Chemotherapy (commonly referred to as chemo) is among the conventional standard of care for treating cancer, which consists of a combination of specific drugs that kill cancer cells. There are over 100 different types of cancer, the name given to a collection of related diseases where cells begin to divide and spread to other tissues in the body. According to the CDC, cancer is the second leading cause of death in the U.S. (one of every four deaths is due to cancer) and in 2016 there were nearly 1.7 million new reported cases of cancer and almost 600,000 deaths. Chemotherapy works by stopping cancer cells from proliferating or slowing the rate of growth. Unfortunately, while chemo targets fast-growing cancer cells, it also kills healthy cells that grow and divide quickly such as the epithelial cells that line our GI tract and those that make our hair grow. Because healthy cells are caught in the crossfire, patients who are battling cancer are often battling a long list of painful side-effects, including fatigue, anorexia, pain, alopecia, among many others that may cause them to stop treatment prematurely.

According to a recent study published in Frontiers in Pharmacology, scientists have discovered a new delivery method for chemotherapy that targets malignant cells and leaves healthy ones alone! This novel technique provides a bit of hope as it could allow doctors to lower drug dosages as well as reduce patients’ suffering from the harsh adverse effects associated with chemo treatment, which could, in turn, increase compliance and improve overall disease prognosis.

The Gut “Chemo-Brain” Connection

In another recently published study in the journal Scientific Reports, researchers from Ohio State University may have discovered a solution to improve undesirable gastrointestinal and cognitive side-effects that are caused by chemo. According to the researchers, this in vivo animal model is the very first to uncover the link between both gut symptoms and brain symptoms in the context of chemotherapy treatment. The results from this animal study are similar to previous human trials that elucidated how the composition of the human gut microbiome was altered by chemotherapy drugs. When the treated mice were injected with a common chemotherapy agent compared to the mice receiving placebo, researchers realized multiple simultaneous reactions: “Their gut bacteria and tissue changed, their blood and brains showed signs of inflammation, and their behaviors suggested they were fatigued and cognitively impaired,” indicating that the neuroinflammation caused by chemo is correlated with disrupted colonic and bacterial homeostasis in the host.

Compared to the controls, the treated mice showed signs of intestinal permeability, which could trigger immune system overactivation, signaling the brain microglia (brain immune cells) with its own inflammation which is the culprit behind “chemo brain.” The term “chemo-brain” refers to cognitive impairment and mental fogginess that lingers for months or even years after the cancer is gone. This new phenomenon, “Chemo-brain,” affects more than half of cancer survivors and is becoming more common as cancer therapies extend patients’ lifespans.

This novel research sheds light on how the health of our gut microbiome affects more than just our digestive tract; the composition of the gut plays a critical role in many other (if not all) systems of the body, especially the immune and nervous systems. It also adds to the existing evidence supporting how the health and wellbeing of our gut are linked to the health and wellbeing of our brains which can lead to better interventions for cancer patients to promote a beneficial bacterial composition of the gut that protect against neuroinflammation in order to reduce the symptoms of chemo-brain. 

Eat More Pre- and Pro-biotics

It seems Hippocrates was right when he said: “All disease begins in the gut”. This evidence paves the way for functional medicine practitioners to step in and help this patient population attenuate the symptoms they experience during chemotherapy. In addition to implementing an anti-inflammatory diet such as the Mediterranean diet or a plant-based ketogenic diet, recommending cancer patients increase their daily intake of prebiotic and probiotic-rich foods, as well as supplementing with high-potency pre and probiotics (e.g., spore-forming, human-strain probiotics) may be key interventions for helping reduce the negative side effects most patients undergoing chemotherapy experience. Prebiotics are fiber-rich foods that are non-digestible by humans but fermented (or “eaten”) by the beneficial and commensal bacteria residing in the gut, improving the composition of the gut microbiome. Prebiotic-rich foods include asparagus, chicory, Jerusalem artichokes, leeks, garlic, onions, green-tipped bananas, apples, dandelion greens, raw cacao, flaxseeds, jicama root, and whole oats. Healthy probiotic-rich foods include Korean-style kimchee, sauerkraut, kombucha, raw kefir and yogurt, miso, natto, and tempeh.