect as a lifelong dietary habit before diagnosis. This is what patients are looking for.”
This research was inconclusive on the last point, not determining if these compounds provided the most benefits when they’d been consumed before or after diagnosis.
Dr. Paller also points out that these studies involved women who had undergone traditional treatment and were not using food as a primary means to avoid recurrence.
She explains, “It is critically important to stress that these studies were conducted on women who received medical and/or surgical treatment for breast cancer, and that these foods and phytonutrients should not be considered as alternatives to treatment.”
You can read the whole study here.