17 Sep 2014 Debunking some food allergy myths

Given the life-threatening nature of food allergies, one would think that the stakes are too high for myths and pseudoscience. Unfortunately, this is not the case and confusion surrounding these conditions abounds. SA’s allergy experts, FACTS (Food & Allergy Consulting & Testing Services), lays out the facts on some common myths.
But who is responsible for this confusion?
– Is it physicians not keeping up-to-date with science, offering ill advice and misdiagnosing reactions?
– Is it consumers looking frantically for answers and relying on unsound sources to make self-diagnoses?
– Is it the internet with its abundance of unregulated information – some true, but much not?
– Or is it marketers of alternative-medicine providers conjuring up their own definitions of allergies and conveniently offering their own ‘cures’ to ‘fix’ these?
Neither one is solely responsible, but rather it is likely the combination of these misinformation sources that cause food allergy myths to spiral out of control.
Food producers, in particular, need to be cognisant of these myths, especially since their consequences may manifest in the manner in which allergens are controlled and how their risks are conveyed to consumers.
Myth #1: Any adverse reaction to a food is an allergy and most people have one
With the great deal of media attention surrounding food allergies, it is not surprising that over 30% of the population believe that they have a food allergy and 30% of parents think that their children have at least one.
The truth: According to the World Allergy Organisation (WAO), approximately 1 – 2% of adults and 5 – 8% of children genuinely suffer from true food allergies. Thus, the true prevalence of food allergy is considerably lower than the perceived prevalence. Much of the confusion surrounding food allergy likely stems from the very poor understanding of the condition and the fact that both the public and health-care providers often erroneously attribute any adverse food reaction – ranging from intolerances to food poisoning – to an allergy.
How did this myth arise? Incorrect medical diagnoses, sloppy studies and distorted messages sent via lay press and marketers, likely lead many more people to think they have food allergies than is actually the case.
Food allergy vs. food intolerance: the facts
Food allergies and intolerances are not identical. Differences between these adverse reactions include the mechanism by which they proceed and the involvement of the immune system, as well as the food component responsible for eliciting the reaction.
Food allergy is an abnormal immune response to one or more of the proteins in a food, which the body mistakenly perceives as being ‘harmful’. Ingestion of even tiny amounts of an offending food can trigger reactions, which typically affect the skin, respiratory tract, gastrointestinal tract and cardiovascular system. Symptoms of food allergies range from mild to fatal, the onset of which is normally immediate (within minutes), although delayed allergic reactions also occur.
Food intolerance is a term used to describe various physiological responses to foods or food components, but which do not involve the immune system and do not proceed via allergy-like mechanisms. Food intolerances can include, amongst others, enzymatic defects (e.g. lactose or fructose intolerances, where the body lacks the enzymes to break down these compounds) and pharmacological responses (reactions to naturally-derived or added chemicals in foods). The onset of intolerance reactions is generally slower than in food allergy, but the symptoms can be similar and are often confused.

Myth #2: Celiac disease is an allergy to gluten
The terms ‘celiac disease’, ‘gluten allergy’ and even ‘gluten intolerance’ are often used interchangeably, but these are not the same thing…
The truth: Celiac disease is a hereditary, life-long disorder of the small intestine, caused by the ingestion of gluten. The term ‘gluten’ is usually used in the medical literature to refer to the proteins in wheat, rye, barley and possibly oats that are responsible for causing adverse effects in celiac sufferers.

While celiac disease does involve an auto-immune response, it is neither a true allergy nor a true food intolerance and it does not follow the same mechanism as either of the latter. The symptoms of celiac disease are generally not immediate as with food allergies, however, they can be just as damaging. These include small intestine damage, nutrient malabsorption and potential secondary diseases such as anaemia and vitamin deficiency. Celiac disease is believed to affect 1 – 2% of the general population.
How did the myth arise? Much of the misinformation relating to celiac disease and allergies can probably be traced back to the lay press and self-diagnoses based on internet forums. While wheat is a recognised allergen, many people have probably misinterpreted this as referring to gluten. Wheat allergy is an immune reaction to one or more of the proteins in wheat only, thus wheat-allergic individuals may be able to tolerate rye and barley, but celiac sufferers will generally not tolerate all three.
Myth #3: Allergic reactions to seafood are due to iodine
There is a widely-held misconception that iodine is the compound responsible for causing both seafood allergies and adverse reactions to radio-contrast media or ‘dyes’ administered intravenously during CT scans.
The truth: Allergies to seafood (fish, crustaceans and molluscs) have nothing to do with iodine, nor are they related to adverse reactions to radio-contrast media. Iodine is not an allergen and no one is allergic to it. This trace mineral is, in fact, found in table salt and many other foods, and is required in the human diet for normal thyroid functioning. Rather, allergies to seafood occur due to the body’s immune response to one or more of the proteins present within the muscle tissue of these species, mainly the parvalbumin proteins in fish and the tropomyosins in crustaceans and molluscs. Several researchers have dispelled this myth in the scientific literature over the years, but the misconception has been hard to put to rest – primarily since the medical fraternity itself has helped to propagate it.
How did this myth arise? In a study conducted in 1975, it was observed that 15% of patients who experienced reactions to radio-contrast media also reported being allergic to seafood. The researchers thus inferred that iodine in both seafood and these media could be to blame. Largely overlooked, however, was that the same number of individuals in the study had also reported allergies to other foods e.g. eggs and milk. Nonetheless, many health professionals (mistakenly) began to and continue to inquire about a patient’s history of seafood allergy prior to administering radio-contrast media, a practice which has no scientific basis and which has only led the public to believe that such a link exists.
Note: Although reactions to contrast media can occur, these proceed via a non-allergic (non-IgE mediated) mechanism and are not due to iodine, but rather due to other substances in the contrast. A prior reaction to these media does not mean that seafood needs to be avoided and vice versa.
Source: FACTS August 2014 newsletter; see more at http://www.factssa.com/