A recent report in the British Medical Journal (BMJ) suggests that three to four cups of coffee per day could increase your lifespan—sort of.

This isn’t entirely new information; we and others have covered coffee and health/longevity before. What’s special about this new report is that the researchers analyzed evidence from more than 200 systematic reviews and meta-analyses (scientific studies that compiled and analyzed lots of other scientific studies). So, this is really a “study of studies of studies.” All of the evidence they found indicates that drinking three to four cups of coffee per day (about 400 mg) is associated with a ~17% reduction in mortality risk, and a ~15% reduction in risk for heart disease and stroke. Based on their analysis, coffee consumption is also associated with a ~18% reduction in cancer risk, a ~30% lower incidence of diabetes, and ~27% lower Alzheimer’s disease risk. Oh, and no good evidence for harmful effects. 🙂

Sounds great, right?

Sure, but there’s a bit of a catch. Almost all of the evidence from these studies is what we call “observational.” That is, the researchers followed people over time and observed or recorded what they were doing (how much coffee they drank, who ended up developing heart disease, etc.), but they didn’t actually perform a trial. It makes sense; it would be hard to round up a few thousand people in their 40s, tell some not to drink coffee for the next 30 years and others to have three to four cups per day—and then see who develops diseases down the road. But it’s an important distinction. We can’t be sure that the people drinking coffee in observational studies don’t live longer just because they’re a bit wealthier (more money to spend on joe) and therefore healthier. So, we may never be able to say for sure that coffee reduces your risk for some diseases. Still, the evidence is piling up, and as we’ve explained here before, it looks like a hot beverage routine might good for you in other ways, too.

(Feature photo courtesy of pixabay.com)