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The French Paradox: What Does it Tell Us? XXIst Annual Congress of the ESC
This press release accompanies a presentation given at the XXIst Congress of the European Society of Cardiology and does not necessarily reflect the opinion of the European Society of Cardiology
THE FRENCH PARADOX: WHAT DOES IT TELL US? Definition The French Paradox is the lower-than-expected rate of mortality from coronary heart disease (CHD) in a country where traditional risk factors of CHD (hypertension, hyperlipidemia, smoking, diabetes) are not less prevalent than in other industrialised countries and where the diet is rich in animal saturated fat. According to British epidemiologists (Law and Wald, Br Med J May 1999), CHD mortality in people aged 55-64 was 487 (per 100 000, official statistics) in Britain in 1992 and 128 in France for men (ratio 1:4). It was 153 and 27 for women (ratio 1:6). After correction for undercertification of CHD as a cause of death in France, the ratios remain 1:2 in men and 1:3 in women. However, the prevalence of the main risk factors, including the consumption of animal fat, was similar in both countries. There is now a consensus to say that the French Paradox cannot be simply explained by a lower prevalence of the traditional risk factors in france compared with other countries. Proposed explanations for the French Paradox 1) The undercertification bias The MONICA Project (organised by the WHO) has shown in certain countries, in particular in France, a quite large difference between the CHD death rate given by the official statistics and the MONICA data. Thus, when analysing the French Paradox, the first question is whether it does not result, at least partly, from an undercertification bias. Official CHD death rate in men is 130 (per 100 000) in France and respectively, 199 and 141 in Italy and Spain. In women, the numbers are 24, 36 and 26. Taking into account the undercertification bias (as shown in the MONICA Project), corrected numbers for men are 234 for France and 199 and 170 for Italy and Spain. Corrected numbers for women are 58, 41 and 38. Corrected numbers for Germany and Belgium being 322 and 330 for men and 86 and 93 for women, it means that CHD mortality in France is probably intermediate between the Northern and Southern European countries with a deviation which does not exceed 10 %. Thus, official statistics underestimate CHD death rate in France and overestimate the French Paradox. 2) Food pattern and North-South gradient Comparison of the food pattern of the Northern and Southern European countries (Ducimetière and Richard, Nutr Metab Cardiovasc Dis 1992) shows that France clearly departs from the North-South gradient model with a large and positive deviation for the consumption of dairy products and meat. In other words, according to agricultural statistics, France resembles a Northern country for the consumption of animal fat whereas the French CHD death rate is intermediate between that of the Northern and Southern countries. This constitutes the French Paradox for CHD. The next question is: what is the protective factor ? Among the protective dietary factors characteristic of the Mediterranean diet, only the consumption of wine of the French is not intermediate between that of Northern and Southern countries whith a clear higher-than-expected consumption in France. This led to the hypothesis that in France the untoward effects of high consumption of meat and dairy products are, at least in part, counteracted by intake of wine ethanol (Renaud and de Lorgeril, Lancet 1992). Actually, the strongest negative association between alcohol consumption and platelet function (a marker of the risk of thrombotic complication) is in men with the highest intake of saturated fats (Renaud et al, Am J Clin Nutr 1992). In the Lyon trial, the inverse association between wine ethanol intake and platelet function was seen only in patients following a Western-type diet (rich in saturated fat) not in the Mediterranean diet group (de Lorgeril and Salen 1999). An argument in favor of this thesis comes from the inspection of the causes of non-CHD death in European countries. Non-cardiovascular causes of premature death are considerably higher in French men: 870 compared with 710 and 655 in Italy and Spain and 649 and 710 in Germany and Belgium. As underlined by Ducimetière et al, the phenomenon is restricted to men and largely explained by the high incidence of alcohol-related causes of death (liver cirrosis, cancer of the upper gastrointestinal tract, accident, suicide, violence) in French men. In contrast, French women are small drinkers with more than 60 % of them drinking only one or less glass per day on average (Dang Tran et al, Eur J Epidemiol 1998). Therefore, French women do not suffer from the same alcohol-related diseases as the French men. Accordingly, French women do not lose the advantage of the French Paradox for CHD and their life expectancy is one of the best in the world whereas life expectancy of French men is not better than that of other Europeans. 3) The dietary diversity factor Human eating (and drinking) behaviour is a complex and multidimensional phenomenon and if the French Paradox does have a dietary explanation, the answer may lie in the overall quality of the diet rather than in a single food or beverage. Dietary diversity evaluation may shed a new light on the cardioprotective effect of the French dietary habits as low dietary diversity scoring, characterised by omission of several food groups, is associated with increased CHD mortality (Kant et al, Am J Clin Nutr 1993). Actually, it was reported that the percentage of the French adult population with a high dietary diversity score is remarkably high compared with a comparable US population (90 % against 33 %). Again, French women had the highest dietary diversity score (Drewnowski et al, J Am Diet Assoc 1996). Further studies are however warranted to explore the importance of this factor in the French Paradox. What the French Paradox tells us In summary, we can say that there are 4 main possible explanations for the French Paradox: 1- Undercertification of CHD as a cause of death 2- North-South gradient 3- High consumption of wine ethanol in France 4- High diversity of the French dietary habits Thus, the French Paradox is mainly explained by the combination of dietary factors including the many aspects of the Mediterranean style diet (in the South of France), alcohol and wine consumption (everywhere in France but especially in the North) and perhaps dietary diversity (everywhere in France). However, the main lesson to be drawn from the analysis of the possible causes of the French Paradox is that we need to know more about the specific dietary habits of the French women as, in addition to a low CHD death rate, their life expectancy is one of the best in the world. French women may serve as a reference for any population at high risk of CHD. Press Conference "Complementary remedies in cardiology – facts and fiction", August 30, 1999, 10:10-10:50
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