Eating white fruit and vegetables protects against strokes. This is the first known link between food colour and health effects.
The aim of the study was to investigate a possible link between health and the colour of fruit and vegetables. To do this, Oude Griep used a large dataset belonging to RIVM. This institute followed 20,000 healthy Dutch people aged between 20 and 69 for ten years. The researchers looked at the number of strokes - fatal or otherwise - after ten years. Then they look to see whether there was a link between the strokes and the colour of the fruit and vegetables eaten. They distinguished four categories: green (spinach), orange (oranges), red/purple (grapes) and white (apples). The colours reflect the presence of different compounds in the various fruit and vegetables.
The only relationship found was for white fruit and vegetables. Every additional 25 grams of white fruit and vegetables eaten - mainly apples and pears - reduces the risk of a stroke by 9 percent. This relationship can still be seen after correcting for other health factors. 'This result is a first indication,' emphasizes Oude Griep. 'The effect needs to be confirmed for other populations. Only then can it be used as the basis for a health recommendation.'
It is not clear how the white colour can prevent strokes. 'Fruit and vegetables are very complex,' says Oude Griep. 'Apples and pears are rich in dietary fibre and quercetin. But these days we no longer assume an effect is due to a single compound. We prefer to look at food products in their entirety.'
Oude Griep's research was funded by the Product Board for Horticulture. She denies that this had an influence on the outcome: 'We wrote the research questions before we started to think about who could fund it. Also, the funding organization had no influence on the analysis and report.'