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Longer Life Through Coffee Drinking?

Coffee, the worlds number one stimulant, may increase your lifespan (a little bit) Ian Musgrave

There is a persistent belief that drinking coffee is bad for you. Some alternative medicine systems eschew all coffee drinking (but are enthusiastic about coffee enemas). Certainly if you overindulge the sleeplessness and tremors will remind you of the perils of too much of a good thing. But there is a longstanding belief that long term consumption of coffee is in some nebulous way “bad”. This is despite coffee being packed with the sorts of antioxidants you would pay good money for at the health food store.

Now a new study suggests that people who drink coffee are less likely to die.

Wow! Great! I’ll just fire up the espresso machine then.

Hold on, firstly, the effect is modest, you are around 10% less likely to die if you are drinking 6 or more cups of coffee a day. Secondly, it’s an association. We don’t know if it’s the coffee drinking leading to less death, or something else which coffee drinkers are more likely to do.

Oh, so I should pack the espresso machine away.

No, there is now a fair bit of evidence that modest coffee consumption can give you some degree of protection against things like Parkinson’s Disease and Alzheimer’s disease (again though, we don’t know if it’s coffee per se that gives protection, or something else that coffee drinkers do). And coffee tastes good too.

But the apparent health benefits of any food or beverage should not be an excuse to overindulge, like the people who use the reported benefits of drinking modest amounts of red wine as an excuse to drink bottles of the stuff in one go.

So while I get the espresso going, what is the latest evidence?

A research team followed a group of nearly 400,000 people for 14 years, or until they died ( whichever came first). They gave the people extensive questionnaires about coffee drinking, food consumption, lifestyle and measured a range of health parameters at the start of of the study. Then after the 14 years they looked at the death rates in coffee drinkers and non-coffee drinkers.

They found that more coffee drinkers died.

Wait! What!

That’s the problem with looking at these sorts of studies simplistically. There are a whole other bunch of factors that influence death rates. In epidemiology speak these are called “confounders” (because They confound interpretation). It turns out that most coffee drinkers also smoke, so the increased death rate was due too smoking differences between coffee and non-coffee drinkers.

If the researchers had not measured smoking rates in the people, they would have been fooled into thinking that coffee was bad for you. This is also why we say that the coffee drinking - less death is just an association, the increased life-span could be due to something that wasn’t measured, even though lots of things were measured.

So how did they work out coffee drinking was good for you?

In epidemiology speak they “ controlled for the confounders”. If you compare just smokers who don’t drink coffee with those that do, coffee drinking smokers livers longer than non-coffee drinking smokers. Of course, it’s not quite as simple as that. When you have a lot of measurements you have to do some clever mathematics to sort it all out.

So is it a good study?

Yes, they had a big group of people they followed for a sufficiently long time, they only looked at people who were reasonably healthy when they started following them (so disease progress patterns couldn’t mess things up) and they measured a heck of a lot of lifestyle factors.

One problem is, as the researchers point out themselves, that they only asked people about their coffee consumption at the beginning of the study. So they had no way of knowing if people decreased or increased their consumption, or switched to or from decaf.

Another thing they didn’t measure was the type of coffee, apart from crudely separating caffeinated from non-caffeinated. So we have no way of knowing if most people were drinking Floor-Sweepings brand instant coffee or Heart Burtser double espressos.

The latter information is important if we want to generalise to other populations. US coffee as generally consumed is somewhat different in strength to how the Europeans take it. I vividly remember visiting a friend of mine in Seattle. At the time I was working as a postdoctoral student in Berlin. There was an industrial strength filter coffee machine outside my lab door, pumping out vicious black heart starters almost 24/7. My mate proudly took me to the street in Seattle where he claimed the best coffee in the US was served.

It tasted like pinkelwasser. That is not a compliment.

Sounds uninspiring, so how is coffee making people live longer?

Chlorogenic acid, a key antioxidant in coffee Ian Musgrave

We know how it’s not doing it. It’s not caffeine, as decaffeinated and caffeinated coffee had pretty much the same effect (except for injuries and accident, where caffeinated coffee was a clear winner).

Coffee is chock full of antioxidant chemicals such as polyphenols and Chlorogenic acid. We know that people who consume foods rich in antioxidants have better health outcomes and live longer than people who don’t. We also know that feeding people pure antioxidant vitamins is a waste of time. The antioxidant status of food may be unrelated to health, but may be a marker for something else in these foods.

So whether it’s the antioxidants in coffee is unclear. This hasn’t stopped companies from adding extra antioxidants to instant coffee though (although they were doing this well before this study came out). Maybe it’s something completely unrelated, like coffee drinkers are more likely to walk to their local coffee shop, getting a bit more exercise.

