Gut flora predominates this week, as prompted by an article in Diabetes Forecast. This article explored the connection between intestinal bacteria and obesity, Type 2, and Type 1. Let's get to know two phyla in particular. (Need a refresher on biological classification? I did.)
The Firmicutes: a phylum of bacteria, mostly Gram-positive. You might recognize such genera as Bacilli, order Lactobacillales (think yogurt); and Clostridia (think botulism).
The Bacteriodetes: another phylum, comprising the classes Bacteroidetes, Sphingobacteria, and Flavobacteria, which are not as much fun as they sound.
What's the significance of these two broad groups? Jeffrey Gordon of Washington University in St. Louis leads the pack in showing that obese and lean animals and humans have different Firmicute/Bacteroidete ratios. Specifically, obese mice have more firmicutes and fewer bacteroidetes. Similarly, obesity in humans is associated with altered gut flora and decreased bacterial diversity.
The difference, according to the DF article, is because firmicutes more efficiently ferment indigestible polysaccharides to produce short-chain fatty acids. That is to say, the firmicutes can digest starches we can't and make energy for us to use better than bacteroidetes can. Better energy extraction leads to more fat storage leads to gaining weight more easily.
As if that weren't enough, gut microbiota changes after gastric bypass surgery, the latter of which has profound effects on Type 2 diabetes. "Profound" as in "goes into remission." Gut flora strikes again.
There's still more: in a small study published in Nature, children who went on to develop Type 1 diabetes saw a decline in firmicutes and an increase in bacteroidetes, while their case-controlled match saw the opposite trend. Furthermore, the healthy children had more abundant bacteria overall. This study is too small to draw firm conclusions about the hygiene and/or leaky gut hypotheses, but it's fascinating nonetheless. And props to Giongo et al. for quoting Tolstoy.
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