20
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Probiotics: hype or helpful? An interview with Professor Jens Walter.
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- Title
- Probiotics: Hype or Helpful? H2CT Ann Reardon
- Authors
- How To Cook That
- Duration
- 27:38
- Published
- Jun 20 2025
This is a great interview, thanks for posting!
One thing that wasn't covered in depth: Fermented foods. Eating fermented foods can increase microbiome diversity and improve other markers of gut health.
Many store-bought fermented foods, like a jar of sauerkraut, have been pasteurized and don't have any live bacteria. Thankfully, most fermented foods are cheap and easy to make at home! Standard cabbage, salt, a kitchen scale, and a container are all you need to make fantastic sauerkraut. Kombucha just needs a few cheap teabags, some sugar, and a bit of starter liquid from a previous batch (or a scoby) - so much cheaper than the store.
Plus, fermented foods are just plain delicious, regardless of potential health benefits.
Great video! Every time I read some popsci article about the gut microbiome (even in reputable media like recently National Geographic), there are inevitably either incorrect things or concepts simplified way too much to the point of being wrong. I see nothing wrong here and I just wish the video was 4 times as long.
I want to say I fucking love the idea of participating in a gut microbiome restore study where a PhD researcher prepares literally all my food for several weeks, lol. I'd do that in a heartbeat.
These are some interesting additions to the topics in the video that they did not talk about, probably because there wasn't enough time:
Probiotics: the metabolites that bacteria produce can also literally be antibiotics that they create to destroy other bacteria in your gut. This can be useful when the other bacteria are pathogenic, but in that case taking the probiotic in the long term is not a good idea because the pathogenic bacteria can become resistant, just like with antibiotics you take in pill form. If you do find probiotics that make you feel better in some way but they stop working after a month or two, this can be the reason.
Fecal microbiome transplant: The question is not just "for which conditions does it work?" but also "how to do it?" The reason why it's successful for c. diff is because a small microbiome shift from any healthy donor microbiome is usually enough to restore balance and cure it. For more complicated illnesses we seem to require much bigger shifts using multiple (sometimes many) transplants done every day from a compatible donor, possibly with prep using antibiotics etc. How to select good compatible donors? What is the best overall treatment protocol? We don't know yet. This is one of the big reasons for conflicting data.
You sound very familiar with this area of study. Do you work in the field?
Really interesting about gut bacteria naturally producing antibiotics. It makes sense; evolve ways to knock out competition so you can better thrive on the limited resources. If this is all happening on its own in our gut, I'm assuming that the antibiotics produced are different enough than the ones we intentionally administer that any resistances built up in the gut naturally don't impact the effectiveness of the medicine?
They are not so different because most of our antibiotics are "stolen" from microorganisms and barely modified. (they are chemically synthesized, but the structure is mostly the same as naturally produced antibiotics).
There is a billion years chemical war between microorganism going on everywhere including our guts. Many resistance mechanism are preexisting and only need to be slightly modified or upregulated to make microorganisms more resistant.
but many resistance mechanism are costly (either it make some enzyme less effective, or it cost energy to maintain) so microorganisms tend to revert back to non-resistant when they no longer need it (they usually keep a dormant copy of what they need to become resistant again, leading to "induced resistance" phenotype). Over time we get a kind of equilibrium.
If anything, our use of antibiotics (massive doses) would impact gut bacteria's antibiotics use (smaller dose to hamstring the competition) much more than the other way around.
Multi resistant super bug are the microorganisms trying to adapt to an environment of high antibiotics use (hospital).
I do not work in the field, I spent years studying it in my free time out of necessity (microbiome issues likely at least heavily influencing my chronic illness). Did my best avoiding pseudoscience and outdated information (not easy), my knowledge is relatively deep but very narrow, only related to things that likely directly affect me.
Adding to what Pepetto said, some bacteria do actually produce the same antibiotics that we put into pills, but I think most only produce bacteriocins, which compared to our antibiotics have quite a narrow spectrum of targets and iirc are usually less chemically stable. Bacteria can produce multiple different bacteriocins with different targets, so the effect on the microbiome can still be quite significant.
I think that most if not all of the (not many) probiotics used to affect the oral or nasal microbiome in order to reduce the chances of infections or cavities work on this basis: they introduce a bacterial species that produces 2 - 3 bacteriocins which target common pathogens.
Ann Reardon of Youtube channel "How To Cook That" interviews Professor Jens Walter, a gut microbiome expert. They talk about the current state of research on the microbiome, its relation to health outcomes, supplements currently on the market, and influences of diet and lifestyle.
Super interesting discussion, thanks for sharing it! One section in particular that caught my attention was about emulsifiers though... especially since I use an emulsifier (xanthan gum) in my own homemade ice cream. However, since Prof Walters didn't go into too much detail about their potential effects, I decided to ask Perplexity AI's Deep Research mode (which actually cites its sources) about it. And the results were interesting as well, and actually surprised me since, while there were some concerns about potential inflammatory effects and issues in "vulnerable populations" (i.e. premature infants), there actually seem to be a fair number of potential positives associated with its consumption too.
Click to see AI output related to "Effects of Xanthan Gum on the Gut Mucous Membrane"
Effects of Xanthan Gum on the Gut Mucous Membrane
Xanthan gum's effects on the gut mucous membrane and intestinal barrier are complex and context-dependent, with research revealing both potentially beneficial and concerning impacts depending on dosage, individual microbiome composition, and population studied.
