How Does Good Bacteria Help the Immune System?

The Gut Microbiome and Immune System Connection

The gut microbiome and immune system are critically interconnected, having evolved together in a mutually beneficial (or symbiotic) relationship over time. In other words, the health and function of your immune system are dependent on the bacteria living in your gut. And the community of gut microbiota is influenced by the health of your immune system (in addition to your diet and environment).

What is the Gut Microbiome?

There are trillions of microorganisms (bacteria, viruses, fungi and more) inhabiting the human body. You can find these microscopic critters on your skin and in places such as your nose, throat and genitals. However, the largest collection of bacteria resides in your intestinal tract forming the gut microbiome.

Within the intestinal tract itself, billions of native bacteria coexist with human cells — influencing nearly every physiological function.

Researchers are still unraveling exactly how these microorganisms impact and interact with our biological systems, it’s become evident that the colonies of microbiota living in and on the human body actively impact our health and play a significant role in maintaining homeostasis.

Each one of us has a unique mix of species (some harmful, some helpful) living in our gut microbiome, which have widespread effects on our overall health and well-being. Believe it or not, the bacteria colonized in your gut impacts just about everything, ranging from cognitive function, behavior and mood to metabolism, heart health, and immune response.2

Therefore, maintaining a balance of beneficial bacteria in your gut is imperative for good health, especially when it comes to your immunity.

More Bacteria Than Human

While scientists originally thought that the number of microbial cells outnumbered human cells 10 to one, more recently, they’ve determined the ratio is much closer to one-to-one. There are around 30 trillion human cells in the body and an average of 38 trillion microbial cells, making us only 43% human. And while they only make up about 1-3% of our total body mass, these microorganisms have a tremendous impact on our bodily functions.5

The Symbiotic Relationship Between the Gut Microbiome and Immune System

While the immune system is a vast network of cells, tissues, organs and proteins spread throughout the body — 70-80% of the immune system is in the gut, where it interacts with the microbiome.3

Research suggests that the gut microbiome and immune system have coevolved in a mutualistic relationship to protect our health. The immune system’s number one job is to patrol the body for foreign substances, launching a complex biological immune response in defense. However, given the trillions of (mostly helpful) microorganisms inhabiting the body, our immune system must be able to quickly distinguish between friendly and unfriendly microbiota.

As it turns out, the bacteria in our gut plays a crucial role in regulating our immune response, ensuring the immune system responds effectively to potentially risky microbes without destroying the beneficial bacteria in your gut. In return, the immune system helps maintain a stable community of microbiota, governing the crosstalk between the two.4

Gut Microbiota and Immune System Interactions

Interactions between your immune system and gut microbiome begin at birth when you first ingest bacteria. Over time, the bacteria in your intestine informs the development and strength of your immune system — priming it to respond quickly and effectively to unfriendly foreign substances.5

The majority of immune cells accumulate within gut-associated lymphoid tissues, known as Peyer’s patches located in the small intestine. This includes B cells, T cells, macrophages and dendritic cells, each with their unique specialized role in immune defense.

Peyer’s patches are covered by a thin tissue called epithelium that contains specialized M cells that transports substances from inside the intestinal tract into the Peyer’s patches. Within the Peyer’s patches are immune receptors, such as Toll-like receptors (TLRs) on B cells, T cells and dendritic cells, that sense microbial signals indicating whether to tolerate or attack a foreign substance.4

Communication between immune cells and microbiota is essential for a robust immune response. Helpful bacteria in the gut microbiome send signals to the nearby immune cells, letting the immune system know that they are friendly and safe (and don’t need to be attacked); while also helping them recognize unwanted microbes to eliminate.

How Does Good Bacteria Help the Immune System?

Maintaining a rich diversity of helpful bacteria in your gut promotes a strong, resilient immune system. The more good bacteria residing in your gut, the clearer the communication is between microbiota and immune cells, and the less room there is for unfriendly microbes to move in.

Eating a diet rich in vitamins and fibers in the form of whole foods is one of the best ways to ensure a population of good bacteria in your gut; as is taking a probiotic, which delivers live strains of helpful bacteria to the microbiota thriving in the large intestine.

A cutting-edge postbiotic (nonviable microbial cells), IMMUSE™ LC-Plasma is a unique strain of good bacteria. Rather than interacting with the microbiota in your large intestine, IMMUSE meets with an important, influential immune cell located within the Peyer’s patches of the small intestine. It is the first strain of bacteria clinically shown to directly activate pDCs, plasmacytoid dendritic cells, a rare subset of immune cells that act as leaders of the immune system.

Once consumed, IMMUSE™ travels through the intestinal tract to the small intestine where M cells pick up the small particles and transfer them into the Peyer’s patches, signaling to the TLRs on pDCs. Activated by IMMUSE™, pDCs then signal, rally and organize other pivotal immune cells, priming the immune system to respond quickly when necessary. In a similar manner to the microbiota, IMMUSE™ directly stimulates the immune system and has become a ground-breaking comprehensive immune activator.

Activated by IMMUSE, pDCs then signal, rally and organize other pivotal immune cells, priming the immune system to respond quickly when necessary. In a similar manner to the microbiota, IMMUSE directly stimulates the immune system and has become a ground-breaking comprehensive immune activator.

Click the button below to learn more about IMMUSE and how this once-a-day postbiotic can support your health year-round.

What is IMMUSE LC-Plasma


1Kato L M,, The role of the adaptive immune system in regulation of gut microbiota. Immunol Rev. 2014 July;260(1):67-75.

2Hacquard, S. et al. Microbiota and host nutrition across plant and animal kingdoms. Cell Host Microbe. 2015 May 17;603–616.

3Wiertsema S, et. al., The Interplay between the Gut Microbiome and the Immune System in the Context of Infectious Diseases throughout Life and the Role of Nutrition in Optimizing Treatment Strategies. Nutrients. 2021 Mar 9;13(3):886.

4Zheng d, et. al., Interaction between microbiota and immunity in health and disease. Cell Research. 2020 May 20; 30, pages492–506.

5Jiao Y, et. al. Crosstalk Between Gut Microbiota and Innate Immunity and Its Implication in Autoimmune Diseases. Frontiers in Immunology. 2020 Feb. 21;11, 282.