French paradox

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Cheese, like this Brie de Meaux, is high in saturated fats, and is a popular food in French cuisine. Brie 01.jpg
Cheese, like this Brie de Meaux, is high in saturated fats, and is a popular food in French cuisine.

The French paradox is an apparently paradoxical epidemiological observation that French people have a relatively low incidence of coronary heart disease (CHD), while having a diet relatively rich in saturated fats, [1] in apparent contradiction to the widely held belief that the high consumption of such fats is a risk factor for CHD. The paradox is that if the thesis linking saturated fats to CHD is valid, the French ought to have a higher rate of CHD than comparable countries where the per capita consumption of such fats is lower.

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It has also been suggested that the French paradox is an illusion, created in part by differences in the way that French authorities collect health statistics, as compared to other countries, and in part by the long-term effects, in the coronary health of French citizens, of changes in dietary patterns that were adopted years earlier. [2]

Identifying and quantifying the French paradox

In 1991, Serge Renaud, a scientist from Bordeaux University, France—considered today the father of the phrase—presented the results of his scientific study into the term and actual scientific data behind the perception of the phrase. [3] This was followed by a public documentary broadcast on the American CBS News television channel, 60 Minutes .

In 1991, Renaud extended his studies in partnership with then junior researchers, cardiologist Michel de Lorgeril and dietician Patricia Salen. The three enhanced Renaud's study, with their paper concluding that: a diet based on southwestern Mediterranean cuisine (which is high in omega-3 oils, antioxidants and includes "moderate consumption" of red wine) created lower cases of cancer, myocardial infarction and cardiovascular disease; partly through increasing HDL cholesterol whilst reducing LDL cholesterol. [3]

Statistical illusion hypothesis

In 1999, Malcolm Law and Nicholas Wald published a study in the British Medical Journal , [2] using data from a 1994 study of alcohol and diet to explain how the French paradox might actually be an illusion, caused by two statistical distortions.

First, Law and Wald attributed about 20% of the difference in the observed rates of CHD between France and the United Kingdom to the under-certification of CHD in France, relative to the UK. [2] [4]

Second, Law and Wald presented a time-lag hypothesis: if there were a delay in serum cholesterol concentrations increasing and a subsequent increase in ischaemic heart disease mortality, then the current rate of mortality from CHD is more likely to be linked to past levels of serum cholesterol and fat consumption than to current serum cholesterol levels and patterns of fat consumption. They wrote, [2]

We propose that the difference is due to the time lag between increases in consumption of animal fat and serum cholesterol concentrations and the resulting increase in mortality from heart disease—similar to the recognised time lag between smoking and lung cancer. Consumption of animal fat and serum cholesterol concentrations increased only recently in France but did so decades ago in Britain.

Evidence supports this explanation: mortality from heart disease across countries, including France, correlates strongly with levels of animal fat consumption and serum cholesterol in the past (30 years ago) but only weakly to recent levels. Based on past levels, mortality data for France are not discrepant

In addition, the French population has become increasingly overweight. A study published by the French Institute of Health and Medical Research (INSERM) revealed an increase in obesity from 8.5% in 1997 to 14.5% in 2009, with women showing a greater tendency toward obesity than men. [5]

Impact

Cultural impact

The overall impact of the popular perception, in the English-speaking world, that the French paradox is a real phenomenon, has been to give added credibility to health claims associated with specific French dietary practices.

This was seen most dramatically when, in 1991, an early account of the then-novel concept of the French paradox was aired in the United States on 60 Minutes. The broadcast left the impression that France's high levels of red wine consumption accounted for much of the country's lower incidence of cardiac disease. Within a year, the consumption of red wine in the United States had increased by 40% [6] and some wine sellers began promoting their products as "health food." [7]

The cultural impact of the French paradox can be seen in the large number of book titles in the diet-and-health field that purport to give the reader access to the secrets behind the paradox:

Other books sought to boost their credibility by reference to the French paradox. The American edition of The Dukan Diet , written by Pierre Dukan, a Paris-based doctor, is marketed with the subtitle, "The real reason the French stay thin".

Scientific impact

The existence of the French paradox has caused some researchers[ who? ] to speculate that the link between dietary consumption of saturated fats and coronary heart disease might not be as strong as had previously been thought. This has resulted in a review of the earlier studies that suggested this link.

Some researchers[ who? ] have thrown into question the entire claimed connection between natural saturated fat consumption and cardiovascular disease. In 2006, this view received some indirect support from the results of the Nurses' Health Study run by the Women's Health Initiative. After accumulating approximately 8 years of data on the diet and health of 49,000 post-menopausal American women, the researchers found that the balance of saturated versus unsaturated fats did not appear to affect heart disease risk, whereas the consumption of trans fat was associated with significantly increased risk of cardiovascular disease. [8]

Similarly, the authors of a 2009 review of dietary studies concluded that there was insufficient evidence to establish a causal link between consumption of saturated fats and coronary heart disease risk. [9]

Possible explanations

Explanations based on the high per capita consumption of red wine in France

It has been suggested that France's high red wine consumption is a primary factor in the trend. This hypothesis was expounded in a 60 Minutes broadcast in 1991. [10] The program catalysed a large increase in North American demand for red wines from around the world. It is believed that one of the components of red wine potentially related to this effect is resveratrol; [11] however, the authors of a 2003 study concluded that the amount of resveratrol absorbed by drinkers of red wine is small enough that it is unlikely to explain the paradox. [12]

Red wine was considered a possible explanation, but proved unlikely to explain the paradox. Red Wine Glass.jpg
Red wine was considered a possible explanation, but proved unlikely to explain the paradox.

