Objective: To examine the association between plasma vitamin C concentrations and the risk of acute myocardial infarction.
Design: Prospective population study.
Setting: Eastern Finland.
Subjects: 1605 randomly selected men aged 42, 48, 54, or 60 who did not have either symptomatic coronary heart disease or ischaemia on exercise testing at entry to the Kuopio ischaemic heart disease risk factor study in between 1984 and 1989.
Main outcome measures: Number of acute myocardial infarctions; fasting plasma vitamin C concentrations at baseline.
Results: 70 of the men had a fatal or non-fatal myocardial infarction between March 1984 and December 1992. 91 men had vitamin C deficiency (plasma ascorbate <11.4 µmol/l, or 2.0 mg/l), of whom 12 (13.2%) had a myocardial infarction; 1514 men were not deficient in vitamin C, of whom 58 (3.8%) had a myocardial infarction. In a Cox proportional hazards model adjusted for age, year of examination, and season of the year examined (August to Octoberv rest of the year) men who had vitamin C deficiency had a relative risk of acute myocardial infarction of 3.5 (95% confidence interval 1.8 to 6.7, P = 0.0002) compared with those who were not deficient. In another model adjusted additionally for the strongest risk factors for myocardial infarction and for dietary intakes of tea, fibre, carotene, and saturated fats men with a plasma ascorbate concentration <11.4 µmol/l had a relative risk of 2.5 (1.3 to 5.2, P = 0.0095) compared with men with higher plasma vitamin C concentrations.
Conclusion: Vitamin C deficiency, as assessed by low plasma ascorbate concentration, is a risk factor for coronary heart disease.