Abstract

To increase the knowledge on food allergy in Norway, the Norwegian National Reporting System and Register of Severe Allergic Reactions to Food was established in 2000. Cases of severe reactions to food are reported by first-line doctors on a one-page form. Serum samples of the patient may be sent together with the form for analyses of specific IgE-antibodies to a panel of food allergens. Specific IgE to pollen allergens are also analyzed since plant foods in general often have homologous protein sequences that may cause cross-reactions. By the end of 2015 the Food Allergy Register had received 1470 reports. Results from the Food Allergy Register show increased prevalence in sensitization to hazelnut, peanut and birch pollen from 2000 up to 2016. Analysis of the birch pollen-homologues in hazelnut and peanut show that the increase is mainly due to cross-reactions caused by sensitization to birch pollen. Over time, a change in the age distribution of the reported patients was noted. The age groups showed two peaks at 0-5 years and 21-35 years up to 2008, changing to only the one group of small children in 2015. The four most common foods the children are sensitized to have changed from being egg >, milk >, hazelnut and >peanut, to equal numbers being sensitized to peanut and egg, with hazelnut and milk as the third and fourth most common allergen. From the age of 6 years, sensitizations to hazelnut and peanut have constantly been most frequent. In 2015, however, the third and fourth most common foods to cause sensitizations changed from being celery and shrimp to wheat and celery, respectively. Reactions to fish are seldom reported. The gender distribution 40: 60 men: women have been constant over the years, but in small children the distribution is 70: 30 boys: girls.