allergen myths debunked - Part
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.
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?
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.
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.
two-part newsletter aims to dispel a few of the common myths surrounding
food allergy and to shed light on the true nature of these adverse reactions
and their impacts on potential sufferers.
Any adverse reaction to a food is an allergy and most people have one
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
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.
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
allergy vs. food intolerance: the facts
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.
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.
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.
#2: Celiac disease is an allergy to gluten
terms ‘celiac disease’, ‘gluten allergy’
and even ‘gluten intolerance’ are often used interchangeably,
but these are not the same thing…
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.
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.
news just in: Call to modify ‘gluten-free’ definition
by Chilean regulators
Chilean Ministry of Health has proposed that the definition of
‘gluten-free’ in the Food Health Regulations (Decree
977/96) be modified so that the term and its symbol can only be
used on foods testing for =1 ppm prolamin. This proposed threshold
is considerably lower than the 20 ppm gluten level defined by
Codex and adopted by most other jurisdictions, including South
Africa, regulating ‘gluten-free’ claims. While the
intention of the Chilean regulators is undoubtedly to protect
celiac sufferers, the effects of this modification will not only
lead to fewer ‘gluten-free’ products being available
on the market, but it will also pose a significant challenge in
terms of verifying the claims using the existing analytical techniques.
Currently available detection methods (ELISA and dipstick devices)
have not been specifically developed and validated to detect gluten
at such low levels. It thus remains to be seen whether this proposed
amendment will be enforceable and if there are real benefits in
having limits that are so much stricter than those issued by other
AOAC Food Allergen Community Newsletter 5(1), 2014.
#3: Allergic reactions to seafood are due to iodine
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
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.
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
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.
Beaty, A.D., Lieberman, P.L., Slavin, R.G. (2008). Seafood allergy
and radiocontrast media: are physicians propagating a myth? American
Journal of Medicine, 158: e1-4.
Chafen, J.J.S., Newberry, S.J., Riedl, M.A., et al. (2010). Diagnosing
and managing common food allergies: a systematic review. Journal
of the American Medical Association, 303:1848-1856.
Coakley, F.V., Panicek, D.M. (1997). Iodine allergy: an oyster
without a pearl. American Journal of Roentgenology, 169: 951-952.
Huang, S.W. (2005). Seafood and iodine: an analysis of a medical
myth. Allergy and Asthma Proceedings, 26: 468-469.
Katelaris, C.H. (2009). 'Iodine allergy' label is misleading.
Australian Prescriber, 32:125-128.
Pawankar, R., Canonica, G.W., Holgate, S.T., Lockey, R.F. (Eds)
(2011). WAO White Book on Allergy. Pp 47-53. Milwaukee, Wisconsin:
World Allergy Organization.
Schabelman, E., Witting, M. (2010). The relationship of radiocontrast,
iodine, and seafood allergies: a medical myth exposed. Journal
of Emergency Medicine, 39:701-707.
Shehadi, W.H. (1975). Adverse reactions to intravascularly administered
contrast media: a comprehensive study based on a prospective survey.
American Journal of Roentgenology, 124:145-152.
Sloan, A., Powers, M.E. (1986). A perspective on popular perceptions
of adverse reactions to foods. Journal of Allergy and Clinical
Woods, R.K., Stoney, R.M., Raven, J., et al. (2002). Reported
adverse food reactions overestimate true food allergy in the community.
European Journal of Clinical Nutrition, 56:31-36.
is food allergy increasing?
prevalence of allergic conditions, e.g., asthma, eczema and food
allergy, has been steadily increasing. Researchers have no explanation
for this; however a number of hypothesis have been proposed. Genetics
does play a role but is not the major cause for this and other
possible influences have been proposed. The hypothesis theory
argues that not being exposed to "dirt", i.e., avoiding
sources of microbial and other factors stimulating our immune
system, results in a switch of our immune system to one favouring
the development of allergies. Other proposed causes are the shift
away from breast feeding of infants, starting infant feeding of
solids too early, pollution, and additives and preservatives in
food. However the evidence to support these theories are not robust
and to date, no single obvious cause or causes have been identified
to explain the increase.