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The French Paradox explained by the time lag theory
by Dr Philip Norrie M.B.M.Sc.M.Soc.Sc.
An article entitled " Why Heart Disease Mortality is low in France - the time lag explanation" by Malcolm Law and Professor Nicholas Wald at the Wolfson Institute of Preventative Medicine appeared in the British Medical Journal 1999:318:1471-1480 in May. It criticised the French Paradox theory and proposed a new explanation for the phenomenon.

The French Paradox is the observation that the French, who have a high cholesterol diet with full cream sauces and pates for example, and smoke, have much lower mortality from ischaemic heart disease than other western countries with a similar diet and smoking habits. The French Paradox was explained by Professor Serge Reynaud in 1991 as due largely to the higher consumption of wine (particularly red wine) by the French when compared to other consumers.

Law and Wald argue that all alcohol has a cardio-protective effect and that, furthermore, the French Paradox is due to three other factors: Firstly, that the French medical profession do not document all manifestations of ischaemic heart disease, such as heart failure as due to coronary heart disease, but list them as "poorly specified cardiac causes". Thus there is an under reporting of the incidence of ischaemic heart disease in France, which the authors argue explains about 12% of he difference between the cardiac mortality rate between France and Great Britain.

Secondly, French women smoke at a third of the rate of British women which significantly reduces the rate of ischaemic heart disease in French women compared to British women because smoking contributes greatly to the pathogenesis of ischaemic heart disease.

The third and last reason forms the crux of their argument; Law and Wald argue that the basis for the bulk of the French Paradox is that the differences in levels of heart disease reflects the lower cholesterol diet that the French enjoyed thirty years ago and not their current high fat diet. A lower cholesterol diet is associated with much lower rates of ischaemic heart disease and, according to Law and Wald, it is this time lag in cholesterol consumption that explains why the French have lower incidence of ischaemic heart disease. Eventually, when their current high cholesterol diet takes effect, their incidence of heart disease will rise and match rates in other Western countries.

Comparisons of consumption of selected food based on FAO food balance shhets show that 35 years ago the French consumed more meat than the British and had similar fat intakes. What is important, which has been propounded by Serge Reynaud and Curtis Ellison, is that French consumption of fruit, vegetables and vegetable oils, as well as red wine of course (rather than the British consumption of animal and dairy fats) is higher, which has lead to the incorporation of the Mediterranean diet as part of the French Paradox.

To me the vascular disease protection afforded by wine is multifactorial;

First of all there is the "alcohol effect". Alcohol is the medically active component of wine, and alcohol in any form favourably alters the balance of fats in the blood, stimulating the liver to produce 'good' high density lipoproteins (HDL), which leaches out cholesterol from the blood vessel walls, carrying it to the liver for excretion via the bile.

Alcohol also helps inhibit clotting as it decreases platelet aggregation or 'stickiness'. This effect lasts for 24-48 hours; hence for alcohol to have a protective effect it must be drunk regularly and moderately. Beer and spirits are usually consumed on an empty stomach, whereas wine is consumed slowly by sipping over a meal. Hence the wine is absorbed slowly, because it is consumed slowly and the stomach emptying time is much slower when it is full of food.

There is the anti-oxidant benefit of reducing 'bad' low density lipoproteins incorporation into blood vessel walls due to wine's potent anti-oxidants such as resveratrol, quercitin and epicatechin and it doesn't matter if the wine is red or white. There have been many studies by Troup(1), Vinson and Hontz(2) and Jung (3) for example which have shown that white wine is just as effective as red wine as a cardio-protective agent. Dark ales, stouts and aged whiskies also possess this anti-oxidant effect. Polyphenols also protect, together with alcohol, against blood clotting, and may relax blood vessel walls to allow better blood flow.

If Law and Wald's argument is that it is mainly the different levels of cholesterol in diets that accounts for the paradox and not the alcohol consumption, then it follows by their logic, that the rate of coronary heart disease (CHD) in countries with a similar British genetic stock and diet as Great Britain should have a similarly high rate of CHD independent of alcohol consumption.

This we can prove is not so. Let us follow the CHD track record of British descendents overseas, who have a similar genetic pool and diet, as related to their drinking habits. Dr. Rodney Jackson from the Department of Epidemiology at the University of Auckland, New Zealand (4) has shown that alcohol consumption significantly reduces CHD when comparing abstainers, moderate drinkers and heavy drinkers in Auckland. Dr. Kevin Cullen's Busselton study (5) has also shown that alcohol consumption significantly reduces rates of CHD, particularly in British genetic pool and diet, and it was the first research in the world to show this effect in women. It is, however, Professor Leon Simon's Dubbo study (6) which really shows the benefits of moderate alcohol consumption on a British based population. In his study moderate drinkers, both men and women, lowered their mortality rate by 51% (compared to Dr. Cullen's one third improvement) when compared to non -drinkers. This shows that the marked health benefit of moderate consumption of alcohol is still valid on a British population.

To conclude, Dr. Law and Professor Wald concentrate heavily on consumption of animal fats, and fail to mention the importance of the Mediterranean diet as part of the French paradox. The Mediterranean diet encourages the consumption of less meat and more fish, grains and cereals, vegetables, fruit, olive oil and of course wine in the every day diet if CHD is to be reduced. Secondly, the tables illustrate that the French have enjoyed a high fat diet since 1965, i.e. for more than thirty years. If the researchers' theory were correct, France would be showing an increase in rates of CHD whereas in fact rates continue to fall.

Perhaps Curtis Ellison's comments sum up the debate;

"All in all, this paper presents some interesting topics for discussion over a nice bottle of wine, but adds little to a serious scientific inquiry into what factors are protecting the French from coronary heart disease".

Dr. Philip Norrie is a general practitioner, vineyard owner and a historian of wine and health. He is a member of the AIM editorial board.

References: (1) Troup.G et al. Free Radical Scavenging abilities of beverages: International Journal of Food Science and Technology 1995, 30,P 535-537. (2) Vinson.J and Hontz B Phenols antioxidant index: Comparative Antioxidant Effectiveness of red and white wines. Advance American Chemical Society Abstracts January 15th 1995. (3) Jung.C et al Moderate red and wine consumption and the risk of CHD. Herz/Kreisl 31 (1/99). (4) Jackson.R. et al Alcohol Consumption and risk of coronary heart disease BMJ Vol 303 p??. Cullen.K et al Alcohol and Mortality in the Busselton Study. International Journal of Epidemiology ???. (6) Simons.L et al Alcohol intake and survival in the elderly: a 77 month follow up in the Dubbo study. AUST NZJ Med.1996,26 p 662

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