To determine the plasma ascorbic acid concentrations among men in North Karelia (Finland) and in Pitkäranta (Republic of Karelia) and to test how a short intervention would affect the plasma concentrations.
The baseline survey was done as a cross-sectional population survey. A subsample was selected to the intervention study and randomised to treatment and control groups.
North Karelia province in Finland and the Pitkäranta area in the Republic of Karelia.
In the cross-section population survey the stratified random sample of men between 25 and 64 years of age was 1000 in North Karelia and 500 in Pitkäranta. Participation rates were 68% and 77%, respectively. Plasma ascorbic acid measurements were made in one-third of the sample. In Pitkäranta 60 men, having very low plasma ascorbic acid concentrations, were invited to the intervention study.
A controlled intervention study was made with blackcurrant-strawberry nectar in which vitamin C content was approximately 70 mg/100 g. The treatment group drank two times daily 200 ml nectar for 4-5 weeks. After intervention plasma ascorbic acid concentration was measured from both treatment and control groups.
Plasma ascorbic acid concentrations were very different in the two areas. In Pitkäranta 93% of the men and in North Karelia only 2% of the men had plasma levels suggesting severe vitamin C deficiency. After intervention 46% of the men in the experimental group compared with 5% in the control group had plasma ascorbic acid concentrations exceeding 23 mumol/l (4.0 mg/l).
In addition to a high smoking prevalence the very low ascorbic acid concentration among men in the Republic Karelia can have an effect on the high cardiovascular disease mortality.