A fibre called pectin, which is found in a broad range of fruits and vegetables, can prevent cancer, according to an ongoing study by the Institute of Food Research.

Professor Vic Morris has been heading the research on pectin in labs using hi-tech microscopes and the findings suggest the fibre inhibits cancer-causing protein Gal3.

The implication, said Morris, is that it would be advisable for consumers to focus on eating a wide variety of fruits and vegetables rather than relying on “super foods” such as blueberries and spinach.

The much-vaunted benefits of “super foods” have spurred a boom in sales over the last two years. Sales of blueberries rose, for instance by 132 per cent in that period. A spokeswoman for the British Nutrition Foundation said: “We should not be focusing on these types and ignoring other fruit and vegetables. There are still not enough people getting their five-a- day requirement.”