1.19 Coffee and caffeine

“We want to do a lot of stuff; we’re not in great shape. We didn’t get a good night’s sleep. We’re a little depressed. Coffee solves all these problems in one delightful little cup.”

Jerry Seinfeld

Few substances have embedded themselves in our consciousness as a productivity tool as much as coffee and caffeine.

There is a considerable amount of evidence about what caffeine can do to your body. It is worth being aware, as it is possible that you’re getting more negative effects than benefits, depending on how much you take and your own susceptibility. Don’t assume anything.

One thing is certain. We are all drinking more coffee and consuming considerably more caffeine than we did a few years ago.

Coffee has been around for centuries, imbibed by the rich. Starbucks opened their very first store in Seattle in 1971. There are now over 26,000 stores in 70 countries. Their revenue in 2017 was over $21 billion. And that’s just Starbucks.

The British Coffee Association reports that 55 million cups of coffee are drunk in the UK every single day. Remarkably, 16% of people who visit coffee shops do so daily. It doesn't specify whether or not they are all writers. Glancing around your average coffee shop, you may wonder.

There is a decent amount of evidence that some people can become psychologically and physiologically dependent on caffeine. That’s the very definition of an addiction.

There is also no doubt that caffeine can, at low doses, improve your mood and help you become more alert. However, at higher doses it can have a quite intoxicating effect. Usually that’s fine, because people then don’t tend to drink any more and the whole thing is self-limiting.

Some people would argue that taking caffeine is more of a deeply entrenched habit rather than a compulsive addiction in the same way as some other substances. It’s possible you may even scoff at the notion that caffeine use can be problematic.

The Diagnostic and Statistical Manual lists all the possible mental disorders and it is now in its fifth edition (DSM-5). It recognizes several caffeine use disorders. The first, and one that many people will have had some experience of is caffeine withdrawal. There is also caffeine-induced anxiety disorder, caffeine intoxication, caffeine-induced sleep disorder, and one catch-all term with the spectacularly unimaginative name of “caffeine-related disorder, not otherwise specified.” Helpful.

The good news

There is some good news with caffeinated beverages. Or at least some of them.

There is evidence that the antioxidant effect of the polyphenols in tea and coffee has benefits, although there are mixed results. I've read studies that show a reduced risk of cancer from drinking coffee, but I would always be extremely careful about interpreting studies related to diet, as inevitably they can only show associations. Working out causation is a very different task.

There are also studies that show coffee can lengthen the telomeres.

Telomeres are chains of redundant and repetitive DNA that sit at the end of our chromosomes. They shorten as we get older and they are, in effect, a marker of cell biological age. If your telomeres are shorter, you are at greater risk of cancer. However, caffeine ingestion from sources other than coffee can shorten the telomeres. I should also point out that having a normal weight, staying clear of smoking and alcohol, and getting regular exercise will do far more to slow the shortening of your telomeres than anything else.

There is other general evidence that coffee drinking is associated with a reduced risk of death.

A large study published in July 2017 enrolled over half a million people in 10 European countries and found overall mortality was lower in men and women. It found that in women there was a reduction in death from circulatory disease and stroke. However it was also noted that there was an increase in deaths from ovarian cancer.

There is clear evidence that taking some caffeine on board can improve performance in sport. There is also little doubt that coffee, or rather caffeine, can increase alertness, given it is a mild central nervous system stimulant. A study back in 1991 suggested that a coffee after lunch could help that dip many of us experience on a daily basis.

"I drink a lot of black coffee and it's something I don't want to stop. It's probably my only serious vice, if one could call coffee a vice. I enjoy it and it helps me be productive."

Joanna Penn

The bad news

It is possible to suffer from caffeine intoxication.

How much caffeine is there in your typical cup of coffee? Amounts typically vary from around 150mg to much greater amounts in your largest cups served in coffee chains. A 250ml can of Red Bull has 80mg of caffeine. A Starbucks grande has 320mg. If you get into your local coffee shop and chug back one of those bad boys, you may well over-cook it a little.

Caffeine intoxication is diagnosed in people that have recent caffeine use, usually in excess of 250 mg, and five or more symptoms from the following list:

I don’t know about you but I’ve easily met these diagnostic criteria.

Caffeine withdrawal

The symptoms of caffeine withdrawal include headache, significant tiredness, difficulty concentrating, and changes to mood including lower mood and irritability. Flu-like symptoms have also been described.

You only have to experience three of these to be officially diagnosed as having caffeine withdrawal in terms of DSM-5. Normally these would happen within 24 hours of stopping caffeine use.

Caffeine and other medical problems

Too much caffeine can cause problems with headaches, but it is also true that withdrawal from caffeine can cause problems with headaches. Caffeine is known to trigger migraine, and it has a role in people who have problems with anxiety. I know if I drink more than two cups of coffee my anxiety levels tend to rocket and while I have plenty of neurotic traits, I’m not particularly prone to problems with anxiety. I find it is all driven by the caffeine.

I’ve also met a lot of patients who have had problems with irritable bowel syndrome triggered by caffeine. It’s also very common for people to have bladder and urinary problems that can be traced back to over-consumption of caffeine. Some people are just more sensitive to it.

Overall

“[Avoid] over-consumption of caffeine, coffee or tea in order to keep going, as opposed to going out and getting some exercise, which achieves the same end result but in a far healthier way."

Andrew, The Healthy Writer survey

It is easy to end up taking a lot of caffeine in a day. Every street corner in some quarters seems to offer coffee in all shapes and sizes. A systematic review of the evidence of the adverse effects of caffeine on health looked at literally hundreds and hundreds of papers. The long and short of it is that taking 400mg of caffeine in a day is unlikely to give you any problems.

However this comes with a whole bunch of conditions.

These kinds of studies average everything out across populations. And given there are literally thousands of papers it is averaging it out across hundreds of thousands of patients. However, there are hardly any studies where sleep is not affected by late-night ingestion of caffeine, and headaches have been shown to be associated with caffeine in all sorts of ways.

You, of course, are an individual and your susceptibility is unlikely to be bang on the average for everything.

Perhaps you are the kind of person who is a little bit prone to getting a dicky stomach, or perhaps you are prone to full-blown irritable bowel syndrome with a whole host of gastrointestinal and other symptoms that go along with it. What caffeine does to you won’t be reflected in the studies.

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