We don't know. My understanding of the current meta-studies is that there is a slight positive effect on general health and life expectancy associated with drinking reasonable amounts of coffee.<p>But think about that more -- what else could be associated with drinking coffee? People who drink coffee every day might be more likely to have a job, which means (in the US) that they're more likely to have health insurance and higher socioeconomic status, which can cause increases in life expectancy too.<p>Which suggests that it could be the case that if you're <i>thinking about</i> drinking coffee every day, you've probably already benefited from the positive effects regardless of whether you actually go ahead and drink it.<p>While I don't think we're going to be able to isolate the measurement of positive effects, we can say one thing: while we can't measure causal positive effects on health, we're at least not seeing strong <i>negative</i> effects on health from moderate coffee drinking.<p>The argument's just over whether coffee is causing the slightly-better health that people who drink it experience, or merely correlating with it.
If you're asking for scientifically proven statements: I don't know, I doubt anyone does.<p>If you're asking for opinions: after having been a regular (sometimes extreme) coffee drinker for more than 20 years (until about 3 months ago), I'd say no. Whatever disputed positive effects it might have (mildly stimulating, supposedly preventing depression, for me personally it seemed to prevent distraction mostly, but so does suitable music... ), we know for sure that it screws up your sleep and, in many cases, digestive system. I sleep better and am more productive now (I think) than before and on top of that I also got rid of an annoying routine (making coffee N times/day) and a resource I depended on (and might miss during zombie apocalypse, for example). But for people who smoke for example, it's probably negligible either way.
If you have a healthy habit of drinking fresh water, drinking moderate amounts of coffee is mostly beneficial, since coffee is a diuretic.<p>Otherwise you may fuzz up your concentration along with your gastrointestinal system.
In moderate amounts (1-2 cups a day, or a bit more), it has beneficial effects.<p>For people who drink 1-2 pots a day, I've seen it cause gastrointestinal issues, ulcers, reflux, and other issues.
According to this article, yes: <a href="http://www.theatlantic.com/health/archive/2012/11/the-case-for-drinking-as-much-coffee-as-you-like/265693/" rel="nofollow">http://www.theatlantic.com/health/archive/2012/11/the-case-f...</a><p>Seems to cover a lot of studies, but it could be a "submarine" post. <a href="http://www.paulgraham.com/submarine.html" rel="nofollow">http://www.paulgraham.com/submarine.html</a>
Brendan Brazier (former professional Ironman triathlete) talks about coffee in his book "Thrive" and explains that you're basically "borrowing energy" that you eventually have to pay off at some point. Coffee in itself is not bad but one should use it wisely.
You will find many articles which suggest that coffee is healthy and cures xyz.. and the very next article which will suggest that it will kill you.<p>You be the judge. The safest way to do it, is not to overdo it.
I have an incurable medical problem, genetic in nature. I have gotten off a lot of prescription medication. How I eat is a big part of how I manage my condition. Caffeine is a stimulant similar to some of the prescription drugs I have gotten off of. I consume plenty of diet coke but I am not a big coffee drinker. I do occassionally drink it for medicinal purposes, usually something mocha since I really am not crazy about coffee. As I resolve underlying issues, my general consumption of coffee, chocolate and diet coke has gone down. I just no longer need so many stimulants, so I just don't crave it.<p>Thus I suspect coffee is "healthy" for some people in much the way that an albuterol inhaler is good for some people: If you have some mild health issue which is treatable with stimulants, having moderate treatment as part of your diet is better than having no treatment. If coffee is something you seem to need, you might do well to look into things like allergies, respiratory problems, etc.