3 ms·

Hygiene hypothesis still seems dubious to me. The notion that hygienic lifestyles can lead to a weaker immune system or microbiome is plausible, but I'd actuall

by tootie 6y ago

Hygiene hypothesis still seems dubious to me. The notion that hygienic lifestyles can lead to a weaker immune system or microbiome is plausible, but I'd actually be pretty surprised if it translated into worse long-term outcomes like life expectancy. Being exposed to lots of pathogens can have some pretty big downsides. We're only just beginning to understand long-term COVID symptoms and it's possible we've missed long-term symptoms of lots of pathogens. I have had chronic canker sores my whole life (cause by retrovirus) that I definitely could live without. ERVs kinda freak me out too.

GenerocUsername 6y ago
Think of it this way: your body has machinery built to combat pathogens. If there are no pathogens to fight, the bar for what is considered a pathogen lowers until eventually those machines are attacking healthy tissue and can cause many issues. Allergies, Lupus, and many others are already caused by similar mechanisms, and pushing society into ever more clean states will likely lead to more issues. The only real cure would then be taking immune-suppresants. Or we just need to embrace that nasty bacteria are a natural environmental feature important to our homeostasis
- wpasc 6y ago
  Agreed with this entirely, see my nearby comment.
- pishpash 6y ago
  That's my hypothesis for how homo sapiens goes extinct -- becoming ever more dependent on nature-shaping or external machinery to augment weakened selection pressure, but very fragile to sudden changes and always fighting fires.
- monopoledance 6y ago
  > a weaker immune system or microbiome is plausible > Think of it this way: ... OP already said it's plausible. Your image doesn't add to the evidence at all. The truth is, we have no idea about immune and gene regulation. A lot of the simplistic understanding you learn in school is falsely making people believe the body is a "machine" we can control or even comprehend. Medicine doesn't know shit. All we have, are some correlations with an increase in autoimmune disease, allergies and lymphoma, and increasing hygiene. Could also be microplastics or hormone disruptors, social isolation, stress, overweight, lack of sunlight, climate change... . The immune system is insanely complex and a huge bag of innovation and legacy making many functions redundant and incredibly hard to decipher. And some "healthy exposure" to pathogens really is a coin toss, as it may not be the contact, but surviving the sickness you benefit from. So a severe fever may slightly decrease your cancer risk, but comes at the risk of dying from, well, severe fever.
- tootie 6y ago
  I don't think those are the only options. Once the diversity of human microbiomes are better mapped, it would seem be to pretty simple to manufacture a dose of healthy bacteria for your gut or your blood. Something that could be administered safely in a controlled dose.
wpasc 6y ago
I wouldn't argue that returning to hyper non hygiene would be better, but there has been a steady and remarkable rise in Autoimmune diseases, allergies, and asthma in the last few decades. Each of these conditions have long term consequences and complications. The hygiene hypothesis link to the microbiome and "training" of the immune system link is plausible and more and more research is backing it up. Moreover, given that the immune system and inflammation continue to be found to have a role in virtually every long term disease, the hygiene hypothesis should not be taken lightly. There are a variety of sources backing up my points, you can look around; just note i am NOT saying that any of the links are certain, just that the amount of evidence that does exist far surpasses the point where the hygiene hypothesis is dubious IMO, IANAD.
- jnxx 6y ago
  > The hygiene hypothesis link to the microbiome and "training" of the immune system link is plausible and more and more research is backing it up. There is also the hypothesis that the plague epidemics caused a shift to autoimmune diseases because it needed humanity to shift to a more trigger-happy immune system. Another factor could be the much better state of nutrition than in the old times. Malnutrition has massive negative effects on the immune response, and nutrition was pretty shaky for much of human history, so better nutrition could also cause some autoimmune issues.
- TomSwirly 6y ago
  The American obsession with cleanliness dates to the 1950s, so I'm a little confused as to what your argument is here. > that the amount of evidence that does exist Such as? It would be nice to see some actual evidence and not simply guilt by association.
  - wpasc 6y ago
    Please note, i am not claiming certainty and there are studies that point against the hygiene hypothesis. I am just stating that there is a growing body of evidence for the links between household cleanliness (and use of certain household cleaning products) and microbiome disruption. And links between microbiome disruption and prevalence of disease. For the American obsession with cleanliness in the 1950's, two things: autoimmune is hard to diagnose and many suffered in silence for decades AND cleaning up a lot is distinctly different from the proliferation of chemically based cleaning products many of which containing anti bacterial ingredients. Many look at the trend of autoimmune rise starting in the 70's and 80's. Let's say you're right about the 50's cleanliness, the children born then might not have been diagnosed, the cleanliness trend started then but built up to have large effect over 20-30 years, and/or it took time for chemicals to proliferate into household daily cleaning. I am NOT a tin foil hat wearer. I have an autoimmune disease and have researched the topic a lot. I am claiming NO certainty, just that the immune system is woefully insufficiently understood and that links with growing evidence should NOT be ignored. https://onlinelibrary.wiley.com/doi/abs/10.1111/apm.12023 https://onlinelibrary.wiley.com/doi/abs/10.1111/apm.12023 https://oem.bmj.com/content/74/9/684.abstract https://oem.bmj.com/content/74/9/684.abstract https://www.atsjournals.org/doi/full/10.1164/rccm.200612-1793OC https://www.atsjournals.org/doi/full/10.1164/rccm.200612-179... https://www.embopress.org/doi/full/10.15252/emmm.201707882 https://www.embopress.org/doi/full/10.15252/emmm.201707882 https://www.cmaj.ca/content/190/37/E1097?_ga=2.113661191.1490908815.1539388800-1636001196.1539388800 https://www.cmaj.ca/content/190/37/E1097?_ga=2.113661191.149... https://www.sciencedirect.com/science/article/abs/pii/S0171298507000332 https://www.sciencedirect.com/science/article/abs/pii/S01712... https://www.sciencedirect.com/science/article/abs/pii/S0171298507000393 https://www.sciencedirect.com/science/article/abs/pii/S01712...

