The role of intestinal microbiota in irritable bowel syndrome

Abstract

In recent years, impressive advances in the knowledge about a vast number of microbes living in the human body and interactions between the microbiota and the human body have been observed. All micro-organisms that live in the human body consist of around 10 ^ 14 cells. The number of microbial cells colonizing the human body is ten times higher than the number of its own cells and the weight of all micro-organisms is about 2-2.5 kg. The number of bacterial genes is 50-100 times greater than the number of genes in the human body. Nowadays, the human microbiota is often regarded as a “newly discovered organ” or even as a “supergenome”. The results of many studies have revealed that disruption of the bowel microecosystem may affect the development of irritable bowel syndrome (IBS) symptoms. Therefore, manipulation of the gut microflora was hoped to be a new tool in the treatment of this disease. Various methods (probiotics, prebiotics, antibiotic therapy, transplantation of faecal flora) have been used to modify the intestinal microbiota by supporting the expansion of bacteria considered beneficial and reducing the number of those regarded as harmful, thus alleviating the IBS symptoms. There is much evidence in the literature to suggest that the intestinal microbiota and the gut-intestinal axis are important factors in the pathogenesis of IBS. Moreover, the literature findings have demonstrated beneficial effects of modifying the intestinal flora composition in alleviating IBS symptoms. Although the pathophysiology of IBS and the role of the intestinal microflora and gut-intestinal axis in it are well known, many issues are still to be elucidated. Further research into the bacteria identified in stool and colon mucosa of healthy individuals should provide more information on restoration of intestinal homeostasis in IBS patients.

Treating irritable bowel syndrome through an interdisciplinary approach

“…Therefore, it would be necessary to evaluate safety concerns, especially given that the microbiome may be adversely impacted by exclusion diets. Interestingly, a reduction in symptoms through diet was actually observed in the case of an individually modified diet, aligned together with the patient [6,22]. This phenomenon may indicate the patient’s psychological need to be “looked after”, rather than the presence of a digestive disorder, and explains the overall difficulties in establishing the relevance and efficacy of particular food components.…”

“…Proper functioning of the GBA is considered essential for physiological functioning of the digestive system, whereas the intestinal microflora is an important element of the GBA. The terms microbiota and GBA are already used interchangeably to indicate the mutual interactions with the central nervous system (CNS) [22].…”

“…The human body is a host organism for trillions (10 13 -10 14 ) of microbes residing in the intestine. Although the majority of the GI tract microbiota is still uncharacterized, it is certain that it consists of a great variety of microbes and is responsible for maintaining physical and mental health [22,23]. Microbiota dysbiosis is considered a basic factor that plays a role in initiating and maintaining IBS, whereas the GBA is regarded as substantial, as it integrates brain and GI functions through a bidirectional neurohumoral communication system [21].…”

“…The relationship between diet and composition of the intestinal bacterial flora and bacterial fermentation products can therefore play an important role in the etiology of the disease, directly or indirectly causing IBS symptoms [22]. According to some publications, however, there is not sufficient evidence for diet treatment efficacy and there are conflicting views on dietary recommendations [5,22,48]. Discrepancies relate to issues such as fiber supplementation, highly recommended and prescribed for many years, especially for IBS-C.…”

“…The latest research shows, however, that only soluble fiber is effective (e.g., psyllium), whereas insoluble fiber (e.g., bran) can exacerbate pain and abdominal symptoms [13,19]. Flare-ups are usually caused by high-fat foods, raw fruit and vegetables, milk products, drinks containing caffeine, and an excessive supply of artificial sweeteners [19,22]. Therefore, dietary interventions focused on elimination or restrictions were often implemented.…”