Buy One, Get One Free: Two Papers on the Bacterial Microbiome that Caught My Eye

Flash sale!!!  Two for the price of one today at The Biome Buzz!

The first study that I want to share with you was performed in a collaboration between Japanese, Harvard and MIT scientists, and was published in the elite journal, Nature.[i]  The researchers looked at the bacterial microbiomes of 160 centurions, average age of 107, and compared them to the younger peers, aged 85-89 and a second group, aged 21-55.  Those who survived to extreme old age have higher levels  of bacterial species which produce secondary bile acids. [ii]   Remember back in January of 2020, I first started covering the bile acids story which has really taken off in terms of research.    It turns out that bile acids, which are produced by the liver to digest fats, are HUGE players in health and inflammatory status.  (If interested, you can read even more about them on The Biome Buzz.  Here and here are just a couple more examples.)

These scientists believe that secondary bile acids protect the intestines from pathogens and also regulate the inflammatory response.  To confirm this, the researchers took the bile acids from these remarkably old people and in vitro, treated common pathogenic bacteria with them.  One molecule called isoalloLCA strongly inhibited the growth of Clostridium difficile.  This proved to the be case in a rodent model as well:  animals infected with C. diff but supplemented with isoalloLCA did not get sick.  The molecule also protects against the growth of many other pathogens as well:  “These findings suggest that specific bile acid metabolism may be involved in reducing the risk of pathobiont infection, thereby potentially contributing to the maintenance of intestinal homeostasis.” Further research will follow, looking at the link between longevity and bile acids.

The second bit of research I wanted to draw to your attention to was published in JAMA Network Open, and showed, in a cross-sectional study of over 2000 adults, that a more diverse microbiome is associated with a markedly lower risk of insulin resistance and type 2 diabetes.  There were 12 specific species which appear to be tied to lower risk of diabetes:  Clostridiaceae 1, Peptostreptococcaceae, C sensu stricto 1, Intestinibacter, Romboutsia, 2 types of Christensenellaceae, Marvinbryantia, and 4 types of Ruminococcaceae.[iii]

Several of these species have been previously found to be related to insulin resistance, but several are new findings. Interestingly, many of these are butyrate producers.  How many times have I talked about the importance of this, in regards to health on this blog?!  (Look here and here and here as just 3 examples of many more!) The researchers also point out that several of these have also been linked to obesity.   They conclude, “In this cross-sectional study, higher microbiome α diversity, along with more butyrate-producing gut bacteria, was associated with less type 2 diabetes and with lower insulin resistance among individuals without diabetes. These findings could help provide insight into the etiology, pathogenesis, and treatment of type 2 diabetes.”

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[i] Yuko Sato et al, Novel bile acid biosynthetic pathways are enriched in the microbiome of centenarians, Nature (2021). DOI: 10.1038/s41586-021-03832-5

[ii] https://medicalxpress.com/news/2021-07-centenarians-distinct-microbiome-longevity.html

[iii] https://www.medpagetoday.com/endocrinology/diabetes/93842?vpass=1

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