Professor Katrine Lindholm Bøgh from DTU Food has been researching food allergies for more than 20 years, and is enlightening us on everything we know—and don't know—about these allergies.
Are more people getting food allergies?
There are many studies suggesting that food allergies are on the rise, but I think we should be cautious about saying that it is a globally alarming problem. Because we don't actually know for sure.
Most studies are conducted in the West, where we have the resources for—and where citizens may also be focused on—allergy testing. Despite the abundance of Western data, however, there is still a lot of uncertainty associated with saying that a dramatic increase is being seen in the incidence of food allergies.
This is because data is difficult to compare, because studies use different survey methods, and because different allergies are being investigated. At the same time, most data relates to children, with many of them outgrowing their allergy. And we lack proper data on the adult population.
Why do some people develop food allergies?
Developing an allergy is a complex cascade of events in the body involving the immune system and many different types of cells and tissues, so even though researchers around the world have been studying food allergies for decades, an answer still hasn't been found.
For many years, we have known that there are eight foods—the Big Eight—that cause the majority of allergic reactions: peanuts, eggs, milk, soy, wheat, fish, shellfish, and tree nuts. Now, a ninth has been added: sesame seeds.
Since allergies are predominantly triggered by proteins in food, research has focused on proteins in particular. Findings show that the proteins which primarily cause food allergies can be divided into a few groups in which the proteins are molecularly similar. However, we still don't understand why they act as allergens while other proteins do not.
And our knowledge is sparse regarding the interaction between proteins and the immune system, and this is also an area that my research group is working on.
In the research field in general, lifestyle and environmental factors are also being looked at more than ever before.
How can lifestyle and environment play a role?
Various hypotheses have been tested, one of which is that ultra-processed food and its additive content play a role. A new focus area that has gained traction in recent years concerns the chemicals in our environment, and whether they lead to us absorbing food allergens more easily into our bodies.
We also know that allergic reactions can occur via so-called co-factors. Co-factors can be alcohol, stress, exercise, and medication, and it has been found that some people may react to a food that they can normally tolerate when exposed to a co-factor. We don't yet fully understand why this happens to them.
You have said that one should eat foods before applying them to the skin. What do you mean by this?
It was once thought that it was best to wait as long as possible before introducing highly allergenic foods to young children, but unfortunately it turned out that this actually increased the risk of developing food allergies. This is because you can still be exposed to food allergens, just through your skin. This can happen, for example, when applying care products that contain food ingredients.
And there are many products that contain food ingredients. Our research group conducted a study for the Danish Environmental Protection Agency where we investigated how many cosmetic products such as shampoo and creams contain food ingredients, and we found this to be the case in more than 25 per cent of the products.
Children—and especially those with childhood eczema where the skin barrier is broken—are at a higher risk of developing allergies when the first time they encounter a highly allergenic food ingredient is via the skin rather than through what they eat. This is because humans are designed to build tolerance through diet.
What should we look out for in future?
We must ensure, among other things, that in developing new foods we do not introduce a new peanut, i.e. an allergen that many people react to and which can lead to very serious reactions and potentially death. We also need to be careful that we don't put allergy sufferers at further risk. We can see, for example, that shellfish allergy sufferers can also react to insects.
The same goes for new food ingredients, which we also need to follow. Recently, there have been several reports of an increase in allergies to peas. Peas are not exactly a new food, but the industry has modified peas, and uses pea protein to fortify other foods. Suddenly, we're being exposed to larger amounts of pea protein, and in a different way than before.
Even when we want to utilize side streams or residual products from the food industry, we risk exposing consumers to new or increased exposure to proteins that we either haven't eaten before, or which we can normally tolerate, but which in larger quantities can lead to allergies.
It all requires close monitoring. The best thing would be to develop robust methods for assessing and predicting the level of risk.
