Coffee and Your Health: Getting Meta About Coffee Studies

Score one (more) for coffee. That's the conclusion drawn by Aaron E. Carroll in the New York Times (More Consensus on Coffee’s Benefits Than You Might Think ). This isn't going to be news to those of you who've seen our coverage of the health benefits of coffee, of course. However, there's an important takeaway in Carroll's journalism that you'll find useful when you're trying to assess the validity of scientific research, whether that research is on the health benefits of coffee, the health impact of eggs, or even the existence and causes of global warming. If you follow science as a layperson, it's easy to get more than a bit confused even when you have a decent grasp of the concept being studied. For one thing, science doesn't remain static. That's a good thing, since we're always finding new tools and methodologies, which bring with them new (and hopefully better) ways to push back at our ignorance in how we understand the world. That can turn out to be a double-edged sword, however, since multiple studies of the same subject can seem to see-saw back and forth, and since some interests in industry and politics are in the habit of magnifying even the smallest doubt or question regardless of what the evidence says, as long as it serves their own ends (as you will no doubt have noticed if you've given the debates over vaccinations or climate change even a cursory glance). The big takeaway from Carrolls article, therefore, isn't just that coffee has many health benefits if consumed correctly (i.e., in moderation, and without loading it down with sugar and fat). It's the methodology. Rather than taking one or two studies and comparing them, Carroll looks at so-called Meta Studies, which aggregate peer-reviewed research on a subject (preferably studies with a larger pool of subjects, especially if they're longitudinal) and evaluate the research based on the patterns that emerge when examining the data. Something that only occurs rarely, or in a smaller sample size, or in a poorly-controlled study, is going to be given less weight than something that occurs across the majority of samples. When viewed this way, the scientific and medical research on coffee comes into much sharper focus. It also, not surprisingly, becomes much more consistent. In summary -- as the USDA noted in its most recent dietary guidelines -- not only do you not have to worry about your coffee. You can enjoy it. Embrace it, even. Because, as the science increasingly shows, it's good for you.* *The usual cautionary notes apply, of course. Cut back on sugar and cream and additives, as we've mentioned above. Don't give coffee to your kids. And stay away from it if you have medical reasons to do so.