In recent years, it’s become increasingly apparent that the composition of microbes in your gut — which is as distinct to you as your fingerprint — plays an enormous role in health and disease prevention. Your gut flora influences the function of various internal organs, such as your skin, lungs, breasts and liver.¹

For example, recent research² by the National Institute of Health shows gut microbes control antitumor immune responses in the liver, and that antibiotics — by depleting your gut of valuable bacteria — can alter the composition of immune cells in your liver and trigger tumor growth.

Aside from cancer, dozens of other health conditions have been traced back to the influence of gut microbes as well, including obesity, depression, chronic fatigue syndrome, Parkinson’s and allergies,³ just to name a few. One of the reasons for this is because your gut is the main residence of your immune system.⁴ Disrupt your gut microbiome and you automatically disrupt your immune function, which can have far-reaching consequences. As noted in a paper published in Clinical and Experimental Immunology:⁵

“The crucial position of the gastrointestinal system is testified by the huge amount of immune cells that reside within it. Indeed, gut-associated lymphoid tissue (GALT) is the prominent part of mucosal-associated lymphoid tissue and represents almost 70 percent of the entire immune system; moreover, about 80 percent of plasma cells … reside in GALT.”

How Your Microbiome Influences Your Cancer Risk

Previous studies have shown certain gut bacteria quell inflammation, which is an underlying factor in virtually all cancers, whereas others promote it. As noted in a recent article in Nature,⁶ “bacteria have been associated with cancer initiation and progression. Some of these microbes activate inflammatory responses and disrupt the mucus layers that protect the body from outside invaders, creating an environment that supports tumor growth.”

Certain cancers have also been found to have infectious underpinnings. For example, Heliobacter pylori (H. pylori) has been linked to gastric cancer. The International Agency for Research on Cancer actually defines this microbe as a carcinogen.⁷ Interestingly, H. pylori has also been linked to a reduced risk of esophageal adenocarcinoma, demonstrating the complexity involved and the organ-specific effects microbes can have when it comes to their impact on cancer.

Similarly, hepatitis C virus has been shown to play a role in hepatocellular carcinoma, chronic Salmonella enterica infection has been linked to gallbladder cancer, and Haemophilus influenza and Candida albicans have been identified in lower respiratory tract tumors. Gut microbes have also been found to influence the effectiveness of cancer treatment.

Gut Bacteria Influence Effectiveness of Anticancer Drugs as Well

Recent research adds support to the idea that targeting the gut microbiome could be a real game-changer in the fight against cancer, as the presence of certain gut bacteria appears to boost the patient’s response to anticancer drugs. Several clinical trials are now being launched to see whether outcomes can be improved simply by manipulating the patient’s gut flora.

One way in which gut bacteria improve the effectiveness of cancer treatment is by activating your immune system and allowing it to function more efficiently. Researchers have actually found that when these specific microbes are absent, the anticancer drug may not work at all.⁸ Such was the case with cyclophosphamide, a chemotherapy drug.

Part of the mechanism that allows cyclophosphamide to work is that it damages your intestinal lining, allowing bacteria to travel into your spleen and lymph nodes, where they then activate the necessary immune cells to combat the cancer. As you probably know, your immune system is your first line of defense against all disease, including cancer, and when functioning well, cancer cells are eliminated before they can grow into a tumor.