If you want to boost immune health, start with gut health! Tuning up your immune system means tending to all the bacteria friends that live inside your gut. Although your immune system is made up of cells, tissues, and organs, approximately 80 percent of your immune system lives in your digestive tract. A healthier gut means a better functioning immune system. Learn how to improve the inner ecosystem in your digestive tract for robust immune health.
Mind Your Microbiome
Your microbiota is the collection of bacteria, fungi, and viruses that live inside and on you. You are made up of slightly more bacteria than human cells, and these bacteria even have their own genome, your microbiome. These microbes (bacteria make up the bulk of the, by far) influence our mood, weight, metabolism, digestion, immune function, disease expression, and even produce certain vitamins for us. They have evolved alongside us over time in a mutually beneficial relationship: We provide a host, and they provide us with benefits our bodies can’t do for us. They also protect your health by displacing harmful bacteria and producing antimicrobial compounds.
Your microbiota begins evolving as soon as you’re born and is unique as your own fingerprint. The more bacterial species we have in our digestive tracts, the healthier we are. Robust bacterial diversity keeps our immune system strong, improves digestion, and helps keep bad bacteria in check. Humans harbor around 300-500 bacterial species, but these numbers are dwindling because of factors that kill our beneficial bacteria, like antibiotics, medications, poor diet, alcohol, sugar, chemicals in our environment, and hormonal birth control.
The good news is you can improve your bacteria diversity and your immune health with dietary and lifestyle improvements.
Your Gut Bacteria & Your Immune Health
Your immune system is super complex, but on a basic level, it identifies foreign and potentially harmful compounds it perceives as a threat so it can both destroy them so you don’t get sick and remember them in the future. The immune system has two types of responses: innate immunity and adaptive immunity. The innate immune system is our first line of defense and is always present, whereas adaptive immunity is created in response to exposure to a foreign substance. Once activated against a specific type of antigen, adaptive immunity remains throughout your life (like developing immunity to viruses you contracted).
Bacteria educate our immune system. Throughout life, we are constantly exposed to new things through our gut, nose, and lungs, via our food and environment. The immune system has to monitor these exposures and maintain a balance so you don’t react unfavorably to everything foreign. Diverse gut flora established in early life with many types of bacteria, fungi, and other microorganisms, is crucial for this, as it teaches the cells of the immune system that not everything is bad. (source) People who have severe and/or numerous allergies and reactions often have poor microbial diversity or too many strains of unfavorable bacteria that cause the immune system to overreact to foods or environmental agents, causing a flood of histamine.
Everything we eat and drink passes through the gut, so it needs to be in good shape to kill potential pathogens that may hitchhike in on your food and kill you (this is another main reason the majority of your immune system is in your gut). And the types of food we eat will influence our health positively by nourishing the bacteria in there that keep us healthy or negatively by causing inflammation and stress that kills the good guys in your gut. We don’t want that.
You have both “good” and “bad” bacteria in your gut, and that’s how it should be. BUT you should have far more good bacteria (about 85%) than bad (about 15%). An imbalance within the gut will impair the gut barrier and increase disease risk. In fact, bad strains of gut bacteria are linked to inflammation, heart disease, obesity, and even diabetes. (source)
We also know that almost all autoimmune conditions originate in the gut, and if you have an increased autoimmune response, you are going to have a weakened immune system due to the overactive immune system misfiring and attacking your own tissue instead of foreign invaders. This type of immune response means your immune system is having trouble distinguishing between self and other, and it is preoccupied fighting things it shouldn’t fight. It’s not focused properly to fight the bad guys.
What Causes Gut & Immune Health Imbalance?
- A nutrient-poor diet encourages bad bacteria and yeast overgrowth in the gut, leading to a damaged ecosystem. Too much refined sugar, soda, processed food, fast food, and alcohol rob your body of the nutrients it needs to stay healthy, fight infection, and nourish your gut bugs.
- Overuse of medications: Anti-inflammatories, antibiotics, acid blocking drugs, and steroids damage the gut and impeded normal digestive function.
- Infections, overgrowth of bad bacterial strains, and gut imbalances, including small intestinal bacteria overgrowth (SIBO), yeast overgrowth, and parasites. Read more about that here.
- Toxic overload, including mercury, pollutants, and mold toxins. Your exposure may be increased if you work with chemicals like in a hair salon or auto shop.
- Poor digestive health, meaning you’re not producing adequate enzymes to break down food, and you have poor bacterial diversity. Stress, acid-blocking medications, and zinc deficiencies can all contribute to lack of adequate digestive enzyme function. Zinc is critical for healthy immune function and helps you produce enough stomach acid to break down your food properly.
- Stress. Chronic stress changes the terrain of the gut by contributing to inflammation and encouraging bad bacteria to grow out of control. As a result, good bacteria numbers dwindle.
How to Boost Your Immune Health (via your gut!)
- Feed your gut bacteria! Read my post on that here. Think of these guys as your internal garden that needs to be properly watered and fertilized. You also want to eat plenty of prebiotic-rich fruits and veggies that feed your probiotics. Beef up on leafy greens, banana, blueberries, asparagus, radish, alliums, artichokes, apple, legumes, green tea, and fermented foods of course. Read about my gut healing superstar foods here. The good news is your gut bacteria begin to respond to positive diet changes within a few days. You want to eat prebiotic foods that encourage akkermansia, one of your most beneficial bacteria.
- Eat an anti-inflammatory diet (read how here) to encourage new bacteria to develop. This is one of the most important diet changes to make to encourage bacterial diversity. (source: Healthy Gut Healthy You)
- Get nutrients that boost gut and immune health: zinc, vitamin C, collagen, fermented foods like raw kraut and kefir.
- Repair leaky gut: inflammation causes your gut to become more permeable, and that stresses your immune system. Leaky gut is also a risk factor for autoimmune disease. Here’s my leaky gut repair protocol, or try my 21 day gut reset.
- Get moving. Exercise positively impacts your gut bacteria and is plain old good for your body.
- Reduce stress and focus on sleep: stress is a major cause of inflammation, and poor sleep is a main cause of stress. So many of us have sleep issues. Here are a few tips to create healthy sleep hygiene.
- Ditch the chemicals in your home and on your body. They are endocrine disruptors that also kill your beneficial bacteria.
- Avoid alcohol. It kills beneficial gut bacteria, causes inflammation, and feeds yeast and bad bacteria.
- Try a gut reset! Click here for my 21 day gut reset to jumpstart gut healing. Remember, it only takes a few days to positively influence beneficial gut bacteria levels.
- Probiotics boost immune health and crowd out bad bacteria that weakens gut health and contributes to inflammation. (source) But, you need to choose the right probiotic for your body. Here’s how. Remember to get your fermented foods and drinks for probiotics too!
Mary Vance is a Certified Nutrition Consultant and author specializing in digestive health. She combines a science-based approach with natural therapies to rebalance the body. In addition to her 1:1 coaching, she offers courses to help you heal your gut and improve your health. Mary lives in San Francisco and Lake Tahoe in Northern California. Read more about her coaching practice here and her background here.