The health of your gut flora (the interacting trillions of bacteria of a couple of hundred different species that make up the pound of bacteria that you carry primarily in your large intestines) is more important than your genetics to your overall health. Thus, your health is a result of diet, gut flora adapted to your diet and exercise. Everything else, your genetic risks, environmental toxins, etc. are of only minor impact.
I am trying to paint the big picture of how the food that you eat and your gut flora interact to determine your health, by which I mean whether you get sick, become obese and/or bloat with gas.
Health Depends on Gut Flora
If you are healthy, you have a couple of hundred different species of bacteria that help you to digest the protein, fats and carbs that you eat in meat and vegetables. Your body easily digests protein and fats in meat, fish, eggs and dairy, because enzymes to digest them are present in your stomach and small intestines. The only carbs that your body can digest are some simple sugars and starch. The rest of the polysaccharides present in plants cannot be digested without the help of bacteria. The polysaccharides that your gut flora can digest are fermentable, soluble fiber, e.g. resistant starch, pectin, inulin, arabinogalactan, xylans, beta-glucan, etc. If you can’t digest soluble fiber, because you have damaged gut flora, dysbiosis, and are missing essential bacterial species normally found in a healthy gut, then the soluble fiber just passes through as insoluble fiber and readily dehydrates into hard, constipated stools. Partial digestion due to just a few missing bacterial species produces the symptoms of food intolerances.
Constipation Results from Dysbiosis
The bottom line is that the volume of healthy, soft, firm stools is made up of gut flora that digested dietary soluble fiber and converted it into more bacteria. If you eat more soluble fiber, this food for your gut flora, will produce proportionately more bowel movements.
Gut Flora Guide Immune System Development
Most of cells of your immune system are in the lining of your gut and there are particular species of gut bacteria directly involved in the development of immune cells that have different functions as they spread throughout your body. Some of these cells are aggressive and attack pathogens, while others make sure that the aggression doesn’t get out of control and cause autoimmune diseases or allergies.
Gut Flora Divided into Groups to Show Involvement in Disease
Recent studies have demonstrated the role of gut bacteria in producing nutrients, vitamins and neurotransmitters. To highlight the essential role of gut flora in disease, I have divided the hundreds of species of gut bacteria into groups to illustrate their direct involvement in development of the immune system and regulation of the flow of dietary nutrients involved in obesity. A recent study shows that an infection can produce a change in gut flora associated with marshaling additional fatty acid nutrients for the host instead of just producing more gut flora. Chronic change of gut flora in this way leads to obesity. Other types of dysbiosis contribute to infections, cancer, autoimmune disease, allergies, food intolerances, gas and bloating.
Group A Bacteria Provide Aggressive Immunity
There are several dozen species of bacteria in healthy gut flora, including the filamentous bacteria, that trigger the development of the aggressive part of your immune system that attacks pathogens, and kills cells of your body that are infected with viruses or are cancerous. Most antibiotics don’t permanently damage this group of bacteria, so after a course of antibiotics you can usually still stop infections. Excessive suppression of aggressive immunity contributes to cancer.
Group B Bacteria Provide Suppressive Immunity
There are dozens of other species of bacteria, including Clostridia, that control the development of the suppressive half of your immune system that produces immune cells, such as regulatory T cells, Tregs, that stop the aggressive cells of your immune system from attacking your own cells and innocuous things such as food and pollen. Many common antibiotics damage these species of bacteria and are thought to contribute to the development of autoimmune diseases and allergies. Inflammatory bowel disease is characterized by a simplified gut flora with only half the healthy number of bacterial species. Resistant starch preferentially feeds these bacteria to enhance suppressive immunity and in some individuals cure autoimmune disease.
Group C Bacteria Convert Soluble Fiber to Short Chain Fatty Acids (SCFA)
The fermentable soluble fiber in your diet is typically from vegetables and it is converted by the largest and most diverse group of bacterial species into short chain fatty acids. Each different plant polysaccharide, and there are hundreds, requires many enzymes for complete digestion to the simple molecules used by the bacteria to make its own proteins, fats and polysaccharides. Absence of bacteria that are specialized for the digestion of particular polysaccharides or other dietary components can disrupt gut flora and cause digestive disturbances that are experienced as food intolerances (also confused with food allergies that are rare.) Some of the bacterial species convert polysaccharides into butyric acid and other short chain fatty acids that are the major source of energy for cells that form the lining of the intestines. These SCFAs are also a major food source for other gut bacteria.
Group D Bacteria Convert SCFAs to Fecal Bacteria to Produce Bulk of Bowel Movements
In healthy people, the SCFAs produced by gut flora feed the intestines and the remainder produced in the large bowel is converted into more gut bacteria, which forms soft stools. Antibiotics typically damage these bacteria and result in constipation. These bacteria are typically more sensitive to antibiotics than those that digest the soluble fiber and produce SCFAs, so the excess SCFAs pass into the blood stream and contribute to obesity instead of stools. Lean mice with gut flora exchanged from obese mice, become obese. Cattle are fed antibiotics to enhance the conversion of corn polysaccharides into SCFAs and body fat prior to slaughter.
Group E Bacteria convert Soluble Fiber to Methane and Hydrogen, Bloat
Increased volume of the intestines, bloating, results from conversion of soluble fiber into methane, hydrogen and carbon dioxide gases. Some of this gas is absorbed into the blood and can pass from the large intestines, through the blood, and back to the stomach and small intestines. Helicobacter pylori, the cause of stomach ulcers and gastric cancer, can utilize hydrogen from the blood as an energy source.
In Summary:
A+B+C+D = healthy, normal weight
A+C+D = normal weight, autoimmunity and allergies
B+C+D = normal weight, susceptibility to cancer, chronic Lyme disease, food poisoning
A+B = normal weight, constipated
A+B+C = obese, constipated
A+B+D = normal weight, food intolerances
A+B+C+E = obese, constipated, bloated
Cure for Dysbiosis and Associated Diseases is Repair of Gut Flora
The excitement about the use of resistant starch (RS) and probiotics with Clostridia and other soil bacteria to reverse the symptoms of autoimmune diseases is based on the ability to repair gut flora damaged by poor nutrition and antibiotics. Low carbohydrate diets that do not provide soluble fiber to feed gut flora lead to dysbiosis and chronic diseases. Resistant starch, as the name suggests, passes on to the colon by avoiding digestion with amylases in the small intestines and acts as a soluble fiber to feed gut flora in the colon. Clostridia convert the RS to sugars and SCFAs usable by other gut flora. Note that some species of Clostridia produce toxins and it is these pathogens that take over in hospitals after the healthy species are killed off with antibiotics. Fecal transplants are the best treatment for these hospital acquired infections.
I have discussed the role of hygiene, muddy veggies, fermented foods, etc. in several other posts on repair of gut flora.
Complete repair of gut dysbiosis is possible, but it requires more than just changes in diet and dairy probiotics, as typically recommended erroneously by the medical industry.
Health is dependent on:
- an Anti-Inflammatory Diet,
- gut flora adapted to your diet
- exercise and
- adequate sleep
The rest (genetics, vegan vs. paleo, environmental toxins, organic veggies, GMOs, etc.) are minor contributors, less than 10% in aggregate, to overall health.
ref.