The role of the microbiome in cancer risk and healing

One of the keys to my healing with chemo the second time around was looking after my gut microbiome. Chemo and antibiotics can have a devastating effect on your gut. An underperforming gut microbiome not only affects your toilet habits but also impacts your immunity system and mental state. 

I’ve always had limited success with probiotic supplements. The jury is still out as to whether they can survive the acid in the stomach before they make their way to the lower intestines.

The answer lies in the power of prebiotics, including fibre from legumes and resistant starch. Supplementing with resistant starch found in green bananas is the best thing I’ve ever done for my gut. 

I also take probiotics in the form of coconut yoghurt and kimchi. I don’t bother with probiotic supplements anymore. Instead, I have a smoothie or vegetable juice with green banana-resistant starch and yoghurt daily and a targeted synbiotic.

The following article takes a look at the science behind the connection between the vitality of your gut microbiome and cancer. What I’ve found out is that not only is the vitality of the gut microbiome implicated in developing cancer but it also plays a major role in the efficiency of cancer treatment. 

The gut microbiome and cancer – the science

The human body is full of benevolent bacteria that aid everything from breaking down food to fighting illness and balancing mood. Called the microbiome, bacteria help keep us healthy and alive. Studies show how replenishing the microbiome improves the effectiveness of cancer treatments and helps relieve the side effects.¹

The body contains trillions of organisms, including bacteria, viruses, yeast, protozoa, fungi and archaea, known collectively as your microbiome. We have ten times more bacteria inside our bodies than cells. There are also specific microbiomes, including the gut microbiome (GM) and the urinary microbiome (UM). The GM alone contains over 100 trillion microorganisms.

Scientists have found a relationship between the occurrence of cancer and the health of the microbiome, and the effectiveness of treatment. Our microbiome can become unbalanced. These changes can be associated with certain diseases, including cancer. The research shows that a more diverse GM can improve the effectiveness of immunotherapy. This point is of particular importance for me when undergoing immunotherapy.

A study published in the Frontiers of Immunology showed how the microbiome affects tumour progression, initiation and progression through direct effects on the tumour cells and indirectly through manipulation of the immune system. The microbiome also determines response to cancer therapies and can predict disease progression and survival. A healthy microbiome improves immunotherapies and decreases their toxicity.³

According to an article in the BMC Cancer journal, microbiome modulation is one of the most promising new strategies in medicine to improve the health of individuals. Research has shown that dietary intervention can reshape the GM in relation to cancer. This reshaping can take the form of an intake of prebiotics, a low intake of fat, a plant-based diet, and a low intake of red meat. Weight reduction and exercise are also necessary.⁴

Eating nutritious foods high in fibre and resistant starch can help feed the beneficial bacteria that already live inside our gut. These are called prebiotic foods. You can eat foods that contain beneficial bacteria to help repopulate your GM. Fermented foods such as yogurt, sauerkraut, and kombucha have these bacteria. These are called probiotic foods.

Cancer treatments such as chemotherapy can disrupt your gut microbiome. Research shows that probiotics may reduce diarrhea in people receiving chemotherapy for cancer.

I found that eating prebiotics in the form of a diet rich in vegetables and fruit helped me during and after chemo. I also tried probiotics with limited success. But what turned things around for me was adding green banana-resistant scratch to my morning juice or afternoon smoothies. 

The gut microbiome and chemotherapy

The vitality of the GM has been linked to cancer and shown to alter the effectiveness of anticancer treatment. A compromised GM is associated with resistance to chemo drugs and immunotherapy. This relationship is an important point as chemo and antibiotics are known to have a devastating effect on the GM. This is the reason why it is important to eat a plant-based diet and reduce fat and processed meat intake during chemo. Unfortunately, your oncologist is likely to encourage you to eat sugary and fatty foods to keep your weight on, but this is going to do nothing to help your GM.

