Where Immunity Begins + How To Boost It

Where Immunity Begins + How To Boost It

While many of us hoped for a back-to-school season free from COVID concerns, the reality is the virus is still lingering and with breakthrough cases and the rise of the Delta variant (and others), immunity is back to the forefront of our minds. And it’s not just COVID, either. Going back to the classroom or office means facing all types of germs, including the seasonal flu, the SARS-CoV-2 virus variants, and various bacteria that can cause anything from strep to staph. 

I know many of you are frustrated and disappointed that COVID isn’t in the rearview mirror by now. I get it! We’re living in some pretty crazy times. All we can do is stay calm, and of course, focus on the one thing that can make us resilient in the face of any infection — improving the health of our immune system from it’s very core, which just so happens to be the gut.

Why Immunity Begins in the Gut

The belief that immunity begins in the gut used to be considered “fringe” or “woo-woo.” But in recent years, it’s gone fully mainstream. Take a recent study , for example. Published in the British Medical Journal , the study analyzed the gut microbiome of 100 patients with a positive COVID diagnosis by collecting blood and stool samples. The results showed that although Covid-19 is primarily a respiratory illness, there is strong evidence the GI tract is involved in the disease. More specifically, the patients with more severe cases of COVID-19 had a different gut microbiome makeup than those with more mild cases of COVID-19. For example: Patients with severe disease had elevated concentrations of inflammatory cytokines like C-reactive protein and lower levels of beneficial gut bacteria that help reduce inflammation, like Faecalibacterium prausnitzii , Eubacterium rectale and Bifidobacteria

This study is just one relevant example of how when it comes to immune threats, having a diverse, plentiful, anti-inflammatory community of gut bacteria is key. And it’s not just external immune threats from an outside invader like a virus or bacteria, either. The gut is also key to preventing autoimmune conditions, too. Autoimmune disease occurs when your body loses the ability to distinguish between outside invaders and it’s own tissue; as a result, your immune system starts attacking your body’s tissues by accident. 

Studies show that the gut microbiota play a “crucial role” in autoimmune disease, especially those that occur in the gut, such as Crohns’s and ulcerative colitis. The authors of one study even wrote that “The gut microbiota maintains the homeostasis of our immune system.” But how does this work, exactly? The authors of the same study wrote that there are several mechanisms at play here, including the gut’s ability to affect the functioning of antigen-presenting cells (white blood cells that present foreign proteins to our B and T cells to develop an advanced immune response), dendritic cells, and the activity of inflammatory cytokines and T cells, which are key to the intelligence and accuracy of the immune system. In the not-so-distant future, I feel confident saying that the gut microbiome will be a key target for the treatment of autoimmune disease. 

So, if the gut is so key to our immune system, then how do we support it? One of the best places to start is eating a gut-friendly diet free from common gut-disruptors like added sugar, processed dairy and meat, excess alcohol, and inflammatory grains, like the refined white flour found in most packaged foods, like crackers and cookies. 

Beyond that, there are a ton of ways to fortify your gut to take your immune health to the next level. 

5 Ways to Fortify Your Gut to Uplevel Your Defenses

1. Eat Fermented Foods (And Fiber!)

If you’re a frequent reader of the HAPPY GUT® Blog, you know that I’m a big fan of fermented foods. (In fact, I did a three-part series on fermentation last year around this time!).  A recent Stanford study, showed that a diet high in fermented foods might be the best diet for gut health. The study tested a high-fiber diet against a high fermented foods diet and found that the fermented foods diet led to lower inflammation levels and increases in microbial diversity in participants. That said, fiber isn’t something to skim on! The same study showed that fiber supported immunomodulation, which is the immune system’s ability to react appropriately to different threats. You can learn more about the best diet for gut health in my recent blog about the topic! I dive deeper into the study and what it means for my approach to gut healing.

