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/
