Hold your apples and put the carrots down. A new study of 500,000 Europeans has found that eating five portions of fruit and veg a day may not prevent cancer after all. For years, public health campaigns have told us to scoff more broccoli if we want to live past Christmas, and it turns out they may have been selling us a lemon.

The suggestion was once made that a hefty intake of vegetables could prevent up to 50% of cancers. Now, it appears, the best-case scenario is more like 2.5%. Which, frankly, is lucky, since many of us didn't eat five portions a day, even when we believed that eating beetroot was the nutritional equivalent of a quick dose of chemotherapy.

In 2008, a survey by the Food Standards Agency found 59% of people in England, 54% of people in Scotland, 50% of the Welsh and a meagre 45% of Northern Irish people ate the requisite number of tomatoes each day. The rest of us looked at supermarket shelves groaning with fresh produce, thought of Jamie Oliver's encouraging big face, and still bought a pack of digestives instead. So shoot me, we thought. I want a biscuit, and a satsuma just won't cut it. Wait a minute - chocolate chip ginger nuts? Ginger is a tuber, right? This is both a biscuit and a vegetable. That counts as a win.

The problem with healthy-eating campaigns is that they don't play to our strengths. We all know that cake is less healthy than cabbage. We just prefer cake. And even if we quite like cabbage, when someone tells us to eat it, we don't want it anymore. If you give people a set of rules, we will simply try to subvert them. We are mischievous that way. Or perhaps we're just stupid.

The Health Food Manufacturers' Association released a report a couple of years ago saying that two-thirds of Britons thought chips counted as a five-a-day vegetable. Nutritionists appeared on the news, decrying our ignorance. Stupid Britons, thinking a potato is a vegetable. Well, I've been vegetarian for over twenty years, so I've eaten quite a few veg in my time. And I think a potato is a vegetable too.

We should embrace this new research that frees us from the fruit and veg tyranny. Maybe if we stop thinking we have to eat five portions every day, we might just eat vegetables because they're nice. And look at the upside: bananas are the most popular fruit in the country. If we start eating less of them, we won't be any more likely to get cancer. We will, however, be considerably less likely to slip on a banana-skin. Cancer rates may stay the same, but there will be a dramatic reduction in broken arms.