We examined trends and educational differences in serum total cholesterol and in the consumption of major sources of saturated fat in diet from 1992 to 2007 in the district of Pitkäranta in the Republic of Karelia, Russia, and North Karelia, Finland. We also examined which saturated fat sources were associated with serum cholesterol in the two areas. Our study period encompasses the years of major changes in the political and economical system in Russia after the collapse of the Soviet Union in 1991.
During the study period, serum cholesterol levels fluctuated in Pitkäranta. No apparent educational differences were seen. Dramatic changes in food habits selected as indicators of saturated fat intake occurred in Pitkäranta; using butter in cooking tumbled in all education groups, whereas consuming fatty cheese on a daily basis became substantially more common, even more so in the high education group than among subjects with a low educational level. In North Karelia, the changes in cholesterol levels were in line with the changes in food habits. As the consumption of foods with saturated fat decreased, so did the cholesterol levels in the population. In addition, as the educational differences in food habits narrowed, so did the educational difference in cholesterol levels. Parallel changes have been observed in Lithuania, a Baltic country that was part of the Soviet Union until 1991, where using butter on bread halved and using vegetable oil in cooking increased six fold from 1993 to 2007 . In Lithuania, the changes in serum total cholesterol were in line with the favourable changes in diet; serum total cholesterol fell by about 0.50 mmol/l in 1993–2007. Consumption of cheese was not reported in this study.
The sources of saturated fat in diet that were associated with serum cholesterol levels were quite different in the two areas, namely the district of Pitkäranta in the Republic of Karelia, Russia, and North Karelia, Finland. In Pitkäranta, drinking fat-containing milk had the strongest association with serum cholesterol in our study. In North Karelia, Finland, on the other hand, using butter in cooking and using butter on bread were most strongly associated with cholesterol.
In Pitkäranta, drinking fat-containing milk may reflect other food habits that were not included in our study, e.g. frequent use of fatty meat or smetana (Russian sour cream), though it emerged as the single significant predictor of cholesterol in our study. In North Karelia, drinking fat-containing milk did not seem to be associated with cholesterol. However, in our analyses, ’drinking fat-containing milk’ included all milk types that contain some fat, and it is likely that ‘fat-containing milk’ had on average a lower fat content in the data from North Karelia compared to the data from Pitkäranta. This might partly explain the weaker association between milk and cholesterol in North Karelia. Unlike in North Karelia, low-fat milk was not readily available in Pitkäranta over the study years. Regarding the data from North Karelia, milk that contains only 1% fat was also included in the category ‘fat-containing milk’, even though Finnish nutrition recommendations recommend it together with skimmed milk.
In Pitkäranta, consumption of cheese was more common among subjects with higher educational level. Similar differences have been observed earlier in Finland as well , but in our study, which only included North Karelia in eastern Finland, the educational differences in fatty cheese consumption did not reach statistical significance. Daily consumption of low-fat cheese was more common among subjects with a high education in 1992. It seems that in Finland, persons with a higher education may have been the first to shift from fatty cheese to low-fat cheese, but the educational differences have levelled off with time.
Despite their common history before the Second World War, the district of Pitkäranta in the Republic of Karelia, Russia, and North Karelia in Finland have been economically and politically distinct from each other since. Our study in these two distinct areas gives rise to several methodological questions. One such issue is how feasible is it to use questionnaires that are basically similar in different settings, even if the questions and multiple-choice options have been modified to suit local circumstances. In many cases, the questionnaires have originally been designed for one target population, in our case Finnish citizens. For example, in Finland, it is very common to spread butter or margarine on bread. However, this is not the case in Russia, where bread is often eaten without spread and the important sources of fat are likely to be something else.
Our study only included dairy fat sources as indicators of saturated fat intake. There are, however, other important sources of saturated fat like meat and meat products as well . A self-administered questionnaire with only a few food-related questions cannot include all important sources of saturated fats. Furthermore, it cannot measure the share of the total fat intake accounted for by saturated fat.
The situation with cardiovascular disease has been very different between North Karelia, Finland, and the Republic of Karelia, Russia. North Karelia started in the 1970’s with very high CVD rates and very high average serum cholesterol level and has had a fairly steady decline thereafter. On the other hand, Russia had initially much lower CVD rates, but during the last few decades marked increase. The initially lower level of serum cholesterol in Russia can obviously be explained by the low availability and accessibility of dairy fat products in Russia. The later increase indicates the changing economic situation, while in Finland active health promotion has been behind the marked reduction in the consumption of dairy fat products and CVD rates.