Ituzzip t1_j2ovk5n wrote
Reply to comment by homeostasis3434 in A study on obese patients suggests the gut microbiome affects obesity levels. Microbial diversity decreased in obese subjects, and the reduction trend was correlated with the severity of obesity. by glawgii
The studies are literally being done to accumulate data to be able to test this logic.
You have your logic in that you suspect diet is the primary causative factor, and changes in microbiome follow, and it’s perfectly reasonable logic.
But it’s also possible that the microbiome affects things like hormone levels, creates fermentation byproducts like lactic acid and acetic acid that change blood sugar profiles and the speed of digestion, it’s possible the microbiome affects appetite, and different microbes could cause people to tend to eat less without conscious thought about it.
Or a sudden change in microbiome could induce metabolic changes quickly, which would eventually revert to baseline without behavior changes, but remain robust if people keep supplying the different microbes.
Or there could be a combination of multiple factors and inputs that are more complex than anyone has thought of so far.
Logic can make perfect sense and still turn out to be wrong—that’s why the studies are being conducted.
Even if diet comes first and microbial changes follow, studying the microbiome could someday identify a causative link between obesity and things like gastrointestinal cancers.
It will take many studies and a large accumulation of data before people are able to draw any conclusions or even figure out what the more important kinds of tests are.
SaltZookeepergame691 t1_j2p2aez wrote
There are number of trials looking at microbiota interventions and obesity, and none have found any effect.
It may be that we aren’t using the right protocol, but it really does seem that if there is an effect it is far smaller than previously believed.
Latest trial to my knowledge is this one: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2799634
Others include but are not limited to:
https://www.ncbi.nlm.nih.gov/pubmed/33346848
https://pubmed.ncbi.nlm.nih.gov/31301451/
https://pubmed.ncbi.nlm.nih.gov/32150549/
Even the animal models that launched this research are overhyped, finding marginal effects in tiny experiments often with improper controls or analysis approaches.
Ituzzip t1_j2p4ysz wrote
I suspect that scientific research interest and funding has been too fixated on obesity itself as a catch-all target for all the health issues associated with obesity.
There might be more value in understanding why all these conditions are connected to obesity, and whether microbes play a role in them.
But that’s just conjecture on my part. Given the complexity of this phenomena and our very limited current understanding of the microbiome, we have not come close to exhausting all the options.
But again, we won’t know what questions to ask until we get a wider base of information to use to find patterns.
SaltZookeepergame691 t1_j2qxy40 wrote
I think the take home here from the above trials is that the hype far, far exceeded the evidence - if microbiota modulation for obesity was a drug requiring substantial financial investment, it very likely would have been dropped in preclinical development, and it certainly would have been dropped after these negative pilot trials. By contrast, the effect of, say FMT on single and multiple recurring C diff is very obvious, and the RCT evidence for an effect in ulcerative colitis is at least mixed, if not somewhat promising.
The reason for the focus on obesity, rather than say obesity-associated CVD or CKD or NAFLD or extra-GI cancers, is that these conditions take years to develop, in a relatively small number of people - it should be much easier to see an effect on weight in people already obese, if one exists. There is some very limited evidence that microbiota intervention can improve glucose homeostasis in people, but I wouldn’t hang my hat on those studies.
[deleted] t1_j2qzlc6 wrote
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