Healthy adults who consumed at least five servings of fruit and vegetables daily had lower blood pressure than adults who consumed fewer servings over a period of time. The findings support previous research showing that a fruit and vegetable rich diet boosts levels of antioxidants in the blood and reduces blood pressure in the short term.
To investigate the long term effects of such a diet, the researchers at the University of Oxford in the UK assigned nearly 700 adults aged 25 to 64 to follow their regular diet or to eat at least five servings of fruit and vegetables daily. One serving is equal to 80 grams (about one medium-sized piece of fruit or half a cup of cooked vegetables). Adults who took vitamin pills were not included in the study.
Over the next 6 months, levels of certain antioxidants including vitamin C, lutein and beta-carotene increased in the group of adults encouraged to increase their fruit and vegetable intake but not in the other group. There were no changes in body weight or cholesterol levels but the systolic blood pressure (the pressure of the blood on the arterial walls each time the heart contracts) of adults who consumed more fruit and vegetables fell by about 4 mm Hg and their diastolic pressure (the pressure during the resting phase between contractions) fell by 1.5 mm Hg. This fall in blood pressure achieved in the study is unlikely to be attributable to reduced fat intake or changes in physical activity.
The researchers suggest that a higher intake of potassium, which is abundant in many fruits and vegetables is associated with lower blood pressure. Lower levels of sodium may also contribute to the benefits. The effects of a fruit and vegetable rich diet on antioxidants and blood pressure would be expected to decrease cardiovascular disease and, consequently the risk of stroke in the general population.
The Lancet May 2002, Vol. 359 (9320)