Saturated fats are found in a wide range of common foods, including meat products, hard cheese, cream and palm oil. The Study found that by 2002, deaths from coronary heart disease had dropped by over a third in the 45-64 age group - a 38 per cent drop for men and 42% for women.

Over a similar period (to 1999), people were consuming 7 per cent less saturated fat, while consumption of polyunsaturated fats had risen by 57 per cent. The sharp drop in deaths cannot simply be explained by the effect of any polyunsaturated fat, say the authors, but is likely to be related to the type consumed.

Rapeseed and to a lesser extent soya bean oil made up most of the rising numbers of polyunsaturated fats available in Poland in the 1990s - both of which contain omega 3 and omega 6 fatty acids, also thought to reduce heart problems, says the BMJ report.

Looking at fruit consumption, the researchers found that although consumption of imported fruit rose during the 1990s - from 2.8kg/year per person in 1990 to 10.4kg/year by 1999 - the increase was not enough to influence death rates by more than 1 or 2 per cent.