17 October 2010

Accounting and History, not Red Wine

Yesterday's FT had an intriguing and fascinating letter about the so-called "French paradox" which asks why the French have such low levels of heart disease yet a diet rich in saturated fats.  Red wine has been the popular answer.  Professor Timo Strandberg suggests another.  Here is an excerpt:
According to a skilful dissection of this myth in the British Medical Journal by professors Malcolm Law and Nicholas Wald in 1999 (May 29), wine consumption may actually explain little of the paradox. Some of it has pertained to a habit of French doctors not to ascribe all deaths basically due to coronary artery disease (for example heart failure) to a coronary cause.

A major part of this paradox is, however, explained by a time lag, the slow development of atherosclerotic coronary artery disease during several decades. Fewer coronary deaths during the 1970s and 1990s in France than in Britain (or the US) were simply reflecting much lower saturated fat consumption and lower cholesterol levels in France during earlier decades. While saturated fat consumption started to increase in Britain from the late 19th century and reached a plateau during the 1930s, this increase did not happen in France, a Mediterranean country, until from the 1970s.

But we may not be seeing a reciprocal increase of heart disease in France any more, because of early adaptation of modern cardiovascular prevention. Already during the 1990s, French patients were receiving cholesterol-lowering drugs some nine-fold more frequently than their British counterparts. Eating lots of cream, cheese and butter-rich croissants may not be so dangerous, if you are on a statin.
Interpreting data requires knowing something about the data and its context.  Nothing can be taken for granted.