Are you healthy? Full of energy? If so, you probably don’t think about your immune system very much. Fall brings colds and flus, and to prevent these, you may decide to up your intake of vitamins C and D because you’ve heard they support immune function. After that, will you forget about your immunity again?
Listen up: Supporting immune health goes much deeper than adding a few vitamins once a year. You’ve got to look to your gut—even if you’re feeling healthy at the moment.
Your far-reaching immune system
Your immune system operates throughout your body to protect you from everything from germs to toxins. It responds to perceived invaders in two ways. The first, known as the innate immune response, happens immediately; it’s part of your body from birth and is your first line of defense. Your skin, your cough reflex, invisible chemical cues—they’re all barriers your innate immune system uses to thwart harmful substances.
The adaptive immune response, while not immediate, is more complex and only targets specific invaders. Once activated, the adaptive immune system can produce “memory cells” that make future responses against a specific invader more efficient.
Which parts of your body are involved in mounting your immune defense? Your bone marrow has a starring role, and the thymus (a small gland under your breastbone), spleen, tonsils, adenoids, skin, liver, and lymphatic system all house and/or produce various immune cells and chemicals.
To understand how your gut is involved, it helps to drill down into the last item on that list: the lymphatic system.
Why I’m passionate about the gut
As a child and into adulthood, I experienced severe intestinal issues. I grew up in the South eating lots of fried foods and heavy meats. I was sick with what seemed like hundreds of colds and flus, and I was prescribed antibiotics galore. The result was debilitating constipation.
My desire to overcome my own misery fueled my passion to learn how to feel well, and then how to maintain vibrant health—for myself and others. I’ve discovered, as have scientists and integrative doctors, that the key lies in the gut-immune health connection!
Your lymphatic system in a nutshell
The lymphatic system is an extensive roadway of channels that carry a fluid called lymph throughout your body. Lymph is like blood plasma (the clear part of blood), and it’s rich in white blood cells known as lymphocytes.
There are different types of white blood cells (aka “leukocytes”), but their common goal is to destroy cells that could damage your body. Lymphocytes and other leukocytes recognize antigens (toxins or other foreign substances). Some lymphocytes even produce antibodies (blood proteins that neutralize specific bacteria, viruses, and other substances considered threatening). In short, lymphocytes are a major part of your adaptive immune response—your very own specialized army.
What does this have to do with your gut?
Lymph tissue can be found throughout your body, but it’s especially concentrated in your gut as “gut-associated lymphoid tissue” (GALT). In fact, thanks to the GALT, about 70 percent of your immune cells are actually located in your gut! In addition to lymphocytes, there are many different immune cells in the GALT, including mast cells, dendritic cells, and macrophages.
The GALT is quite diffuse. Areas within the mucous lining of your GI tract are hotbeds of defense. Toward the end of your small intestine, there are GALT “command centers” known as Peyer’s patches. Your appendix houses swaths of GALT and supports the fight against many types of infection. And GALT is abundant in the colon too.
Have you experienced swelling and tenderness in your neck when you’re fighting off a cold or flu? That’s your lymphatic system at work. Specifically, the symptoms are from inflamed lymph nodes. Lymph nodes located along the roadway of your lymphatic system filter lymph and help your body deal with toxins and other dangerous issues. Lymph nodes are located at a number of sites around your body—under your arms and in your groin, for example … and in your neck!
What about the microbiome?
Besides your lymphatic system, your immune system has other allies within your gut. Beneficial bacteria are found on and within your body in many areas, especially in your intestinal tract. These beneficial intestinal microbes help you digest food and make vitamins, and they communicate with your immune system to maintain your health!
The “good” microbes aren’t alone in your gut. Pathogens (potentially dangerous microbes), commensals (bacteria that seem to be neither beneficial nor harmful, except when they overpopulate), viruses, and fungi all exist together to create what’s known as your microbiome: the incredible community living within.
To get or maintain a healthy microbiome, the goal isn’t to kill its less desirable elements. Instead, we should strive to maintain a diverse balance. Researchers have found that nearly everyone carries some pathogenic microbes. In healthy bodies, these pathogens generally don’t cause disease. They simply coexist with the rest of the microbial community. Issues present when the normal ratio of good bacteria to commensals and pathogens is disrupted. Inflammation begins, and that’s when disease processes appear to unfold.
Show me the research!
I’ve followed the newest studies on the gut-immune health connection for decades. Research on this topic is more exciting each day. Every new paper reminds us that these breakthroughs are only the beginning. For example, recent studies have shown that
- the gut microbiome directs the immune system to fight melanoma in mice
- bacteria in the gut influence vitamin A to regulate the intestinal immune system
- signals from immune cells in the gut may help protect against obesity
- it’s not just genes, but how children’s bodies respond to their own microbiome that’s predictive of future diagnoses of type 1 diabetes
- changes in the amount and diversity of gut microbes are closely intertwined with the progression of type 2 diabetes
It’s clear from these studies (and many others) that the most important thing you can do for your health is to actively support your gut and immune system.