The gut or gastrointestinal tract is a long tube that starts at the mouth and ends at the anus. It is within this system that what we eat is processed with nutrients being absorbed and waste being excreted as stool(1). The process of digestion can be broken into four main sections, oral processing to mechanically break down food; gastric processing to begin the chemical breakdown; small intestinal processing to allow the absorption of nutrients from macromolecules; then water removal occurs in the colon(1,2).
This digestive process is known to be aided through the action of the gastrointestinal microbiome. The gastrointestinal microbiome is a diverse collection of microorganisms (including bacteria, fungi and viruses), which populates the gut of all mammals(3). Bacteria are the most studied constituent of
the microbiome, up to 100 trillion of them are known to exist within the human gut, the majority being located in the cecum of the small intestine with the Bifidobacterium and Lactobacillus families being predominant(4). Exposure to microorganisms within the birth canal means your microbiome begins formation from the moment you are born(5). Furthermore, recent research suggests that the developing baby also comes in contact with these microbes within the womb(6). As a result, the maternal microbiome can impact factors such as obesity risk(7,8) , mental health(9) and immune response(10) within their child. Alongside inheriting gut flora from our mothers, our microbiome can be modulated through diet. Studies have found that high sugar and processed high fat foods promote harmful bacterial growth(11). On the other hand, foods high in fibre encourage growth of protective bacteria(12).
Gut dysbiosis is the term for an imbalance between beneficial and harmful strains of bacteria. The result of this occurring can trigger gut hyperpermeability, with decreased selectivity of the gut barrier, allowing passage of unwanted particles(13). This hyperpermeability is often the basis of intolerances or allergies due to small food particles or toxins to passing through the gut barrier and being identified in the blood by the immune system as foreign. Furthermore, gut dysbiosis has also been associated with gas, bloating, diarrhoea and constipation as well as issues such as trouble sleeping, unintentional weight loss or weight gain and more (14,15).
Recent research has investigated the use of probiotics in preventing or treating several health conditions related to the microbiome, where dysbiosis might be involved. Probiotics are defined as “live microorganisms that confer a health benefit to the host when administered in adequate amounts”(16). Probiotics have been observed and studied in fermented foods such as fermented milk products for several years, with the benefits of including them in your diet now becoming clear(17). Studies in recent years have examined the positive impacts seen when probiotics are given in cases of gastrointestinal issues (such as Irritable Bowel Syndrome(18), autoimmune conditions, childhood obesity, and for mental health issues like anxiety and depression(19). Probiotics are thought to restore the composition of the microbiome and introduce beneficial functions to gut microbiota communities, resulting in the prevention of gut inflammation and other systemic disease phenotypes. Future advances in our understanding of the importance of the microbiome and the mechanisms by which probiotics can effectively modulate it, may not only help to improve the credibility of probiotic supplementation but also prompt development of novel strategies for treatment or prevention of diseases. SOURCES
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