The recent research out of the University of California Davis on how prebiotics improve the quality of the microbiome is particularly fascinating.[i] There is a constant battle between various bacterial species in the gut for dominance. Prebiotics, you’ll recall, are indigestible dietary fibers that feed bacteria. Certain foods are high in these fibers, like garlic, leeks, onions, Jerusalem Artichoke, dandelion greens, asparagus, banana and/or, you can take prebiotics in pill form.
When gut microbes consume prebiotic fibers, they produce higher levels of short chain fatty acids which, in turn, signal the lining of the large intestine to maximize oxygen consumption. This limits then the amount of oxygen diffusing into the lumen of the gut. As most beneficial bacteria thrive in low oxygen environments, this leads to higher levels of anti-inflammatory species.
When anything goes wrong with this signaling pathway (or not enough prebiotic fiber is consumed), there are higher oxygen levels in the gut which make us more susceptible to aerobic pathogens like salmonella.
The arbiter of this SCFA/oxygen cycle, responsible for maintaining this cycle of protection, is the peroxisome proliferator receptor gamma (PPARg). PPAR is a major player in modulating inflammation. PPAR agonists reduce the inflammatory response.
I did some surfing around on the ‘net, and found a really good article on all this in, believe it or not, Optometry Times. The author looks at the relationship of the gut flora to the onset of diabetes: “A reduction in gut bacterial diversity precedes the onset of clinical diabetes. Reduction of intestinal species that produce short-chain fatty acids (SCFAs), especially butyrate but also propionate and acetate, appears to be particularly important. These SCFAs improve insulin sensitivity by stimulating peroxisome-proliferator agonist gamma receptors (PPARg), analogous to the PPARg diabetes medication, pioglitazone (Actos, Takeda).”[ii]
By the way, there are natural PPAR agonists as well like resveratrol, for example.
The research on the importance of prebiotics has definitely been accelerating in recent years, for a very good reason.