True health starts in your gut: Immunity

Every day, your body is tasked with defending you against the infectious, outside world. Thankfully, you’re armed with an incredible and complex immune system that is ready to launch an attack if harm comes your way. In fact, over 70% of your immune cells live within the gut, where food, water and other substances must be scanned for stowaway microbes that could infect you.

Many of the chronic symptoms I see every day in a clinical setting are linked to assaults on the immune system within the walls of the intestines. The truth is that the first and most important step in building and maintaining a strong immune system is taking care of your gut.

What is the immune system?

The immune system is a network of organs, cells and proteins that work together within the body to identify, protect and defend against harmful bacteria, viruses, fungi, and toxins created by microbes. Once the immune system identifies a dangerous microbe, it creates a memory of it so it can identify and destroy it faster and more effectively if it ever enters the body again. This protection is called immunity.

Your body has primary lymphoid organs, the bone marrow and thymus, that create specialized immune cells called lymphocytes. Secondary lymphoid organs consist of the lymph nodes, spleen, tonsils, and tissues within mucous membrane layers such as the nose, mouth, and gut.

How is the immune system related to the gut?

Your gut houses the largest body of lymphoid tissue, referred to as the GALT or gut-associated lymphoid tissue. It consists of a variety of immune cells that identify, contain and kill pathogens, all aimed at keeping you safe.

Because so much of your immune system is harbored in the gut, insults to the digestive tract such as injuries and infections or even overgrowth of your natural microbiome can lead to a dysregulated immune system. Chronic inflammation, autoimmunity and even metabolic diseases can be linked back to the GALT.

What are symptoms of poor gut-related immune function?

If your GALT is hit with chronic insults like a high-sugar diet, toxin-producing microbes, injury to the tissue or similar, you can experience a range of unwanted symptoms. While symptoms may occur in the digestive tract such as bloating, constipation, diarrhea, cramping, or similar, often the symptoms of an overburdened GALT are felt all over the body.

When the GALT is triggered to respond, the inflammatory process ensues leading to damage to the intestinal tissue and signals to the nervous system that there is a problem. That is why symptoms of poor gut-related immune function may also lead to:

  • Acne, eczema, and psoriasis
  • Joint and muscle pain
  • Headaches
  • Congestion, allergies, and asthma
  • Hormone imbalance
  • Cardiovascular disease
  • Blood sugar imbalance and diabetes
  • Autoimmunity
  • Obesity

How can I support a healthy GALT?

Maintaining a healthy GALT means taking the pressure off of your immune system whenever possible and providing the necessary support for optimal function. Thinking about what goes into your body is critical.

Healthy food that has been properly washed and prepared is the first step in preventing infection in the gut.

Chewing well and eating in a calm environment increases the acid production in the stomach, your first line of internal defense against infections making their way into the gut.

Eat foods high in vitamin A, zinc, selenium, vitamin D, iron, and vitamin C (or supplement when needed) to provide necessary micronutrients to immune cells.

Avoid alcohol and other toxins that damage the GALT

Eat a high-fiber diet which has been shown to reduce inflammation and build a healthy GALT and reduce susceptibility to pathogens. Aim for 35 grams of fiber a day, with at least 15-20 grams provided by soluble fiber sources.

About Megan Barnett, MS, CNS

Megan Barnett, MSMegan Barnett is a functional medicine practitioner in Portland, Oregon. In her clinical practice, she helps patients identify the root cause of their health problems, then designs individualized and evidence-based approaches to alleviate symptoms and help their bodies heal. She has a Bachelor of Science in Dietetics from Kansas State University and a Master of Science in Nutrition and Functional Medicine from University of Western States.