By Clare Wilson
Pass the fruit bowl. Five a day just doesn’t cut it anymore – we should be eating 10 portions of fruit or vegetables a day to reduce our chances of dying from a heart attack or cancer.
That’s according to a review of 95 previous studies of the relationship between diet and health. “Five a day is good, but more is even better,” says Dagfinn Aune of Imperial College London.
We have long known that people who eat more fruit and vegetables tend to live longer. Official advice in the UK is to eat five portions of fruit and veg a day. A portion is about 80 grams, equivalent to an apple, two tangerines or three heaped tablespoons of peas. But targets are higher in some other countries, such as the US, where it is eight to ten a day.
Other research has suggested benefits from eating seven portions a day, although this wasn’t an upper limit.
Go for broccoli
In the latest review, people who ate 10 portions of fruit and veg a day had nearly a third lower risk of death than those who ate none during the course of the studies – which followed people for between three and thirty years. Most of the benefits stemmed from reductions in the rates of heart disease and cancer, the commonest causes of death in western countries.
Risk of cancer, for instance, fell as people ate more cruciferous vegetables – such as broccoli – and other green veggies, although this finding came from only a few studies that investigated the benefits of particular types of produce.
Aune says the higher target should not discourage people struggling to eat five a day, as more health benefits were seen in increasing from zero to five a day than in going higher still. “Just don’t stop at five,” he says.
The findings may not convince everyone, though, as the studies reviewed were not randomised controlled trials – the best kind of medical evidence – but just observed what people ate and the rates at which they died. So they could have been biased by the fact that people who are financially better off tend to eat more healthily, and live longer for other reasons, such as smoking and drinking less, and getting better medical care.
But Aune says most of the studies would have tried to adjust their results for these problems. “In most of the analyses the results were quite similar no matter what they adjust for. But it’s always a possibility that there could be confounders.”
A previous analysis found there was no reduction in risk of death from eating more than five portions of fruit and veg a day, although this was smaller, reviewing only 16 studies.
Journal reference: International Journal of Epidemiology, DOI: 10.1093/ije/dyw319