A passion for garlic, red wine and onions cannot explain the low levels of heart disease in France, which have baffled doctors for decades. Instead, the most likely reason is the lower levels of animal fat the French were eating 30 years ago, before the fast-food explosion of pizzas and hamburgers.
Scientists have been trying to explain the "French paradox" for years. This is the paradox: the French eat a diet with similar levels of fat to ours, and have similar levels of blood cholesterol, but only one Frenchman dies of heart disease for every four Britons who die.
The explanations offered focus on the higher consumption of alcohol, especially red wine, in France and the ubiquitous use of garlic and onions. In 1988, the French drank an average of 13.1 litres of absolute alcohol a head compared with 8.5 litres a head in Britain.
Dr Malcolm Law and Professor Nicholas Wald of the Wolfson Institute for Preventive Medicine in London dismiss this theory as inadequate to explain the difference. Writing in the British Medical Journal they say the extra drinking by the French accounts for less than 5 per cent of their heart disease advantage and there is no good evidence that garlic or onions are protective, they say. Instead, they suggest the reasons for the discrepancy can be found in the recent culinary history of both countries.
The British penchant for fish and chips and fry-ups in the 1950s and 1960s has been replaced by the growth of fast foods but the fat content of the national diet has remained unchanged and consistently high. But in France the fat content of the average diet was lower than in Britain until the introduction of burgers and pizzas from the 1970s, when it increased to the same level as here.
There is a time lag of 25 to 35 years between changes in the diet and effect on heart disease rates because it takes decades for dietary fat and blood cholesterol to cause thickening of the arteries.
Heart disease rates in Britain and France in the 1990s reflect the differences in their diets in the 1960s and it will be at least another decade before the French reap the consequences of the fast-food explosion that began 30 years ago.
Although there is a long time lag for the build-up of risk it can be reduced by changes in the diet in two years. Dr Law said: "It is important to stress that if you reduce fat in the diet the risk of heart disease falls quickly."