But this advice may be changing, at least on the frontiers of oncology. A recent article in the BMJ journal stated that “manipulating the microbiome via antibiotics, probiotics, faecal transplant or nanotechnologies may potentiate the antitumour effects of chemo drugs or immunotherapy.” In the future, tumour-associated bacteria will predict cancer, target more effective treatment and reduce side effects.⁵

Chemotherapy has a devastating impact on the GM and alters the physiological and psychological function of the patient. Understanding chemotherapy’s long-term effects on the GM is critical to improving patients’ physical and mental health. According to a study in the BMC Cancer journal, restoration of the gut microbiota could potentially prevent or reverse the psycho-physiological deficits following chemotherapy.⁶

A Northwestern University study also found that specific types of gut bacteria can protect good bacteria from cancer treatments by reducing harmful, drug-induced changes to the GM. The research concluded that new dietary supplements, probiotics or engineered therapeutics could help boost cancer patients’ gut health.⁷  

But there is no need to wait for Big Pharma to catch up with this development. You can start cultivating a healthy microbiome now by eating a more plant-based diet and upping your intake of prebiotic foods and supplements.

I can attest to the devastating effect of chemo on my own GM in 2019. It came on top of extensive antibiotic treatment in the hospital for Sepsis. During the chemo itself, my arms became infected, requiring further antibiotic treatment. It’s little wonder that I found the chemo hard to tolerate and little wonder that it didn’t prevent the spread in 2021. 

During my second encounter with chemo, I ate a more plant-based diet and took medicinal mushrooms as well as prebiotic supplements like green banana starch. My chemo the second time was more effective, and the side effects significantly reduced. I also recovered faster from the chemo the second time around.

Restoring the gut microbiome with resistant starch

Being told to eat more fibre is one thing. But we also need to eat the right fibre to both prevent cancer, enhance treatment and rebuild our microbiome after chemo or a course of antibiotics. According to current research, we need to eat a wider variety of fibre from food. What we need to eat more of is fermentable fibres such as resistant starch, which help to support good gut bacteria.⁹

CSIRO research from Australia shows that eating resistant starch leads to positive changes in the bowel. Resistant starch feeds the good bacteria that live in our GM. It resists digestion in our small intestine and moves on to the large bowel as food for the good guys.

When good bacteria ferment resistant starch, they make short-chain fatty acids. These fatty acids supply energy to the cells lining the large intestine, promoting their well-being. 

The good news is that we can feed our GM by eating foods rich in resistant starch, including the following: 

• lentils
• peas
• beans
• cooked and cooled potato, 
• cold pasta salad 
• firm bananas

This is another reason why a Mediterranean diet or a diet centred around plant-based foods is so beneficial to all of us. These diets are rich in good fibre and resistant starch.

A study in the National Library of Medicine demonstrated that personalised approaches for resistant starch are required to promote a healthy gut.¹⁰ This was because while all resistant starches resist digestion by human enzymes, they differ in their effects on the microbiota. Individual variation in the GM also influences good fatty-acid production. This is why I eat a wide variety of resistant starches and fibres and do not rely on one alone.

I eat at least one serving of lentils, beans or peas once a day, usually at lunch, with a raw leafy green salad and kimchi. I also supercharge my gut with green banana-resistant starch in the form of a supplement in my morning juice or afternoon smoothie. This diet enabled my GM to recover from chemo quickly and resist most of the destructive effects of chemo during treatment. The results were a better outcome and fewer side effects.

