BY HOW MUCH DOES FRUIT AND VEGETABLE CONSUMPTION REDUCE THE RISK OF ISCHEMIC-HEART-DISEASE

Objective: To quantify the relationship between fruit and vegetable co nsumption and the incidence of ischaemic heart disease. Design: A meta -analysis of cohort studies of the relationship between ischaemic hear t disease and markers of fruit and vegetable consumption, namely dieta ry intake of fruit, vegetables, carotenoids, vitamin C, fruit fibre an d vegetable fibre, and serum concentration of carotenoids and vitamin C, adjusted for other risk factors. Main outcome measures: Risk of isc haemic heart disease at the 90th centile of consumption relative to th at at the 10th, equivalent to about a four-fold difference in fruit co nsumption and a doubling of vegetable consumption. Results: The associ ation with ischaemic heart disease was of similar magnitude for all si x dietary markers of fruit and vegetable consumption. The median of th e six estimates was that risk was 15% (range 12-19%) lower at the 90th centile of consumption than at the 10th. The estimates were generally adjusted for the possible confounding effect of other heart disease r isk factors. The serum studies of vitamin C were consistent with this; those of carotenoids suggested a larger difference (43%) bur were not adjusted for the important confounding effect of smoking. The substan ces in fruit and vegetables responsible for the protective effect on h eart disease are uncertain but the effect is commensurate with the est imated protective effects of the potassium and folate in fruit and veg etables. Beta-carotene or vitamin E are not likely to be important bec ause randomised trials of these vitamins in large doses have shown no reduction in heart disease mortality. Conclusions: The risk of ischaem ic heart disease is about 15% lower at the 90th than the 10th centile of fruit and vegetable consumption.