Is caffeine good or bad for us?

Caffeine is never far from the headlines but is it good or bad for you? Dr Sandra Sünram-Lea spoke to Graihagh Jackson about the science behind the issue...

Sandra - Again it's difficult; it's the same as Thomas said before in terms of some of the other effects we see. You know the worries - does it raise heart rate, is that dangerous in the long term.  I think what we can say is that moderate dosage of caffeine doesn't seem to do you any harm and it can, actually, improve your cognitive performance to a certain extent.

Graihagh - How much caffeine are you talking about?  Are you talking about a cup of coffee, a cup of tea?

Sandra - Well this is the our point you know when we talk about moderate dosages.  There's different amount of caffeine in different cups of coffee depending on how they were brewed.  Tea usually has less caffeine in it.  We also have caffeine in chocolate.  You don't only take in caffeine in the form of a cup of coffee, you have caffeine in other substances as well.  The effects we found on cognition are usually in the range between 40-150 mg.  So, 40mg that would be a very small cup of espresso, for example; 150 mg that would be a quite large cup of brewed coffee, for example...

Graihagh - So if I was having on a regular basis say, maybe, two large coffees a day, is there any evidence that suggests going over that dose, maybe 200 mg a day might be bad for our health?

Sandra - There is no direct evidence that it would be unless you already have high blood pressure or if you are pregnant or, indeed, in children and adolescents - it's not  recommended.  The chances are it wouldn't do you immediate harm but if you do it over a longer period of time, particularly if you had high blood pressure anyway or if you're somebody who suffers from anxiety, you might actually make that worse.  But again, you know, people are different and for some people they might actually enjoy the buzz they get from coffee and a higher buzz from a higher dose - for other people that might be detrimental.

Graihagh - So if it's not necessarily good or bad for us - what about addiction because some people talk about being addicted to coffee and if they don't have any they get a headache - is there any truth behind that?

Sandra - I think here we have to differentiate addiction and withdrawal symptoms, so people can get headaches if they don't take caffeine.  Now this is due to what Thomas mentioned before - the adenosine receptors in the brain - they are blocked because we take in caffeine.  Now if we don't have our dosage of caffeine, then we have a higher increase in the transmission of the adenosine system, and that might actually lead to dilation of blood vessels so the headaches come on, we feel more tired.  Obviously, if we now take another cup of coffee or any other kind of substance that contains caffeine, we'll feel better again.  So there is definitely this kind of withdrawal symptoms and they make us somewhat dependent on caffeine.

However, when we look at addiction, then caffeine has a very, very low addictive potential.  So what we have; we have a form of dependence but we don't really have addiction.

Graihagh - We also have sugar and caffeine together with these energy drinks.  Does glucose and caffeine seem to have some kind of combined effect?

Sandra - They seem to have some combined effect simply because they act on different aspects of cognition.  So, for example, we have glucose is more good for complex tasks, decision making, particularly memory.  Caffeine on it's own is good for attention tasks, simple tasks where we have to have sustained attention.  If we take both substances together, we can see beneficial effects above and beyond those we see with these two substances in isolation.