7 ms·
Human microbiome myths and misconceptions
- chasil 3y agoThis was something interesting that I read recently on (reducing) staph colonizations: https://news.ycombinator.com/item?id=34713431 https://news.ycombinator.com/item?id=34713431 This came well after the University of Iowa protocols for mitigating staph prior to surgical procedures (it's all about the nose, a favorite place for staph to inhabit): https://now.uiowa.edu/news/2013/06/be-gone-bacteria https://now.uiowa.edu/news/2013/06/be-gone-bacteria
- epgui 3y agoIt’s a good article, but I have the following criticism (i’m not the biggest expert, but I’m a biochemist): - many of these myths are things I’ve never heard before. I’m wondering how prevalent some of these really are. - some of these seem to be targeted towards uncharitable interpretations of ideas that could be explained more carefully - there are much more prevalent popular myths that are not mentioned. - I disagree about their take on how new of a field of research this is. I think they’re not taking big enough of a step back. I would say without hesitation that the field of nutrition, as a science, is VERY young. And yet it predates the study of the microbiome by a generous margin. I think this is a matter of perspective.
- MrRolleyes 3y ago> many of these myths are things I’ve never heard before. I’m wondering how prevalent some of these really are. It would be very odd for the average person to worry about who coined the term "microbiota", how many bacterial cells there are per gram, the weight of the human microbiota, etc. I'm guessing many of these myths are encountered only in niche communities that nonetheless deserve addressing—I'd guess that most of these myths don't interact with the average or median human.
- tremon 3y agoThese don't appear to be general-public myths, but misapprehensions from fellow scientists working in the field. Most of them are too specific ("Firmicutes:Bacteroidetes ratio", really?) to be prevalent among non-scientists. Also, this one is curious: - There are 10^12 bacterial cells per gram of human faeces They first say "it is incorrect", then continue with "the real figure is typically between 10^10 and 10^11" -- that's just one order of magnitude off, on a 12-digit number. The pedanticism is strong on that one. It only makes sense if they're addressing their fellow colleagues, who are supposed to know better.
- epgui 3y ago> These don't appear to be general-public myths, but misapprehensions from fellow scientists working in the field. I am a biochemist and read a few relevant journals regularly, and that’s precisely what I’m talking about.
- bumby 3y agoHere’s what may be a more charitable interpretation: A prevalent layman’s myth is that the bacteria in our gut outnumber our human cells by a wide margin (the article quotes the myth as 10:1). That’s a striking figure to a layman and “only” an order of magnitude off from what they claim is the true 1:1 ratio.
- MrRolleyes 3y agoI can't say I've ever considered the ratio of gut bacteria to human cells in my life. I find it difficult to imagine this consideration is itself very prevalent outside of people who are particularly neurotic about gut bacteria.
- bumby 3y agoI’m certainly a layman on this topic and have heard this quoted often in lay forums like podcasts, and have even said similar myself.
- MrRolleyes 3y ago[dead]
- pinkorchid 3y agoI think it's unfair to characterize this as a layman's myth given that it was a widely quoted figure in the literature at least until 2016. https://www.cell.com/cell/pdf/S0092-8674(16)00053-2.pdf https://www.cell.com/cell/pdf/S0092-8674(16)00053-2.pdf (Are We Really Vastly Outnumbered? Revisiting the Ratio of Bacterial to Host Cells in Humans)
- teekert 3y agoI’ve heard and believed most of them (I am a biologist). Yesterday I came across the 1 kg of microbiome statement in Nemo in Amsterdam (a science/do museum for kids). So I consider them prevalent fwiw. I actually thought it proven that the microbiota was seeded during vaginal birth and may lead to more issues for caesarean section delivered kids. I guess it all just sounded so logical. I know I know, that’s the most dangerous thing.
- t-3 3y agoThe microbiome is seeded during vaginal birth, the point the article makes is that this is only a temporary microbiome, and is unlikely to have any reflection in the microbiome vry long after birth and none after weaning.
