Until a few years ago, scientists had little knowledge of the effects that the gastrointestinal tract has on the health of our body. Today, however, most experts confirm the impact it has on our health overall.

In the gastrointestinal tract reside billions of microbes. These help fight pathogenic bacteria or other pathogenic microorganisms, which are the main causes of various diseases. Researchers point out that the gut microbiome plays an active role in maintaining the immune homeostasis of the gastrointestinal tract.


The important role of the Intestinal Microbiome

Studies show that the gut microbial balance is essential for maintaining a fully functioning immune system. The gastrointestinal tract is colonized by billions of bacteria. 85% of these bacteria are probiotic, namely they enhance the proper function of our body, while 15% of them may, under certain conditions, become pathogenic.

Medical issues of the gastrointestinal tract can later lead to acute and chronic diseases. The function of the intestinal mucosa, the state of the microbiome in relation to the action of the intestinal nervous system are associated with the occurrence of autoimmune diseases. Irritable Bowel Syndrome, and even gluten intolerance, have been implicated in the development of autoimmune diseases.

The Gastrointestinal system coordinates the function of the Immune System

The gastrointestinal tract is an integral part of the immune system because it comes in contact with factors that enter our body, such as food and microbes. As a gateway, the gastrointestinal tract coordinates the immune response to proteins, components and microorganisms. When it recognizes an ingredient as food, it allows it to be digested and absorbed into the bloodstream. On the contrary, this regulation is absent when consuming foods that have undergone intense industrial processing.

Recurrent inflammation or infection and constant weakness and fatigue are signs of immune system dysfunction. Inflammatory bowel conditions have been linked to Crohn’s disease, ulcerative colitis, rheumatoid arthritis and vertebral arthritis.

Lactic acid is released into the gut microbiome, which promotes the secretion of the digestive enzymes which are needed to digest food. The microbiome, in fact, prevents the installation of pathogenic bacteria in our body, maintaining a slightly acidic pH, which repels bacteria. In this way, a healthy microbiome strengthens our immune system. This is because 70-80% of our immune system is located in our gut and the proper balance of microbes, as part of the microbiome, keeps the immune system healthy.


The basis for a healthy and functional Immune System

The gastrointestinal tract is considered to be the largest immune organ in the body, which plays a key role in regulating the homeostasis of the immune system. It contributes to the body’s defense, in which epithelial cells provide a natural barrier and they cooperate with immune cells, in order to eliminate pathogens and limit their direct contact with the epithelium.

Contrary to previous beliefs, the intestinal epithelial barrier is not a static natural barrier, but interacts strongly with the gut microbiome and the cells of the immune system. In fact, the “inhabitants” of the intestine, namely the intestinal microbiome, enhance the maturation of the immune system on two levels: innate and acquired immunity. The human body is a biochemical machine that operates under strictly predetermined conditions. Any deviation can cause problems, which can manifest as diseases, after a certain period of time. Therefore, good health of the digestive and gastrointestinal system is vital for the proper function of the immune system.


Dr. Nikoleta Koini, M.D.

Doctor of Functional, Preventive, Anti-ageing and Restorative Medicine.
Diplomate and Board Certified in Anti-aging, Preventive, Functional and Regenerative Medicine from A4M (American Academy in Antiaging Medicine).


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Irritable Bowel Syndrome and Indicated Diet



  • Klingberg E, Strid H, Sta˚ hl A, et al. A longitudinal study of fecal calprotectin and the development of inflammatory bowel disease in ankylosing spondylitis. Arthritis Res Ther 2017; 19: PMC5289027.
  • Peyrin-Biroulet L, Ferrante M, Magro F, et al. Results from the 2nd Scientific Workshop of the ECCO. I: Impact of mucosal healing on the course of inflammatory bowel disease. J Crohns Colitis 2011; 5: 477–483.
  • Nishimura S, et al. CD8+ effector T cells contribute to macrophage recruitment and adipose tissue inflammation in obesity. Nat Med. 2009;15(8):914–920.
  • Talukdar S, et al. Neutrophils mediate insulin resistance in mice fed a high-fat diet through secreted elastase. Nat Med. 2012;18(9):1407–1412.
  • Ramanan D, Cadwell K. Intrinsic Defense Mechanisms of the Intestinal Epithelium. Cell host & microbe. 2016;19:434-41. doi:10.1016/j.chom.2016.03.003.
  • Marchiando AM, Graham WV, Turner JR. Epithelial barriers in homeostasis and disease. Annu Rev Pathol. 2010;5:119-44. doi:10.1146/annurev.pathol.4.110807.09 2135. PMID:20078218
  • DiGiulio DB. Diversity of microbes in amniotic fluid. Semin Fetal Neonatal Med. 2012; 17:2–11.
  • Jiménez E, Fernándes L, Marín M, et al. Isolation of commensal bacteria from umbilical cord blood of healthy neonates born by cesarean section. Curr Microbiol. 2005; 51:270–274.