Paul Alper points to this news article reporting on an observational study of 170,000 British people, finding that “Those who drank 1.5 to 3.5 cups of coffee per day, even with a teaspoon of sugar, were up to 30 percent less likely to die during the study period [approximately seven years] than those who didn’t drink coffee.”
A reduction of mortality by 30% seems implausibly high; on the other hand, it’s not impossible. Indeed, the news article quotes the journal editor who says, “It’s huge. There are very few things that reduce your mortality by 30 percent.” Alternatively, the news article states, “there may be other lifestyle factors contributing to that lower mortality risk among people who drink coffee, like a healthy diet or a consistent exercise routine.” I guess that smoking and drinking would be the biggest factors. I took a quick look at the research paper, and they do adjust for smoking and drinking, along with many other factors, but I don’t know exactly how that adjustment was done.
I’m not saying they did anything wrong; indeed, the authors of the research paper are in a damned-if-they-do, damned-if-they-don’t position, where if they find a small difference, people can say it’s no big deal, and if they find a big difference, people can say they don’t believe it. Still, they found a big difference, and I don’t know what to believe.
Reporting this sort of observational pattern seems like a good start, in any case. I’d like to reduce my own risk of dying in the next seven years by 30%, but I can’t quite bring myself to start drinking coffee every day.
So, yeah, I have nothing useful to add here. What do you expect?—It’s just a blog post! Seriously, I think it can be valuable for me to post sometimes just to express my ignorance and uncertainty. It’s a big world out there, and I have no insight, intuition, or expertise on this one.