DIETARY NON ENZYMATIC ANTIOXIDANT CAPACITY AND THE RISK OF CARDIOVASCULAR DISEASES – AN EPIDEMIOLOGICAL APPROACH

ABSTRACT Cardiovascular diseases are the leading cause of premature death and disability in the world. A diet containing high amounts of plant-based foods has been associated with a reduced risk of cardiovascular diseases and the beneficial effect has been attributed to the antioxidants found in the foods. However, findings from randomized controlled trials on the role of antioxidant supplementation have been disappointing, reporting null results or even harmful effects. It has been suggested that antioxidants interact with each other to promote cardiovascular health. Therefore, the Non Enzymatic Antioxidant Capacity (NEAC) assay has been proposed, which measures the antioxidant potential of different dietary sources considering interactions between them. This thesis aimed to further clarify the effect of dietary antioxidants on the risk of cardiovascular diseases, with particular interest in measuring NEAC from diet. The specific aims were to prospectively study whether dietary NEAC is associated with a lower risk of myocardial infarction, stroke and heart failure in subjects free from CVD or cancer. Four studies were conducted using data from two large Swedish cohorts. Multivariable Cox proportional hazard regression models were fitted to estimate hazard ratios (HRs) with 95% confidence intervals (CIs). In the Swedish Women’s Lifestyle and Health Cohort (n = 45,882), a higher baseline dietary NEAC was inversely associated with the risk of myocardial infarction (quintile 5 vs. quintile 1: HR: 0.60, 95% CI: 0.45-0.81, p for trend < 0.05) and heart failure (tertile 3 vs. tertile 1: HR: 0.63; 95% CI: 0.43-0.93; p for trend < 0.05) in young to middle aged women, whereas no association was found between dietary NEAC and stroke. In the Swedish National March Cohort (n = 34,543), dietary NEAC was inversely associated with the risk of overall (quartile 4 vs. quartile 1: HR: 0.77, 95% CI: 0.61-0.96; p for trend < 0.05) and non-fatal myocardial infarction (quartile 4 vs. quartile 1: HR: 0.72; 95% CI: 0.56-0.92; p for trend < 0.05), but not with fatal myocardial infarction. The association seemed to further be stronger in women compared to men. To conclude, these findings support the hypothesis that a diet with high NEAC might protect from the development of myocardial infarction and heart failure and that the beneficial effect might be exerted through interactions between antioxidants. Whether this is true for stroke needs to be further investigated. Nevertheless, it is suggested to implement high amounts of antioxidant rich foods and beverages, such as fruits, vegetables, whole grains and tea, in the daily diet to lower the burden of cardiovascular diseases.