Microbiome Interactions and Bacterial Adaptation
Recent groundbreaking research has revealed that xanthan gum significantly interacts with gut bacteria, particularly in industrialized populations. The ability to digest xanthan gum is surprisingly common in human gut microbiomes from industrialized countries and appears contingent on a single uncultured bacterium in the family Ruminococcaceae. This primary degrader cleaves the xanthan gum backbone before processing the released oligosaccharides, while some individuals also harbor Bacteroides intestinalis that feeds on the smaller carbohydrates released by the Ruminococcaceae bacterium.[1][2][3]
This bacterial adaptation has occurred remarkably quickly, considering xanthan gum was only introduced into the modern diet fifty years ago. The genetic signatures of these xanthan gum-degrading bacteria are relatively absent in samples from microbiomes of people from non-industrialized countries, suggesting that widespread consumption may actively alter gut microbiome composition.[4][5]
Protective Effects on Gut Barrier Function
Paradoxically, some research suggests xanthan gum may offer protective benefits for the gut barrier. Studies in mice have shown that dietary xanthan gum administration can maintain both the diversity and absolute abundance of the microbiota during antibiotic treatment. This protective effect appears to work through multiple mechanisms: xanthan gum may bind to oral antibiotics in the gut, reducing their bioavailability and allowing beneficial bacteria to survive.[6][7]
The protective microbiota effects translate to improved colonization resistance against pathogenic bacteria. Mice fed xanthan gum experienced limited to no Clostridioides difficile colonization after antibiotic treatment, compared to significant colonization in control mice. This protection likely occurs by maintaining metabolic mechanisms that exclude pathogens, including bile salt metabolism and nutrient competition.[7][6]
Short-Chain Fatty Acid Production and Metabolic Effects
When degraded by gut bacteria, xanthan gum leads to the production of short-chain fatty acids (SCFAs), particularly butyrate and propionate. These SCFAs play important roles in intestinal health, including nourishing colonocytes, maintaining gut barrier function, and contributing to total caloric intake. Research has shown significantly higher butyrate and propionate concentrations in mice consuming xanthan gum compared to standard diets.[5][6]
Inflammatory Responses and Potential Concerns
However, some studies have raised concerns about xanthan gum's inflammatory potential. Research in mice found that dietary xanthan gum promoted a pro-inflammatory state by elevating the pro-inflammatory cytokine TNF-α in mesenteric and retroperitoneal adipose tissues, as well as elevating IL-6 in retroperitoneal adipose tissue. TNF-α is considered one of the most potent pro-inflammatory cytokines and is upregulated in intestinal inflammation.[8]
These findings support clinical observations suggesting potential inflammatory effects, particularly in vulnerable populations. However, it's important to note that most animal and human studies have found no damage to the intestinal mucosa following xanthan gum consumption, even in large doses.[9]
Critical Safety Concerns in Premature Infants
The most serious safety concern relates to necrotizing enterocolitis (NEC) in premature infants. Multiple case reports have documented an association between xanthan gum-containing thickening agents and the development of late-onset colonic NEC in premature infants. The FDA received 22 adverse event reports suggesting this association, revealing a distinct illness pattern.[10][11][12]
The mechanism behind this association may involve xanthan gum's laxative properties and its ability to alter gut barrier function in the immature intestinal environment of premature infants. This has led to strong cautions against using xanthan gum-based thickeners in this vulnerable population.[11][12][13]
Intestinal Barrier and Permeability Effects
Research on xanthan gum's direct effects on intestinal barrier function shows mixed results. Unlike some other emulsifiers that clearly disrupt tight junction proteins and increase intestinal permeability, xanthan gum appears to have either neutral or potentially beneficial effects on barrier function. Some sources suggest it may even enhance intestinal barrier function, thereby reducing the risk of intestinal diseases.[14][15]
However, there are concerns that xanthan gum, like other emulsifiers, could potentially disturb the intestinal lining and allow histamine and other inflammatory substances to pass through more easily. The viscous, gel-like properties of xanthan gum may also affect nutrient absorption rates by forming a non-diffusible aqueous layer that influences the diffusion of nutrients into the intestinal lumen.[16][17]
Dosage and Individual Variation Considerations
The effects of xanthan gum on gut health appear highly dose-dependent. At typical dietary levels found in processed foods, effects are generally minimal. However, at higher doses (such as 15 grams per day in research studies), xanthan gum acts as a "highly efficient laxative" and can cause significant changes in gut microbiota composition and SCFA production.[9]
Individual variation in gut microbiome composition also plays a crucial role. Only certain individuals possess the bacterial machinery necessary to effectively degrade xanthan gum, and this capability can develop over time with exposure. This suggests that effects on the gut mucous membrane may vary significantly between individuals based on their unique microbiome profile.[9]
Conclusion
Xanthan gum's effects on the gut mucous membrane are multifaceted and depend on numerous factors including dosage, individual microbiome composition, age, and health status. While it can provide protective benefits for gut barrier function in some contexts and populations, concerns remain about inflammatory potential and serious safety issues in vulnerable populations, particularly premature infants. The rapid adaptation of gut bacteria to this relatively new food additive highlights the dynamic nature of human-microbiome interactions and the need for continued research into the long-term effects of widespread consumption.
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That topic gave me pause as well, and I also suspect that we're not getting enough detail and nuance in this limited interview. An "emulsifier" is such a broad category, including "natural" sources like mustard and egg yolks, that it almost feels as meaningless to talk about as "[ultra] processed food" without establishing a more narrow definition for discussion.
Yeah, as much as I enjoyed the video, I actually wish it was way wayyyyyy longer so Prof Walters could have gone into more detail on many of the topics he was only able to briefly touch on. It did prompt me to start looking into a bunch of related stuff myself though, so it was still a totally worthwhile submission and watch. :)