Due to the expected growth of the world population to 9 billion people by 2050 and the threat of shortages of raw materials and food, people are eagerly looking for new innovative ideas in an
environmentally and economically sustainable way to win proteins and enhance the food industry.
Creating more sustainable diets will result in less animal-based and more plant-based foods. Several
alternatives for meat have been proposed so far, like beet leaves, algae, but also insects.
Insects, such as mealworms, are widely consumed around the world, but not yet in the Western world.
Since well-known allergens have been detected in mealworm, concerns have been raised about its
potential allergenicity.
In order to understand why people become allergic to something like the mealworm, we first need to
understand what allergies are. We will thereby focus on food allergy and come back on the example of
the mealworm again later in the lecture.
Food allergy is an acute reaction upon the ingestion of food that can result in mild, moderate, but also
severe symptoms. Even fatal reactions occur. Typically the symptoms start within minutes after
ingestion up to half an hour. The most frequently involved foods are cow’s milk, hen’s egg, peanut and
hazelnut in children and fruits, in particular apple, peach and kiwi, nuts, like hazelnut and walnut and
peanut in adults. The overall prevalence of allergies is estimated at 2 to 4%, with the highest prevalence
in children. However, most people show tolerance to proteins.
Allergy is associated with other so called atopic diseases such as allergic rhinits, allergic asthma and
eczema. Over the past 2 decades the prevalence of atopic diseases including food allergy increased
fourfold. The causes for this increase are largely unknown. Factors like paternal smoking, decreased
incidence of infections and decreased exposure to large animals probably play a role.
Food allergy is the result of an undesirable reaction of our immune system to otherwise harmless
substances like food. This happens in patients with a genetic predisposition to become allergic.
The first phase of becoming allergic to food is by getting sensitized to that food. Sensitisation means the
development of specific antibodies of the IgE type. Let's take the example of peanut allergy. The
allergenic substances of peanut (and other foods) are proteins. Peanut contains several allergenic, but
also non-allergenic proteins. The number of allergenic proteins, called allergens, in peanut is currently
estimated at 15.
Peanut allergens are taken up by dendritic cells in the gastrointestinal tract. Dendritic cells are a subset
of white blood cells and , they can be considered as the first line of defense from the immune system.
They present the peanut proteins to other cells of the immune system, the second line of defense, which
results in the production of specific IgE antibodies to peanut. These antibodies bind to mast cells in the
skin and basophils in the blood. This whole sequence of events is called the sensitization phase, or in
other words: the phase in which one becomes allergic.
When a sensitized patient is re-exposed to peanut the allergenic proteins bind to IgE antibodies on mast
cells and basophils, which subsequently release their content of many different inflammatory mediators
like the well-known histamine. Histamine and the other inflammatory mediators lead to the classic
symptoms of an acute food allergic reaction: itching and swelling of the mouth and lips, rhinitis and
conjunctivitis, skin symptoms, gastrointestinal symptoms and in case of severe reactions also respiratory
and cardiovascular symptoms.
The diagnosis of food allergy is based on taking a careful history: the food that was ingested, the time
interval between ingestions and how soon after ingestion the symptoms started, whether similar
symptoms were present on a previous exposure and the development of the specific symptoms over
time. Further analysis consists of detection of specific IgE antibodies by skin prick test, blood test or
both. Recent developments in the way we diagnose food allergy involve the use of specific allergen
components instead of extracts of the whole food. This has the potential to increase the diagnostic value.
The gold standard is the double blind provocation, which is demanding for the patient and requires
dedicated hospital facilities and a well-trained staff.
The therapy of food allergy is still in its infancy. Currently there is no curative therapy. So patients have
to avoid the foods for which they are allergic. In real life this can be very challenging, especially when the
food is used in many different food products, as is the case for milk, egg, peanut and hazelnut. In addition,
most patients are allergic to more than one food, on average about six different foods, which they all
have to try to avoid. Current strategies for food package labeling often result in misinterpretation,
misunderstanding and even in risk taking behavior, because of the large amount of products that contain
precautionary statements, like: ‘made in a facility that also produces … or may contain traces of .. etc.
Also mistakes in the preparation of food e.g. in restaurants contribute to the risk. Therefore patients are
advised to always take emergency medication with them, like antihistamines and the adrenaline auto-
injector, tot treat themselves in case of an acute allergic reaction, prior to consulting an emergency
department, or allergy specialist.
Let’s come back to the case of mealworm: recent research revealed that introduction of mealworm in the
food chain might lead to a considerable risk of allergic reactions in shrimp and shellfish allergic patients,
and possibly also in patients with other allergies. This illustrates that the introduction of novel foods
needs to be accompanied by careful assessment of the allergenic risks. For mealworm the outcome of the
assessment of the allergenic risks means that products containing mealworm need to be adequately
labelled, which is currently not always the case.
Current research further focusses on curative treatment options. Different vaccination therapies have
been tried so far with varying degrees of success. Oral administration of increasing doses of peanut
resulted in increased tolerance to peanut, but the effect seems only to last as long as the treatment is
given. Moreover the treatment is hampered by a substantial number of sometimes severe side-effects.
The epicutaneous route of administration was explored recently with only mild side-effects, but efficacy
mainly in children and clearly less in adults. Hypoallergenic vaccines are under development that
promises fewer side effects, but their efficacy has to be established.
To conclude: the prevalence of food allergy is probably on the rise resulting in many diagnostic and even
more therapeutic challenges in the near future. This may also affect the development of alternative
sustainable foods that are high in proteins.
