I like wine, especially red wine. My tastes range from elegant to earthy. In fact, I’m not terribly discriminating – I like to sample them all.
I also feel the need to justify my red wine indulgences. So I’m always looking for news about the positive health effects of drinking red wine. (This is a classic case of System 2 rationalizing a decision that was initially made – for entirely different reasons — in System 1. My System 1 made the decision; my System 2 justifies it.)
As you may know, there’s plenty of good news about red wine and good health. Generally, drinking red wine is associated with better health and longer life. It’s a J-shaped curve, “…light to moderate drinkers have less risk than abstainers, and heavy drinkers are at the highest risk.” Drink a little bit and you get healthier; drink too much and you get unhealthier.
Is there a cause-and-effect relationship here? It certainly hasn’t been proven. All we’ve been able to show so far is that there is a correlation. A change in one variable is correlated to a change in another variable. Just because variable A happens before variable B, doesn’t mean that A causes B. (That would be the post hoc, ergo propter hoc fallacy as the President points out in West Wing).
Yet many scientists have assumed that there is a cause-and-effect relationship and framed their studies accordingly. The typical approach is to break down the various elements of red wine to isolate the ingredient(s) that cause the beneficial health results. Is it ethanol? Is it resveratrol? Notice the assumption: there is something in the wine that causes the beneficial health result. The studies are narrowly framed.
Is this good critical thinking? Maybe not. Maybe we’re framing too tightly and assuming too much. Maybe there’s a third variable that causes us to drink red wine and be healthier.
I started thinking about this when I stumbled across a study conducted in Denmark more than a decade ago. The Danish researchers didn’t study wine. Rather, they looked at human behavior. More specifically, they looked at 3.5 million grocery store receipts.
The Danish researchers asked three interrelated questions: 1) What do wine drinkers eat? 2) Is this different from what non-wine-drinkers eat? 3) If so, could the differences in overall diet be the cause of the health effect?
The researchers looked at several specific combinations:
I won’t try to summarize everything but here’s the key finding:
“This study indicates that people who buy (and presumably drink) wine purchase a greater number of healthy food items than those who buy beer. Wine buyers bought more olives, fruit or vegetables, poultry, cooking oil, and low fat products than people who bought beer. Beer buyers bought more ready cooked dishes, sugar, cold cuts, chips, pork, butter, sausages, lamb, and soft drinks than people who bought wine. Wine buyers were more likely to buy Mediterranean food items, whereas beer buyers tended to buy traditional food items.”
So, does wine cause good health? Maybe not. Maybe we framed the question improperly. Maybe we’ve been studying the wrong thing. Maybe it’s the other things that wine drinkers do that improve our health. As usual, more studies are needed. While I wait for the results, I think I’ll have a nice glass of Priorat.