Coronary risk factors, diet and vitamins as possible explanatory factors of the Swedish north-south gradient in coronary disease: a comparison between two MONICA centres

Objective. To investigate whether differences in serum lipids, diet, plasma vitamins or other risk factors explain the higher incidence of cardiovascu lar disease in the northern parts of Sweden, compared to Goteborg on the we st coast. Design. A comparison between the two Swedish MONICA populations in northern Sweden (NSW) and in Goteborg (GOT) in 1990. Setting. Norrbotten and Vasterbotten counties in the north of Sweden and th e city of Goteborg on the west coast. Subjects. In the north 1583 men and women aged 25-64 years were investigate d, and in Goteborg 1574 men and women. Plasma vitamins were examined in a s ubsample of men aged 40-49 (n = 259). Main outcome measures. Serum lipids, blood pressure, anthropometric measure ments, smelting habits, physical activity, diet, education, and plasma vita mins. Results. NSW men and women had mean serum total cholesterol of 6.30 ( standard deviation 1.23) mmol L-1 and 6.12 (1.33) mmol L-1, compared to 5.7 5 (1.14) mmol L-1 and 5.67 (1.24) mmol L-1 in GOT men and women (P = 0.0001 ). NSW men and women were shorter and had higher body mass index than in Go teborg. Cigarette smoking was slightly more prevalent amongst GOT men and w omen. Goteborg men and women more often had more than compulsory school edu cation, compared to NSW men and women, whereas there were no differences in physical activity during leisure time. There were no differences in vegeta ble consumption, whereas fruit was consumed more frequently by NSW women co mpared to GOT women, with a higher intake of fibre and ascorbate. Consumpti on of wine and total alcohol consumption were higher in Goteborg, whereas N SW men and women drank significantly more coffee. In the subsample of men ( aged 40-49) who had plasma vitamins measured, men in Goteborg had slightly higher mean retinol concentrations (P = 0.005) and lutein and zeaxanthine l evels (P = 0.006 and 0.009, respectively) compared to northern men, but the re were no differences with respect to alpha- or beta-carotene, ascorbic ac id or lipid-adjusted vitamin E. NSW men had slightly higher plasma iron and magnesium concentrations (P = 0.005 and 0.001, respectively). Conclusion. The largest and most consistent differences between Goteborg an d northern Sweden were found for serum cholesterol, probably reflecting dif ferences in intake of saturated fat. The differences in serum cholesterol m ay explain a substantial part of the differences in coronary heart disease morbidity and mortality. We found no consistent differences concerning vege table and fruit consumption. More alcohol was consumed in Goteborg. Differe nces in education and childhood conditions, as reflected in differences in height, may contribute to the north-south gradient with respect to CHD inci dence and mortality.