In Breaking Down Fiber, Our Gut Bacteria Do Us Yet Another Healthy Favor

And here is yet another reason why we love our good gut bacteria.  This research perfectly illustrates our symbiotic relationship with our old friends.

As my regular readers know, there is so much we still don’t know about fiber:  exactly how does it benefit us? How does each exactly affect the gut biome?  Is one better than another for a specific condition?  Thus, I was excited to see this work out of the University of Illinois Urbana-Champaign (together with researchers at the University of Michigan and a Japanese university).[i]   Grains including oats, rye, wheat and rice contain a fiber (polysaccharide) I’d never heard of:  arabinoxylans.  Like many kinds of fiber, humans are incapable of digesting it on our own.  Many of our normal gut bacteria can break down the simpler components of arabinoxylans; however, those components that are complex contain a substance called ferulic acid, which most bacteria cannot break down.  Ferulic acid though is extremely beneficial for us:  it has antioxidant, anti-inflammatory and immunomodulatory properties in conditions ranging from Alzheimer’s to cardiovascular diseases to cancer.

If we can’t break down arabinoxylans ourselves, and most microbial species can’t either, how can we access the ferulic acid contained in the fiber?  They combed through the bacteria of the biome, looking at both genes and digestive activity, and discovered that a group of Bacteroidetes bacteria, including Bacteroides intestinalis – others of which had not as yet been categorized – have enzymes that can break down arabinoxylans.  One bacteria in particular is extremely adept at getting at the ferulic acid, releasing large amounts of into the gut.  And in a show of true symbiosis, as I mentioned above, none of the bacteria use ferulic acid themselves; they leave it all for us. Says the leader of the study, ““These bacteria can sense the difference between simple and complex arabinoxylans to deploy a large set of enzymes that function like scissors to cut the linkages in complex arabinoxylans into their unit sugars, and at the same time release the ferulic acid.”[ii]

The thinking for the future:  for those with illnesses known to benefit from ferulic acid, the scientists hope to create targeted probiotics which contain these ferulic acid-releasing species…and of course, consuming a diet high in foods which contain arabinoxylans can also be a part of the treatment plan.

So in my continued efforts to have a “Jolly January,” more good news on biome news front.  It just feels like we are getting closer and closer to figuring out how to treat disease through manipulating the microbiome in natural, non-invasive, ways.


[i] Gabriel V. Pereira et al. Degradation of complex arabinoxylans by human colonic Bacteroidetes, Nature Communications (2021). DOI: 10.1038/s41467-020-20737-5


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