Hazelnut allergy

Most adults in central Europe who are sensitised to hazelnut react to Cor a 1. This protein looks like the main birch pollen protein, Bet v 1, so the antibodies are really aimed at birch. Reactions linked to Cor a 1 are usually limited to the mouth and throat: itching, tingling, mild swelling. Roasting tends to reduce them.

A smaller group is sensitised to hazelnut storage proteins such as Cor a 9 and Cor a 14. These survive heat and digestion, and they are associated with more widespread reactions. Specialists treat that pattern more cautiously. The panel measures both kinds. Which pattern applies to you is something a doctor reads from these component results and your history.

The classic description is itching or tingling of the lips, mouth or throat within minutes of eating raw hazelnuts, often in people who also sneeze in spring. This is called oral allergy syndrome or pollen food syndrome.

Less often, people report hives, stomach symptoms or breathing trouble. Swelling of the throat or trouble breathing is an emergency. Call 112 (EU) or your local emergency number.

Hazel trees release pollen in late winter, often from January. Hazel pollen shares similar proteins with birch and alder pollen, so people sensitised to one often show the others. Reacting to the pollen does not automatically mean reacting to the nut, and the reverse is also true.

The panel measures the nut, not hazel pollen. Birch (Bet v 1) and alder (Aln g 1) are the pollen markers that sit closest to hazel.

The lab measures IgE to five single hazelnut proteins (molecular components). There is no whole hazelnut extract on the panel. Your lab report gives each a measured value and class, from Negative to Very high, on the same report as birch and alder pollen, so you can see the pattern. Sensitisation is not the same as a clinical allergy. Discuss the result with a doctor before you change what you eat.