Allergies, asthma, autoimmunity on the rise: one reason why...
The data shows that the incidence of asthma, allergy and other autoimmune conditions like type 1 diabetes is on the rise. Especially in the West. I mean we have all seen it, with most schools now banning nuts completely (given the rise of severe nut allergies). Plus, more skin conditions like psoriasis and eczema, not to mention the dreaded asthma, in young children than ever before.
Unfortunately, as usual, there doesn’t appear to be a single simple answer. However, the latest research is increasingly pointing in one direction…
Guess what: it's our environment and the way we now live our lives.
What’s causing this?
Asthma, allergies, eczema and autoimmune conditions are often broadly linked together as they tend to have some commonalities. It's a complex interplay, but they are all related to the immune system. Specifically our immune system not working quite as it should. It also usually involves our old friend chronic inflammation click here for a reminder why we are facing more trouble than ever with this.
Part of this is genetic, but it doesn’t explain it all. Type 1 Diabetes, an autoimmune condition where the body attacks itself inhibiting the production of insulin, is a prime example. It is the most common autoimmune condition in young people and highest ‘in European countries, probably due to environmental factors’ (Xie et al., 2014).
The science suggests that genetics accounts for around 60% (2) which leaves a good chunk potentially caused by other factors. This is where epigenegtics also comes in. As a reminder, this is how our environment influences our body by switching particular genes on or off.
So what are these ‘environmental factors’?
One theory on the rise is the so-called ‘hygiene hypothesis’. As the name suggests, this is the argument that we have become ‘too clean’ or overly sterile. Particularly in the West, with our love of hand-sanitizers, antibiotics and overall germ-phobia.
How credible is this and how does it make any sense?!
Interestingly this isn't a new observation. It was first identified in the 80s, where it was shown that children in large families seemed to suffer less from a skin condition called atopic dermatitis. This was then followed up by a whole host of other studies showing that there were lower overall rates of allergic disease in children in rural Europe. Specifically those who lived lifestyles that involved raw milk/animal/stable exposure in the first year of life. The research following has strengthened this argument…
But, how can being ‘too clean’ have an effect?
It comes back to the gut and the microbes within it. The gut is one of the main heartlands of your immune system. It also appears that when it comes to optimum functioning, the more microbes you have (in good balance) the better…
In fact when your gut microbiome isn’t in order, especially at the vulnerable stage when your immunity is developing, you open yourself up to malfunction and issues with allergy and autoimmunity. Amongst other things. The cleaner and more ‘antibiotic’ we are, the more microbes are eliminated, hurting the diversity of the gut microbiome and its delicate balance.
‘Allergy, mainly in the form of atopic eczema and later asthma, has been linked to specific microbial features. Numerous studies suggest that early development of the infant gut microbiota influences the risk of allergic diseases later in life. This has been attributed to an inappropriate development of gut microbiota and associated disruption of immune homeostasis during the first year of life’. (1)
What equals an inappropriate development of gut microbiota?
Well as far as we understand it at this point (research is still ongoing): it is where you have low diversity and large imbalances. Click here for much more on this.
There are other factors that impact how a baby’s gut develops of course click here to learn more on how it is built and influenced, and when these are missing we can get a further reduction of diversity and imbalances forming.
For example, ‘a host of additional studies established that in addition to the findings noted above, absence of early antibiotic exposure, exclusive breastfeeding for the first 4 months of life, vaginal delivery, furry pets in the home during infancy, lack of maternal antibiotic use during pregnancy, and maternal animal exposure during pregnancy all were associated with lower rates of allergic disease. Taken together, these clinical observations established a strong link between microbes and the development of allergic disease’. (3) Click here for more about the specific factors that impact a baby’s gut construction.
Taking this a step further, when the microbes in our gut are knocked off, we see other linked issues like inflammation and also leaky gut. Click here for much more on inflammation, but what is leaky gut? Why is this a problem? This is essentially where the filtering mechanism that the gut is supposed to perform (allowing the right things through and stopping the bad) isn’t working as it should - the gut then becomes more permeable. When things that shouldn’t get through into our bloodstream do, you get inappropriate immune reactions and inflammation, which can show up as allergies etc.
‘It has been shown that microbiota perturbations during early infancy may generate a proinflammatory environment that facilitates the development of autoimmune disease’. (1)
Less of the ‘right’ microbes and the right food for them prebiotics also means less short chain fatty acids, which are produced by the gut microbes. These are the lesser known heroes of the gut world, which are known to have anti-inflammatory effects (click here to learn more). Partly, via their protection of the all important gut barrier and ensuring nasties can't get through into the bloodstream.
It's also interesting that the research shows that these effects are not just in the gut - they have been linked to asthma, the skin and even the brain. Interestingly diseases like schizophrenia and autism are now considered to also have an inflammatory component, suggesting that these ailments could also be associated with changes in intestinal microbiota. (2)
So what can we do about it??
‘By modifying the diet it might be possible to improve the intestinal microbiota to promote an anti-inflammatory response of a patient suffering from autoimmunity.’ (2) One of the coolest things we have discovered is that there is a lot you can do to help your gut out pretty easily and quickly. In fact it has been shown that the makeup of the microbes in the gut can be changed in as little as 24 hours by what you eat click here for more on that.
What type of change do we want?
Well it looks like we need more diversity and not less: ‘studies have indicated that a reduced microbial diversity of early-life microbiota directly correlates with later development of atopic eczema...a reduced gut microbiota diversity during the first month of life is associated with a higher prevalence of asthma in 7-year-old children.’ (1)
Increasing the barrier function: A study performed in Type 1 diabetic patients showed a significant increase in intestinal permeability compared to healthy controls, (2) further a study looking at Italian affected children showed that the more the microbiota makeup was compromised, the greater the intestinal permeability. (2)
The earlier the better: We have learnt that the early days matter a lot - particularly when it comes to appropriate immune response. The time from conception to 2-3 years (when the gut microbiome is thought to stabilise) is key: ‘A direct association of specific microbial patterns early in life with the development of asthma years later has not yet been unequivocally established [in humans], since genetic, epigenetic, and other environmental factors also affect the development of the disease. Nevertheless, it is becoming increasingly clear that the intestinal microbiota plays a crucial role in the perinatal programming of asthma...recent evidence suggests that the risk of suffering from asthma is higher in infants who exhibited gut microbiota dysbiosis during the first 100 days of life and that this risk is associated with particular bacterial groups.’ (1)
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