Introduction
The human gastrointestinal tract is colonised by a complex ecosystem of microorganisms. Beneficial intestinal bacteria have numerous and important functions, e.g., they produce various nutrients for their host, prevent infections caused by intestinal pathogens, and modulate a normal immunological response. Therefore, modification of the intestinal microbiota in order to achieve, restore, and maintain favourable balance in the ecosystem, and the activity of microorganisms present in the gastrointestinal tract is necessary for the improved health condition of the host.
Gastrointestinal Tract Microbiota and Immunity Boosting
GI Tract’s active microbiological ecosystems contain a mass of bacteria that is crucial for the maturation of immune cells. In the gut, many bacteria from the microbiota and those that reach the intestine through food intake, coexist with each other and with the immune cells associated with the lamina propria of the villi. This intestinal microbiota does not interact directly with the epithelial cells; however, the microbiota stimulates the maturation and functionality of the immune cells through their metabolites.
Probiotics
There is a group of beneficial bacteria called probiotics. Probiotics are defined as “Live microorganisms that when being administered in appropriate doses, confer a benefit to the health of the host”. Many probiotic bacteria are members of the intestinal microbiota, some of which have been increasingly incorporated into foods to improve the gut health by maintaining the gastrointestinal microbial balance.
Immunologic Benefits of Probiotics:
- Activate local macrophages to increase antigen presentation to beta lymphocytes and increase secretory immunoglobin A (IgA) production both locally and systemically.
- Modulate cytokine profiles.
- Induce hypo responsiveness to food antigens.
Non-Immunologic of Probiotics:
- Digest food and compete for nutrients with pathogens.
- Modify pathogen derived toxins.
- Stimulate epithelial mucin production.
- Alter pH to create an unfavourable local environment for pathogen.
The immune response is initiated by innate immunity following exposure to foreign substances or tissue injury. Innate immunity exerts protective roles in host homeostasis in part by priming adaptive immune responses against persisting insults and inducing inflammation. However, the unbalanced immune response leads to severe inflammation and uncontrolled tissue damage and disease. Sensing of the intestinal microbiota by the host mucosal immune system plays significant roles in maintaining intestinal homeostasis and inducing systemic protective responses. Thus, manipulation of the intestinal microbiota is a potential alternative approach for maintaining health and preventing and/or treating diseases.
Lactobacillus, Bifidobacterium, and Saccharomyces are three extensively studied and commonly used probiotics in humans and animals.
Several beneficial effects of probiotics on the host intestinal mucosal defences system have been identified. These include blocking pathogenic bacterial effects by producing bactericidal substances and competing with pathogens and toxins for adherence to the intestinal epithelium. For intestinal epithelial homeostasis, probiotics promote intestinal epithelial cell survival, enhance barrier function, and stimulate protective responses from intestinal epithelial cells. Most importantly, modulation of the immune system is one of the most plausible mechanisms underlying the beneficial effects of probiotics on human health. Probiotics have been found to enhance the innate immunity and modulate pathogen-induced inflammation via toll-like receptor-regulated signalling pathways.
Probiotics play a role in defining and maintaining the delicate balance between necessary and excessive defence mechanisms including innate and adaptive immune responses. Points of interaction with the immune regulation for probiotics include bacteria direct interaction with intestinal epithelial cells or following internalization by M cells through interaction with dendritic cells and follicle-associated epithelial cells, initiating responses mediated by macrophages and T and B lymphocytes. Regulation of gene expression and signalling pathways in the host cells are two major mechanisms underlying probiotic action leading to immunomodulation.
Key Points Are:
- Regulation of host immune responses is probiotic gene specific, and the function of probiotic genes also depends on host microenvironment.
- Probiotic-derived factors mediate probiotic action in the regulation of host immune responses.
- Probiotics exert different levels of immune-regulatory effects in a host-dependent manner, including gene expression, protein synthesis, signalling pathways in immune cells and in intestinal epithelial cells.
During cold and flu season it is important to consume foods that enhance the immune system. Have you heard the saying “it all lies in the gut?” There is truth to this as 70-80% of our entire immune system resides within the gut.
Probiotics can Help to Boost the Immune System and Ward Off Inflammatory Responses in the Gut.
The lining of the small intestines is full of lymph nodes. When necessary, inflammation in the intestines creates a pathway for the immune system to carry out an attack against invading viruses and bacteria. However, when inflammation is present but not needed, illnesses such as allergies, the flu, and chronic infections can occur. Probiotics offer a beneficial defence against the effects caused by this unwarranted inflammation.
Probiotics also keep the gut healthy, to ensure the immune system functions well.
Probiotics can also modulate the immune system, enhancing the body’s innate immunity. This modulating effect helps alleviate excessive inflammation in the gut, thereby boosting immune function.
Probiotics can Boost the Body’s Immune Function and Assist the Body in Warding Off Infections.
Some recent studies support a significant role of probiotics for humans and animals as a barrier against microbial infection. In one study,1 probiotics were beneficial in offering complete protection for mice from a viral infection pathogen.
The probiotics lengthened the survival rates from the pneumonia virus of mice that were infected. A randomized, parallel, double-blind, placebo-controlled study2 showed that consumption of certain probiotics for a 12-week period could reduce the risk of acquiring common cold infections in healthy individuals. The occurrence of catching one or more common colds, the length of days with common cold symptoms, and the symptoms from the cold were all reduced.
A recent New Zealand study conducted with professional rugby players showed probiotics enhanced the player’s ability to ward off and fight colds. This study involved 30 rugby union players who received either a probiotic supplement (3 billion CFUs/day), or placebo, for four weeks. During this period, 80% of the placebo group experienced a single episode of the common cold or stomach upset, 53% of those in the probiotic group encountered such illness.
In the placebo group, the duration of illness was 5.8 days; duration among probiotic subjects was 3.4 days. The authors of this study suggested: “These positive effects of probiotic supplements provide evidence for the beneficial effects of daily supplementation with these probiotic strains in highly trained rugby union players.”
How do Probiotics Boost Immune Health and Help Prevent Viruses?
Some intestinal microbes have a presence that is correlated with healthy intestinal flora. However, the metabolic end products of their growth are organic acids (lactic and acetic acids). These acids tend to lower the pH of the intestinal contents, thus creating an atmosphere for harmful bacteria. Probiotics secrete antibacterial peptides, capable of killing off harmful bacteria in the gut.
Probiotics in the GI tract help to reinforce the barrier function of the intestinal lining, lowering the chance of bacteria in the intestines entering the bloodstream. This function may decrease infections and immune-related reactions, thus supporting the health of the immune system.
Conclusion
Knowledge of intestinal flora is growing, and it is becoming evident that we need the protection of these beneficial bacteria. Quality supplements and raw fermented and cultured foods are great sources of probiotics. Be sure you’re getting these in your diet, or taking a quality soil based probiotic supplement!
References:
- www.mdpi.com/journal/nutrients, Nutrients 2017, 9, 1021; doi:10.3390/nu9091021
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4006993/
- https://www.enviromedica.com/wellness/probiotics-immune-system/
- https://www.pharmatutor.org, PharmaTutor Magazine | Vol. 2, Issue 4
Please wait for the next article for more information on Probiotics.