Can probiotics and fermented foods help us fight cancer?


We behind this blog own and operate a kombucha microbrewery, and we want to begin this post by saying that kombucha is not a cure for cancer, and neither is sauerkraut, yogurt, applecidervinegar or other probiotics. For those afflicted with cancer, there don’t appear to be any miracle cures or easy solutions, and clinical “western” medicine, with the standards of controlled human trials to develop drugs and treatments, appears to be the best route to go for treatment. Having said that, we believe, based on careful reading of many peer-reviewed studies, that there is convincing evidence that kombucha and other probiotics may play a role in preventing and treating cancers.

A rapidly growing area of research in probiotics has been the role of our microbiomes in our susceptibility to cancers, and interest in the potential for probiotics to help stave off cancer. Most of this research has focused on colorectal cancers, but a lot of research has also been conducted into stomach cancers caused by a bacteria Helicobacter pylori. The research is promising, and hopefully, with more research, and emerging technologies to study our microbiomes, we will soon know much more about how large a role probiotics can play in the prevention and treatment of cancers.

Europeans have a lifetime risk of developing colo-rectal cancers of about 2% (1), and a 5-year survival rate of 65% (2) . It is the third most common type of cancer worldwide (1). In a meta-analysis of animal studies investigating the effect of probiotics on colo-rectal cancers, 80% of the studies found a reduction in cancers with probiotics and that reduction was generally amplified when prebiotics were added. In addition to inhibition of cancer formation, studies have also found that probiotics, when administered after cancerous lesions have formed slowed or stopped their growth (3). It was suggested that the mechanisms for the cancer fighting actions of probiotics was a combination of the following factors:

  • Competing with and displacing other components of the gut microflora.
  • Producing antibacterial agents, including bacteriocins (and bacteriocin-like components), to control the growth of other members of the microflora.
  • Producing lactic and other organic acids, thereby lowering the luminal pH and thus modulating enzyme activity.
  • Improved immune system function- upregulating immune system activities which target and destroy or inhibit cancer growths

Research indicates with increasing certainty that diets high in red meats, fats, and especially processed meats increase our risk for colon-cancer, and the mechanisms for this, while not established, appear to arise from increased concentrations of N-nitroso compounds and heterocyclic amines and studies have shown that some micro-organisms are more adept at taking up and detoxifying such compounds (4). In animal studies bacteria from the groups Bacteroides and Clostridium appear to increase formation and severity of colonic tumors while bacteria from the most common probiotic groups Lactobacillus and Bifidobacteria have been shown to prevent or slow tumorigenesis (5, 6, 7, 8, 9)

In addition to colorectal cancers, probiotics have been increasingly studies as potential therapeutic agents to combat stomach cancer. There is a great deal of research on the potential for probiotics to treat or prevent infections with Helicobacter pylori. H. pylori, as it is commonly called, is a bacteria that colonizes our stomach and, among other effects, causes stomach ulcers. It affects an amazingly large portion of the global population, with nearly 50% of the world’s population, mostly in the developing world, infected. Australian researchers Drs. Barry Marshall and Robin Warren received the Nobel prize in 2005 for their work “discovering” it in 1982. It was an amazing discovery, in part because it was amazing that we only discovered its prevalence so recently. It is estimated that 60% of stomach cancers are due to H. pylori (10, 11, 12,). Stomach cancer is the fifth leading cause of cancer and the third leading cause of death from cancer. In 2012 it occurred in 950,000 people and caused 723,000 deaths (1). Research on probiotics in treating or preventing H. pylori has been very promising. A number of studies have found that ingestion of Lactobacillus and Bifidobacterium containing yogurt helped control or prevent H. pylori infections (13, 14, 15,)

The specific mechanism of cancer inhibition of probiotics remains to be elucidated, and, due to the multi-faceted protective effects of probiotics this is a major challenge. In addition, most of the research discussed here occurred in animal models not in humans. Much research remains to be done before a specific probiotic, prebiotic, or synbiotic can be therapeutically administered for cancer treatment. However the evidence is compelling that probiotics derived from common dairy fermentations as well as their co-occurring symbionts have a role to play in the treatment and prevention of colo-rectal and stomach cancers.

