Healing the Gut: Reduce Cancer Treatment-Related Damage
Introduction
When a person undergoes cancer treatment—whether chemotherapy, radiation, immune checkpoint inhibitors, or surgery—we often underestimate the collateral damage to the gut lining. But we know that damage to the gut barrier (known as intestinal hyperpermeability or, more commonly, "leaky gut") can make systemic inflammation worse, increase the risk of infections, compromise immune health, increase the risk of cachexia, and potentially affect the success of treatment.
So, the question becomes: how can we support and repair the gut barrier during and after cancer therapy?
Why the gut barrier matters?
Why is the gut so important?
The cells lining the gut are just one cell thick. To allow nutrients to enter the bloodstream while preventing bacteria and other foreign matter from escaping, the junctions between them tightly shut, forcing everything to pass through the cell walls.
Chemo and radiotherapy often damage the lining, disrupting the tight junctions, reducing the mucus layer that protects the gut lining, and upsetting the balance of gut bacteria.
When the barrier loses its integrity, metabolic by-products, such as lipopolysaccharides, can leak out. This triggers systemic inflammation, endotoxaemia, and can lead to mucositis or sepsis (1).
The latest research shows a link between the health of the gut barrier and microbiome with the effectiveness of cancer therapy, better responses and fewer side effects (2).
So, supporting gut health isn't a 'nice add-on'; it helps with treatment too.
Therapeutic strategies to support gut health during treatment
There are 4 different ways that you can improve gut health during treatment, according to research. They are:
Probiotics
Faecal Microbiota Transplantation (FMT)
Dietary interventions
Nutritional supplements.
Probiotics
Probiotics have sound evidence for their effectiveness in healing the gut after cancer treatments. They work in several ways.
They help stop pathogenic bacteria, including Clostridium difficile and Staphylococcus aureus, from colonising the gut. C. difficile, in particular, is common among many cancer patients, and it's difficult to treat. The usual treatment is antibiotics, but the infection often returns repeatedly. One probiotic is especially effective against it: Saccharomyces boulardii, often referred to as SB. As well as competing directly with pathogens, it produces metabolites that can lower the pH of the gut, which inhibits their growth, and can be antimicrobial too (3).
Our guts contain many immune cells, and probiotics help to support these cells, so they help to suppress inflammation in the gut. Specifically, Lactobacillus rhamnosus GG and L. acidophilus, and Bifidobacterium breve and B. infantis are very effective, producing short-chain fatty acids (SCFA) like butyrate, propionate and acetate, which are the agents that reduce inflammation. Some other Lactobacillus species, Lactobacillus casei BL23 and Lactobacillus acidophilus NCFM have also shown antitumour effects (4).
Mucositis starts when the chemo drugs and radiation cause damage to the lining of the gut, which causes inflammation. The inflammation causes more destruction, which breaks down the lining of the gut and causes ulceration. The ulceration can then become infected with pathogens, which causes even more inflammation (5). So, the action of probiotics in reducing inflammation and reducing the number of pathogenic bacteria is significant in reducing mucositis.
Some probiotic strains can also repair the tight junctions between the cells lining the gut, stimulate the production of mucus to protect the gut, as well as suppress inflammation. These particular strains include Lactobacillus plantarum, Lactobacillus rhamnosus and Escherichia coli Nissle 1917 (4).
Some doctors consider the use of probiotics during treatment to be dangerous. Indeed, there have been a few isolated cases of them getting into the bloodstream and causing infection. But the research shows that this is rare. If you have had recent surgery, the risk is possibly higher, particularly if you are immunosuppressed. So, it is important to discuss the use of probiotics with your medical team before using them.
If you choose to use them, ensure that you wash your hands thoroughly afterwards before you touch any cannulas or ports, as this is usually how infections happen.
Faecal Microbiota Transplantation (FMT)
This is a procedure that is done by doctors. It involves transplanting faeces from someone with a healthy microbiota. Doctors usually administer it via an enema, a colonoscopy, a nasogastric tube, or oral capsules, which contain freeze-dried stool.
In studies on chemo-treated animals, it is effective against weight loss, colon shortening and mucositis. It also reduces diarrhoea and helps to reduce damage to the gut lining (6).
There are significant safety risks involved. Infections can spread from the donor to the recipient, and there have been reports of adverse events after FMT in patients receiving cancer treatment (6). But the benefits may outweigh the risks. You can discuss them with your oncologist.
Dietary interventions
Prebiotics
Bacteria feed on prebiotics, which are types of fibre. That enables beneficial bacteria, like Lactobacillus and Bifidobacterium, to multiply, producing more SCFAs, and reducing inflammation.
Some foods are prebiotics. They include:
Jerusalem artichokes
Chicory root
Onions
Garlic
Asparagus
Leeks
Bananas (especially green ones, which are rich in resistant starch)
Oats
Barley
Apples
Cocoa
Konjac root
Flaxseeds
Jicama
Wheat bran
Avocado
Seaweed.
If you aren't used to eating a lot of fibre, start small and work up. Otherwise, it can give you digestive discomfort, like bloating and wind.
Supplements of prebiotics are also available. These include partially hydrolysed guar gum (PHGG) and slippery elm powder, which are both gentle on delicate digestions, inulin and galactooligosaccharides. The latter two may not suit you if you are sensitive to FODMAPS or have IBS.
As well as feeding helpful bacteria, prebiotics can be helpful during chemotherapy treatments. Inulin makes some drugs work better. You can find it in chicory root, onions, garlic, Jerusalem artichokes, leeks, asparagus and bananas. Oat fibre and pectin, found in apples, can reduce enterocolitis caused by methotrexate (7).
