The Gut Microbiome and Health - Naturopathic Perspectives
The human gastrointestinal tract (GIT) alone contains 10x14 microorganisms including bacteria, viruses and fungi [1]. That's approximately 100 times more microbial cells than human cells which shows how much of an impact they can have on human health [1]. The term to describe the range of microorganisms found in an environment is ‘microbiota’ [2]. The environment in which the organisms live is termed ‘microbiome,’ in this case the human GIT [2]. Humans and microorganisms have evolved together over time forming a symbiotic and mutually beneficial relationship [1]. Some of the benefits conferred by gut microbiota include maintaining the integrity of the mucosal barrier of the GIT, vitamin and nutrient production and immune system regulation [1]. There is an optimal balance working in the GIT, disruption of this balance can result in a host of symptoms as certain microorganisms can have detrimental effects on the body and can contribute to disease[2]. This is termed dysbiosis [2].
Diseases Impacted by Dysbiosis of the Gut
Inflammatory Bowel Disease (IBD)
IBD is an umbrella term for two diseases: chron’s and ulcerative colitis. Both are conditions in which inflammation results in damage to the intestinal tract resulting in abdominal pain, nutrient deficiencies and systemic illness.Dysbiosis is a cause and an outcome of IBD [3]. In IBD, the immune system is overly aggressive within the digestive tract resulting in inflammation. The immune system also attacks certain microorganisms as it has been observed that there is a diminished microbial diversity in those with IBD [3]. Protective organisms such as Bifidobacterium and Clostridium species are reduced, while destructive species like Proteobacteria and certain strains of E.coli are increased [3]. These destructive species further promote inflammation and activate disease triggering immune responses [3].
Depression
The brain-gut-microbiota axis is bidirectional [4]. The brain communicates with the gut and the microbes in the gut can communicate with the brain [4]. The central route of communication is implicated through the vagus nerve, which directly connects the GIT to the brain [4]. Inflammation is one of the hallmarks of depression and can alter the function of the gut barrier leading to changes in gut bacteria [4]. Patients with depression notably have a different microbiota with reduced levels of health promoting bacteria, than non-depressive individuals [4]. This dysbiosis further contributes to the symptoms of depression as the bacteria that is communicating with the brain is proinflammatory [4]. And the cycle continues.
Rheumatoid Arthritis
Rheumatoid arthritis is an autoimmune condition meaning the immune system is attacking self-cells, specifically within the joints [5]. It is proposed that since autoimmune markers such as Rheumatoid factor and anticitrullinated protein antibodies are present in the blood well before joint inflammation occurs, the autoimmunity may stem from sites such as the GIT or airway mucosa [5]. The disproportionate inflammatory response has been shown to be triggered by dysbiosis in the gut as certain bacteria activates autoreactive immune cells [5].
Type 1 Diabetes Mellitus
Type 1 diabetes is an autoimmune condition that results in destruction of the beta cells of the pancreas. This results in no insulin release and impaired glucose regulation. Usually the disease presents in childhood. As shown in Rheumatoid arthritis, the gut bacteria are able to affect the immune system. Certain bacteria contain an endotoxin called lipopolysaccharide (LPS) which stimulates the inflammatory response and impairs pancreatic beta cell function [6]. Some studies have shown that people with type 1 diabetes have more circulating LPS then non-diabetic individuals [6]. LPS can also damage the intestinal mucosa leading to more inflammation and increase in exposure to environmental antigens triggering the already reactive immune system[6]. In type 1 diabetes, gut diversity and stability are reduced compared to non-diabetic individuals [6]. The low diversity has been proposed to limit the ability to digest diverse diets which further leads to diminished microbiota contributing to disease [6].
