Gut Health And Immunity

Gut Health And Immunity
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“All disease begins in the gut” Hippocrates

The gut is well-recognised for its central role in immunity2, however poor gut health is ubiquitous3. If you experience digestive symptoms such as constipation, diarrhoea, or reflux, it is imperative that you support your digestion, not least given the intimate connection between gut and immune health.

We envisage four pillars of gut health:

  • Digestion and absorption
  • Motility
  • Integrity and immunity
  • Microflora

We find that individuals prone to low immunity tend to also present with imbalances in at least one of these ‘pillars’. Crucially, when their digestion is optimised, so too is their immune function.

How we chew our food is a cornerstone of our ability to extract nutrients from it. When we eat too quickly, our food is harder to digest. This drives nutrient depletion, including those required for immune system support (e.g. vitamin A,4 C,5 D,6 zinc7). This can be exacerbated if digestion is also compromised by low levels of stomach acid, which often arises due to advancing age8 and proton pump inhibitors (PPIs)9. Gallbladder issues can have a role to play in driving low immunity too, by impairing fat digestion and the absorption of fat-soluble nutrients (including vitamin A and D).

Poor nutrient absorption can weaken our immune system further. This arises when the absorptive surface of the small intestines is deformed (e.g. due to coeliac disease10) and/or the gut lining is chronically hyperpermeable (‘leaky gut’) due to gluten,11 gut dysbiosis,12 alcohol,13 and stress.14,15 Intestinal hyperpermeability, in particular, dysregulates the immune system by driving diarrhea and thus, poor nutrient absorption, and also chronic inflammation throughout the body.16,17

If we are prone to diarrhoea, food moves through the bowel too quickly which limits the time available for digestion and absorption. Meanwhile, constipation promotes re-circulation of toxins which have the capacity to hamper the immune system, such as aflatoxins from mould.18,19 Low dietary fibre is a common driver of constipation, which can also make our gut susceptible to infection by reducing the diversity and abundance of beneficial bacteria living there.20 Likewise, stress can increase the risk of infection by reducing the concentration of secretory IgA in our mucus secretions, which is otherwise a vital first line of defence.21 The gut microbiome, so critical to immune stimulation and acting defensively, is profoundly challenged by the modern world, notably C-section delivery,22 formula-feeding,23 and antibiotics.24,25 Strikingly, preliminary research indicates that patients with COVID-19 are prone to gut dysbiosis.26

When our gut health is compromised, we pick up infections more easily. When we have an infection, we tend to eat a more restricted diet due to a lack of appetite. This can go on to compromise our nutrient status and digestion even more, creating a vicious cycle of poor gut health and low immunity.

An excellent barometer of sound gut health is the absence of digestive symptoms (e.g. reflux, bloating, flatulence), and an ability to pass at least one daily dark brown, sausage-shaped stool which is clean upon wiping with no undigested food visible. If this is not the case for you, poor gut health is likely increasing your risk of low immunity. Therefore, be sure to nourish your gut this winter and support your immune system, through nutrition (e.g. probiotics,27,28 prebiotic fibre,29polyphenols,30 L-glutamine,31 and zinc32) and lifestyle interventions (e.g. stress management, daily physical activity). Your body will thank you for it!

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October 20, 2020
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