I've blogged before about caffeine, but thought a bit more info might be of interest.
We all know that caffeine is addictive: I can vouch for that personally. A year or so ago I cut down from my 6 double espressos a day to only 3 - and really struggled to do it.
Just so that we know what we're talking about, an addictive substance (a drug, if you will) has the following attributes:
I can vouch for all of those with my espressos.
But how much caffeine is actually in an espresso?
In a study published in the Food and Function journal in January 2012 the researcher Thomas Crozier and colleagues tested the amount of caffeine in coffee shop espressos in Glasgow. They purchased 20 espressos over several days and took them back to the lab to analyse the caffeine content.
The study showed that caffeine concentration varied 56mg to 322mg, although only 4 contained over 200mg.
(By the way, the Food Standards Agency recommends an upper limit for women in pregnancy of 200mg)
What was more interesting was that even espresso brought from the same coffee shop varied in caffeine content over different days. Crozier bought the same blend from Starbucks over 6 days - the amount of caffeine in supposedly the same cup of coffee from Starbucks varied from 260mg to 564mg.
Remember, to that often (like me) people drink double espressos, so that could be upwards of a 1000mg a time (if you're lucky, or unlucky, depending on your viewpoint).
In 1909 when Coca-Cola was launched a large part of it's success was based on the caffeine content which then had 80mg of caffeine per 250ml serving. These days, the caffeine content of Coke is down to 20mg (according to the US Drug Administration).
Monster energy drink contains 86mg per 250ml.
Red Bull contains 80mg per 250ml.
So a lot of the espresso's that Crozier's team studied had a lot more caffeine than the energy drinks that sometimes get a bad press.
As I've said before, I'm not a nutritionist, but if you want to talk to someone who is, drop me a message and I'll put you in contact with someone who can talk a lot more knowledgeably about the subject than me.