A Naturopathic Approach to Gut Dysbiosis
Probiotics
In terms of the above conditions, probiotics are an appropriate choice of therapy to mitigate symptoms related to dysbiosis. Before taking probiotics however, it is important to speak with a health care provider like a naturopathic doctor as not all probiotics work the same. In the treatment of ulcerative colitis, traditional probiotics play a limited role, but the specific strain E. coli Nissle and probiotic combination VSL#3 have been shown to maintain remission and reduce inflammation [3]. Other strain specific probiotics that are optimal choices for IBD are F. prausnitziiwhich protects the gut, maintains the gut barrier and stimulates the protective aspect of the immune system [3]. To reduce the effects of dysbiosis in depression, psychobiotics which are a family of probiotics that have a positive effect on mental health can be utilized [4]. Psychobiotics have also expanded to include prebiotics which are soluble dietary fibers that feed the gut bacteria [4]. In studies using psychobiotics such as FOS and BGOS (prebiotics), participants showed decreased waking cortisol which is the stress hormone that is a marker for anxiety and depression [4]. Further, specific strains such as bifidobacterial longum decreased morning cortisol and subjective levels of anxiety as well as increasing cognitive functioning [4].
Probiotics have a wide safety profile for rheumatoid arthritis [7]. Their effect on reducing some proinflammatory cytokines of the immune system like IL-6, has been proven, but not other markers of inflammation or pain [7]. It seems that diet rich in probiotics like fermented foods, dietary fibers and a variety of vegetables, have stronger evidence for reducing pain than probiotics taken as a supplement [7]. There is strong evidence that dysbiosis is present in autoimmune diseases like Rheumatoid arthritis and probiotics help to restore healthy mucosal barrier function and reduce impact of harmful bacteria [7]. However, autoimmune conditions are multifactorial and other aspects of the disease needs to be addressed. In combination with other treatments like lifestyle, diet, botanicals and hormone regulation, probiotics can also add to treatment success.
Like other autoimmune conditions, individuals with type 1 diabetes mellitus have a compromised mucosal barrier [8]. The research for strain specific or multi-strain probiotics to treat the diabetes is limited, however, probiotics can restore the intestinal barrier and can restore bacterial balance. Dietary factors, such as prebiotics and complex carbohydrates are fermented by gut bacteria which produce a short chain fatty acid called butyrate [8]. Butyrate helps to maintain gut integrity, reduce intestinal permeability and are anti-inflammatory; all important in treating autoimmune conditions [8]. Further, there is some evidence which supports gluten free eating [6]. Celiac disease, another autoimmune condition in which an individual creates autoantibodies against gluten, has been linked with other autoimmune conditions [6]. A gluten free diet in those with type 1 diabetes can reduce immune burden and can theoretically prevent celiac disease from being triggered [6].
References
[1]Thursby E, Juge N. Introduction to the human gut microbiota. Biochem J. 2017; 11:1823-1836.
[2]Marchesi JR, Adams DH, Fava F, et al. The gut microbiota and host health: a new clinical frontier. Gut 2016; 65:330-339.
[3] Sartor RB, Wu GD. Roles for Intestinal Bacteria, Viruses and Fungi in Pathogenesis of Inflammatory Bowel Disease and Therapeutic Approaches. Gastroenterology 2017; 152: 327-339.
[4]Dinan TG, Cryan JF. The Microbiome-Gut-Brain Axis in Health and Disease. Gastroenterol Clin N Am 2016; 1-13.
[5] Horta-Baas G, del Socorro Romero-Figueroa M et al. Intestinal Dysbiosis and Rheumatoid Arthritis: A Link between Gut Microbiota and the Pathogenesis of Rheumatoid Arthritis. Journal of Immunology Research 2017; 1-13.
[6] Han H, Li Y et al. Gut Microbiota and Type 1 Diabetes. International Journal of Molecular Sciences 2018; 19: 1-11.
[7] Mohammed AT, Khattab M et al. The therapeutic effect of probiotics on rheumatoid arthritis: a systematic review and meta-analysis of randomized control trials. Clinical Rheumatology 2017; 1-11.
[8] Harsch IA and Konturek PC. The Role of Gut Microbiota in Obesity and Type 2 and Type 1 Diabetes Mellitus: New Insights into “Old” Diseases. Medical Sciences 2018; 6(2): 1-28.
