In last week’s wellness spotlight, a lecture from the 2019 Congress of Clinical Rheumatology was highlighted. James T. Rosenbaum, MD, Chief of Ophthalmology at the Legacy Devers Eye Institute in Portland, Oregon and also Chief of Arthritis and Rheumatic diseases at the Oregon Health and Science University spoke on the microbiome and rheumatic disease:
“I submit to you that in any disease that has an immune component — whether it’s Alzheimer’s, Parkinson’s, autism, atherosclerosis, obesity, diabetes and any disease that you are seeing in your clinics with an immune component — the microbiome is having some effect,” Rosenbaum told the attendees, “Whether it’s a small effect or a large effect, it is hard to say, but in these experimental rodents, it’s a huge effect. And one day, we will have therapy that is directed toward repairing or changing, or altering, that microbiome.”
The next three wellness spotlights will focus on intestinal eubiosis and dysbiosis. Research has shown that it’s the gut microbiome and not the ocular microbiome that has the greatest influence on chronic immune dysfunction in the eyes or elsewhere. In fact, the gastrointestinal microbiota is now considered to be a vital human organ.
THE HUMAN GUT MICROFLORA
1. Contains roughly 100 trillion viable microorganisms which is 10 times the number of cells in the human body from over 1000 different species representing a mutually beneficial symbiotic relationship
2. Weighs 1-1.5 kg and rivals the liver in the number of biochemical reactions in which it participates
3. The most important component is the colonic microflora where bacterial concentrations far outweigh those found elsewhere and bacterial species can be divided into potentially harmful or health-promoting groups
The remainder of this article will focus on the health benefits of the colonic microflora. Eubiosis is defined as a state of healthy balance within the GIT microbial population, maintained by sensitive interactions between living and non-living components in this enclave of the external environment. In the next two weeks we will focus on dysbiosis, its causes, and treatment.
HEALTH BENEFITS OF THE COLONIC MICROFLORA
There are many health benefits of the colonic microflora. The following are three of the main ways beneficial bacteria in the colon promote health.
1. Modulate the immune response: Via metabolic and molecular molecules, good bacteria induce local and systemic tolerance. Systemically, this is effected by Treg cells that are induced in the GALT via epigenetic changes, and maximally induced by the combination of nutrients such as vitamins A and D as well as probiotics. Lack of these good bacteria leads to the opposite immunophenotype (excess of inflammatory, and Th17 cells) and the resulting predispositions toward metabolic, allergic, and inflammatory disorders.
2. Colonization resistance: Probiotic bacteria produce antimicrobial substances, promote mucosal immunity, and occupy receptor sites- all of these synergize to reduce intestinal colonization with pathogens. The gut is vulnerable to colonization or overpopulation with harmful inflammation-inducing and mucosa-damaging bacteria.
3. Protection against increased intestinal permeability (leaky gut) and increased bacterial translocation: Metabolites such as butyrate, a short chain fatty acid produced by beneficial microorganisms, have a trophic effect on gut mucosa. Lack of such microbe-derived metabolic support predisposes toward failure to maintain a high-integrity/fidelity mucosal barrier. A well-known consequence of reduced colonization resistance is increased translocation of intestinal bacteria in the GALT and portal circulation, wherein bacterial DNA and LPS famously promote hepatic damage and systemic inflammation, including the formation of an immune response against bacterial DNA and other cross-reacting immune responses.
Vasquez, A. Human Microbiome and Dysbiosis in Clinical Disease. 2014 ICHNFM.ORG
SHORT CHAIN FATTY ACIDS
As noted above, beneficial bacteria produce short chain fatty acids (SCFAs) and this is done through fermentation of unabsorbed carbohydrates in the colon. SCFAs have many health promoting effects. The three main SCFAs are butyrate, propionate, and acetate. SCFA’s decrease colonic pH, improve colonic epithelial barrier function, protect against colon carcinogenesis, have trophic effects on the small intestine, improve laxation, improve circulation to the colon and the liver, improve mineral absorption, and decrease colonic and systemic inflammation.
Other benefits of a healthy colonic microflora include improved digestion and nutrient absorption where 10% of the daily vitamin E needs are met. Healthy colonic microflora are also involved in the production of vitamins such as the B group and vitamin K.
Healthy colonic microflora participate in xenobiotic metabolism which is important for the absorption and proper functioning of phytoestrogens, lignans, flavonoids, and some medicinal herbs. They also participate in weight management and have been shown to play a vital role in energy homeostasis. (Turnbaugh et al. 2006)(Cani & Delzenne,2009)(Cani & Delzenne, 2011). Microbiota from obese individuals has been shown to have an increased capacity to harvest energy from the diet.
Dysbiosis is defined as qualitative and quantitative changes in the intestinal flora, their metabolic activities, or their local distribution that produces harmful effects on the host. In any condition where immune dysfunction occurs, current research is showing that dysbiosis plays a role. Next week we will review the causes and then we will highlight ways to treat it the following week.