How is the immune system controlled by the gut?
With cold and flu season upon us, everyone is prepping to avoid getting sick yet again this year. One of the best ways to prepare is by strengthening your gut health. 70-80% of the immune system resides in the gut. This makes your gut health a huge factor in your ability to remain healthy. In this article, we will help you understand how the immune system is controlled by the gut.
How is the immune system controlled by the gut?
Structures of the gut that control the immune system
As we mentioned above, between 70-80% of the immune system resides in the gut. But what exactly does that mean? And why is it important to know when trying to boost your immunity?
70-80% of your immune cells are housed within your gut. Since that is where they stay until they are used, your gut controls when and how they are released to fight infections and other immune system irritants.
The gastrointestinal tract is set up to be the first line of defense. You have
- The intestinal microbiota — these are the bacteria and other microorganisms that live in your microbiome. When there is a healthy balance in the types of microorganisms living here, they are very efficient in stopping an infection before it can cause any problems.
- The intestinal epithelial layer — this should be a tight junction that keeps the bacteria within your gut and keeps other cells out. When this becomes compromised, it allows organisms to float about in places they don’t belong which can reduce your immune system’s ability to fight infection and lead to a constant state of inflammation which weakens cells and immunity.
- The mucosal immune system — the mucosa is a structure that supports and protects the intestinal epithelium. It’s the first line of defense and acts sort of like a sticky mouse trap. Bacteria can stick to this and then be removed before they can affect your immune health.
Now, just because your gut is well-armed, doesn’t mean this is the only way it is controlling your immune system.
How gut microbes control the local immune system
Your local immune system is divided into two parts: innate and adaptive.
Your innate immune system comprises your skin, mucous membranes, enzymes, and antimicrobial proteins. Some of the special cells that are specific to your innate immune system include granulocytes, natural killer cells, and macrophages. The innate immune system also works directly with the intestinal epithelial cells.
Meanwhile, your adaptive immune system‘s main cells are T- and B- lymphocytes. While your T cells help to control your B cells, your B cells are what secrete antibodies. These cells are what “learn” which cells shouldn’t be in your body and what your body needs to do to fight them off.
Your gut microbes give off different types of metabolites which can support your local immune cells. Short-chain fatty acids (SCFA), tryptophan metabolites (which maintain intestinal health), and bile acid derivatives all have abilities to protect your immune system.
Pattern-recognition receptors (PRR) in response to microbe-associated molecular patterns (MAMPs) affect immunity. If there are excessive reactions from them, it can lead to systemic inflammation or autoimmune diseases. Chemokines and cytokines work directly with this response and their secretion is controlled by gut microbes.
How gut microbes affect systemic immunity
Your gut microbes can either help support your systemic immunity greatly or cause a severely negative impact on it.
Gut microbes release SCFA which has a large impact on the metabolism of cells — this is especially important for your T and B cells. Butyrate, a SCFA, helps to inhibit systemic inflammation by supporting these cell types. In addition, signaling molecules from the gut microbes can induce the activation of macrophages, natural killer cells, and neutrophils.
However, if the signaling molecules or other metabolites produced by the gut microbes are pro-inflammatory they can cause systemic inflammation. This can lead to the excessive PRR activation we mentioned earlier which causes long-term inflammation and autoimmune disease development.
This is why what we feed our gut is so important for immune health.
Using nutrition to support your gut and immune health
If gut health is so important to our immune health, we can definitely understand that what we eat and put into our guts drastically affects our immune system and how well it functions.
The biggest focus you should have when deciding on foods to eat are ones that will support a healthy gut microbiome. Essentially what you’ll want to focus on here is what gut microbes like to eat the most and that offer your body beneficial side effects.
If you’ve ever seen a GIF of someone eating happily and there are little hearts floating off of them, this is kind of what happens with your gut microbes. As they eat foods they enjoy they give off molecules that go out into your body and help to repair it. The molecules also work with your immune system to strengthen its defenses, improve its processes, and keep the cells healthy and ready to fight.
The best foods to feed your gut microbes are dietary fiber, prebiotics, polyphenols, and probiotics (if it is okayed by your doctor).
Prebiotics are one form of dietary fiber that helps to support the gut and immune systems. Prebiotics take a while to be fermented and the gut microbes often give off short-chain fatty acids from them. Prebiotics also allow for gut microbes to replicate more, healthier strains of bacteria to inhabit the gut and further improve the integrity of the gut microbiome. Polyphenols are a great source of prebiotics.
Dietary fiber also helps to keep the intestinal tract clean and works with different receptors of the immune system to keep the intestinal epithelium strong.
Probiotics are often suggested to improve gut health. It makes sense to add more bacteria to the gut microbiome to improve diversity and quantities. However, since every person’s gut microbiome is as distinct to them as their fingerprint, it is difficult to say which bacterial strains would be beneficial. Also, some people are sensitive to probiotics if they have a suppressed immune system.
Another problem with probiotics is that they are sometimes killed by stomach acid and never reach the gut microbiome to have any beneficial effect.
However, some studies find probiotics and the inclusion of probiotic foods a great way to support your immune system. Getting sources of probiotics like kimchi has the potential to help improve your immune system. However, it should not be looked at as a cure-all and should be added to other healthy lifestyle changes.
Exercising regularly, sleeping well, and a healthy (diverse) diet can help to improve your gut microbiome and strengthen your immune system so that whatever you come across, your body is ready to take it on.
Atrantil is a great source of prebiotics and polyphenols. Ask your doctor about Atrantil Pro for the added benefit of probiotics you can actually use.