Fruit and vegetable consumption and the risk of cardiovascular diseases

Background: Prospective cohort studies have shown that the consumption of total fruit and vegetables is associated with a lower risk of coronary heart disease (CHD) and stroke. It is not known which aspects of fruit and vegetable consumption contribute to these beneficial associations. The objective of this PhD research was to investigate different aspects of fruit and vegetable consumption, i.e. amount, processing, variety and color, in relation to 10-year incidence of CHD and stroke. Methods: Data were used from the Monitoring Project on Risk Factors and Chronic Diseases in the Netherlands (MORGEN Study). This is a prospective population-based cohort study in over 22,000 men and women aged 20 to 65 years who were enrolled from 1993 to 1997. We selected 20,069 participants who were free of cardiovascular diseases (CVD) at baseline and were followed for an average of 10 years for non-fatal and fatal cases of CVD. All participants completed a validated 178- item food frequency questionnaire at baseline to measure habitual dietary intake in the previous year. Results: During follow-up, 245 cases of CHD and 233 cases of stroke were documented. An inverse dose-response relationship was observed between total fruit and vegetable consumption and incident CHD, but not for incident stroke. Participants with a total fruit and vegetable consumption of more than 475 grams per day had a 34% lower risk of CHD (Q4: HR: 0.66; 95% CI:0.45-0.99) compared to those with a low intake (Q1: ≤241 g/d). High intake of raw fruit and vegetables (Q4: >262 vs Q1: ≤92 g/d) was associated with a 30% lower risk of either CHD (HR: 0.70; 95% CI: 0.47-1.04) or stroke (HR: 0.70; 95% CI: 0.47-1.03). Variety was strongly associated with total fruit and vegetable consumption, not with incident CHD or stroke. The intake of deep orange fruit and vegetables and especially carrots was inversely associated with CHD (per 25 g/d increase; HR: 0.74; 95% CI:0.55- 1.00). High intake of white fruit and vegetables (Q4: >171 vs Q1: ≤78 g/d), such as apples and pears, was associated with a 52% lower risk of stroke (HR: 0.48; 95% CI:0.29-0.77). Conclusion: The findings presented in this thesis suggest that total fruit and vegetable consumption was inversely related to incident CHD, but not to incident stroke. Raw fruit and vegetable consumption, however, may protect against CHD and stroke incidence. These results suggest that to prevent CVD at least 50% of the recommended daily amounts of fruit and vegetables should comprise raw fruit and vegetables. Before solid recommendations on different aspects of fruit and vegetable consumption can be made, results from additional prospective cohort and intervention studies are needed.