OverviewOur internal defense system – the immune system does an incredible job of defending the body from foreign invaders. People with a compromised immunity can become vulnerable to different infections, especially cold and flu, as well as cancers. In addition to consuming a healthy diet, we can implement several other strategies to boost our body’s defense mechanisms. Of these, using probiotics is a well-recognized immunity-enhancing approach. Approximately 70%-80% of our immune system resides within the gut, with the gut-associated lymphoid tissue (GALT) representing the largest proportion. Since probiotics confer a healthy digestive system, they also ensure the proper functioning of the immune system occupying our gut.
How Probiotics Enhance the Immune System and Ward off the Pathogens?
1. Improve the Health of the Beneficial Gut ColonizersOur gut flora and the defense system are in a reciprocal relationship with one another. What happens to one will influence the other. Probiotics restore the good bacteria, and hence, they automatically restore your immune function. 
2. Fortify the Host-Gut BarriersOur intestinal epithelial cells form a barrier against the invading microbes. Because probiotics strengthen these gut barriers, they prevent the disease-causing agents from entering into our system. The probiotic-dependent modulation of immunoglobulin A (IgA) responses accounts for the majority of their gut barrier-strengthening properties . IgA is an antibody that is present in abundant amounts in the mucosal linings, including the gut. This antibody serves as the first line of defense against the invasion of the bacteria and viruses into the intestinal membranes.
Moreover, the probiotics minimize the leakage from the intestinal membranes. Intact intestinal membranes deflect the entry of the microbes. The reduced microbial intrusion contributes to a healthy immune system.
Among different probiotics, the Lactobacillus strains are particularly shown to bolster the immune function. 
3. Augment the Function of GALTThe lymph nodes constitute an essential component of the immune system, and as aforementioned, the GALT occupies a large section of the defense system. The IgA antibodies are one of the key elements of GALT. The others include the immune cells, the Peyer’s patches in the small bowel, and the cytokines.  Probiotics cause marked expansion of the GALT, its associated elements, and their functions, all of which impede the access of the foreign intruders. 
4. Secrete antimicrobial peptidesWhen ingested, the viable bacterial strains release substances that slay the monster pathogens. These substances, known as antimicrobial peptides inhibit the major component in the walls of certain bacteria, annihilating them before they make you ill.
5. Accelerate Cytokine ProductionCytokines are immune stimulators that signal the chief cells of the immune system, called white blood cells (WBCs) to migrate towards the site of infection or inflammation. There, the WBCs engulf the immunity attackers. Probiotics bump up the cytokine production, and subsequently, rev up the immune performance through the actions of WBCs.  Probiotics not only benefit adults but also reduce the frequency and severity of cold and flu-like symptoms in children. 
SummaryTo sum up, probiotics optimize immunity and fitness. They not only keep gastrointestinal and airborne infections at bay, but also cure coughs and colds once you catch them.
Dr. Rasheed Huma
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