Hazelnut allergy patterns by age and region in the United States
What it found
In people tested for hazelnut allergy, young children mostly reacted to storage proteins while adults more often reacted to a pollen-linked protein.
Sensitization to one specific protein stayed near 10% across all ages.
What they found
Studies in people
Age changes allergy targets
Among children under 3 years old with hazelnut antibodies, 89.6% reacted to Cor a 9 and 23.1% reacted to Cor a 14. In adults aged 30 to 40, reactions to Cor a 1 rose to 82.5%.
Region affects one protein
Adults in the Northeastern United States had much higher rates of Cor a 1 antibodies than people in other regions. The authors suggest this is due to heavier exposure to tree pollen like birch in that area.
Cor a 8 stays steady
About 10% of people with hazelnut antibodies reacted to Cor a 8. This rate stayed roughly the same across all age groups and regions in the United States.
Overlap with other nuts
People with hazelnut antibodies often had antibodies to walnut or peanut too. The shared reactions were mostly tied to similar protein families rather than the main storage proteins that cause severe reactions in children.
What the authors conclude
- They conclude that which hazelnut proteins trigger an immune response depends heavily on a person's age and where they live in the United States.
- They note that overlapping reactions between hazelnut and walnut likely come from shared protein families, while hazelnut and peanut overlaps are driven by different shared proteins.
- They call for more research linking these test results to actual symptoms people experience after eating hazelnuts.
How it was done
Hazelnut is among the top five foods causing serious allergic reactions, ranging from mild mouth itching to life-threatening responses. Doctors need better ways to tell who might have a severe reaction from who might only have mild symptoms linked to pollen exposure.
Researchers looked at blood samples from 10,503 people in the United States who already tested positive for hazelnut allergy antibodies. They checked each sample for antibodies against four specific hazelnut proteins. A smaller group was also tested for antibodies to peanut, walnut, and cashew proteins.
What it can’t tell you
- This study only looked at blood tests showing immune sensitivity, not whether people actually had allergic symptoms when eating hazelnuts.
- Because it used existing lab records, scientists cannot know what happened to these patients when they ate the food.
Who paid
- Authors work at
- Center for Esoteric Testing, North Carolina; Uppsala University, Sweden; Johns Hopkins University School of Medicine, Maryland
The paper
- Title
- Sensitization profiles to hazelnut allergens across the United States
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Valcour A, Lidholm J, Borres MP, Hamilton RG (2019). Sensitization profiles to hazelnut allergens across the United States. Annals of allergy, asthma & immunology. doi:10.1016/j.anai.2018.09.466Free full textPubMed 30292797DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error