Fiber and The Gut Microbiome

• Ann
• May 28th, 2019

The more research I am reading about fiber and the gut microbiome it blows my mind away.  

Like… seriously, as a dietitian for treating various disease we just need to modify the amount of fiber someone is eating or the amount of protein. I mean that’s not ALL of it but TWO very big components of diet.

So basically, the gist of it is when your gut bacteria eats fiber and protein they produce a byproduct called metabolites which manage to affect a diverse range of your bodily functions.    These guys are soluble, meaning they are absorbed into the cell walls of your intestine where they then enter a large blood vein that connects to the liver, called the portal vein.

From the liver the blood is distributed to the rest of your body.  The non-soluble metabolites are absorbed through the lymphatic system and enter the bloodstream via  the thoracic duct – a structure which drains the lymph into the body’s circulation near the heart (stay with me).

Finally, some neurotransmitters that are produced by gut bacteria travel through the vagus nerve directly to the brain and influence mood.

These entry points that the byproducts from your gut microbiome go through can be described as the relationship between the gut and other organs as an “axis”.  The most commonly one that we’ve heard of is the GUT-BRAIN-AXIS.

Others that have been identified are:

GUT-BRAIN AXIS — Microbially-produced neurotransmitters and other metabolites reach the brain through the vagus nerve

GUT-HEART AXIS – – Gut metabolites such as trimethylamine can enter the blood circulation where they have been associated with heart disease

GUT-LUNG AXIS -The gut and lungs are part of a shared mucosal immune system and gut metabolites have been linked to lung diseases

GUT-LIVER AXIS – Gut metabolites reach the liver through the portal vein, the liver’s primary source of blood

GUT-kIDNEY AXIS –  Gut metabolites can influence the kidneys and likewise, toxins from the kidney (such as when an individual has uremia) can disrupt the gut microbiome

So what does all this mean?

In a nutshell the byproducts (metabolites) that come from either protein or vegetables (fiber) have HUGE influence on your mood, liver, heart, kidney, lung health as well as overall inflammation.

This last little tid-bit and then I am done, I promise (I’m just so excited about this stuff), studies that looked at the impact of both plant and animal protein on the gut microbiome was observed that in general, plant protein increased production of those wonderful short chain fatty acids, which had the effects of increasing gut barrier function and increasing regulatory T immune cells (these reduce inflammation). In contrast, animal protein increased levels of trimethylamine (an amino acid that has been associated with heart disease) and decreased levels of short chain fatty acids, which is associated with heart disease and irritable bowel disease. The research authors speculated this effect is seen because plant protein is accompanied with fiber, whereas animal protein is usually accompanied by fat.

Ok the take away from all that is – FIBER.  Fiber is the cure all – wait.. I don’t want to make a blanket statement like that but fiber IS such a key role in our overall health.

This is not to say that protein from animal meat is the  enemy because it definitely is not. It still has a host of beneficial minerals and vitamins. Eating just enough protein to benefit from its collagen, glycine, Vitamin B12, Heme iron, Zinc, Vit A, Vit k2, Vit D, and whole lot that I’m missing.

Sources:

SHARON, G., GARG, N., DEBELIUS, J., KNIGHT, R., DORRESTEIN, P. C., & MAZMANIAN, S. K. (2014). SPECIALIZED METABOLITES FROM THE MICROBIOME IN HEALTH AND DISEASE. CELL METABOLISM, 20(5), 719–730. HTTP://DOI.ORG/10.1016/J.CMET.2014.10.016

2. CARABOTTI, M., SCIROCCO, A., MASELLI, M. A., & SEVERI, C. (2015). THE GUT-BRAIN AXIS: INTERACTIONS BETWEEN ENTERIC MICROBIOTA, CENTRAL AND ENTERIC NERVOUS SYSTEMS. ANNALS OF GASTROENTEROLOGY : QUARTERLY PUBLICATION OF THE HELLENIC SOCIETY OF GASTROENTEROLOGY, 28(2), 203–209.

3. BROWN, MARK J. AND HAZEN, STANLEY L.(2018). MICROBIAL MODULATION OF CARDIOVASCULAR DISEASE. NATURE REVIEWS MICROBIOLOGY 16:171-181. HTTPS://DOI.ORG/10.1038/NRMICRO.2017.149

4. BUDDEN KF, GELLATLY SL, WOOD DL, COOPER MA, MORRISON M, HUGENHOLTZ P, HANSBRO PM. (2017). EMERGING PATHOGENIC LINKS BETWEEN MICROBIOTA AND THE GUT–LUNG AXIS. NATURE REVIEWS MICROBIOLOGY 15: 55–63. HTTPS://DOI.ORG/10.1038/NRMICRO.2016.142

5. TRIPATHI A, DEBELIUS J, BRENNER DA, KARIN M, LOOMBA R, SCHNABL B, KNIGHT R. (2018). THE GUT–LIVER AXIS AND THE INTERSECTION WITH THE MICROBIOME. NATURE REVIEWS GASTROENTEROLOGY & HEPATOLOGY  15:397-411.

6. EVENEPOEL, P., POESEN, R. & MEIJERS, B. (2017) THE GUT-KIDNEY AXIS. PEDIATR NEPHROL 32: 2005-2014. HTTPS: //DOI.ORG/10.1007/S00467-016-3527-X