- epgui 3y agoWhile this is a better understanding than the parent comment, it's not quite right either. The microbiome acquired at birth and early childhood is EXTREMELY robust to change throughout the rest of a lifetime. As an adult, it's frustratingly difficult / next to impossible to meaningfully change your microbiome. Even if you completely change your diet and you move across the world, your microbiome will be closer to what it was when you were 5 than it will be to anyone in your vicinity. This is a simplification, but the effect is spectacular. What the authors here claim is not that the microbiome is very plastic throughout your life-- merely that it retains some plasticity in very early childhood.
- Alpi 3y agoActually I can relate to those misconceptions as a person who enjoys popular science. I like articles like this since they hopefully help me to fine tune my intuition.
- MarkusWandel 3y agoOne thing I didn't see in this. Probiotics. So you have an active culture yoghurt, for example, that has one or a small number of bacterial species in it. This is claimed to benefit your gut biome. But how? Surely [re]introducing these few species hardly matters, given the overall diversity?
- aziaziazi 3y agoMy 2 cents hypothesis : as some food “kills” many organism (garlic for exemple is an excellent gut cleaner), you also benefit to re-fill “good” organism like those in yoghurt.
- InSteady 3y agoGarlic is both antimicrobial and a rich source of food (oligosaccharides) for many strains of gut bacteria. It happens to be a favorite additive to fermentation recipes for this reason.
- cmckn 3y agoI think you’d have to eat a colossal amount of garlic for its anti-microbial properties to have any measurable impact on your gut bacteria.
- iterateoften 3y agoFrom what I read and researched online is that probiotics aren’t the bacteria you need, but are sort of good neighbors to the needed bacteria and create an environment they need to thrive by balancing pH of the gut and outcompete the “bad” bacteria and yeast.
- epgui 3y agoThe only thing I have to say about that is that pH is probably not very clinically relevant. The rest more or less checks out.
- iterateoften 3y ago
- aziaziazi 3y agoI used to be bloated before my doctor advised me to try eating more bifidus with the help of a popular yogurt brand. It works like a charm: almost no bloating anymore if I got my morning yogurt but gaz seems to come back in a day or two of bifidus abstinence. I’d love to find a diary-free alternative.
- miriam_catira 3y agoIf you have Forager where you live, I'd highly recommend it. It's a cashew based probiotic. https://www.foragerproject.com/ https://www.foragerproject.com/
- aziaziazi 3y agoThanks a lot! I’ll give it a try.
- throw2210 3y agoHave you tried kefir? Regular milk is unbearable to me, and yogurt is better but not too much. Kefir on the other hand made a significant change to my day to day "gut health". **fast edit: and I really mean significant change. kefir + no sugar (low sugar diet)
- potatopatch 3y agoIf someone is making their own Kefir, the grains can also be converted to water Kefir to ferment something non-dairy.
- daoboy 3y agoSo do I still have to drink kombucha?
- epgui 3y agoWhy do you believe you have to drink kombucha?
- daoboy 3y agoI don't really. It was just a silly joke based on the notion that kombucha is supposed to help your gut microbiome but many people think it tastes gross.
- mikrl 3y agoThe cool kids brew/drink kefir now. If you don’t have middle eastern or Slavic tastes you’ll probably think it tastes gross tho.
- slothtrop 3y agoI think I read that the slavs don't like sour things and preferred to drink kefir during a state it was early stages of fermenting / bubbling, which is rather sweet, if you've ever made it yourself.
- mikrl 3y agoYes, I do the secondary fermentation which involves decanting it into a mason jar when it starts to separate, with some fruit pieces and letting it go for another 2-3h before refrigeration. This takes off the tartness and makes it a little creamier. My coworker, who is Iranian, usually just drinks it straight (I don’t know about the fermentation time) or with a little mint and salt since this is typical for West and Central Asia: refreshing because of the hot climate and similar to drinks like doogh or ayran.
- kjkjadksj 3y ago
- JPLeRouzic 3y ago> "“The human microbiota weighs 1 to 2 kg” --- The majority of the human microbiota resides in the colon, They give a reference which appears to not have been cited by anyone??? Yet it's easy to find references (second result in Ecosia search engine). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6313343/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6313343/
- HankB99 3y ago> The average human stool weighs less than 200 g. Guess I'm not average. But TBH, I've never weighed my poop, only occasionally estimated. I always figured if I took a healthy dump before heading out to run, that's be a pound less crap I had to haul around. ;)
- deleted 3y ago[deleted]
- iambateman 3y agoWould someone please do all of us a favor and give an educated overview of what gut bacteria actually is and does? I honestly have no idea and the article just assumed I do.
