The Republic of Karelia in north-western Russia and North Karelia in eastern Finland are situated right next to each other. Part of the Republic of Karelia, including the district of Pitkäranta, was part of Finland until the Second World War, when it was annexed to the Soviet Union. The aim of this study was to explore trends and educational differences in food habits and related biomarkers in Pitkäranta, Russia, and North Karelia, Finland, over a 15-year period, which encompasses the early transition years from a centrally planned economy towards a market economy after the dissolution of the Soviet Union in 1991.

Two population-based repeated cross-sectional datasets from the two areas were used: 1) health behaviour surveys from 1994, 1996, 1998, 2000 and 2004 (total n=3599 in Pitkäranta, total n=3652 in North Karelia) and 2) risk factor surveys from 1992, 1997, 2002 and 2007 (total n=2672 in Pitkäranta, total n=5437 in North Karelia). The data were collected by the National Public Health Institute (KTL) (the current National Institute for Health and Welfare, THL) in Finland. In Pitkäranta, the data were collected by the National Public Health Institute in collaboration with the Central Hospital of Pitkäranta and the Ministry of Health and Social Development in the Republic of Karelia.

The trends and overall prevalence in food habits were very different between Pitkäranta and North Karelia. Food habits changed remarkably in Pitkäranta between 1992 and 2007. The proportion of those who used butter in cooking plunged from 50% to less than 10%. The proportion of those who used butter on bread decreased as well, although not consistently. The proportion of persons who consumed fat-containing milk fluctuated. The prevalence of daily consumption of fresh vegetables and fruit increased notably. In North Karelia, the changes were smaller. A small decrease in the proportion of those who used butter or consumed fat-containing milk was observed. The prevalence of daily consumption of fresh vegetables and fruit also decreased slightly in North Karelia.

The educational differences in food habits were somewhat more notable in North Karelia than in Pitkäranta. In general, food habits were less favourable in the lowest compared to the highest education group in both areas. For example, the use of butter in cooking and the consumption of fat-containing milk were more common among subjects in the lowest education group, whereas the daily consumption of vegetables and fruit was more common among their more highly educated counterparts. The education gradient in the quality of spread used on bread was the opposite in the two areas. In Pitkäranta, using butter on bread tended to be more common among men in the highest education group, whereas in North Karelia, men with a low education used butter on bread more often.

The mean serum total cholesterol did not differ by education in Pitkäranta. In North Karelia, it tended to be higher among subjects in the lowest education group. The mean plasma vitamin C concentration was strikingly low in Pitkäranta throughout the study period. In North Karelia, the overall level of plasma vitamin C was higher. The plasma vitamin C concentration tended to be higher among subjects with a higher education in both areas.

The study demonstrated that food habits may change quite rapidly if the local circumstances change. In Pitkäranta, the availability and prices of foods are possible underlying factors that are related to the remarkable changes in food habits. In North Karelia, active health policy and the health consciousness of the population are probably more important in directing food choices.