Fruit and Vegetables and Cardiovascular Health
Recent results from the Women’s Health Initiative indicate that a diet low in fat but high in fruit, vegetables and grains does not significantly reduce the risk of cardiovascular disease in postmenopausal women. These results were unexpected and almost shocking, seemingly reversing the evidence from previous studies that was thought be solid. Despite these findings, other randomized studies strongly suggest that dietary changes can have beneficial effects on several cardiovascular risk factors, among them blood pressure, lipid levels, homocysteine levels, oxidative stress, inflammation, and endothelial function. Also, a large number of prospective observational studies support that particularly high fruit and vegetable consumption is beneficial, reducing the risk of cardiovascular events. A greater dietary change than the one achieved in the Women’s Health Initiative is probably necessary to have an impact. That higher fruit and vegetable consumption as part of a healthy diet reduces blood pressure has been convincingly shown, but there is also evidence that it is related to lower increases in blood pressure over the life course. Potential nutrients involved include fiber, potassium, magnesium, vitamins, and antioxidants. For potassium, the evidence from supplementation trials strongly suggests that it in part explains the beneficial effects of fruit and vegetables on blood pressure. Although folate has a well-proven effect on plasma homocysteine concentrations and antioxidant vitamins have been demonstrated in experimental studies to reduce oxidative stress, clinical trials on folate or vitamin E supplementation among patients with CHD have been largely disappointing. The lack of primary prevention studies and the partly non equivalence of supplements to the natural form limit the usefulness of these studies. In addition, the abundance of a variety of antioxidants and other beneficial nutrients, like potassium and fiber, in fruits and vegetables highlight that emphasizing higher fruit and vegetable consumption instead of supplements will reduce the burden of cardiovascular diseases in Europe. The evidence, despite the null results from the Women’s Health Initiative, is overwhelmingly supportive here.