About 70% of our immune cells are housed in the lining of our gastrointestinal system, or gut. Our gut is the biggest immune organ of the body. Likewise, it’s also where the majority of our microorganisms reside. This is not a coincidence. It makes complete sense. The food we eat is the largest exposure of foreign material that we bring into our body, so it makes sense for our immune system to reside in our gut. The outside world is literally experienced through the filter of the gut microbiome (and of course through our lungs), defending us against unwanted microbes and toxins.
It’s like an internal ecosystem – a biological community of interacting organisms in their physical environment (our gut). The more diverse the number of beneficial microbial species our gut hosts, the better our immune system will work and the healthier we will be.
A delicate interaction occurs between us and our microbes. The gut immune system is constantly working hard to distinguish between beneficial bacteria and potential pathogens (unwanted invaders). When we lose our microbial diversity (all those different species of microbes) we lose “tolerance”. When our immune system goes wrong, it’s basically losing tolerance. It fails to adequately deal with all that is presented to it, and often reacts to things that it shouldn’t react to. Thus, digestive inadequacies, allergies, food intolerances and autoimmune conditions are mostly the result of an immune system losing tolerance.
Three factors determine if we will lose tolerance:
- Our genetic predisposition
- Our exposure to a bad environmental event or trigger, like an infection
- How permeable our intestinal lining cells are
For most people, improving the integrity of the intestinal barrier is the most practical way to improve immune tolerance.
Increased intestinal permeability, commonly referred to as “leaky gut”, can be thought of as micro-tear’s in the gut lining cells. This is the start of the trouble. Many things in our modern lifestyles can damage this delicate lining. Stress, toxins, undigested food particles, gluten, antibiotics, acid-blockers, processed foods, low fibre diets, pathogens, drugs, alcohol and infections are the main ones. These can lead to unwanted substances (microbes, particles of food, pathogens) getting directly into our blood stream and triggering long-term inflammation.
Be on the lookout for Part 4 tomorrow, we’ll take a look at your microbiome and antibiotics, and what happens to your microbiome when you are prescribed a course of antibiotics, and what you can do afterwards to help yourself restore good order.