Differences in cow's milk composition between Iceland and the other Nordic countries and possible connections to public health

Abstract

Background: The Icelandic bovine herd has been isolated for over 1100 years. Knowledge is needed about how its milk constituents differ from those of milk in the other Nordic countries, where cattle have been interbred with other European races. As milk and dairy products comprise a substantial part of food intake, especially in children, variations in cow's milk composition may be of value when considering environmental factors in public health. Regional variation in milk composition may explain contradictory results from studies on milk consumption and aetiology of diseases, type 1 diabetes mellitus and cardiovascular disease. Objective: To investigate differences in milk composition, particularly substances suggested to influence public health. Design: Analyses of the proteins ß-casein and ß-lactoglobulin, as well as fatty acid profiles and nitrates, were performed in samples of cow's milk as sold to consumers, at four different times during 1 year in three different regions in Iceland and in the capital areas of the other countries. Results: The Icelandic milk was significantly (p<0.05) lower in ß-casein fractions A1 and B and higher in the A2 fraction, lower in ß-lactoglobulin B and higher in A (p<0.001), had less than half in n-6/n-3 ratio and was higher in the very long-chain n-3 fatty acids and conjugated linoleic acid. It was slightly higher in saturated fatty acids. No significant difference was seen in the total amount of ß-caseins, ß-lactoglobulins or nitrates. Conclusions: Although slightly higher in saturated fatty acids, the Icelandic milk has a composition of proteins and fatty acids that may be associated with health benefits.