Human gut microbiota: does diet matter?

Abstract

The human oro-gastrointestinal (GI) tract is a complex system, consisting of oral cavity, pharynx, oesophagus, stomach, small intestine, large intestine, rectum and anus, which all together with the accessory digestive organs constitute the digestive system. The function of the digestive system is to break down dietary constituents into small molecules and then absorb these for subsequent distribution throughout the body. Besides digestion and carbohydrate metabolism, the indigenous microbiota has an important influence on host physiological, nutritional and immunological processes, and commensal bacteria are able to modulate the expression of host genes that regulate diverse and fundamental physiological functions. The main external factors that can affect the composition of the microbial community in generally healthy adults include major dietary changes and antibiotic therapy. Changes in some selected bacterial groups have been observed due to controlled changes to the normal diet e.g. high-protein diet, high-fat diet, prebiotics, probiotics and polyphenols. More specifically, changes in the type and quantity of non-digestible carbohydrates in the human diet influence both the metabolic products formed in the lower regions of the GI tract and the bacterial populations detected in faeces. The interactions between dietary factors, gut microbiota and host metabolism are increasingly demonstrated to be important for maintaining homeostasis and health. Therefore the aim of this review is to summarise the effect of diet, and especially dietary interventions, on the human gut microbiota. Furthermore, the most important confounding factors (methodologies used and intrinsic human factors) in relation to gut microbiota analyses are elucidated.

A proof-of-concept study showing antibiotics to be more effective in irritable bowel syndrome with than without small-intestinal bacterial overgrowth

“…Moreover, such patients may be treated with one course of antibiotics to achieve an initial response, and they may be subsequently treated with alternative forms of therapy such as promotility agents, which are known to prevent recurrence [29], probiotics [20], and a low Antibiotic therapy in IBS directed toward SIBO Ghoshal et al www.eurojgh.com fermentable oligosaccharide, disaccharide, monosaccharide, and polyol diet. Change in the diet has been shown to alter gut flora [30][31][32].…”

Irritable bowel syndrome, the microbiota and the gut-brain axis

“…The interaction between beneficial commensal bacteria and the immune cells results in a downregulation of proinflammatory genes, whereas anti-inflammatory genes are upregulated. 29,30 Although identification of the microbiota is ongoing in the Human Microbiome Project, the majority of GI microbiota is still uncharacterized. It is now certain that it consists of a great variety of microbes with a majority of anaerobic bacteria.…”

Kronik Böbrek Hastalığında Bağırsak Mikrobiyotası ve Diyet Posasının Rolü

“…Genetik, cinsiyet, etnik köken, yaş, ilaç kullanımı, hastalıklar ve en önemlisi diyet intestinal mikrobiyota kompozisyonunda etkilidir (5,12). Anne karnından, neonatal periyoda ve yetişkinliğe kadar mikrobiyomun kompozisyonu ve fonksiyonu üzerinde beslenme tarzının önemi büyüktür (27).…”