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Why Probiotics and Prebiotics Are So Crucial During Chemotherapy

Because there are so many of you undergoing chemotherapy right now, I thought it might be helpful to explain why probiotics and prebiotics are so crucial during chemotherapy (and afterward).

It’s All About The Good Bacteria

The normal healthy intestinal system contains about 100,000 billion bacteria and these bacteria are beneficial to our health. When beneficial bacteria are present, they help us to absorb and digest the food we eat, they keep out bad bacteria and carcinogens, promote healthy metabolism, reduce systemic inflammation, enhance immunity (it is said that 80% of our immune system resides in our guts!), and even support good mental health. Indeed, it is said that at the core of many health concerns there is an imbalance of intestinal bacteria.

Why Chemotherapy Causes A Problem With Good Bacteria

Chemotherapy causes a problem because these drugs go after any rapidly dividing cells, including the cells of the intestinal tract, which are renewed every 4-5 days. That’s why chemotherapy is so hard on digestion. From the mouth to the anus, these cells are killed off unselectively, along with the beneficial gut bacteria.

Supplementing With Probiotics Is Absolutely Crucial For 6 Big Reasons:

1. Probiotics help to replace some of the beneficial bacteria lost during chemotherapy and radiation.

2. Probiotics  help to clean out intestines of potentially toxic pathogens like candida, as well as chemicals and carcinogens (cancer-causing agents).

3. Probiotics appear to help chemotherapy work better. One study on mice revealed that when intestinal bacteria is compromised, chemotherapy drugs don’t work as well as they should [1]. Another study revealed that the commonly-used chemotherapy drug cyclophosphamide relies partially on its capacity to mobilize certain bacteria from the gut into the bloodstream and lymph nodes.  Once inside the lymph nodes, these bacteria stimulate the immune system, which then increases the body’s ability to fight a malignant tumor. [2]

4. Probiotics help to absorb minerals and even produce vitamins.

5. Probiotics help the immune system.  Most alternative health practitioners are aware that supplementing with probiotics provides good support for the immune system and science is getting on board too.  2014 research published in the Journal of Science and Medicine in Sport found that rugby players in New Zealand had about 40% fewer colds and gastrointestinal infections when taking probiotics, compared to taking a placebo [3]

6. Probiotics help to reduce inflammation in the gut [4],  indeed systemic inflammation is reduced when probiotics are taken regularly. Since cancer is an inflammatory process, anything that reduces inflammation is well worth including.

While it is true that some of the beneficial bacteria from your probiotics supplement may be obliterated by chemotherapy drugs, it is recommended to take them anyway in the hope that enough will survive to protect against unwanted organisms such as candida and Clostridium difficile, a particularly nasty form of bacteria that causes infectious diarrhea that can be severe enough to kill.

Other Helpful Things To Protect Gut Flora

Probiotics also come from certain foods.  Including these foods in your daily diet will also help the beneficial bacteria in the gut: sauerkraut, kimchi, kefir, kombucha, miso soup, natto, tempeh, pickles, spirulina.

You can also include prebiotics, which  is indigestible fiber that stimulates the growth of and provides the food for beneficial bacteria in the gut. Include things like asparagus, artichoke, leek, garlic, onion, beans, chickpeas, and lentils.

Inulin is one of the indigestible fibers that good gut bacteria lives on and one of the good things about inulin is that studies on rats indicate it also increases magnesium and calcium absorption  [5], important if you are prone to osteoporosis, as many of us are past a certain age.

Meditation is one surprising modality that actually assists gut flora by alleviating stress, which is a known factor for disrupting healthy gut bacteria.

Avoid antibiotic use whenever possible but if you do absolutely have to have a course of antibiotics, make sure to take probiotics and prebiotics because supplementing is known to reduce an overgrowth of bad bacteria while taking antibiotics. Be aware, however, that there are those who feel that our bodies never fully recover after antibiotic use. Dr Martin Blaser has a very interesting article in the Journal Nature about antibiotic use. He says “Early evidence from my lab and others hints that, sometimes, our friendly flora never fully recover” [5]. This is also mentioned in reference  [1] below.

Avoid eating loads of sugar and carbohydrates, even artificial sweeteners, which are known to harm beneficial bacteria.

If you are undergoing chemotherapy it is a good idea to keep an eye on the possibility of candida developing.  For more information on how to do that, see my article What Is The Candida Breast Cancer Connection.


1.  Gut microorganisms may determine cancer treatment outcome –

2.  The intestinal microbiota modulates the anticancer immune effects of cyclophosphamide –

3.  Probiotic supplementation reduces the duration and incidence of infections but not severity in elite rugby union players –

4. The Roles of Inflammation, Nutrient Availability and the Commensal Microbiota in Enteric Pathogen Infection –

5.  Stimulatory effect of inulin on intestinal absorption of calcium and magnesium in rats is modulated by dietary calcium intakes –

6. Stop The Killing of Beneficial Bacteria, by Dr Martin Blaser –

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