Both ”probiotic” and ”cancer fighting” are among the many health benefits people attribute to kombucha, and there is evidence to support both. However, the anti-cancer effects of kombucha are primarily attributed to the presence of compounds that inhibit cancer and promote the body’s ability to fight cancer, and not to the probiotic properties of kombucha. Nor have there been any studies of how the probiotic effects of kombucha may help fight cancer in humans, and thus, there is limited evidence to support a probiotic role of kombucha in fighting cancer. There have, however, been some studies in vitro (in petri dishes) showing that kombucha inhibits the growth of H. Pylori (16), which may lower the risk for stomach cancer. In addition, many of the characteristics of probiotics that are thought to play a role in the ability of probiotics to help prevent and fight colon cancer (see the bulleted list above) are characteristic of kombucha, so there are certainly grounds to believe that there may be a probiotic mechanism by which kombucha may help prevent and fight cancers. Unquestionably, more research is needed establish a clear link though, and, as with many functional foods,t he cost and effort that would be required to establish such a link (human studies, following cohorts for many years and controlling their diets) may make such studies prohibitively expensive, especially considering the lack of a profit motive for a product which is freely and cheaply available. In future blog posts, we’ll delve into the evidence for the non-probiotic mechanisms by which kombucha may help prevent and fight cancers, for which there is considerably more evidence.


1: World Cancer Report 2014. World Health Organization. 2014. pp. Chapter 1.1. ISBN 9283204298

2: “SEER Stat Fact Sheets: Colon and Rectum Cancer”. NCI. Retrieved 18 June 2014.

3: Commane D, Hughes R, Shortt C, Rowland I. 2005. The potential mechanisms involved in the anti-carcinogenic action of probiotics. Mutation Research 591: 276–289.

4: Wollowski I, Rechkemmer G, Pool-Zobel BL. Protective role of probiotics and prebiotics in colon cancer. Am J Clin Nutr 2001; 73 (suppl): S451–45.

5: Onoue M, Kado S, Sakaitani Y, Uchida K, Morotomi M. Specific species of intestinal bacteria influence the induction of aberrant crypt foci by 1,2-dimethylhydrazine in rats. Cancer Lett 1997; 113: 179–86.

6: Horie H, Kanazawa K, Okada M, Narushima S, Itoh K, Terada A. Effects of intestinal bacteria on the development of colonic neoplasm: an experimental study. Eur J Cancer Prev 1999; 8: 237–45.

7: Singh J, Rivenson A, Tomita M, Shimamura S, Ishibashi N, Reddy BS. Bifidobacterium longum, a lactic acid-producing intestinal bacterium inhibits colon cancer and modulates the intermediate biomarkers of colon carcinogenesis. Carcinogenesis 1997; 18: 833–41.

8: Pool-Zobel BL, Neudecker C, Domizlaff I, et al. Lactobacillus- and bifidobacterium-mediated antigenotoxicity in the colon of rats. Nutr Cancer 1996; 26: 365–80.

9: O’Mahony L, Feeney M, O’Halloran S, et al. Probiotic impact on microbial flora, inflammation and tumour development in IL-10 knockout mice. Aliment Pharmacol Ther 2001; 15: 1219–25.

10: Sim, edited by Fiona; McKee, Martin (2011). Issues in public health (2nd ed.). Maidenhead: Open University Press. p. 74. ISBN 9780335244225.

11: World Cancer Report 2014. World Health Organization. 2014. pp. Chapter 5.4. ISBN 9283204298.

12: Chang, A. H.; Parsonnet, J. (2010). ”Role of Bacteria in Oncogenesis”. Clinical Microbiology Reviews 23 (4): 837–857. doi:10.1128/CMR.00012-10. ISSN 0893-8512. PMC 2952975.PMID 20930075.