Postbiotics
The term postbiotics means the by-products of beneficial bacteria that influence the gut. The best known postbiotics are SCFAs. But scientists are discovering other postbiotics in new research that are proving effective at preventing damage to the gut lining and helping boost the immune system in the gut. This research is in its infancy, so watch this space (8).
Nutritional Supplements
Some vitamins help to prevent damage to the gut during treatment. These include vitamins A, D and E, which are fat soluble. And vitamins B2, B9, and C, which are water soluble.
Vitamin A
In animal studies, vitamin A reduced damage to the intestines, helped prevent diarrhoea, helped the immune system fight C. difficile, and lessened the risk of nutritional deficiencies (9).
You can increase vitamin A intake by eating orange-red vegetables and fruit, such as pumpkin (winter squash), sweet potato, chilli peppers, red capsicum (red bell peppers), carrots, rockmelon (cantaloupe), tomato, and green vegetables.
Folate (vitamin B9)
Folate improves cell repair in the gut in humans and reduced mucositis too (9).
Good dietary sources include green leafy vegetables, asparagus, broccoli, Brussels sprouts, citrus fruits, legumes, wholegrain cereals, liver and other organ meats.
Vitamin C
In an animal study of those treated with 5-fluorouracil (5-FU), vitamin C helped reduce gastrointestinal mucositis and helped prevent the reduction of the mucus lining. In other animal studies where the drug used was methotrexate, it decreased mucositis symptoms (9).
Eating citrus fruits, tomatoes, potatoes, papaya, green and red capsicum (bell peppers), strawberries, kiwifruit, rockmelon (cantaloupe), and green leafy vegetables are all good ways to increase your intake of vitamin C.
Vitamin D
In human studies, vitamin D improved the effectiveness of 5-FU on colon cancer cells and reduced the incidence of diarrhoea in colorectal cancer patients (9).
You can increase your vitamin D levels by eating oily fish, such as salmon, herring, sardines, and tuna, plus cod, eggs, beef liver, butter and cheese, as well as by short periods of sun exposure (not enough to burn the skin).
Vitamin E
Vitamin E reduced inflammation and intestinal damage in animals treated with 5-FU, as well as preventing damage to the mucus lining of the intestines. In human studies, vitamin E improved the loss of neutrophils caused by chemo (9).
You can find Vitamin E in avocado, asparagus, red capsicum (red bell pepper), pumpkin, spinach, collard greens, beet greens, spinach, mango, almonds, peanuts, peanut butter, wheat germ oil, sunflower, safflower, and soya bean oils, and sunflower seeds.
Omega-3 Fatty Acids
In a clinical trial of patients taking combined chemo (docetaxel, 5-FU and cisplatin), those fed a diet with Omega-3 fatty acids suffered less oral mucositis and diarrhoea (9).
Rich sources of Omega-3s are fish and seafood, especially oily fish, like salmon, mackerel, herring, tuna and sardines. For vegetarians, the options are less bioavailable, but include nuts and seeds, such as walnuts, pecans, flaxseed and chia seeds.
Glutamine
Glutamine is a non-essential amino acid that is the major food source for cells lining the gastrointestinal system. In healthy patients, the cells use it to repair and rebuild the gut lining.
A recent meta-analysis examined 5 randomised controlled trials, which included 311 colorectal cancer patients. They found that glutamine significantly reduced the incidence of chemoradiation-induced diarrhoea. This had a positive effect not only on quality of life but also on the nutritional status and immunity of the patients (10).
The patients receiving chemo alone benefited most from glutamine. These patients had a reduction in diarrhoea of 35%. The researchers suggested that the effects of radiation and chemo together were too much for glutamine to repair. The oral dosing of glutamine in the included studies varied between 10 and 30 g per day (10).
In a separate study, patients swished a suspension of 4 g of L-glutamine in water around their mouths and swallowed it twice a day from day 1 of chemo for 28 days. They had previously received chemo without the glutamine and had suffered from oral mucositis. The glutamine significantly reduced the maximum grade and duration of oral mucositis (11).
Some oncologists are wary of using glutamine during chemo. That is because cancer cells usually use glucose as their fuel, but can sometimes use glutamine too. However, glucose is their major source. It is practically impossible to remove glutamine from the diet because all proteins contain it to some extent. And researchers suggest that any downside is more than compensated for by the benefits outlined above (11).
Glucosamine
You may be surprised to hear that glucosamine is good for repairing the gut. It's best known for helping to ease the pain of osteoarthritis. But research shows it does much more than that.
In a small human trial, 3 g of glucosamine hydrochloride per day helped to reduce stomach bloating and constipation by changing the gut microbiome. The body does not absorb glucosamine successfully, so the bulk of it remains in the gut to be metabolised by the gut bacteria, where beneficial bacteria use it (12).
In epidemiological studies, the research shows that people taking glucosamine for an average of 10 years had 5-year mortality rates that were significantly lower than those who didn't. The research also showed reduced cardiovascular disease and mortality. Extensive studies of people taking glucosamine, either with or without chondroitin, showed a lower risk of colorectal cancers, and improvement in inflammatory bowel disease (12).
Conclusion
This article has examined various ways of reducing damage to the gut from cancer treatments. These can help not just improve cancer patients' quality of life, but also how much nutrition they can absorb from their food, which can affect overall survival.
You can find further suggestions for reducing the effects of cancer treatments in my book, Naturally Supporting Cancer Treatment, and discover all the online stores where you can buy it by clicking the button below.
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References
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