Explanations based on multiple factors

In "Lifestyle in France and the United States" (2010), one study reviewed identifies three major factors likely to be involved in the paradox:

Extra virgin olive oil and baguette, often considered a symbol of French culture Extra virgin olive oil and bread baguette (17303095818).jpg
Extra virgin olive oil and baguette, often considered a symbol of French culture

In his 2003 book, The Fat Fallacy: The French Diet Secrets to Permanent Weight Loss, Will Clower suggests the French paradox may be narrowed down to a few key factors, namely:

Clower tends to downplay the common beliefs that wine consumption and smoking are greatly responsible for the French paradox. While a higher percentage of French people smoke, this is not greatly higher than the U.S. (35% in France vs. 25% in U.S.) and is unlikely to account for the weight difference between countries.

Early life nutrition

One proposed explanation of the French paradox regards possible effects (epigenetic or otherwise) of dietary improvements in the first months and years of life, exerted across multiple generations. Following defeat in the Franco-Prussian War in 1871, the French government introduced an aggressive nutritional program[ which? ] providing high quality foods[ which? ] to pregnant women and young children with the aim of fortifying future generations of soldiers (the program was implemented about three decades prior to an analogous initiative in England in response to the Boer War). It has been suggested that the particular timing of this historical intervention might help explain the relatively low rates of obesity and heart disease found in France. [14]

See also

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References

Citations

  1. Ferrières, J (January 2004). Otto, C (ed.). "The French paradox: lessons for other countries" (PDF). Heart . 90 (1). BMJ Group: 107–111. doi: 10.1136/heart.90.1.107 . ISSN   1468-201X. PMC   1768013 . PMID   14676260. S2CID   6738125. Archived (PDF) from the original on 10 August 2021. Retrieved 21 November 2021.
  2. 1 2 3 4 Law, M.; Wald, N. (1999). "Why heart disease mortality is low in France: the time lag explanation". British Medical Journal. 318 (7196): 1471–1480. doi:10.1136/bmj.318.7196.1471. PMC   1115846 . PMID   10346778.
  3. 1 2 B. Simini (2000). "Serge Renaud: from French paradox to Cretan miracle". The Lancet. 355 (9197): 48. doi:10.1016/S0140-6736(05)71990-5. PMID   10615898. S2CID   8142036.
  4. McMichael, J. (2 June 1979). "French wine and death certificates". Lancet. 1 (8127): 1186–1187. doi:10.1016/s0140-6736(79)91862-2. ISSN   0140-6736. PMID   86901.
  5. Matthew Saltmarsh (7 March 2010). "Nestlé Bringing American-Style Diet Plans to Europe". The New York Times.
  6. Phillips, Rod (2014). Alcohol: A History. University of North Carolina Press Books. p. 517. ISBN   978-1-4696-1760-2.
  7. "Surgeon General Wine | Wine ads draw Surgeon General's ire Claim that mild drinking benefits heart is criticized BALTIMORE CITY – Baltimore Sun". Archived from the original on 22 May 2014. Retrieved 14 October 2012.
  8. Couzin, Jennifer (2006). "Women's Health: Study Yields Murky Signals on Low-Fat Diets and Disease". Science. 311 (5762): 755. doi: 10.1126/science.311.5762.755 . PMID   16469884. S2CID   36484516.
  9. Andrew Mente; Lawrence de Koning; Harry S. Shannon; Sonia S. Anand (2009). "A Systematic Review of the Evidence Supporting a Causal Link Between Dietary Factors and Coronary Heart Disease". Arch Intern Med. 169 (7): 659–669. doi: 10.1001/archinternmed.2009.38 . PMID   19364995.
  10. The French Paradox, CBS News, 23 January 2009
  11. Potentially Universal Mechanism Of Aging Identified, ScienceDaily, 27 November 2008
  12. Goldberg, David M.; Yan, Joseph; Soleas, George J. (2003). "Absorption of three wine-related polyphenols in three different matrices by healthy subjects". Clinical Biochemistry. 36 (1): 79–87. doi:10.1016/S0009-9120(02)00397-1. PMID   12554065.
  13. Lynda H. Powell; Rasa Kazlauskaite; Carolyn Shima; Bradley M. Appelhans (June 2010). "Lifestyle in France and the United States". Journal of the Academy of Nutrition and Dietetics. 110 (6): 845–847. doi:10.1016/j.jada.2010.03.029. PMC   3930055 . PMID   20497772.
  14. Newnham, JP; Pennell, CE; Lye, SJ; Rampono, J; Challis, JR (June 2009). "Early life origins of obesity". Obstetrics and Gynecology Clinics of North America. 36 (2): 227–44, xii. doi: 10.1016/j.ogc.2009.03.004 . PMID   19501311.

Sources

Further reading