Healing Your Gut After Chemotherapy

If you’ve been through chemotherapy, you’ve likely experienced the impact of treatment on your digestive system. In fact, some of the most notorious side-effects of chemotherapy come as a direct result of the irritation and damage that is caused by these medications. Healing your gut after chemotherapy is critical, especially given that your gut is the source of your health.

While your GI tract provides the physical space and movement necessary for digestion, it’s your microbiome that determines how protected, active, and effective these functions of our gut are. The microbiome is a complex environment made up of commensal microorganisms (meaning they are beneficial to us) and pathogenic bacteria (which can damage our gut and body). It’s responsible for helping break down the foods you don’t have enzymes for, regulating hormone production (especially your sex hormones, such as estrogen), educating your immune system (to ensure it’s functioning well and is not over-stimulated), and helping to create neurotransmitters necessary to regulate mood (80-85% of your serotonin is actually made in the gut).

What is chemo really doing to my microbiome? 

Ideally, your microbiome is diverse and balanced. Unfortunately, chemotherapy has been shown to dramatically reduce microbiome diversity and shift the types of bacteria present. It’s this change that sets the stage for significant and lingering damage to your gut and digestive function.

Research has shown that chemotherapy noticeably alters the microbiome of patients while they are receiving treatment and after treatment ends. Studies found that chemotherapy resulted in four significant changes:

Reduced bacterial diversity. This decrease in the variety of bacteria is associated with a weaker, more vulnerable intestinal environment and puts GI tissue (mucosa) at increased risk of colonization and invasion by damaging bacteria.

Changes in metabolic pathways. These changes may be happening in response to the oxidative stress being placed on the intestinal microbiome and lead to a reduced ability to stop inflammation.

Increased intestinal permeability + altered mucous layer composition. When the mucous layer that protects the gut is compromised, gut tissue is more vulnerable to damage. This ultimately results in a higher risk of bacteria slipping through a damaged GI tract, leading to infection (a fairly frequent complication of chemotherapy).

More inflammatory microflora.  Not only did chemotherapy alter the overall bacterial diversity, but the microflora that remained were actually shown to create a more inflamed gut environment. This increased inflammation makes the GI tract more vulnerable to infection and can often bring out symptoms similar to those we see in IBS/IBD (cramping, bloating, appetite changes, fatigue, diarrhea, etc).


What can I do about this? 

Research hasn’t caught up enough to tell us exactly which probiotic strains are most effective, but it has started showing us which bacteria can help protect your gut. The best way to start this healing process is through the food you eat! Certain foods have been shown to actually replenish bacterial diversity directly and effectively. A few foods to start including in your daily diet, as you recover and heal your digestive system, include:

Nuts. Not only do these help to add fats, fiber, and a little protein to your diet, but pistachios in particular seem to not only enhance the microbiome but are also showing chemoprotective effects (potentially helping to reduce colon cancer risk). This is all thanks to their B vitamin, polyphenol, and dietary fiber content.

Berries. High in antioxidants, these tasty fruits have been shown to increase bacterial diversity and especially help to increase the amount of good bacteria in the gut.

Fiber. Foods high in fiber can help optimize our bacterial diversity, as fiber is fermented by gut bacteria which helps reduce gut inflammation.

Vegetables. No matter the type of diet studied, significant benefits are always found to be a direct result of vegetable intake. Research has shown the most improvement in regards to increasing digestive activity, microbiome diversity, and the prevalence of those “good” bacteria we love so much.

If you’re looking for a little more targeted support a probiotic can definitely be considered after chemotherapy is over. As a note, your care team may caution you about the risk of probiotics causing infection during chemotherapy, and this concern should not be ignored. For this reason always consult with your Naturopathic Doctor before you consider adding this in during treatment.

Don’t underestimate the impact of seemingly small dietary changes. We often look to the newest, most cutting-edge treatments when we think of cancer care but when it comes to impactful, sustainable health, these small shifts are not only easier to implement but can be maintained longer, which will lay the foundation for meaningful healing.

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Dr. Hayhlee Clarence, ND

Dr. Hayhlee Clarence, ND

Dr. Hayhlee Clarence is a Naturopathic Doctor and co-owner of The Orenda Clinic & Apothecary in Toronto, an integrative clinic created to provide support for those struggling with cancer and hormonal imbalances, including hormone-sensitive cancers. Her practice is focused on cancer support both during active treatment and during aftercare, as women recover and look to take control of their health.