Food Allergies And The Gut MIcrobiome

INEXORABLE RISE

The incidence of food allergies is rising. It would be easy, with its increasing ubiquity, to become blasé about it, but severe food allergies can be life-threatening. And we have to eat, so the risk of unintended consumption is ever present. This must be very stressful to deal with, not helped by there being an EpiPen shortage in the UK this year.

This article from Chicago Magazine is well worth a read if you have time. If not, in brief, this is what it says:

OUR MICROBES

A healthy functioning immune system depends on our gut microbiome.

Mice deliberately bred to contain no gut microbes (germ free mice) have allergic issues.

Germ free mice fed with bacteria from human babies allergic to dairy, then react to milk. Our gut bacteria are involved in whether we have an inappropriate response to food.

Humans don’t tend to eat one another’s poo, but mice do. Allergic mice housed with healthy mice can tolerate problem foods once they have eaten their healthy cage-mate’s microbially-rich poo. This “transpoosion” of microbes via poo helps repopulate the allergic mouse’s gut with microbes that support healthy functioning of the immune system.

Somehow, the state of our gut microbiome - via our immune system - either protects us from food allergies or increases the chances we will suffer from them.

Early introduction of allergenic food stuffs reduces the risk of developing allergies. Children are 80% less likely to develop allergies to peanuts if they eat them between the ages of 4 and 11 months.

Around 8% of children in the U.S. have at least 1 food allergy and 13 % of adults do. In the U.S, the number of reported anaphylactic reactions from food allergies increased by nearly 400% between 2007 and 2016.

 
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WHY?

The leading theory for this explosion in food allergies is Western lifestyle and its impact on our gut microbiome and, therefore, our immune system. Obsession with cleanliness (as opposed to common sense, targeted hygiene) overuse of antibiotics, vaccines, rising levels of caesareans, low levels of breast feeding, reduced exposure to the natural world, reduced diversity in our diets, low levels of unprocessed foods and low levels of fermented foods all affect our gut microbiome, which means our immune system is not challenged or supported in the way it used to be. And people living the “Western” lifestyle are more likely to have a gut lining that is not doing its job properly, leaving our immune system vulnerable.

That is not to say that some of the above practices don’t have important roles to play in the larger health picture but, until now, we haven’t known about the collateral damage they may cause to our gut microbiome and the health consequences that may occur as a result.

The state of our gut lining is an important factor in managing how our immune system is challenged. Some fibre-loving microbes in our gut produce short chain fatty acids (SCFAs) that help maintain the protective layer lining our intestine. The SCFA butyrate appears to be particularly important. If that protective layer is not maintained (with the help of butyrate, produced by fibre-eating microbes), larger substances from our gut can leak into our bloodstream, upset our immune system and lead to food allergies.

 

our options

A great way to encourage levels of SCFAs then, is to eat more prebiotic fibre (fibre which is selectively used by our microbes to benefit our health). Scientists are researching how to skip straight to delivering butyrate as a form of prebiotic therapy, but they need to find a way to deliver it to the large intestine before it has degraded. If they can work out how to do this, it may enable administration to infants at high risk of food allergies – for example those who have arrived by Caesarean or have had to have antibiotics. Or both.

But all this is a long way off and, in the meantime, for children old enough to eat solids, and adults too, a great delivery system that supports our butyrate- producing, gut lining-supporting microbes already exists. It is made in nature, and it goes by the name of FIBRE. You know, in whole grains and vegetables? Eating more fibre won’t guarantee you will outgrow your allergy, but it will certainly act to optimise the gut microbiome that you have.

Other than doing our best to support our gut microbiome through diet, attempts to retrain the immune system have, to date, involved giving people the very foodstuffs that could kill them – in gradually increasing doses. This works but is clearly risky. Now drugs companies are developing two more precise ways of doing this - a tablet and a slow release patch – both target peanut allergies and gradually, but in a highly controllable way, increase exposure to the problem protein in peanuts, thereby retraining the immune system. This won’t necessarily cure your allergy, but the trial results suggest it may prevent you having a severe reaction from accidental exposure.

In the meantime, we should be aware of the things that may increase the risk of developing food allergies (see WHY, above). Some things are beyond our control but, at the moment, we make choices without true understanding of their possible long-term consequences. We are entitled to make informed choices, since it is us who will have to live with the consequences of those choices.