The Digestive System: An Unsung Hero
The digestive system often doesn’t get the recognition it deserves. Beyond breaking down the food you eat, it plays a crucial role in maintaining your overall health. There’s a significant connection between your gut and your immune system, with over 70 percent of your body’s immune system residing in your gastrointestinal tract.
You’ve probably heard of probiotics, the “good bacteria” many people take as supplements. However, every person has a whole ecosystem of microbes in their gut, known as the microbiome. This microbiome consists of bacteria, viruses, fungi, and bacteriophages. It’s a fascinating and complex environment, sometimes referred to as “the last undiscovered human organ.” Scientists are continually uncovering the many ways the microbiome impacts health, from skin conditions to mental wellness and immune system function.
A balanced gut is essential for a strong immune system, helping to fend off potential infections. According to Dr. Shezi Kirmani, a functional medicine and natural health practitioner in Houston, Texas, “When there is an imbalance between good bacteria and bad bacteria in the gut, immune regulation is affected. This makes it harder for your body to fight off infections.”
So, how exactly does the gut microbiome influence the immune system, and what can you do to maintain a healthy balance? Let’s explore.
How Are the Gut & the Immune System Connected?
Much of what you consider your body’s immune response is actually controlled by groups of bacteria in your gut. Besides the microbiome, your gut contains tissue that is part of the immune system, forming the gut-immune system connection.
When experts say that 70 percent of your immune system is in your gut, they are referring to the gut-associated lymphoid tissue (GALT) lining your intestinal wall. This tissue contains lymphocytes (lymph cells) and produces white blood cells, which are crucial components of your immune system. The skin lining the digestive tract, known as the gut epithelial cell lining, houses your GALT. Keeping your gastrointestinal tract healthy ensures that your immune system functions optimally.
Microbes also play a significant role in your gut’s immune system. Your gut microbiome, consisting of more than 100 trillion individual microbes of 2,000 species, sends signals to and from the gut’s immune cells. This microbial community produces hormones, antibodies, and other chemical compounds that break down the cell walls of harmful organisms. These helpful microbes are so intricately involved in your body’s inner workings, including the immune system, that they are practically a part of you.
Interesting Facts About the Gut’s Immune System
The lamina propria, or mucosal gut lining, produces 80 percent of your immunoglobulin A, an antibody linked to a healthy immune response. The gut lining also produces antibodies in response to respiratory allergies, such as pet dander and dust mites, starting from when a child is in the womb. Vaginally-born infants have a gut microbiome similar to their mother’s, while those born by cesarean section have microbiomes rich in Propionibacterium spp. and Staphylococcus. Breastfeeding further nourishes the gut microbiome, strengthening the immune system. Plasma cells in your gut produce antibodies that neutralize sickness-causing pathogens, central to a healthy immune system. The gut epithelium is very thin, allowing nutrients from food to pass through to the bloodstream. If the gut lining gets damaged, often due to leaky gut syndrome, it can negatively affect the immune system. Short-chain fatty acids feed the gut epithelial cells lining the gut and strengthen the gut barrier, also helping to reduce inflammation.
How Your Microbiome Benefits Your Immune System
Why does your body tolerate all these non-human organisms in your gut? They provide numerous benefits! Good gut microbes create an anti-infectious barrier, preventing harmful bacteria from sticking to the gut wall and helping them pass out of the body. Your gut microbes synthesize vitamins your body can use, including B1, B2, B5, B6, B12, K, folic acid, and biotin. They can break down the cell walls of harmful gut organisms and other substances like xenobiotics and sterols (e.g., cholesterol). Gut microbes interact with one another through cell-to-cell signaling, with probiotic strains producing antimicrobial molecules in the gut. Colonization by bad bacteria in the gut can lead to issues like small intestinal bacterial overgrowth (SIBO), chronic infections, autoimmune diseases, and even more serious terminal illnesses.
What Causes Your Gut To Become Unbalanced?
When you’re healthy, there’s a balance between the good and bad microbes in your gut. When something disrupts this balance, it can lower your immunity and make you vulnerable. Here are some potential causes of gut imbalance:
Poor Diet
A diet heavy on junk food and light on nutrition leads to an unhealthy gut. Poor diet decreases the diversity of your microbiome, which can lead to conditions like diabetes, obesity, heart disease, and more. Eating processed foods can contribute to leaky gut, where a weakened intestinal barrier allows disease-causing microbes to enter the gut and nutrients to be lost.
Antibiotics
Antibiotics are used to treat infections, but they also wipe out the good bacteria in your gut along with the bad. Without beneficial bacteria to offset them, harmful microbes can take over, leaving you vulnerable to illness. Always take probiotics or eat probiotic foods when you take antibiotics to repopulate the gut.
Pushing Yourself Too Hard
The hectic pace of life can lead to stress, too much fast food, and insufficient sleep. When we’re focused on the hustle and bustle of daily life, self-care isn’t always a priority. These choices catch up with us, leading to an unbalanced gut.
Overindulgence in Alcohol
Chronic drinking causes unwelcome changes in gut bacteria and increases the risk of leaky gut. Alcohol may also disrupt immune function in the gut and trigger an inflammatory response in the small and large intestines.
Points to Remember
More than 70 percent of the immune system resides in the gut, including the mucosal lining of the GI tract and the 100 trillion gut microbes living there. These gut microbes, your microbiome, play a key role in keeping you healthy. Not only do your gastrointestinal cells secrete antibodies and ward off unwanted invaders, but your healthy gut microbes (probiotics) do too.