- zxcb1 3y agoAnalogous to the macro environment of flora and fauna; an ecosystem of microorganisms exhibiting the same evolutionary patterns and dynamics inside of host bodies
- thenerdhead 3y agoRead “I Contain Multitudes” by Ed Yong. A very approachable book for anyone.
- refurb 3y agoIt’s a nature paper so it’s directed towards scientists not the general public. But also scientists not necessarily doing research in the space. I’m happy to see a bit of myth busting going on. The space is in its infancy but wow do I ever see university press releases touting “microbiome is connected to disease X” a lot and it’s usually based on pretty flimsy evidence. The field will mature over time and no doubt find some interesting connections to human health, but it seems like there is a mad rush to “keep a healthy microbiome” when in fact we don’t even know that much about what a healthy microbiome looks like beyond a few obvious diseases like c. difficile.
- vjk800 3y agoFrom the article: > As examples, Clostridioides difficile can be carried asymptomatically throughout life, and only cause problems in older age when the host is immunocompromised and treated with antibiotics It seems that even c. difficile is not obviously "bad" .
- refurb 3y agoI noticed this too. My comment was more around the strong connection between antibiotic use, C. difficile overgrowth and resulting harm to health. But that comment is a good point that simply the presence of a bacteria doesn’t tell you anything by itself. Reminds me of the people who harbor MRSA in their nose. MRSA can cause a serious infection, but apparently for some people it doesn’t.
- vjk800 3y agoPseudoscience involving human microbiome seems to be very popular here in HN. Whatever health articles gets posted, someone starts touting their favourite internet theory on how it is all completely determined by the human microbiome, using getting a lot of upvotes. I would advice those people to carefully read the caption on Figure 2 in the article: > Changes in faecal microbiota have been associated with a range of diseases in humans. Interestingly, despite the diverse nature of these conditions, and the organs they affect, there are some broadly common recurring microbiota features, such as reduced diversity and increases in facultative anaerobes like Enterobacteriaceae. One common theme amongst these conditions is that they often result in increased levels of inflammation, at local and systemic levels. Such inflammation can, in turn, deplete the gut microbiota (and consequently microbial gene diversity), and allow facultative anaerobes such as Enterobacteriaceae to proliferate. This directly impacts the metabolic output of the microbiota, and its interactions with the host. Additionally, there are other host factors that contribute to disease and gut microbiota composition, such as age, BMI and medication, as well as host metabolism and immune response. This makes it very difficult to distinguish cause from effect in correlation-based studies. In short: it is all much more complicated than you think and separating the cause and effect is something no-one has managed to do convincingly yet. It's possible that the microbiome health really is as important as some people think, but it's also possible that the role is more minor and the changes in it associated with various diseases is just incidental.
- thenerdhead 3y agoThe whole point is that we are constantly finding causal, not casual relationships with our microbiome. Just last week there were two significant discoveries: For what is being found in long Covid for example, a promising hypothesis is viral persistence in the gut causing major dysbiosis and leading to lower production of serotonin. And we even saw the transfer of Alzheimer’s symptoms from an old host to a young one. I think it just shows how important microbes are in our lives and what a strong influence they have. https://www.pennmedicine.org/news/news-releases/2023/october/penn-study-finds-serotonin-reduction-causes-long-covid-symptoms https://www.pennmedicine.org/news/news-releases/2023/october... https://academic.oup.com/brain/advance-article/doi/10.1093/brain/awad303/7308687?searchresult=1&login=false https://academic.oup.com/brain/advance-article/doi/10.1093/b...
- OliverJones 3y agoOne wishes there were a version of this article for science journalists. And, one wishes that a university class on scientific ethics asked students to read this article with a critical eye and figure out what they can learn from it. Myths about human-health topics spread faster than truth sometimes. cf. stomach ulcers and "stress" vs. pylobacter. It's hard to stop that. But it's easier to stop if we're aware of the myths.