Can the gut microbiome influence how well chemotherapy works?

Emerging research suggests that the gut microbiome may influence how cancer responds to certain treatments. Scientists are investigating how specific bacteria and the substances they produce interact with cancer cells, drug metabolism and the immune system.

For example, laboratory studies have found that metabolites produced by Lactiplantibacillus plantarum may help restore the sensitivity of chemotherapy-resistant colorectal cancer cells to 5-fluorouracil (5-FU), a drug commonly used to treat colorectal cancer. 1

Other research has investigated how Enterococcus hirae and Barnesiella intestinihominis may support the immune response associated with cyclophosphamide treatment.2

Meanwhile other studies have shown that having too much of certain species can actually be linked to resistance to chemotherapy. Studies of Fusobacterium nucleatum have linked this tumour-associated bacterium with resistance to certain chemotherapy drugs.

These findings highlight the complex relationship between the microbiome and cancer treatment. However, much of this research is still at the laboratory or animal-study stage, much further research is needed to see how these findings can shape cancer treatment in the future. Watch this Space!

Practical tips to support gut health before and during cancer treatment

Small, individualised dietary changes can help support digestive health and nutritional wellbeing before and during cancer treatment.

• Consider functional stool analysis where appropriate. Before treatment, and again afterwards if clinically indicated, comprehensive stool testing may help identify certain microbial imbalances, digestive markers and potential pathogens, providing additional insight to inform personalised nutritional support. Completing a stool analysis 8-12 weeks post treatment can be extremely useful for helping to get the gut back into recovery.

• Support your gut with food first approach. A diverse diet can provide fibre and other nutrients used by gut microorganisms as their food source. Probiotic supplements are not suitable for everyone, particularly some people who are immunocompromised, so a food first approach is often the safest option to increase microbial diversity.

• Eat a varied diet where tolerated. Include a range of vegetables, fruit, wholegrains, nuts, seeds and pulses to provide dietary fibre and support the gut microbiome.

• Stay hydrated. Drink regularly throughout the day. Hydration is key for adequate digestion and can help reduce constipation. If you experience chronic diarrhoea or vomiting, ask your oncology team whether you need additional fluid and electrolyte replacement.

• Adapt your diet to your symptoms. Smaller, frequent meals may help with nausea or poor appetite, while temporary dietary adjustments may be needed for constipation or diarrhoea. Persistent or worsening symptoms should always be discussed with your treatment team and your Nutritional Therapist.

1. An J, Ha EM. Combination therapy of Lactobacillus plantarum supernatant and 5-fluorouracil increases chemosensitivity in colorectal cancer cells. J Microbiol Biotechnol. 2016;26(8):1490-503. doi:10.4014/jmb.1605.05024.

2. Daillère R, Vétizou M, Waldschmitt N, Yamazaki T, Isnard C, Poirier-Colame V, et al. Enterococcus hirae and Barnesiella intestinihominis facilitate cyclophosphamide-induced therapeutic immunomodulatory effects. Immunity. 2016;45(4):931-43. doi:10.1016/j.immuni.2016.09.009.

3. LaCourse KD, Zepeda-Rivera M, Kempchinsky AG, Baryiames A, Minot SS, Johnston CD, et al. The cancer chemotherapeutic 5-fluorouracil is a potent Fusobacterium nucleatum inhibitor and its activity is modified by intratumoral microbiota. Cell Rep. 2022;41(7):111625. doi:10.1016/j.celrep.2022.111625

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