WAGENINGEN, THE NETHERLANDS. There is ample evidence that a high consumption of fruits and vegetables lowers the risk of stroke. What is not known is whether some fruits and vegetables are more effective in stroke prevention than others. A group of researchers from Wageningen University now answers this question.
Their study included 20,069 men and women between the ages of 20 and 65 years who were free of cardiovascular disease at baseline. During 10 years of follow-up, 226 nonfatal and 19 fatal strokes were recorded (0.11%/year). It is worth noting that 12 of the patients who suffered a fatal stroke had previously had a nonfatal stroke. The majority (60%) of the strokes was ischemic, 19% were hemorrhagic, and the remaining 21% were of unknown origin. All participants completed a validated, self-administered food-frequency questionnaire at enrolment between 1993 and 1997.
Fruit and vegetable intake was grouped according to the predominant colour of the produce. Thus, the green colour group consisted of broccoli, brussel sprouts, cabbage, kale, spinach, endive, and lettuce. The orange/yellow group included citrus fruit, cantaloupe, carrot, carrot juice, and peach. The red/purple group contained red beets, red cabbage, cherries, grapes, strawberries, red sweet pepper, tomato, and tomato juice. The white group consisted of garlic, leeks, onion, apples (including apple sauce and apple juice), pears, banana, cauliflower, chicory, cucumber, and mushrooms.
The average daily fruit and vegetable intake was 378 grams/day with white fruits and vegetables contributing 36%, and orange/yellow fruits and vegetables contributing 29% of total intake. Apples and pears constituted 55% of the white fruit and vegetable intake, while citrus fruits accounted for 78% of the orange/yellow group. After adjustment for lifestyle and other dietary factors, the researchers concluded that study participants whose intake of white fruits and vegetables exceeded 171 grams/day had halved their stroke risk as compared to those whose intake was 78 grams/day or less. Thus, a 25-gram/day increase in the intake of white fruits and vegetables corresponds to a 9% (relative) reduction in the risk of stroke. NOTE: In this study apples and pears constituted 55% of the total daily intake of white fruits and vegetables.
Consumption of green, orange/yellow and red/purple fruits was not associated with a decreased stroke incidence. The Dutch researchers point out that apples are a rich source of quercetin (3.6 mg/100 grams) and dietary fiber (2.3 grams/100 grams) and that other researchers have found that a high intake of flavonoids like quercetin is associated with a 20% reduction in stroke risk.
Oude Griep, LM, Geleijnse, JM, et al. Colors of fruit and vegetables and 10-year incidence of stroke. Stroke, Vol. 42, November 2011