How Do Probiotics Support Immune System Function?*

Trillions of cells make up the microbiota that lives inside your gut. This enormous population of commensal organisms is called the gut microbiome, and scientists are looking at the connection between our overall wellbeing and these organisms.

The popularity of probiotics has brought more attention to the role of gut flora in our overall health. Still, many people don’t completely understand what gut microbes are and how they support our immune system function.

How the Gut Microbiome Interacts with the Immune System

The gut microbiome is comprised of over 100 trillion cells of organisms, including bacteria, fungi, and other microbial species.

We get our first exposure to microbes when we pass through the birth canal and get immune supporting proteins, called antibodies, through breastfeeding. Since the immune system is in development mode for the first few years of our life, these antibodies are crucial to establishing a properly functioning immune system.[1]

As the body grows, the immune system is broken down into two branches called the innate system and the adaptive immune system. The adaptive immune system’s role is to “adapt” to any new or foreign pathogens and eliminate them. Deciding which organisms and microbes are friendly or dangerous is a delicate balance that can be altered through either environmental stress, nutrition, or prescription drug use. Any significant alteration in the gut microbiome can lead to the growth of opportunistic organisms that lead to a variety of health challenges.[2]

Probiotics and the Gut Microbiome

The term “good bacteria” refers to organisms that act as critical allies in regulating the immune response in the gut and preventing harmful pathogens from crossing the epithelial layer. Probiotics typically contain live-forms of the microorganisms known to promote this response and create a healthy gut microbiome. Examples include the bacteria groups Lactobacillus and Bifidobacterium and yeast species Saccharomyces boulardii.[3]

People who take probiotics are usually looking to reduce digestive discomfort.* However, researchers looking into the connection between the gut microbiome and the brain have discovered the gut microbiota also plays a major role in modulating our sleep and mood cycles through the synthesis of neurotransmitters such as melatonin, gamma-aminobutyric acid (GABA), serotonin, histamine, and acetylcholine.*[4]

P People can get probiotics by eating fermented foods such as sauerkraut, kimchi, or yogurt. Supplements are explicitly formulated to contain beneficial microorganisms commonly found in everyday food, which are a great option to consider.

How the Gut Microbiome and Immune System Work Together

The Mucosal Firewal

The microbiota in the gut help protect the body from invading pathogens and support the inflammatory response through two primary strategies.

The first strategy is to help reinforce the mucosal layer that separates the epithelial cells that line the intestinal tract from the rest of the tissue.

The mucosal firewall consists of epithelial cells, mucus, IgA, antimicrobial peptides, and immune cells. The “good” bacteria that line the mucosal regions help the immune system compartmentalize other microorganisms by acting as samples for the intestinal dendritic cells. These cells then interact with B and T cells of the adaptive immune system to produce the crucial antimicrobial antibody IgA and a subset of T cells called T regulatory cells.[5]

Through this symbiotic relationship, the commensal gut microbiota help tailor the immune system response to be induced or suppressed when foreign substances are present.

RELATED CONTENT: Top Ingredients That Support Immune Health

Colonization Resistance

In addition to acting as a testing ground for the immune system as it develops selective ways to detect harmful substances, the microorganisms in the gut also act as a defense system against invading pathogens through colonization resistance. When the gut microbes detect a virulent pathogen they can:[6]

• Alter the environmental conditions to protect the body from pathogenic colonization
• Release antimicrobial metabolites to impair the growth of competitive organisms
• Alter nutrient availability to invading microorganisms
• Modulate signalling to dendritic cells to activate effector T and B cells against pathogens.

It’s important to note that the nutrients needed to help achieve homeostasis are unavailable when the body is put in a state of stress through environmental factors or unhealthy dietary changes. Since our gut microbiota is entirely dependent on the breakdown of chemicals we obtain from our food, it’s no surprise that altering your diet can have a significant impact on the promotion of individual organisms over others.

What has become crystal clear over the last decade of gut microbiota research, is that our gut and immune system are intrinsically tied together with the health and variety of microorganisms living in our gut. Talk to your doctor before making any changes to your diet or supplement routine to ensure you are taking the right steps to bring balance to your health.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

[1] “ Gut Microbiota and Mucosal Immunity in the Neonate - NCBI.” 2018. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6163169/. Accessed June 4, 2020.

[2] “ Role of the Microbiota in Immunity and Inflammation - NCBI.” 2015. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4056765/. Accessed June 4, 2020.

[3]  "Probiotics: What You Need to Know - NCCIH.” 2019. https://www.nccih.nih.gov/health/probiotics-what-you-need-to-know”

[4] “ The Progress of Gut Microbiome Research… - NCBI.” 2020. https://jneuroinflammation.biomedcentral.com/articles/10.1186/s12974-020-1705-z. Accessed June 4, 2020.

[5] “ Role of the Microbiota in Immunity and Inflammation - NCBI.” 2015. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4056765/. Accessed June 4, 2020.

[6] “ Role of the Microbiota in Immunity and Inflammation - NCBI.” 2015. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4056765/. Accessed June 4, 2020.