Why strawberries and tomatoes can be a health hazard for many people

Allergy potential may vary depending on the type of vegetable or fruit

Tomatoes and strawberries enjoy great popularity and are among the most consumed vegetables and fruits. However, many people experience allergic reactions when they eat the otherwise healthy foods. In particular, people with birch pollen allergy show such reactions. A Munich-based research team has now discovered strawberry and tomato varieties that contain fewer allergens.

Maybe people who are allergic to strawberries and tomatoes will not have to go without it soon. A research team from the Technical University of Munich (TUM) dealt in a recent study with the allergy potential of strawberries and tomatoes and found that both the respective variety and the preparation methods influence. The research results were recently published in the journals "Plos one" and "nutrients".

Strawberries and tomatoes are popular fruits and vegetables, but they also cause allergic reactions in many people. Munich researchers now identified ways to breed varieties that are also suitable for allergy sufferers. (Image: alicja neumiler / fotolia.com)

Food allergies are constantly increasing

According to the TUM experts, the incidence of food allergies has steadily increased in recent decades: around four percent of adults and about five percent of children are already affected. The studies focus on tomatoes (botanical: Solanum lycopersicum) and strawberries (botanical: Fragaria x ananassa), which contain allergenic proteins and often trigger allergic reactions.

The triggers are similar to birch pollen allergy

According to the scientists, the allergenic proteins in the tomatoes and strawberries are similar to birch pollen. From this similarity may arise due to a birch pollen allergy and a food allergy. In Italy, even up to 16 percent of the population are affected by a tomato allergy. According to the researchers, 30 percent of those who have birch pollen allergy also suffer from allergic reactions to strawberry fruits.

Immune reactions can express themselves in many ways

Allergic reactions to tomatoes and strawberries can manifest themselves in many ways. The researchers report that allergy to the skin (itchy rash, nettle rash or dermatitis) may irritate the mucous membranes, cause colds and may also cause abdominal pain. Food allergies often show symptoms after eating fresh fruit or vegetables, whereas processed foods often do not trigger reactions.

A protein is the main cause

In two studies, the team led by Professor Wilfried Schwab from the Chair of Natural Biotechnology at TUM quantify the triggering protein in the different strawberry and tomato varieties that is the main cause of the allergic reactions (Sola l 4.02 for tomatoes and Fra a 1 protein for strawberries).

Find the best possible variant for allergy sufferers

In addition to different varieties, the size, shape and color was considered. Furthermore, the experts also examined the possible influence of biological and conventional growing conditions as well as various processing methods from the sun to the kiln drying to freeze drying. The aim of the research was to find the best possible variants for allergy sufferers.

Variety and heat make the difference

Finally, the team examined twenty-three different tomato varieties and twenty strawberry varieties of different size and shape. The results show that the content of the allergen in the different strawberry and tomato varieties varies greatly. In addition, the factor heat seems to have an influence. When the fruits were exposed to heat during the drying process, fewer allergenic proteins were present.

The perfect fruit for allergy sufferers soon available?

However, the growing conditions seem to be negligible in the development of allergenic proteins. Based on the research results, it should now be possible to breed hypoallergenic tomato and strawberry varieties, which can be eaten by allergy sufferers, the study authors conclude. (Vb)