Eating lots of fruit and vegetables with white flesh may help to protect against strokes, says a study in the journal Stroke.
But Dutch researchers say they do not know why people with a high intake of apples, pears, bananas or cauliflower reduce their risk of stroke by 52%.
The study followed more than 20,000 adults over 10 years.
Stroke experts said people should not be put off eating other colours of fruit and veg.
At the start of the study, carried out in The Netherlands, participants were asked to fill in a detailed questionnaire on diet and lifestyle for the previous year.
By using this information and tracking the health of participants over the next decade, researchers were able to examine the link between the colour of fruit and vegetables consumed and stroke risk.
The study found that a 25g per day increase in white fruits and vegetables was linked to a 9% lower risk of stroke.
Of the white fruit and veg eaten, over half was apples and pears. An average apple weighs 120g.
But no link was found between stroke incidence and green (dark leafy vegetables, cabbages and lettuces) orange/yellow (mostly citrus fruits) or red/purple fruits and vegetables.
High in fibre
Linda Oude Griep, lead author of the study and postdoctoral fellow in human nutrition at Wageningen University in The Netherlands, said more research was needed to find out why white flesh was important.
“It is difficult to say which nutrients are responsible in white fruits and vegetables. We know that apples and pears are high in dietary fibre, but there may be other explanations.”
She said it might be useful to consume considerable amounts of white-flesh fruit and veg to prevent strokes.
“Eating one apple a day is an easy way to increase white fruits and vegetable intake.”
Dr Sharlin Ahmed from The Stroke Association said the findings should not deter people from eating other colours of fruit and vegetables.
“All fruit and vegetables have health benefits and remain an important part of a stable diet.
“A lot more research is needed before the colour of our groceries alone is used to determine what health benefits they may have.
“Everyone can reduce their risk of stroke by eating a healthy balanced diet that is low in saturated fat and salt, exercising regularly and ensuring that your blood pressure is checked and kept under control.”