Although some think of it as a relatively modern phenomenon, the first suggestion of what is now known as the 'French paradox' came from a study published in 1819 by an Irish doctor called Samuel Black. He compared the difference in angina found in French and Irish populations and attributed the lower rates in the former to 'the French habits and modes of living, coinciding with the benignity of their climate and the peculiar character of their moral affections.' This was quite prescient, because it wasn't until fairly recently that this concept became widely discussed. Indeed, widespread awareness of this phenomenon is commonly attributed to the screening of the '60 minutes' documentary on this subject in the USA as recently as 1991.
In essence, the 'French paradox' is the observation that although the French don't eat a particularly healthy diet, they show much reduced rates of coronary heart disease when compared with northern European nations such as the UK and Germany. The data are quite startling. Why? The most popular explanation has been that the relatively high consumption of alcohol, and in particular wine, by the French, which in some way acts to protect them from heart disease. Of course, this is just a correlation, for which there is no direct proof, but it does fit well with the results from the large scale population studies on drinking and mortality.
There is still quite a bit of controversy surrounding the French Paradox. For example, some people suggest that the whole thing might just be an artefact of the way the French record their death statistics. However, the idea is now so firmly enmeshed in the public consciousness, and it is so intuitively attractive a hypothesis, that it looks like it is here to stay.