Intestinal flora, genes and disease: the keys

Human intestinal flora is composed by several trillions of bacteria subdivided in a few hundred different species. The protein and fat that we consume are easily digested in the stomach and small bowel through enzymatic action.  Withing the carbohydrates, only simple sugars and starch can be digested without the help of the bacterial population that resides in our bowel. The rest of the polysaccharides (soluble fiber) need bacterial fermentation in order to be digested. If you’re not able to digest soluble fiber because of damaged bowel flora the result will be hard, difficult to pass, constipated stools. The fiber passes  partially digested through your bowel as if it were insoluble.


Summary of the digestive process. Source:Online Sciences.

The majority of the human immune cells reside in the epithelium of the intestinal wall, and there are some bacterias involved in the development of these cells that later expand throughout your whole body. Some of these cells are immunosuppressive and others are immune aggressive. A recent study has shown that changes in the gut flora related to the production of fatty acids will result in obesity in a previously slim individual.

Immunosuppressive flora: There are several species, as the ones of the genre Clostridium, that control the development of T regulator cells, also called Tregs. Tregs avoid that your immune system attacks your own cells or harmless particles such as pollen or food proteins. Many of the common antibiotics damage these species producing the so called autoimmunity or its small representation: allergies. Resistant starch allows us to increase the total number of these bacteria although doesn’t increase the diversity. The intestinal flora of IBD patients is characterized by lower bacterial diversity.

Immune Aggressive flora: Represented basically by filamentous bacteria, which help in the development of aggressive cells that attack virus, bacteria or cancer cells. Common antibiotics don’t damage these bacteria so even after prolonged antibiotic treatment we’re able to defend ourselves from infections. The excessive suppression of these bacteria will lead us to cancer.

There’s a third group of bacteria, the largest and most diverse, that convert soluble fiber into short chain fatty acids such as butyrate, that keeps the intestinal barrier in good shape. A suppression of these bacteria will result in intestinal inflammation and food intolerances. This is the most common result of a prolonged antibiotic treatment.


Effects of butyrate and its derivates. Source: Selfhacked

The last bacterial group converts fiber into gases such as methane, carbon dioxide or hydrogen. An increase in these bacteria (something that is very common when other strains decrease) will give way to gas, bloating and flatulence.


Scheme about the roles of the microbiota

Repairing gut flora will erase the concomitant diseases.

Nowadays there’s a lot of interest in the treatment of gut flora dysregulation with the combination of resistant starch and probiotics. The most common diets used in the treatment of autoimmunity are low to moderate carb, so there’s not enough soluble fiber to feed your microbiota correctly. Therefore, using a non carb source of soluble fiber with certain probiotics that produce butyrate and dietary measures may result in remission of many autoimmune conditions.

Fecal microbiota transplants seem to be the future in this discipline but before that we must find a way of matching donor and recipient. A total repair of the bowel flora is possible but there’s much more needed than just a perfect diet and lactic acid probiotics, as usually recommended on several health sites.

Therefore, health is based mainly on:

  • An antiinflammatory diet
  • Microbiome adapted to your diet
  • Exercise
  • Adequate sleep

Other factors that are usually considered important such as poor quality food filled with pesticides and antibiotics, consumption of GMOs or environmental toxins also contribute but on a much lesser extent (probably no more than 10% of the total).