13: Wang KY, Li SN, Liu CS, Perng DS, Su YC, Wu DC, Jan CM, Lai CH, Wang TN, Wang WM (September 2004). ”Effects of ingesting Lactobacillus- and Bifidobacterium-containing yogurt in subjects with colonized Helicobacter pylori” (PDF). The American Journal of Clinical Nutrition 80 (3): 737–41. PMID 15321816.

14: Michetti, P., Dorta, G., Wiesel, P.H., Brassart, D., Verdu, E., Herranz, M., Felley, C., Porta, N., Rouvet, M., Blum, A.L., Corthesy-Theulaz, I., 1999. Effect of whey-based culture supernatant of Lactobacillus acidophilus ( johnsonii ) La1 on Helicobacter pylori infection in hu- mans. Digestion 60, 203–209.

15: Zhang MM, Qian W, Qin YY, et al. (2015) Probiotics in Helicobacter pylori eradication therapy: a systematic review and meta-analysis. World J Gastroenterol 21, 4345–4357.

16: Sreeramulu G, Zhu Y, Knol W. 2000. Kombucha fermentation and its antimicrobial activity. Journal of Agricultural and Food Chemistry 48 (6): 2589–2594.




What food has probiotics? What do I need to know about the sources?

We’ve already defined probiotics as live bacteria and yeasts that when consumed confer health benefits on humans, but a couple other definitions are also good to know:

Prebiotics are nondigestible compounds, mostly carbohydrates, that promote the survival and establishment of probiotics in our bodies.

Foods that have prebiotics include asparagus, Jerusalem artichokes, bananas, oatmeal, red wine, honey, maple syrup, and legumes, among many others.

what food has probiotics and prebiotics

Asparagus is rich in prebioc inulin, a nutrient that help probiotics establish and thrive in our bodies.

Synbiotics are the combination of probiotics and prebiotics.

Live, unpasteurized yogurt, kefir, fermented sauerkraut, and kombucha are good examples of synbiotics.

We’ll go into more detail about prebiotics, probiotics, and symbiotics in later blog posts, but for now it’s worth noting that in many studies where they actually have looked at the effect of probiotics alone or probiotics with their prebiotics a greater health affect was often observed with the prebiotics and the probiotics than with only the probiotics. This would support consuming synbiotics like live fermented foods.

So, what food has probiotics? Today you can find probiotics in many, many places. There has been huge growth in the marketing and production of “pure” probiotics or probiotic supplements and you can find pills and little packets of probiotics in the pharmacy or health sections in your supermarkets, but much better still, you can find probiotics in many many fermented products, the list of which is enormous. In a later blog post we’ll go into more detail about fermentation, what it is, and why its so central to a healthy and exciting and sustainable diet, but for this post on probiotics a brief introduction is in order: Humans have been fermenting (using microbes to alter the food) food for millennia. Many many societies throughout human history have developed methods for fermenting everything from milk to pickles to mushrooms to grain to meat to fish to just about any food you can think of. Humans ferment food for many reasons including, and perhaps most importantly, food preservation, but also to make food more nutritious, as well as to make it tastier. As a result, most cultures in the world have evolved with fermented foods. Here in Sweden some of the most common food sources are dairy products like yogurt, kefir, filmjolk, sour cream, and some live cheeses, as well as non dairy products like kombucha, lacto fermented (using bacteria instead of only vinegar) vegetables (ex. Sauerkraut), miso, tempeh, and apple-cider vinager. In addition you can find many newer fermented or probiotic products in the refrigerated section of most supermarkets that are vegetable or fruit based. Generally speaking, any raw (uncooked) fermented product is likely to contain both probiotics and prebiotics, but there is little scientific consensus which ones are best or which ones are best for particular health benefits. Yogurt is, at present by far the most studied, largely due to it’s already widespread consumption, and, perhaps as a result of this, it’s being represented by the largest industry. Research into probiotics has shown that, in addition to them having a number of positive health affects they are A) generally considered safe and B) positive responses to them are often dose dependent (ie. the more pre- and pro-biotics consumed the greater the effect).

