AIM: To compare the consumption of the cow milk proteins A1 and B beta-casein among children and adolescents in Iceland and Scandinavia (Norway, Denmark, Sweden and Finland) as this might explain the lower incidence of type 1 diabetes (per 100,000/year, 0-14 years) in Iceland. METHODS: The consumption of A1 beta-casein in each country among 2- and 11- to 14-year-old children was calculated from results on food intake and on cow milk protein concentration. The consumption values were then compared and evaluated against the incidence of type 1 diabetes. RESULTS: There was a significant difference between the consumption of A1 (p = 0.034) as well as the sum of A1 and B (p = 0.021) beta-casein in Iceland and Scandinavia for 2-year-old children. In the same age group, consumption of A1 beta-casein correlated with the incidence of type 1 diabetes in the countries (r = 0.9; p = 0.037). No significant difference in consumption of A1 or the sum of A1 and B beta-casein was found for 11- to 14-year-old adolescents. CONCLUSION: This study supports that lower consumption of A1 beta-casein might be related to the lower incidence of type 1 diabetes in Iceland than in Scandinavia. Additionally it indicates that consumption in young childhood might be of more importance for the development of the disease incidence than consumption in adolescence. Copyright 2006 S. Karger AG, Basel.