If there's one thing that people in Finland do, it's drink coffee. Lots of it. In fact, Finnish people drink more coffee than anybody else in the world.
The trouble with lifestyle studies is that there are just so many other variables. Some who take part in the study might also be vegetarian, or they go to the gym five times a week, or they smoke.
Good researchers try to smooth out these differences, and the latest Finnish study does just that, and accounts for sex, age, body weight, alcohol consumption, and smoking (but leaves out diet).
But it gets more complicated still, because there's coffee and coffee. By the end of the 1960s three-quarters of Finns were drinking pot-boiled coffee. By 1987 the trend had switched and just 25 per cent were drinking boiled coffee, and 69 per cent had turned to filtered coffee.
Researchers discovered a three-fold increase in cases of diabetes among men who drank pot-boiled coffee compared with those who took their beverage filtered. Furthermore, they discovered an inverse association between filter coffee and diabetes. In other words, the more you drank, your risk decreased.
The researchers believe the key protective agent in coffee is chlorogenic acid, which inhibits the onset of diabetes. Levels of acid are determined by the way the coffee is roasted. Filter coffee retains more acid than does boiled coffee, it seems.
Protection is one thing, but what causes type II diabetes in those poor unfortunates still stuck on their boiled coffee? May we suggest processed foods, the one thing the researchers didn't include?
(Source: Journal of the American Medical Association, 2004; 291: 1213-19).