The Scottish Heart Health Study is an ongoing prospective cohort study of men and women carried out to evaluate risk factors for various coronary heart disease (CHD) events. Patient accrual took place between 1984 and 1987. Reports quantifying various risk factors for prevalent CHD at baseline have been published. Furthermore, preliminary evaluation of risk factors for incident coronary events during long-term follow-up and all-causes mortality have been published. The authors of the present article point out that in the preliminary evaluation, intake levels of antioxidant vitamins were evaluated as risk factors unadjusted for total energy intake and that low intake of antioxidants did not rank as high as the "classic" risk factors for coronary heart events with respect to level of risk. In the present evaluation, the authors re-examined intake of antioxidant vitamins adjusted for total energy intake, age, and other CHD risk factors.

Methods:

11,629 participants were recruited through general practitioners from 25 Scottish districts. These were men and women aged 40-59 at baseline. Along with sociodemographic data, "classic" risk factor baseline data included Rose Chest Pain Question responses, medical record evaluation, ECG, BP, and serum total cholesterol. A semi-quantitative food frequency questionnaire was used and specifically validated for antioxidant levels against plasma levels. Nutrient intakes were calculated using standard tables. Dietary carotenoids were calculated as beta-carotene equivalents. Participants were flagged on the Scottish National Health Service Register and followed through hospital discharge data for coronary events and all-causes mortality, including through death certificate data. Mean current follow-up was 7.7 years.

Results:

The total energy-adjusted consumption of vitamins C and E, beta-carotene, and fiber were higher among women than men.

Among men, energy adjusted intake levels of vitamin C, beta-carotene and fiber in the upper quartile were associated with decreased risks of incident CHD (shown in graph). For fiber and vitamin C, intake level in the 3rd quartile was also associated with decreased risk of CHD. There were similar decreases in risk of all-causes mortality. Higher vitamin E intake was mildly associated with decreased risk of all-causes mortality (38% decrease, 95% CI=8,58) and, the authors concluded, with decreased risk of CHD (note: This reviewer noted that the tables reported in the article indicated weaker associations for vitamin E and CHD than found for vitamin C). Among women, whose overall intake of fiber and antioxidant vitamins was higher, only increased fiber intake was associated with decreased risk of CHD or all-causes mortality.

Reference

1. Todd S, Woodward M, Tunstell-Pedoe H, Bolton-Smith C. Dietary antioxidant vitamins and fiber in the etiology of cardiovascular disease and all-causes mortality: results from the Scottish Heart Health Study. Am J Epidemiol 150: 1073-1080, 1999.