How your gut impacts your immunity
Between 70 to 80 per cent of our immunity resides in our gut or digestive system. Isn’t that amazing? This means that healthy digestion is key to healthy immunity.
When I say our gut or digestive system, I don’t just mean the lining and cells of our own body, or in other words in our own DNA. I mean the DNA of our microbiome – the totality of microorganisms such as bacteria, fungi and viruses, and their collective genetic material that are present in or on our body.
Microbiome DNA is critical because it’s estimated that it codes more than 90 percent of our metabolic and biochemical function. I heard some functional doctors discussing this online and they pointed out that humans have half the genes of a rice plant or earth worm, which puts the importance of our gut bacteria in context. They added that humans owe our evolution to the way we’ve used the DNA of our microbiome rather than adapting our own DNA. Wow. How intelligent is our body!
What this means is that humans are dependent on the health of our gut, or in other words, on the diversity and balance of our microbiome.
Yet our modern diet and lifestyle have had an adverse effect on our microbiome, contributing to less diversity and balance, a weakened immune system and a sharp rise in chronic illnesses around the world. Many bacteria are beneficial when they act as a member of a cooperative system, but they can become aggressive and damaging when they proliferate and others die off. Common causes of this include our high-carb die, our lack of whole and natural foods, chemicals and pesticides, alcohol and drugs (both prescription and non-prescription), and stress.
Gut dysbiosis, or an imbalance between the types of organism present in a person's natural microflora, is a key stressor on the body. I see this a lot in my clinic.
This can trigger inflammation. Inflammation is a natural response by body tissues to harmful stimuli such as pathogens, irritants and injury. It’s a precursor to anti-inflaming, the other half of the process of healing. The problem occurs when we consistently eat and live in an unnatural way and get stuck in inflammation and don’t anti-inflame, in part because our cells don’t have the necessary nutrients such as Omega-3 fats and anti-oxidants.
Getting back to immunity, our gut is involved in two functional lines of defence against invaders. It provides a physical barrier and is also part of the innate non-specific immune system. It’s also capable of housing a powerful adaptive immune response.
More specifically
Stomach acid along with the digestive enzyme pepsin neutralise many pathogens or invaders before they enter our intestines
Any surviving invaders encounter lymphoid tissue in the intestines where 70-80% of our immune cells live
The epithelial cells that line the intestines secrete a protective mucous that’s rich in antimicrobial proteins to eliminate where necessary
Healthy microbes in the large intestine help stimulate the immune system, feed the cell lining and crowd out the nasty bacteria. Healthy gut lining cells require a diverse microbiome
Potential challenges to gut health that can impact our immunity are that we
Have low stomach acid – common these days because of refined foods and the lack of zinc in our diet – meaning invaders are let through this gateway to the rest of our body
Don’t eat enough fibre to feed our good bacteria causing reduced diversity
Live a stressful life, lowering stomach acid, stopping normal digestive processes and damaging the gut lining
Are exposed to too many chemicals and pesticides, which damage our gut and kill off our microbiome
Take too many antibiotics and others drug, which kill off healthy gut bacteria and can damage our gut lining
Some practical tips to improve your gut health
Eat mainly fresh whole foods as they come in nature, nothing in a packet, and a mix of raw and cooked foods
Eat plenty of anti-oxidant-rich foods to neutralise free radicals or destructive molecules that come from both inside and outside the body. These include berries, citrus, cloves, black and green tea, potatoes, dark chocolate (95% or cacao buds are good)
Eat probiotic foods that are ‘alive’ such a fermented vegetables, kefir, homemade kombucha and miso to feed your good bacteria
Eat prebiotic foods that feed your good bacteria and lower inflammation, including cold potatoes, raw asparagus, garlic and onions, green bananas, Jerusalem artichoke, dandelion greens, flaxseeds and seaweed
Eat a balance of foods, roughly a third each in terms of energy, of good fat, whole-food carbs and proteins
Reduce chemicals in your food by eating chemical-free or organic where possible and swapping toxic self-care products for natural ones
Reduce chemicals in your environment, including in your cleaning products (that includes hand sanitiser, which doesn’t kill viruses by the way) and air fresheners
Find ways to destress and practice them regularly – walk, move but don’t over-exercise, do yoga, develop a breath practice, meditate, take a bath, listen to music, read. Too much stress doesn’t achieve anything