Tomato allergy has the peculiarity that a person can be allergic to its seeds but not to the rest, and eat the vegetable without developing symptoms, as long as that part is not included. In fact, one of the allergens responsible for the reaction that has been identified is found in this part of the fruit, which is found in the innermost part of the tomato, along with a whitish area called the placenta.
Now, a team of scientists led by the Complutense University of Madrid (UCM) has discovered two new allergens. "These proteins are very stable and resistant to heat treatment and the digestive process, so you can have an allergy even to cooked food, something that does not happen with other food allergens", explains Mayte Villalba, researcher at the Department of Biochemistry and Molecular Biology I of the UCM and main author of the study.
The proteins, which belong to the same family (Sola l 7 and Sola l 6), are found exclusively in tomato seeds. The scientists took samples from 22 patients allergic to the plant from the Infanta Leonor (Madrid) and Malaga Regional University hospitals.
In their medical history, all the patients, with a mean age of 33.5 years, presented different symptoms when consuming the food, from anaphylaxis (severe allergic reaction throughout the body) to urticaria or oral allergy syndrome (changes in the mouth and throat). Some noticed that the symptoms disappeared when the seeds of the vegetable were removed, although most stopped eating it when they noticed the first reactions.
An allergy unknown to many
The scientists used serum samples from the patients to work in vitro with the proteins purified and isolated from the seeds. Both gave positive results in the SPT test, which is used to find out if allergens react on the skin.
The study, published in Molecular Nutrition and Food Research and with the participation of the Center for Plant Biotechnology and Genomics, concludes that both proteins can help in the diagnosis of allergy, which affects between 1.5% and 20%. % of the population and are unaware of a large part of the patients.
“The problem lies in the fact that there are certain parts of the food that are removed during its handling during the preparation of the dish, such as the seeds. When this separation is not carried out, unexpected allergic reactions may appear ”, Villalba points out.
Symptoms will vary depending on multiple factors such as the state of the patient's intestinal tract, the combination with allergens from other foods or the intake of drugs.
Bibliographic reference: Martín-Pedraza L, González M, Gómez F, Blanca-López N, Garrido-Arandia M, Rodríguez R, Torres MJ, Blanca M, Villalba M and Mayorga C. “Two nonspecific lipid transfer proteins (nsLTPs) from tomato seeds are associated to severe symptoms of tomato-allergic patients ”Molecular Nutrition and Food Research 60 (5) May 2016. DOI: 10.1002 / mnfr.201500782.