So if I want to live longer?

Choose you parents carefully, eat plenty of fresh fruit and vegetables, get more exercise, develop or participate in social networks. Why not walk down to your local coffee shop and share a cappuccino with your friends?

Coffee’s ready

Milk and two sugars please.

Join the conversation

10 Comments sorted by

  1. Peter Ormonde
    Peter Ormonde is a Friend of The Conversation.


    Excellent. As usual.

    This notion that eggs, meat, chocolate - any one thing - is Good or Bad seems pretty shallow. As your mate Paracelsus puts it - it's the dose stupid!

    Based on my current coffee consumption I should be around for just on 247 years.

    1. Susan Hemruth


      In reply to Peter Ormonde

      Happiness helps you live longer..if drinking coffee makes you happy, do it!

      Just watch the cream/ milk/ sugar/ whiskey that you add, or take some exercise to offset those things.

    2. Mark Chambers

      Business & Marketing Consultant

      In reply to Peter Ormonde

      Pete, glad I'll have some company then !! Still, chances are pretty good that you'd be eating fresher fruit than me so maybe you'll have a few years on your own. Anyway, nice to see a good health initiative that won't take up any time that we're not already dedicating. Wonder how long it will take before someone suggests that this research really should have been covered by the ABC ?? I'm already concerned ... it's a conspiracy I tell you !! :)

  2. Grendelus Malleolus

    Senior Nerd

    I roast my own coffee and from time to time wonder what the particulate and gas mix I inhale while roasting contains and whether it is beneficial or harmful. Mostly I don't care, roasting relaxes me and I figure I am outside so some of the known gases (NOx, CO, and CO2 are three for example) that can be present. I have no idea about the makeup of various volatile organic compounds that might be present but I try not to inhale more deeply.

    I also hope any bad effects are offset by my moderate consumption - I hope I'm right on that point :)

  3. Paul Rogers


    Yes, notwithstanding the pitfalls of prospective studies, coffee is also associated with lower risk of endometrial cancer, some breast cancers, liver toxicity, diabetes (strong), and even oxidised cholesterol.

    Finding excess risks for cardiovascular disease, as once proposed, with moderate coffee/caffeine consumption is also difficult, in fact the opposite may be true. Here are some tidbits from the Harvard Medical School:

    * Heart failure. Women who drink coffee are slightly less likely to…

    Read more
  4. Alex Holcombe

    logged in via Twitter

    Should we even be suggesting a causal effect of coffee from these observational studies? Let's look at the past record of this kind of evidence. Two statisticians looked for randomized clinical trials (RCTs) that followed up on the kind of correlational links you cite here. They found 12 RCTs that followed up on 52 causal links suggested from observational studies. Of the 52 claims, ZERO were verified. Five found statistical significance in the opposite direction.

    1. Paul Rogers


      In reply to Alex Holcombe

      Alex, I think Ian has been sufficiently cautious in his article. On the other hand, there are approaches that can provide more clues to causality in prospective studies. Dose-response is one; consistency across study, country and cultural (and genetic?) cohort diversity perhaps another; and then systematic review and meta-analysis.

      For example, coffee consumption seems to lower T2 diabetes risk in Americans, Chinese and Europeans. For diseases with a long latency, or agents with possible toxicity…

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    2. Alex Holcombe

      logged in via Twitter

      In reply to Paul Rogers

      Thanks Paul, I'm happy to hear that the studies reviewed ( had inferior methodology, I take your point about supplements, and I know methodology in observational studies are getting better all the time, thanks to structural equation modeling and the like. But there's still the question of whether such improvements are good enough. If they are, hopefully someone (you?) can point us to a list of cases where causal links hypothesised in observational studies were borne out in RCTs.

    3. Paul Rogers


      In reply to Alex Holcombe

      Alex, you are correct to point out the uncertainties inherent in early prospective studies. I think the Nurses Health Study and Willett, Hu and the Harvard group in particular have done much to improve methodologies in recent years.

      Someone closer to the action might be able to point to instances of observational studies being supported by RCTs. (I'm a little on the sidelines, although follow somewhat closely.)

      However . . . in a wonderful irony, it seems that coffee drinking may indeed be *inversely* associated with pancreatic cancer in this meta-analysis.

      Which tends to prove your point!

  5. Kari-Erik Luoto


    There was an Italian study showing that caffeine enhanced the life span of baker's yeast and the professor interpreted the the results in a way that is very good for the caffeine industry. This is just one of the legions of pseudo-scientific advertisement pamphlets funded by caffeine industry.

    Take a look at caffeine pharmacology, and you will soon understand that instead of protecting us from illnesses, it creates them. Caffeine is a psychoactive addictive drug that adjusts the brains towards…

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