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Friday, September 12, 2014

Hey You Low Carbers! Nourish Your Micrbiome!

Hey Folks!
Our Heal Your Gut Challenge will be starting very soon - September 15 to be exact. 

I recently starting discussing butyrate - a short chain fatty acid that is a byproduct of the fermentation that occurs in a healthy and happy gut. We would do ourselves some good to enjoy a diet that is high in fermentable fibre.  Fermentable fibre is that which evades digestion in the upper gut and then FERMENTS in the gut (provided that microbiota is PRESENT).   Folks on a low carb diet may not be getting the fermentable fibre that they need for a healthy microbiome.  Read all about this problem below and why a gut high in acid is beneficial.

I cut and pasted the gist of the article below:

"When it comes to the health and well being of your gut microbes, nothing matters more than fermentable substrates (You can read about here, here, here, here, here, here, here, here, here – you get the idea). As the rules/tenants of basic microbial ecology go, a reduction in fermentable substrates derived from carbohydrates means less energy sources for the microbes – who depend on host-derived substrates as well, as in the case of mucin-degraders like Akkermansia. As fermentation drops, so to does the byproducts of fermentation which include short chain fatty acids (primarily acetate, butyrate, propionate), organic acids, and gases like hydrogen. All of this can and will dramatically shift the pH of the colonic environment. As it stands in a healthy or normal gut, the pH of the colon changes from proximal to distal end, being more acidic in the proximal (front) end than the tail end – mainly as a function of more rapid fermentation as food items empty from the small intestine. As the pH shifts to being more alkaline from less fermentation, a number of shoes begin to drop (or can).
A less acidic environment means acid sensitive groups of bacteria, like those in the Phylum Proteobacteria, which includes a who’s who of bad guys like strains of E. Coli, Salmonella, Vibrio, Helicobacter, might bloom – not a good thing. You see the same blooms following antibiotic treatment. In addition, as pH shifts away from acidic, the genus Bacteroides can also bloom as well, gaining an ecological niche in this less acidic environment courtesy of a low carb diet. For those of you keeping score, many talk about the American gut in general being dominated by Bacteroides as a function of our high fat, high sugar diet. The reality is, it might have to do with what we are not eating – dietary fiber (of all kinds). The all-important butyrate producers Roseburia spp. and Eubacterium also drop in abundance as pH shifts away from acidic as well. A drop in fecal butyrate and butyrate producing bacteria was demonstrated in an elegant study comparing diets of varying amounts of carbs. Given the importance of butyrate in colonic health, any dietary strategy that potentially shifts pH away from acidity as a function of reduced fermentation, might contribute to various forms of IBD.
So, low carb equals a less acidic colonic environment due to the drop in fermentation (and I presume harder, and less frequent stools as a function of reduced biomass from bacteria – or maybe not). As pH shifts, prospects for opportunistic pathogens increase, as does opportunities for gram-negative bacteria like Bacteroides and Enterobacter. When you add this up – and a lot of more shifts in the microbial ecology of the low carb gut – you most certainly have a classic case of microbial dysbiosis – as the name implies, an imbalance. This dysbiosis can lead to issues associated with IBD, autoimmune disease, metabolic disorders and so on. But again, a large cohort of low, low carb dieters has never been looked at using 16S rRNA methods. So the jury is still out – but will be fascinating to see.
A bit of a paradox in all of this is the increased likelihood that a low carb microbial community will most certainly lead to increased gut permeability – a well-known phenomenon whereby microbial parts (lipopolysaccharides, which leads to metabolic endotoxemia) and whole microbes themselves (bacteremia) leak from the intestinal track into the blood, leading to low-grade inflammation that is at the root of metabolic diseases such as type 2 diabetes, obesity and heart disease. So it is a paradox that a leaky gut that can be triggered from a low carb (high fat) diet – and a possible increase in gram-negative bacteria and a reduction in healthy bacteria like Bifidobacterium – doesn’t result in weight gain as demonstrated in study after study in mice and humans. Weird.
I hope people do not take this as some kind of attack on low carb diets – couldn’t be farther from the truth. There is NO AGENDA. Again, NO AGENDA. (It’s worth noting I consume a high fat, high protein, high fiber diet). Just wanted to point out some obvious concerns (maybe unfounded) and that if we get a large enough sample of low carb folks in American Gut, we might be able to provide some interesting insight – or not. Who knows, maybe low carb folks have super healthy gut microbiota (whatever that is).
So to my low carb brothers and sisters out there, try and eat a little more fibrous material if you can – diversity matters –  and help your gut bugs help you. It’s what evolution intended."
 

http://humanfoodproject.com/sorry-low-carbers-your-microbiome-is-just-not-that-into-you/

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