The Relationship Between Gut Health & Your Immune System
Does it seem like your gut is impacted by every virus or sickness you get?
Does it seem like you get sick more often or have worsened allergies when your gut is off?
If you’ve noticed this before, it’s not all in your head! Listen to The Gut Show episode on this topic on iTunes or Spotify, watch the video below, or keep reading to learn why these two systems are interconnected and how they can impact each other.
What is your immune system?
In short, this is a network of organs, tissues, cells, and molecules that work together to protect you from disease. This system is in place to detect and respond to harmful pathogens that are a threat to your health or the wellness of your body, including bacteria, viruses, fungi, parasites, and cancerous cells.
Being without an immune system is like a country without any military, police, or surveillance to protect land and the people on that land.
There are a lot of “soliders” that are part of the immune system, including lymph, lymph nodes, lymphocytes (white blood cells), organs (ex: spleen, tonsils), antibodies, and epithelial cells. There is also the “innate immune system” which includes physical barriers like the skin and mucous membranes, as well as various cells and chemicals that act quickly to contain and eliminate pathogens.
The entire gastrointestinal (GI) tract is part of the innate immune system, as the tissue, the mucous layer lining the gut, and the epithelial cells creating tight junctions of the intestinal wall all are present to be barriers and filters that keep harmful pathogens moving through the body, versus coming in to damage it.
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Digging deeper into the gut… the GI tract also houses a large portion of the immune system and assists in immune system processes, outside of it’s role as part of the innate immune system.
The immune system in the gut includes:
Peyer's Patches: small, connected lymphoid nodules found in the lining of the small intestine that contain immune cells (called B cells and T cells) and help detect + respond to antigens that pose harm
Mesenteric Lymph Nodes: lymph nodes located in the mesentery (tissue attaching the intestines to the abdominal wall) that filter lymph from the intestines and aids in immune cell activation + communication
Gut-Resident Immune Cells: macrophages, dendritic cells, and T cells that are scattered throughout the gut lining to monitor the gut environment for potential threats
Intestinal Epithelial Cells: cells that line the intestinal wall to be a physical barrier against pathogens and to play a role in immune regulation by secreting antimicrobial peptides + communicating with immune cells
Secretory Immunoglobulin A (IgA): the most abundant antibody class in the body, mostly produced in the gastrointestinal tract, that neutralizes pathogens + prevents them from attaching to the intestinal lining
Mast cells: type of white blood cells that have granules made up of inflammatory mediators, such as histamine, heparin, cytokines, and proteases, that are released in response to a perceived threat, including injury, infection, allergens, and other immune signals
Eosinophils: type of white blood cells containing proteins and enzymes that circulate throughout the body in order to respond to + defend against parasites and regulate allergic reactions
While gut microbes found throughout the gut aren’t directly part of the immune system, they are involved in their role of maintaining a strong mucous layer + integrity of the gut lining. They also communicate with and help regulate the function of immune cells, to impact immune reactions.
So when do things go wrong?
If the immune system is activated when it shouldn’t be, including the degranulation of mast cells or increased numbers of eosinophils active in the GI tract, this can lead to gut symptoms in relation to the activation itself + the response to antigens in foods. This is common in those with mast cell or eosinophilic diseases, but can also be present in some cases of IBS or other GI disease.
When the intestinal barrier is more permeable (aka leaky), either due to epithelial cell damage or degradation of the mucous layer, this can also lead to more immune activation in the gut, contributing to overall stress the body (can lead to fatigue, metabolism changes, etc.) and gut symptoms (constipation, diarrhea, bloating, pain, etc.).
This interconnection can also explain the complex relationship between autoimmune conditions, post-viral or bacterial impacts on the gut (causing post-infectious IBS), and digestive conditions/disorders.
If you’re looking for guidance to support both your digestive system and your immune system, our team of registered dietitians may be able to help!
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