Your immune system performs the critical function of protecting your body against threats that can lead to infections and other health issues. Your gastrointestinal tract, or gut, is a vital part of your immune system.

The beneficial bacteria in your gut work with your immune system to protect your health and guard against harmful microorganisms.

Probiotics can support your immunity by helping to balance your microbiome for optimal gut health. In this article, we’ll take a look at how the gut, the immune system, and probiotics interact with one another.

Gut Health and The Immune System

The immune system includes the innate (general) and adaptive (specialized) immune systems.

Innate immunity consists of physical barriers like skin and mucous membranes that keep out foreign substances and special proteins and immune cells, also known as defense cells, that work quickly to attack invading germs.

Adaptive immunity comprises T-cells, B-cells, and specialized proteins called antibodies that can identify and destroy specific bacteria, viruses, and other foreign substances.

The gastrointestinal tract is an essential part of the immune system. It hosts approximately seventy to eighty percent of the immune cells in your body. One of its key functions is to protect the body from harmful microorganisms (pathogens). The gut’s mucosal barrier is one of its first defenses against pathogens.

The gut microbiome and the immune system continually communicate and influence each other’s development and function. The immune system regulates the colonization of the gut microbiome, and the microbiome stimulates the production and activation of both innate and adaptive immune cells.

The microbiome also protects digestive system health by inhibiting the ability of pathogens to colonize, overgrow, and damage the gut.

The beneficial gut bacteria in the microbiome continually monitor for and adjust their ability to inhibit pathogens. They also produce byproducts, such as short-chain fatty acids, with benefits for immunity. Short-chain fatty acids reinforce the intestinal barrier by enhancing its production of protective mucus and anti-microbial compounds.

Probiotics can optimize the gut microbiome for improved immune function. They block pathogens by competing with them for resources and by producing short-chain fatty acids that strengthen the gut barrier. Probiotics can ward off common pathogens like E. coli and H. pylori.

Multiple clinical studies have found that probiotic microbes improve diarrhea, including diarrhea caused by bacteria or viruses, decreasing its incidence, duration, and severity.

Lactobacillus strains, in particular, have been found to reduce infectious diarrhea. Other gut health benefits of probiotics include optimizing digestion and improving gut motility.