Vegetable and fruit consumption, education and plasma vitamin C concentration in Russian and Finnish Karelia, 1992-2002

Objective: To examine (i) whether the consumption of fresh vegetables, fruit and berries is associated with plasma vitamin C concentration and (ii) educational differences in plasma vitamin C concentration in two neighbouring areas in Russia and Finland. Design: Cross-sectional risk factor surveys in 1992, 1997 and 2002. Logistic regression analysis was applied to examine the associations of consumption of selected foods and education with plasma vitamin C concentration. Setting: District of Pitkaranta in the Republic of Karelia, Russia and North Karelia, Finland. Subjects: Adults aged 25-64 years: 579 men and 612 women in Pitkaranta; 974 men and 642 women in North Karelia. Results: The plasma vitamin C concentration was strikingly low in Pitkaranta, Russia across the study years. During the 10 years of monitoring, the mean plasma vitamin C concentration among men ranged from 2.5 to 8.0 mu mol/l in Pitkaranta, Russia and from 27.1 to 53.9 mu mol/l in North Karelia, Finland. In both areas, daily consumption of fruit was most strongly associated with plasma vitamin C, while the association of fresh vegetable consumption with plasma vitamin C was less consistent. Consumption of berries was less important in explaining plasma vitamin C. In Pitkaranta, the plasma vitamin C concentration was lower among respondents in the lowest education group. Conclusions: Differences in the consumption of fresh vegetables and fruit resulted in notable differences in vitamin C status between Pitkaranta and North Karelia in spring. In comparative settings, knowledge of local food culture and validation pilots are important before conducting large population surveys.