How do fruit and vegetables prevent heart disease and type 2 diabetes?

EPIDEMIOLOGY
The association between fruit and vegetable intakes and cardiovascular disease (CVD) has been recently reviewed in Current Opinion in Lipidology [1], but there is much less data about type 2 diabetes. The European Prospective Investigation into Cancer and Nutrition (EPIC) study [2&] has shown a 10% reduction in incident cases of type 2 diabetes comparing the highest to the lowest quintile of flavonoid intake (P¼0.04 for trend) with stronger effects for the individual classes of flavonols, flavanols and flavan-3-ol monomers (18%–27% reduction in risk). Tea, onion, broccoli, apple, grape, coffee, beans, apples and pears are major sources of flavanols in the diet, whereas oranges and grapefruit are major sources of flavonols. Previously, EPIC reported that only green leafy vegetables and not other vegetables or fruit were associated with protection from type 2 diabetes with a 16% reduction with the highest intake [3]. We have found that total vegetables are also related to arterial stiffness as measured by pulse wave velocity [4]. Dietary nitrate has also been suggested as a possible mediator of protection from diabetes, as green leafy vegetables are a rich source of nitrate. In men only, in Finland, berries appear to be protective [5].