What’s all the fuss about probiotics?

Probiotic food and nutritional additives have gained a lot of attention in both research and mainstream media lately. There has been a huge growth in interest in probiotic products over the last 10 years around the world. There is a growing body of evidence to support their importance in our diet; both to treat and prevent specific diseases and as part of a healthy diet. Perhaps unsurprisingly, the global demand for, and production of probiotic products has risen tremendously; to an estimated 32.6 billion US$ in 2014, with a predicted annual increase of 20%. The European market accounts for 42% of this, and dairy products account for 70%. Despite this, the European Union nutritional and health claims regulation adopted in December, 2012 barred the labeling of products as pro-biotic, claiming they are “unauthorized health claims”. This ruling, and these EU regulations have been criticized by many, we believe rightly so, as being overly strict and placing too high a burden of evidence on health claims for which there is in fact a great deal of high-quality scientific support. Before we get into the potential benefits of probiotics and what evidence there is to support those benefits we thought we would take a moment to provide a little bit of background information regarding our digestive system, the human “microbiome”, the term “probiotic” itself, and the history of fermentation and probiotics. This topic is a pretty big can of worms, so while we will do our best to distill the important information, we have to break this post up into a number of sections.


Probiotic products’ are products that contain ‘probiotics’. Definitions of probiotics vary; the word is derived from pro and biota, meaning “for life”. A good definition for the purpose of this blog post is:

Probiotics are live bacteria and yeasts that when consumed confer health benefits on humans.


Acidophulus bacteria in filmjolk consist of different strains, just like the species domesticated dog can does. Many of the positive health effects of probiotics are strain-specific, which is one of the reasons these effects are so complicated to describe.

Bacteria and yeasts (as well as viruses and other single-celled microbes) are naturally found on and in every body. These microbes, which make up the human “microbiome” are so numerous and important that they have even been called our “hidden organ”. Most of these microbes live in our gastro-intestinal tract or “gut” (stomach, large intestines, small intestines colon), but we also have rich microbial communities on our skin and in our mouths, and, for women, in our vaginas; we’ll be focusing on our gut microbes in this post. An estimated 100 trillion microorganisms representing more than 500 different species inhabit every normal, healthy digestive system. In fact, if you count up all these cells, the ones that are in the human body but are not “human” cells, there are 10 times more not human cells in a human body than there are human cells. These microbial communities are very complex and they change in relation to many factors, including if we have taken antibiotics or even if we have a carbohydrate-rich or protein-rich diet, if we are vegetarian or not; in fact, our gut communities change in relation to our diet in as little as 24 hours1. In addition to responding to what food we put into our bodies, the microbes in our gut do A LOT for use. They break down and digest our food into nutrients that we can absorb into our bodies. They also produce important nutrients (vitamins, amino-acids, etc…) that we may not consume in our food. They regulate our immune system and they protect against disease-causing pathogens we may consume orally. These are a few of the many things our gut microbes do for us, and in the proceeding sections of this multi-part blog post on probiotics, as well as in future posts, we’ll go into them in a bit more detail.

The most common types of probiotics are in the bacterial groups (genera) Lactobacillus and Bifidobacterium, but many more exist, and even yeasts (which are fungi) are getting increased attention lately for their potential to confer benefits upon us. One of the tricky things with probiotics is that many positive effects of probiotics are strain-specific, meaning specific bacteria- and yeast-strains do specific things. A “strain” refers to a specific group within a species ex. a golden retriever and a cockerspaniel are two strains of the species domestic dog. As we’ll describe later, this strain specificity of probiotic properties has made research into the health benefits of probiotics and labelling of probiotic microbes much more difficult. In kombucha, the most numerous bacteria are Komagataeibacter sp. (formerly called Gluconacetobacter) and ‘Lactobacillus’, and Acetobacter sp. The most common yeasts are Pichia sp. and Saccharomyces sp 2.

