Editors note: We know we wrapped up the breast cancer awareness last week, but then we found this fascinating paper and just had to write about it. Plus, it is the last day of Breast Cancer Awareness Month, so this post is officially wrapping it up. And oh yeah, Happy Halloween! We hope all our trick-or-treating readers receive plenty of fermented foods tonight.

An article published in the International Journal of Cancer explores the effects of probiotic consumption on mice with a predisposition to mammary cancer. The article also attempts to establish a link between the probiotic and its influence on the immune system.

First, researchers fed mice a high fat diet, similar to a fast food diet. Compared to controls, these mice had a higher incidence of mammary cancer. They then repeated these trials but gave some of these fast food mice Lactobacillus reuteri. Those mice that received the probiotic had a significantly lower rate of mammary cancer symptoms than those that didn’t. The researchers then conducted a study to see if L. reuteri could help protect from cancer when the factor of obesity was removed. In this experiment they genetically predisposed some mice to get mammary cancer, and fed these mice the probiotic. They found that consumption of L. reuteri delayed or completely prevented the development of tumors, when compared to untreated mice. The researchers go on to suggest that L. reuteri may be increasing the production of a specific type of immune cell, the CD25 T-cell, and this immune cell may be exerting the underlying anticancer effects they are observing. They tested this hypothesis by transplanting CD25 T-cells into cancerous mice, and blocking CD25 T-cells in mice that were predisposed to cancer, though given the probiotic. In the mice injected with CD-25 T-cells, their cancer rate decreased. In the mice where CD25 T-cells were blocked, their cancer rates were the same as mice without the probiotic.

Probiotic bacteria decreased already developed tumors, and, in some cases, prevented tumor growth in animals predisposed to cancer by directly influencing the immune system. These results reinforce the idea that probiotics are important for a healthy immune system, which is important for overall health. So keep eating that yogurt, kimchi, and kombucha!