by tootie 6y ago

GenerocUsername 6y ago

Think of it this way: your body has machinery built to combat pathogens. If there are no pathogens to fight, the bar for what is considered a pathogen lowers until eventually those machines are attacking healthy tissue and can cause many issues. Allergies, Lupus, and many others are already caused by similar mechanisms, and pushing society into ever more clean states will likely lead to more issues. The only real cure would then be taking immune-suppresants. Or we just need to embrace that nasty bacteria are a natural environmental feature important to our homeostasis

wpasc 6y ago
Agreed with this entirely, see my nearby comment.
pishpash 6y ago
That's my hypothesis for how homo sapiens goes extinct -- becoming ever more dependent on nature-shaping or external machinery to augment weakened selection pressure, but very fragile to sudden changes and always fighting fires.
monopoledance 6y ago
> a weaker immune system or microbiome is plausible > Think of it this way: ... OP already said it's plausible. Your image doesn't add to the evidence at all. The truth is, we have no idea about immune and gene regulation. A lot of the simplistic understanding you learn in school is falsely making people believe the body is a "machine" we can control or even comprehend. Medicine doesn't know shit. All we have, are some correlations with an increase in autoimmune disease, allergies and lymphoma, and increasing hygiene. Could also be microplastics or hormone disruptors, social isolation, stress, overweight, lack of sunlight, climate change... . The immune system is insanely complex and a huge bag of innovation and legacy making many functions redundant and incredibly hard to decipher. And some "healthy exposure" to pathogens really is a coin toss, as it may not be the contact, but surviving the sickness you benefit from. So a severe fever may slightly decrease your cancer risk, but comes at the risk of dying from, well, severe fever.
tootie 6y ago
I don't think those are the only options. Once the diversity of human microbiomes are better mapped, it would seem be to pretty simple to manufacture a dose of healthy bacteria for your gut or your blood. Something that could be administered safely in a controlled dose.

wpasc 6y ago

I wouldn't argue that returning to hyper non hygiene would be better, but there has been a steady and remarkable rise in Autoimmune diseases, allergies, and asthma in the last few decades. Each of these conditions have long term consequences and complications. The hygiene hypothesis link to the microbiome and "training" of the immune system link is plausible and more and more research is backing it up. Moreover, given that the immune system and inflammation continue to be found to have a role in virtually every long term disease, the hygiene hypothesis should not be taken lightly. There are a variety of sources backing up my points, you can look around; just note i am NOT saying that any of the links are certain, just that the amount of evidence that does exist far surpasses the point where the hygiene hypothesis is dubious IMO, IANAD.

jnxx 6y ago
> The hygiene hypothesis link to the microbiome and "training" of the immune system link is plausible and more and more research is backing it up. There is also the hypothesis that the plague epidemics caused a shift to autoimmune diseases because it needed humanity to shift to a more trigger-happy immune system. Another factor could be the much better state of nutrition than in the old times. Malnutrition has massive negative effects on the immune response, and nutrition was pretty shaky for much of human history, so better nutrition could also cause some autoimmune issues.
TomSwirly 6y ago
The American obsession with cleanliness dates to the 1950s, so I'm a little confused as to what your argument is here. > that the amount of evidence that does exist Such as? It would be nice to see some actual evidence and not simply guilt by association.
- wpasc 6y ago
  Please note, i am not claiming certainty and there are studies that point against the hygiene hypothesis. I am just stating that there is a growing body of evidence for the links between household cleanliness (and use of certain household cleaning products) and microbiome disruption. And links between microbiome disruption and prevalence of disease. For the American obsession with cleanliness in the 1950's, two things: autoimmune is hard to diagnose and many suffered in silence for decades AND cleaning up a lot is distinctly different from the proliferation of chemically based cleaning products many of which containing anti bacterial ingredients. Many look at the trend of autoimmune rise starting in the 70's and 80's. Let's say you're right about the 50's cleanliness, the children born then might not have been diagnosed, the cleanliness trend started then but built up to have large effect over 20-30 years, and/or it took time for chemicals to proliferate into household daily cleaning. I am NOT a tin foil hat wearer. I have an autoimmune disease and have researched the topic a lot. I am claiming NO certainty, just that the immune system is woefully insufficiently understood and that links with growing evidence should NOT be ignored. https://onlinelibrary.wiley.com/doi/abs/10.1111/apm.12023 https://onlinelibrary.wiley.com/doi/abs/10.1111/apm.12023 https://oem.bmj.com/content/74/9/684.abstract https://oem.bmj.com/content/74/9/684.abstract https://www.atsjournals.org/doi/full/10.1164/rccm.200612-1793OC https://www.atsjournals.org/doi/full/10.1164/rccm.200612-179... https://www.embopress.org/doi/full/10.15252/emmm.201707882 https://www.embopress.org/doi/full/10.15252/emmm.201707882 https://www.cmaj.ca/content/190/37/E1097?_ga=2.113661191.1490908815.1539388800-1636001196.1539388800 https://www.cmaj.ca/content/190/37/E1097?_ga=2.113661191.149... https://www.sciencedirect.com/science/article/abs/pii/S0171298507000332 https://www.sciencedirect.com/science/article/abs/pii/S01712... https://www.sciencedirect.com/science/article/abs/pii/S0171298507000393 https://www.sciencedirect.com/science/article/abs/pii/S01712...