So, if every healthy body contains trillions of helpful microbes anyway, the question is why it is beneficial to consume additional products containing probiotics? One reason to consume probiotic products is to replenish the good bacteria in your guts after e.g. an antibiotic treatment. This has been one of the most common “medical” uses of probiotics; doctors routinely advise patients to eat some live yogurt after a round of antibiotics to help recolonize the GI tract after the antibiotics have potentially killed a lot of the microbes living there. Another reason is to treat a number of diseases that affect us, including chronic diseases like Crohn’s disease, ulcerative colitis, Irritable Bowel syndrome, eczema or viral or bacterial diarrhea. Recent research has also indicated, however, wider ranging potential health benefits of probiotic supplementation including reduced inflammatory responses, reduced allergies, lower blood pressure, weight management, and even cancer prevention. However, the evidence to support these claims is complex and while it is very convincing for some of the aforementioned claims (like treating diarrhea) it is less certain or very preliminary for others. In the following posts on probiotics we’ll go into more detail about the evidence supporting the health benefits of probiotic supplementation, and the consumption of probiotic fermented foods and drinks like kombucha, as well as recent changes in the food labelling laws that affect how probiotic products can be marketed. But first, in the the next post we’ll discuss how to get probiotics and what are good sources of them.



1: Clemente JC, Ursell LK, Parfrey LW, Knight R. 2012. The Impact of the Gut Microbiota on Human Health: An Integrative View. Cell 148: 1258-1266.


2: Marsh AJ, O’Sullivana O, Hill C, Rossa RP, Paul D. Cottera PD. 2014. Sequence-based analysis of the bacterial and fungal compositions of multiple kombucha (tea fungus) samples. Food Microbiology 38: 171-178.


Hello, welcome to Roots Kombucha’s blog, which we have called “Rooted in knowledge”.  Here we are going to write about the knowledge and science behind a lot of the topics we, as brewers, fermenters, and food and drink producers find relevant and interesting. We’re gonna discuss obvious topics like probiotics, fermentation, and microbiology as well as related issues like nutritional research and labeling laws, and maybe anything else we think of that’s interesting.

Our thinking is that “Rooted in knowledge” should be a place to go to get a bit deeper understanding of some important topics that interest a lot of us.  We are often frustrated by how superficial a lot of what’s out there on the web is, oversimplifying complex issues and making huge statements in a brochure-like way, without any evidence to back it up, leaving us wondering how credible they are. Then, on the other extreme you have scientific articles, which are hard to find for most people, hard to access (paywall), and, for many, even harder to read. We want to make this informative, give you the nuances, and hopefully still make it easy to read and interesting. We hope that we can help you better understand and filter the flood of health-related info we are deluged with. Are ginger, turmeric, and lacto-bacteria really that good for me? Why has the EU banned companies from using the term “probiotic”? What’s the difference between “fermented” and “rotten”? What are antioxidants or enzymes, how do they work and should I care? These are a few of the topics we plan on delving into.

Our name “Rooted in knowledge” derives from our pride that what we do, what we produce, what we market, and what we write here, are just that, rooted in science. We started this blog because we think that a lot of customers and friends are interested in the knowledge that we have about fermentation, nutrition, health, and food chemistry and we’re happy to share it, hopefully in nicely sized, entertaining, interesting portions.

When we write “we”, we mainly mean one of Roots Kombucha’s founders, Nicholas Rosenstock. Beyond being a kombucha brewer, Nick has a doctorate in microbiology and is a fermentation fanatic, science-, gardening-, food-, and nutrition-nerd and the personification of the type of person the T-shirt designers had in mind when they printed “Fuck Google…ask me”. He knows, quite simply, a lot, and has a burning desire to spread his knowledge far and wide. Nick’s cofounder Matthias Lehner is also working on this blog as well is their partner Elin Rosenstock.