To sum it up...
Evidence that fruit and vegetable consumption has a protective effect against CVD comes mainly from observational epidemiological studies. Most of these studies show a decrease in the risk of CHD and CVD with fruit and vegetable consumption. However, as fruit and vegetable intake is associated with particular social, cultural, and lifestyle characteristics that might also confer protection against CVD and, as these confounders are not adequately controlled in observational studies, the conclusion that a causal relationship exists between fruit and vegetable intake and CVD prevention is not justified. Controlled, nutritional prevention trials are still scarce, and the results so far have not shown conclusively that fruit and vegetable intake protects against CVD, in part because the dietary interventions have not been intensive enough to enable optimal analysis of their putative effects.
Under rigorously controlled experimental conditions, fruit and vegetable consumption is associated with a decrease in blood pressure—an important CVD risk factor. The effects of fruit and vegetables on plasma lipid levels, diabetes, and body weight have not yet been thoroughly explored. The hypothesis that components of fruit and vegetables decrease atheroma formation and prevent its complications has been explored in animal models, in vitro cell culture systems and in human studies using integrated end points. In view of the complexity of fruit and vegetable composition and of disease pathophysiology, the relevance of these models to biological plausibility of the association between fruit and vegetable consumption and CHD remains debatable.
In conclusion, fruit and vegetables should be eaten as part of a balanced diet, as a source of vitamins, fiber, phytochemicals, and water. Substitution of harmful foods with fruit and vegetables might reduce CVD events and provide a basis for public health recommendations. Confirmation that fruit and vegetables per se have a protective effect against CVD awaits further evidence from nutritional prevention trials and clinical interventions on cardiovascular risk factors. In particular, the quantities of fruit and vegetables necessary for optimal prevention and target population are yet to be defined.