Episode 5 of The Microbiome Podcast: Diet and its impact on our microbiota and health with Drs. Erica and Justin Sonnenburg

As we read on yesterday's blog post, dietary fibers alter the microbiome. On this week's episode of The Microbiome Podcast we talked in depth with Drs. Erica and Justin Sonnenburg from Stanford University about dietary fibers and their impact on our microbiota and our health.  Erica and Justin wrote a book that was published today called The Good Gut: Taking Control of Your Weight, Your Mood, and Your Long-term Health. You can buy it here on Amazon and it's a highly recommended read for anyone interested in the microbiome. 

Check out the newest episode on iTunes, Stitcher, or listen on our website. 

We will continue answering your questions on the podcast so please call 518-945-8583 with any questions for us or for next week's guest, Dr. Elaine Hsiao.

See below for more detailed show notes from today's episode: 

(1:17) Dr. Rob Knight received a Creative Promise in Biomedical Science Prize from the Vilcek Foundation. Read more.
(3:09) Rob Knight also published a book called Follow Your Gut: The Enormous Impact of Tiny Microbes. Click here to buy it on Amazon. 
(3:33) uBiome recently began a pregnancy microbiome study to better understand how the bacteria in our bodies change during and after pregnancy. Find out more on the uBiome website. 
(4:56) Microbiome Therapeutics performed a clinical study with an investigational drug in type 2 diabetics taking metformin and found that the drug resulted in more tolerability for patients and fewer side effects than metformin without the drug. Read more.  

In the (9:40) conversation with Erica and Justin Sonnenburg (read more about their research), we talked about several topics pertaining to diet and dietary fiber and its impact on our microbiota and health. We also discussed: 

(11:49) Why they decided to write the book.
(16:05) Their personal experiences having children and the importance of nurturing their health and its impact on their lives.
(17:55) Dietary fibers and differences among various types of fibers in our diets.
(26:15) How fast does diet change the microbiota?
(32:05) Bacteroides thetaiotaomicron and why it is Erica and Justin's favorite microbe and a study Justin published in 2005 while he was in Jeff Gordon's lab. Read the paper here.  
(37:35) How microbiome therapies are going to look in the future. 
(41:00) How eating better can make an impact now on our overall health. Read the seminal obesity and microbiome paper Erica mentions from the Gordon laboratory. 

We also answered two other (44:00) listener questions about phage therapy and organic vs. non-organic baby and adult foods. 

Next week we will be talking with Dr. Elaine Hsiao from Cal Tech so please call 518-945-8583 with your questions about autism and the microbiome as well as the microbiome's ability to regulate serotonin levels. 

Our microbiome has a taste for beer

Many humans enjoy the taste of bread, beer, soy sauce, and other yeasty treats because they taste so darn good.  As it turns out though, we may not be only ones who like these flavors.  A report published last week in Nature describes the discovery of bacteria in our guts that survive by off the yeast in our diets.

The researchers noted that many gut bacteria from the phylum bacteroidetes have genomes that contain genes for enzymes that are capable of degrading complex carbohydrates, including one called α-mannan.  Curiously, the primary source of α-mannan in the gut is on cell walls of ingested yeasts such as Saccharomyces cerevisiae.  The researchers performed a variety of experiments that confirmed that at least one of the bacteroidetes, Bacteroides thetaiotaomicron, could metabolize the yeast cell wall molecule.  The scientists also hypothesize that B. thetaiotaomicron evolved this ability as an adaptation to the changing human diet which includes yeasts from of leavened bread and fermented alcohols. The ability to break down and utilize yeast cell wall components as energy gives B. thetaiotaomicron a competitive edge in living in the gut over other bacteria with less metabolic options.

The B. thetaiotaomicron can thrive in the human intestine because of their evolved symbiotic relationship with the human host: the bacteria breaks down the yeast for the human, while at the same time gaining a source of energy.  This type of relationship is probably quite common in the gut and likely extends to other popular foods.  Who knows, but knowing what we do about the gut-brain axis, maybe these bacteria are actually causing our cravings for bread and beer.