Nora Ephron's many-faceted career includes acclaim as a film director, producer, screenwriter, and novelist. Now she may also claim fame as an intuitive epidemiologist -- thanks to her recent column in the New York Times ("The Chicken Soup Chronicles" ).
Ephron is acutely observant of certain health and cultural correlations -- the type of links often seen in dire health warnings in the popular media. She notes, for example, that she drinks chicken soup when cold symptoms first appear -- and then acquires a cold. So, she asks, does chicken soup cause colds? She has observed that breast-feeding is much more common now than it was, say, a couple of decades ago -- in part because it supposedly decreases the risk of allergies in babies. But then she also observed that there seems to have been a decided increase in the incidence of allergies in babies over the same period. So, she asks, could breast-feeding actually be causing rather than preventing allergies?
Obviously, these fortuitous associations wouldn't move any epidemiologist worth his or her salt to say that breast-feeding and chicken soup actually cause allergies and colds. Ephron has, however, put her finger on a basic misunderstanding that underlies many of the health scares we see in the media -- with sometimes unfortunate results.
For example, the observation that children develop autism symptoms after receiving various vaccines has been much touted by anti-vaccine activists and plaintiffs' lawyers as "proof" that vaccines -- or a preservative that used to be found in them -- cause autism. The scientific fact that they don't has not dissuaded the activists from using such propaganda. This misunderstanding has made some parents reluctant to have their babies vaccinated -- not a wise move.
The next time you read about trans fats causing heart disease or high fructose corn syrup causing obesity, think back to Ephron's examples of association that don't rise to the level of causation and relax.
See also: ACSH's report on understanding causation and our report Celebrities vs. Science: Scientists Correct the Misstatements of the Stars.