2. Stress Less

If there’s one surefire way to sabotage the immune system, it’s stress. One groundbreaking study followed medical students throughout their education and found that the student’s immunity decreased every year under the stress of  the same three-day examination period. The data showed lower levels of immune cells that help fight infections, such as natural killer cells and T-cells. T cells are also responsible for helping the immune system distinguish between the body’s own tissues and outside invaders, making them key players in autoimmune disease prevention . Some of my favorite ways to relieve stress are yoga and meditation.

3. Get More Mushrooms

It might seem strange since vitamin C and zinc get all the attention for immune health, but my favorite superfood for immune health is actually mushrooms. Mushrooms contain polysaccharides called 1,3 and 1,6 beta glucans, which have demonstrated immune-modulating and even anti-tumor properties . Countless studies have shown that beta glucans can stimulate the immune system’s defenses against a whole array of threats, including bacterial, viral, fungal, and parasitic infections. How does this work? Beta glucans stimulate leukocytes , which are also known as white blood cells. These cells rush to an area of injury or infection to protect the body from further harm. Beta glucans also increase innate immunity and by doing so increase our defensive barrier to infections.

4. Exercise

If you want to give your immune system the best fighting chance against infection, exercise is a must. My friend Mike Mutzel ( @metabolicmike on Instagram) recently posted about the benefits of exercise for fending off viruses. According to a new study on over 100 subjects tracked over the past year, regular exercise drops your risk of being infected by and contracting a severe form of COVID-19.  Exercise has also been shown to flush viruses out of the lungs, positively affect white blood cells, and prevent bacteria from growing by raising body temperature.  

5. Fix Your Leaky Gut

If you want to have optimal immune health, fixing leaky gut is a must. Leaky gut is a condition that occurs when the integrity of the intestinal barrier becomes compromised, allowing toxins and other particles to slip through into the bloodstream where they create chronic inflammation, can create food sensitivities, and lead to immune disruption. I specifically designed my 28-Day HAPPY GUT® REBOOT to fix leaky gut. It includes digestive enzymes, probiotics, and other supplements that help with true gut healing.

The five steps above are just a few of the many ways to help supercharge your immune system by supporting gut health. That said, sometimes even the healthiest among us end up feeling under the weather. If you do get sick, it’s important to support gut health in the short-term. After all, studies show that your gut microbiome is highly responsive to lifestyle factors, especially diet, and can start to change in as little as one day. If you’re fighting something, consuming foods that are gut-friendly can help you fuel your immune system. One of my favorite recipes for this is my Golden Miso Immunity-Boosting Soup . I turn to this recipe whenever I feel a scratchy throat, a stomach bug, or the sniffles coming on. I’ll also make it if a loved one is feeling sick as a preventative measure! Here’s how to make it at home.

Golden Miso Immunity-Boosting Soup

 Golden Miso Immunity-Boosting Soup


  • 1 tablespoon avocado oil 
  • 24 fluid ounces of bone broth (I like the brands Bonafide and Kettle & Fire
  • ½ onion, chopped 
  • 2 medium garlic cloves, chopped 
  • Peeled fresh ginger root (about the size of your thumb)  
  • Peeled fresh turmeric root (about the size of your thumb)
  • One medium-sized sweet potato, chopped into 1-inch cubes   
  • ¼ cup golden miso (or add to taste) 
  • ½ medium yellow onion 
  • 1 cup Shiitake mushrooms, sliced  
  • 1 teaspoon of chopped dill 
  • 1 large handful of collard greens 
  • Salt and pepper


  1. Add avocado oil to large soup pot on medium heat
  2. Saute onion and garlic on medium heat for about 3 to 5 min until aromatic
  3. Add in ginger and turmeric and saute until softened 
  4. Add bone broth (love the Bonafide or Kettle & Fire brands) and increase heat to high until boiling 
  5. Add in carrots, sweet potato, collard greens, and shiitake mushrooms
  6. Lower heat to slow boil for 15 to 20 min until vegetables are soft 
  7. Lower to simmer and add-in golden miso and chopped dill
  8. Allow soup to cool slightly, serve, and ENJOY!!!
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