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How to Maintain your Gut Health While on Chemotherapy

Cancer treatments such as chemotherapy, radiotherapy and immunotherapy work to destroy cancer cells in the body. However, these can often be intensive for the patient and side-effects such as nausea, vomiting, diarrhoea, loss of appetite and fatigue, have been reported. Emerging evidence highlights that these cancer treatments can negatively affect gut health by reducing the diversity of the bacteria in the gut and increasing the abundance of harmful bacteria. This can further lead to inflammation and greater risk for infection.

On the other hand, taking care of your gut microbiota can lead to better treatment outcomes. A review of the scientific literature found that a balanced and complete microbiota aids chemotherapy effectiveness. From this, researchers found that the gut microbiota may be a useful indicator to predict chemotherapy efficacy.

There are multiple strategies to maintain good gut health while on chemotherapy, which can lead to better treatment outcomes.

1) Probiotic supplementation

Combining probiotic supplements with chemotherapy drugs have been shown to alleviate some adverse symptoms. A review of 12 clinical studies found that probiotics significantly reduced the risk of chemotherapy-induced diarrhoea and oral mucositis (irritation and swelling of the mouth), where the more species of probiotics taken led to a lower risk for more severe symptoms. However, a study that investigated the use of a single-species probiotic supplement in colorectal cancer led to a reduced severity in diarrhoea and abdominal discomfort. This research shows that targeted probiotic treatment (i.e. specific species for specific types of cancer) can decrease the likelihood and severity of chemotherapy-related symptoms in the gut.

If you are interested in probiotic supplementation, it is recommended you check with your oncologist or care team to ensure it aligns with your other treatments.

2) Dietary patterns

Many diets such as Mediterranean, vegetarian/ vegan, and increased soy intake are associated with a reduced risk for cancer diagnosis, mortality and recurrence. However, no scientific studies suggest that these can improve chemotherapy treatment outcomes. Although emerging evidence shows that intermittent fasting, caloric restriction and the ketogenic diet can improve chemotherapy-related symptoms and its efficacy, more human studies are required to draw definitive conclusions. Patients with cancer may have increased nutritional requirements, and may experience symptoms that discourage eating e.g. loss of appetite. In these cases, dietitians can provide tailored nutrition to help maintain health and normal body functioning.

3) Gut Nourshing Foods

As suggested, research shows that good gut health have positive benefits towards cancer treatment outcomes. Therefore, gut nourishing foods such as prebiotics and probiotics can be included as part of a healthy diet throughout cancer treatment. Here are some common mistakes when i comes to a gut nourishing diet.

The link between gut health and chemotherapy treatment is bi-directional – while chemotherapy can cause negative effects on the gut, taking care of your gut can lead to better treatment outcomes. If you’re currently on chemotherapy, consider talking to a doctor or dietitian to individualise these tips based on your specific circumstance.

Four Seasons Dietetics have recently partnered up with Sydney Adventist Hospital to offer dietetic services to cancer patients. You can now book your appointment online to speak with our dietitian who specialises in cancer nutrition. You don't have to be a SAH patient to access our services. Telehealth and in-person appointments availab.e


Liu, L., Bai, Y., Xiang, L. et al. Interaction between gut microbiota and tumour chemotherapy. Clin Transl Oncol (2022).

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Feng J, Gao M, Zhao C, Yang J, Gao H, Lu X, Ju R, Zhang X and Zhang Y (2022) Oral Administration of Probiotics Reduces Chemotherapy-Induced Diarrhea and Oral Mucositis: A Systematic Review and Meta-Analysis. Front. Nutr. 9:823288. doi: 10.3389/fnut.2022.823288

McQuade, R. M., Stojanovska, V., Abalo, R., Bornstein, J. C., & Nurgali, K. (2016). Chemotherapy-Induced Constipation and Diarrhea: Pathophysiology, Current and Emerging Treatments. Frontiers in pharmacology, 7, 414.

Routy B, Le Chatelier E, Derosa L, Duong CPM, Alou MT, Daillère R, et al. Gut microbiome influences efficacy of PD-1-based immunotherapy against epithelial tumors. Science (New York, NY). 2018;359(6371):91–7. 

Mittelman S. D. (2020). The Role of Diet in Cancer Prevention and Chemotherapy Efficacy. Annual review of nutrition, 40, 273–297.

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