Science - December 2, 2015

Edible insect can provoke allergies

Rob Ramaker

People that are allergic to shellfish and dust mites run the risk of also reacting to edible insects, even if the insects have been baked. This calls for caution now that eating insects is becoming more common in the West.

Image: in 2012 the first Dutch insect cook book was published.

Sarah Broekhoven concluded this in her thesis that she defended on Tuesday.

Around the world people traditionally eat insects, except for in the West. But it seems that this taboo is decreasing. The insect cook book written by the Wageningen professor Arnold van Huis and Marcel Dicke received a lot of attention in the Netherlands. And a UN report that explains why proteins from ‘micro livestock’ is more sustainable than for example pig or cattle meat was immensely popular. In specialty shops and sometimes even in supermarkets you can already find mealworms and grasshoppers on the shelves. Yet still a couple of practical hurdles need to be overcome before edible insects are ordinary.

Uncertainty about safety is one of those obstacles. For example, there are anecdotes known about people that experience an allergic reaction after eating insects. The Voedingscentrum (Dutch nutrition centre) warns people with shellfish and dust mite allergies. After all, edible insects like shrimp or dust mite belong to the arthropods and their allergy inducing protein are very similar. That is why Van Broekhoven was interested if people with a known allergy were indeed sensitive. ‘It is a logical first step to find people with an allergic reaction for edible insects.’

[There] are known anecdotes about people that experienced an allergic reaction after eating insects.

With laboratory experiments Van Broekhoeven showed that the blood of seven people with shellfish or dust mite allergies indeed had antibodies against mealworms and reacted with an immune reaction to the proteins. This even happened when the mealworms had been baked, although the reaction was weaker. Precisely this test was particularly relevant, Van Broekhoven explains, ‘in our country it is presumable that we will not eat the insects raw’. Blood samples of sixteen people that had unrelated allergies, for example pollen, showed no reaction to mealworm proteins.

The blood tests alone are no proof that patients will actually react, says Van Broekhoven, but indications of this are beginning to accumulate. A group of scientists of the TNO and the UMC Utrecht suggested on a congress in October in 2014 that people with a prawn allergy also reacted when insect proteins were pricked on their skin. The researchers are still working on the ‘blind’ test where the reaction on the insect proteins are compared to placebos to provide definite proof.

In the Netherlands about 5 percent of the population has a food allergy, says Van Broekhoven. It differs between people how heavily they react. This varies from light irritation in respiratory tract to life-threatening anaphylactic shock.