Coffee beans.

Coffee: Health Effects and Addictive Properties

It’s Monday and you know what that means. Whether you like it pure and strong or with milk, sugar and your favourite flavours added, drinking coffee is an indispensable ritual for many of us. Scientists, like myself, are no exception. In fact, a few years ago, the infographic in Fig. 1, based on a survey by Dunkin’ Donuts, did the rounds. (Click it to see the full top 15 list.)

Biggest coffee-consuming professions.

Fig. 1: The top 5 biggest coffee-consuming professions. (Source)

I certainly learned to drink coffee during my studies and research internships. The flexible hours and the way a project can latch onto you are not conducive to a regular sleeping schedule, and coffee becomes a staple. When you’re cramming things into your head for an exam and you need a break (which you feel you do every half hour or so) the default thing to do is to get some coffee.

Coffee is definitely part of what makes many scientists go. It also brings them together during coffee breaks (where they still mostly talk shop.) I, for one, am not particularly surprised that scientists are up at the top of this list.

Is It Good For You, Though?

This year, however, I decided to cut down on the coffee. Last year was the year I decided to be healthier: get in shape, watch my diet, stop being lazy and get more stuff done. Now what I decided wasn’t working anymore was the intake of cup after cup of coffee every day, especially since I liked to saturate my coffee with plenty of sugar.

It was one of these things I knew in the back of my mind not to promote my health, and moreover I noticed that I had trouble going without it. If I didn’t drink coffee for a day or two, I would get a headache and become lethargic, and if there’s one thing I can’t stand, it’s being dependent on something that shouldn’t be of consequence to my life.

So I decided to take matters back into my own hands. I reduced my consumption to a comfortable one or two cups of coffee a day, rarely a third, and I forgo it altogether on days I wake up at my own pace.

All in all, though, my conception of the health risks (or benefits) of drinking coffee were vague at best. I knew it would probably not be a good thing to drink a lot of coffee, but my main motivation for cutting back was feeling dependent. So, I decided to see what scientific research had been done (probably fueled by plenty of cups) into the effects of coffee.

The Good News

It turns out the medical world has been doing lots of research into the health effects of coffee. If you search for coffee- and health-related articles with Google Scholar, you’ll find no shortage of literature that looks into correlations between coffee consumption and various health issues.

Luckily I found an article by Butt & Sultan (stop snickering) that reviewed all of this literature, to save me the trouble. (Find it here.) The article reports that coffee actually has quite a few beneficial health effects. Coffee contains various antioxidants, for starters. Regular consumption of coffee has been shown to reduce your chances of becoming inflicted with:

  • Alzheimer’s
  • Parkinson’s
  • Diabetes mellitus
  • Various types of cancer (liver, kidney, colon)

So, drinking coffee definitely isn’t all bad. It’s a product rich in all kinds of natural components that can help to keep you healthy. Definitely all good reasons to have that cup in the morning, and don’t cancel your morning coffee break just yet!

The Bad News

Unfortunately, it’s not all smooth sailing. Coffee has been linked to reduced chances of some illnesses, but with increased chances for others. Not surprisingly, drinking too much coffee can mess with your sleeping patterns due to the caffeine, causing insomnia and all the issues arising from that. Large doses of caffeine have also been correlated with various cardiovascular problems and can even trigger heart attacks: a sudden large dose of caffeine can be a tremendous shock to your system.

These results are serious, but are mostly related to excessive coffee consumption. As with any good thing, it’s not so good anymore if you overdo it.

Fry from Futurama: 100 Cups of Coffee

Fig. 2: There’s always such a thing as ‘too much.’

The Ugly News

Besides these negative effects, there are also the issues relating to the dependence on coffee you develop if you drink it regularly.

Withdrawal symptoms from caffeine use have been reported for a long time, but only in the last decades has it been systematically researched. While it may not seem like a very high priority, I’m still glad someone decided to look at these symptoms and positively relate them to coffee, because it took me a while to come to the conclusion that my headaches were due to caffeine dependence. I thought I was coming down with something; that it was because I’d been out for a run in cold weather; or that I was just tired. Slowly the coffee pattern emerged, but I still wasn’t quite sure.

However, now I’ve found a paper that looked into this. The authors (Juliano & Griffiths) looked at scientific articles reporting experiments and surveys concerning various symptoms, and tried to see if there was enough evidence to conclude that they were caused by caffeine withdrawal. They found a host of symptoms that fit the description.

If you’re a heavy coffee drinker, you can try this out for yourself. When you stop consuming coffee, cold turkey, you have about a 50% chance of noticeably suffering from the following symptoms:

  • Headache
  • Drowsiness
  • General sense of decreased wellbeing or contentedness
  • Inability to concentrate

Also, about a 25% chance of the following:

  • Fatigue
  • Feeling you lack energy
  • Irritability
  • Decreased alertness
  • Nausea
  • Blurred vision
  • “Flu-like” symptoms

Furthermore, some studies reported subjects feeling less sociable or even depressed. A noticeable craving for coffee was also found in some people. Most of these symptoms were stronger the more coffee a person was used to drinking.

The conclusion is that caffeine withdrawal is real: if you regularly drink coffee, you can become addicted. Is that a serious concern? Well, that’s for everyone to decide for themselves.

The Wrap-Up

So, what’s the verdict? Is coffee good or bad?

Looking at the literature, I find that the health effects are not as bad as I imagined: there are lots of positive effects, more of them documented than there are negative ones. The negative effects are serious, but seem to mostly be associated with excessive amounts of coffee.

What does that mean, though? When does coffee become excessive? The general consensus seems to be that for adults, drinking up to four cups of coffee a day is unlikely to harm you, if you are otherwise healthy (and not pregnant.) It may even be quite beneficial, due to the positive effects mentioned above. However, if you are used to drinking more than four cups a day, you may want to consider cutting down.

Of course, this is assuming you drink just coffee. If you like to pour copious amounts of sugar or whole milk into your coffee, those are things that need to be taken into account separately; they may offset any benefits you’re getting from coffee. Four mocha frappuccino’s with whipped cream and chocolate sauce a day are not going to do your health any good.

In any case, all things considered, drinking coffee in moderation is not a bad habit at all. It helps you stay focused, alert and motivated; properties anyone can put to good use (and scientists definitely so.) In moderation, it even has a few health benefits. So, if you, like many of us, have made a habit out of coffee, you can rest easy: you don’t have to give it up. Just be sure not to take it to extremes!

Marco is a theoretical (bio)physicist, currently engaged in unraveling the sequence-dependent dynamics of DNA molecules to earn his PhD at Leiden University. Other passions include literature and history.

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