The urinary microbiome and bladder cancer

While much of the focus on the microbiome and the relationship to cancer has been on the GM, there have been some recent studies on the urinary microbiome. The UM is now emerging as an essential factor influencing bladder cancer development and therapeutic responsiveness. A study in the National Library of Medicine shows that the health of the microbiome has an impact on bladder cancer at each stage of its development and influences the antitumour immune response.¹¹

Further studies in the Frontiers of Microbiology found that a UM rich in certain types of bacteria in women is related to a lower incidence of bladder cancer.¹²

Having had my bladder removed and replaced with a neo bladder means that looking after my UM is of high importance to prevent UTIs. Another good reason for avoiding UTIs at any stage is to avoid the use of antibiotics which are like a nuclear option for your microbiome. An article in Omnibiotics listed several strategies that I follow to prevent infection:¹³

• Cranberries can help prevent bacteria from sticking to the lining of the urinary tract reducing the risk of UTIs. I have been taking a high-strength cranberry supplement since undergoing surgery.
• Blueberries also help protect against harmful bacteria settling in the lining of the urinary tract. I always have a bag o frozen blueberries in the freezer. I have a handful on my morning porridge as well as in smoothies and for a light dessert.
• Vitamin C – Vitamin C helps keep the urine acidic, making the conditions less hospitable for harmful bacteria to survive. I take between 500 and 1,000 mg of vitamin C via a high-quality supplement, as well as eat plenty of fruit and vegetables. 
• Probiotics – The good bacteria in your microbiome, referred to as probiotics, are powerful aids to help fight against UTIs. I take my probiotics in the form of fermented foods as well as ensure I eat plenty of fibre and resistant starch

Conclusion

The more I looked into the relationship between the microbiome and cancer, the more the penny dropped. It’s all about the microbiome. The science backs this up. There is no doubt that the health of the microbiome health has a direct link to developing cancer and to its response to treatment. It also makes sense why fibre-rich diets such as the Mediterranean and other plant-based diets are so beneficial for the prevention and treatment of cancer.

References

1. Your Microbiome and Cancer: What to Know; Available at URL: https://www.cancer.net/blog/2020-12/your-microbiome-and-cancer-what-know
2. The gut microbiome: what the oncologist ought to know; Available at URL: https://www.nature.com/articles/s41416-021-01467-x
3. New Insights Into the Cancer–Microbiome–Immune Axis: Decrypting a Decade of Discoveries; Available at URL: https://www.frontiersin.org/articles/10.3389/fimmu.2021.622064/full
4. Gut microbiome and its role in colorectal cancer; Available at URL: https://bmccancer.biomedcentral.com/articles/10.1186/s12885-021-09054-2
5. The role of gut microbiota in cancer treatment: friend or foe?; Available at URL: https://gut.bmj.com/content/69/10/1867
6. The Potential of the Gut Microbiome to Reshape the Cancer Therapy Paradigm: https://jamanetwork.com/journals/jamaoncology/article-abstract/2791672
7. The chemo-gut study: investigating the long-term effects of chemotherapy on gut microbiota, metabolic, immune, psychological and cognitive parameters in young adult Cancer survivors; study protocol; Available at URL: https://bmccancer.biomedcentral.com/articles/10.1186/s12885-019-6473-8
8. Good bacteria can temper chemotherapy side effects; Available at URL: https://news.northwestern.edu/stories/2021/05/good-bacteria-can-temper-chemotherapy-side-effects/
9. Resistant starch; Available at URL: https://www.csiro.au/en/research/plants/crops/grains/resistant-starch
10. Resistant starch: impact on the gut microbiome and health; Available at URL: https://pubmed.ncbi.nlm.nih.gov/31765963/
11. The Urinary Microbiome and Bladder Cancer: Susceptibility and Immune Responsiveness; Available at URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7605348/#:~:text=Recently%20a%20commensal%20urinary%20microbiome,cancer%20development%20and%20therapeutic%20responsiveness.
12. Profiling the Bladder Microbiota in Patients With Bladder Cancer; Available at URL: https://www.frontiersin.org/articles/10.3389/fmicb.2021.718776/full
13. What is a Urinary Tract Infection and Can Probiotics Help Prevent Them? Available at URL: https://www.omnibioticlife.com/can-probiotics-help-prevent-urinary-tract-infections/