(THE STAR/ASIA NEWS NETWORK) - Negative reactions to food elements or environmental factors are known generically as allergies - which is technically a range of responses to allergens, which are the natural or synthetic compounds which provoke such reactions. All allergies are inflammatory reactions against allergens - and the immune system responses may be very mild (such as a little itch from an insect bite) or very severe and life-threatening (such as anaphylaxis, a dangerous whole-body reaction to ingesting certain proteins). As non-coeliac gluten sensitivity (NCGS) is very probably an allergic response of some kind, it would help to explore the nature of allergies.

Increasing incidence of allergies

The World Allergy Organisation (WAO) reported the incidence of human allergies has been growing for some decades and estimated in 2011 that 30% to 40% of the world's population is affected, especially in countries such as the United States, with more expected each year.

An immediate question is: WHY are modern humans seemingly so prone to developing allergies? Simple explanations such as the widespread availability of junk food or presence of environmental contaminants (eg. pesticides) do not explain the 60 per cent of the human population not affected by allergies. Please do not misunderstand - lousy food and polluted environments will almost certainly end peoples' lives prematurely, but the salient points are: (i) 60 per cent of people do not suffer any reactions even while eating crap food or mucking around in polluted areas; and (ii) the number of people with allergies is increasing each year. How come such a significant (60 per cent but dwindling) percentage of the population can avoid being affected by the allergens that affect the other (40 per cent and increasing) proportion of humans? It is impossible that such large segments of the population do not encounter the same allergens on a daily basis.

No simple answers

There are several plausible explanations for this odd pattern - and they are somewhat convoluted and probably interlinked in various ways. For a start, despite the discomfort, research suggests that allergies conferred certain evolutionary advantages in our distant past - uncontrollable reactions to insect bites, animal fur, vegetation or other allergens ensured that Palaeolithic humans did not choose to inhabit dangerous places or eat too much harmful food, even if they wanted to. An allergic reaction is a visceral, non-negotiable signal to stop doing whatever is invoking the response. Non-fatal allergic reactions may also help prepare the immune system against a greater attack - a response to the toxins in a wasp sting can prime the body to produce more defence helper cells that can combat a larger attack by more wasps (and instil caution against stinging insects in general).

It is therefore feasible that the immune systems of most modern humans are still more attuned to natural factors in the environment, and not yet wholly sensitised to compounds such as modern food additives and pollutants which have been around for less than two centuries. Note again that not being allergic to such compounds does not mean that the stuff is good for health at all - it just means that people do not react badly to them.

Too hygienic?

Yet the number of people with allergies is growing each year, and the inescapable conclusion is that more and more people are indeed becoming sensitised to their food and/or environments. This phenomenon may be partly explained by the Hygiene Hypothesis (HH). Modern sanitation habits have prevented human immune systems from encountering allergens such as pathogens (germs, fungi, viruses) and noxious compounds - which is an unnatural state of affairs in evolutionary history. Over-sanitation in itself may not be problematic but the HH contends that the human body's innate (and powerful) ability to counter allergens means that such energy, in the absence of any genuine pathogens, can be misdirected into developing strong reactions to substances which are normally harmless.

The problem with the HH is that there is currently no real explanation as to why this misdirection happens; ie, why normally harmless compounds get targeted by the immune system and become severe allergens. To be honest, there may never be a definitive answer. This is because of the extremely complex matrix of possible allergens (which may be individual or combinational) and types of allergic responses (which may also be individual or combinational) which needs to be investigated and explained in a rational manner.

It's the gunk too

It is indisputable that many people are also reacting negatively to modern additives and food treatments. These range from fertilisers, pesticides, hormones, artificial flavours, food texturisers, antibiotics, preservatives, chemical residues, etc - all available on your dinner plate, and undoubted contributors to the increase in global allergies. There are no reliable statistics on the actual impact due to the huge variety of such compounds.

Worms and bacteria

There are studies which suggest certain intestinal parasites can temper allergic responses in mammals. Research with mice using helminths (parasitic worms) known as Heligmosomoides polygyrus bakeri indicated that the worms can perturb the host immune system and prevent it from reacting to the parasites and also other allergens. This is possibly also a factor in the growth in the number of allergies as human intestinal parasites are almost unheard-of in modern societies.

Other studies have identified that imbalances in the human gastrointestinal microbiota (HGM, or bacteria in human guts) adversely affect the body's immune system. It is undeniable that the HGM significantly affects inflammatory responses to ingested food.

An experiment which introduced different strains of gut bacteria into mice demonstrated that segmented filamentous bacteria provoked inflammatory responses in their guts while strains of Clostridial bacteria induced anti-inflammatory reactions to the same diet. An interesting 2006 paper from Maastricht University also identified a tangible link between the disproportionate presence of the bacterium Escherichia coli and/or Clostridium difficile in the guts of human infants and subsequent childhood eczema and other skin allergies. In short, an unbalanced HGM or even worse, dysbiosis (impairment of the HGM) can manifest itself in many unusual ways, including allergies - if you are interested, please read: A time for gut feelings - Part 2.

Other factors

Nobody understands exactly why - but anyone can develop new allergies at any point in life. It may be linked to changes in the HGM, possibly after it has been perturbed by disruptive agents such as tobacco, medications (especially antibiotics), alcohol, stress, pesticides, pollution, bacterial invasion, etc - this disruption may trigger a profound adjustment of the immune system. Having a sudden or long-term stressful lifestyle, with an excessive aggregation of stress-related hormones may also be a factor as such hormones can affect the enteric nervous system which oversees the autonomous functions of the gastrointestinal organs and indirectly the HGM.

Last but not least, some people have convinced themselves that they have an allergy when in fact there are no genuine physiological issues. Someone who despises offal might feel extremely ill or even throw up when encountering liver in a meal but that does not mean there is any biological reason for the reaction. One extreme example is anorexia, though you would be pleased to hear that it was very easy for me to overcome urges to starve myself.

A short, fascinating 2013 paper in the British Medical Journal, "Implausible results in human nutrition research" by John Ioannidis, noted that, "Almost every single nutrient imaginable has peer reviewed publications associating it with almost any outcome" - in short, many foods which have been studied are often presented with divergent conclusions depending on the research teams. And it is difficult for ordinary folks to ascertain which outcomes are relevant, questionable or downright implausible without access to the data and technical statistical tools. Just because some people wrote a "research paper" does not automatically confer credibility to the conclusions reached - this applies especially to relative risk and benefits assessments arising from small studies, a common tactic used to promote (generally useless) supplements.

One might suggest that such confusion, often sponsored by interested parties, is what keeps people buying all kinds of products for the wrong reasons. This is one reason large-scale double-blind trials are preferable as they are usually the most unbiased.

After exploring allergies, the next part summarises an investigation specifically into NCGS. This, as mentioned, is mostly a self-diagnosed syndrome - and in a moment of abdominal distress, I had made the same diagnosis. That is not to say any self-diagnosis of NCGS is problematic - but it took a long while to figure things out, as you will see.