Effect of Fibre and Nutraceuticals on Microbiome and Intestinal Barrier
Maya Surjadjaja
Klinik Spesialis Gracia Patricia, FK Ukrida , RSAL Dr. Mintohardjo
“Every day we live and every meal we eat we influence the great microbial organ inside us - for better or for worse.”
Giulia Enders, Gut: The Inside Story of Our Body’s Most Underrated Organ
At about 8 to 9 meters in length, the human intestine provides the largest interface between our body and the outside world. The intestinal lining determines which substances can enter the bloodstream from the digestive tract. To maintain a functional barrier, several mechanical properties of the intestinal epithelial cells are essential and account for various defense mechanisms.
In a healthy gut, the intestines are resistant to harmful substances. Under physiological conditions there is a tightly control of mucosal antigen with specific immune cells, chemokine and cytokine mediators lead to anergy and therefore to mucosal tolerance.
Gut barrier function involves the regulation of translocating luminal content such as antigens and bacteria that pass through the epithelial cell layer; either between the epithelial cells (paracellular route) or through the cells (transcellular route) into the underlying mucosa. Many of the conditions associated with a leaky gut show signs of both increased paracellular and transcellular permeability
The gut barrier homeostasis is dependent on the relationship between the gut microbiota and the intestinal epithelium. The commensal flora is continuously in contact with the intestinal epithelium and has been implicated to shape the intestinal barrier structure. Commensal luminal bacteria inhibit the colonization of pathogens by production of bacteriocins, pH modification of the luminal content, and competition for nutrients. During normal circumstances the symbiosis between the gut microbiota and host is well balanced.
One of the major discovery in understanding the role of gut permeability in health and disease has been the discovery of zonulin, a physiologic epithelial and endothelial permeability modulator. Gut dysbiosis causes inappropriate production of increased amount of zonulin with succeeding functional loss of gut barrier function, along with microbiota-derived antigen and endotoxin trafficking from the lumen to the lamina propria triggering innate and immunoregulatory responses causing a pro-inflammatory micromilieu. A dysbiosis of the gut microbiota has been associated with several diseases associated with a leaky gut such as diabetes, depression and Alzheimer’s disease
Dietary components come into contact with intestinal lumen for a long time and are likely to regulate gut microbiota and intestinal permeability. Dietary fiber is recognized as a protective nutrient for the intestinal barrier and contributes to maintaining the microbiota in a healthy state. These beneficial effects are mediated by SCFAs, and epithelial IL-18 appears to be involved in a molecular mechanism of barrier-regulation.
Inflammation of the gastrointestinal tract interrupts the natural balance between the mucosal immune system and normal gut microbiota. Modulation of inflammatory pathways demonstrates how DHA decreases bowel inflammatory levels. . Omega-3 (ω-3) polyunsaturated fatty acids (PUFAs) can influence the inflammatory state of a range of cell types, including endothelial cells, monocytes, and macrophages.. Supplementation with PUFAs should be taken into account along with prebiotic and probiotic supplementation. It intent to improve the microbiome composition and diversity.
Human studies have reported significant associations between vitamin D and microbiome composition. Bacterial enrichment differed in individuals with higher serum 25(OH)D, it is likely that microbiota is mediated indirectly by vitamin D's immunologic properties. Bacteria interacts with the host and leads to stimulation or inhibition of immune responses. Lack of vitamin D signalling due to dietary deficiency or genetic impairment of VDR expression/activity can impair physical and functional barrier integrity.
L-Glutamine, the most abundant and conditionally essential amino acid, plays a vital role in the maintenance of mucosal integrity. Among the various tissues using glutamine at high rates, the intestine utilizes about 30% of total glutamine. Glutamine is a key nutrient for the intestine. In the small bowel mucosa, glutamine supplies fuel for metabolism, regulating cell proliferation, repair and maintaining the gut barrier functions. Studies in healthy adults reported that three quarters of enterally provided glutamine is absorbed into the splanchnic tissues, and most of the absorbed glutamine is metabolized within the intestine. Depletion of glutamine under conditions of extraneous exercise and severe trauma or shock results in villus atrophy, decreased expression of tight junction proteins and increased intestinal permeability. Glutamine promotes enterocyte proliferation, regulates tight junction proteins, suppresses pro-inflammatory signaling pathways, and protects cells against apoptosis and cellular stresses during normal and pathologic conditions.
Intra‐ and extracellular zinc concentrations can affect gut microbiota behavior and vice versa. This can contribute to alteration of gut microbiota composition, namely “dysbiosis,” starting from initial “eubiosis.” Oral zinc therapy can restore intestinal permeability in CD patients probably through its ability to modulate TJs both in the small and the large bowels
Nutrients are closely related to intestinal health and permeability that are actively investigated as a hot topic of scientific research. Clinicians should be aware of the potential of barrier dysfunction in gastrointestinal diseases, and the potential of nutrients as a target for future therapy.
Keywords: dietary fiber, dysbiosis, glutamine, intestinal barrier, leaky gut.
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