While previous studies have linked high consumption of fruits and vegetables with lower stroke risk, the researchers' prospective work is the first to examine the association of fruits' and vegetables' color groups with stroke. The color of the edible portion of fruits and vegetables reflects the presence of beneficial phytochemicals such as carotenoids and flavonoids.
Researchers examined the link between fruits and vegetables color-group consumption with 10-year stroke incidence in a population-based study of 20,069 adults, with an average age of 41. The participants were free of cardiovascular diseases at the start of the study and completed a 178-item food frequency questionnaire for the previous year.
Fruits and vegetables were classified in four color groups: green, such as dark leafy vegetables, cabbages and lettuces; orange/yellow, such as citrus fruits; red/purple, such as red vegetables; and white, such as apples and pears.
During 10 years of follow-up, 233 strokes were documented. Green, orange/yellow and red/purple fruits and vegetables were not related to stroke. However, the risk of stroke incidence was 52% lower for people with a high intake of white fruits and vegetables compared to people with a low intake.
Each daily increase of 25g in white fruits and vegetables consumption was associated with a 9% lower risk of stroke. An average apple is 120g.
"To prevent stroke, it may be useful to consume considerable amounts of white fruits and vegetables," Linda M. Oude Griep, M.Sc., lead author of the study and a postdoctoral fellow in human nutrition at Wageningen University in the Netherlands, said in a news release. "For example, eating one apple a day is an easy way to increase white fruits and vegetables intake.
"However, other fruits and vegetable[s] color groups may protect against other chronic diseases. Therefore, it remains of importance to consume a lot of fruits and vegetables."
Apples and pears are high in dietary fiber and a flavonoid called quercetin. In the study, other foods in the white category were bananas, cauliflower, chicory and cucumber. Potatoes were classified as a starch.
U.S. federal dietary guidelines include using color to assign nutritional value. The U.S. Preventive Health Services Taskforce recommends each day selecting vegetables from five subgroups: dark green, red/orange, legume, starchy and other vegetables.
Before the results are adopted into everyday practice, the findings should be confirmed through additional research, according to Oude Griep. "It may be too early for physicians to advise patients to change their dietary habits based on these initial findings," she said.
The study appears in Stroke: Journal of the American Heart Association. To download a PDF of the study, visit http://bit.ly/nggBT2.
An accompanying editorial notes that the finding should be interpreted with caution because food frequency questionnaires may not be reliable.
In addition, wrote Heike Wersching, MD, MSc, of the University of Munster in Germany, "the observed reduction in stroke risk might further be due to a generally healthier lifestyle of individuals consuming a diet rich in fruits and vegetables."
From the September 21, 2011, Prepared Foods' Daily News.