But is coffee good for the heart? Yes, but in the right amounts

Die-hard fans of the ritual of having a coffee first thing in the morning or after lunch can breathe a sigh of relief. The latest scientific statement from the American Heart Association, recently published in *Circulation*, gives coffee top marks: up to 5 cups of ‘American-style’ coffee (240 ml each, equivalent to around 400 mg of caffeine per day – a small cup of espresso contains 60–80 mg) are considered safe for most adults and, in some cases, even appear to be associated with a reduced risk of certain cardiovascular diseases, such as heart failure, ischaemic heart disease and stroke.

The paper, authored by a working group led by Gregory M. Marcus, Professor of Medicine at the University of California, San Francisco, is the result of an in-depth review of the most recent literature on the relationship between caffeine and the cardiovascular system – a field of research that is far from straightforward to explore. But Marcus himself is quick to make an important point: these benefits relate to ‘pure’ coffee – that is to say, ‘black’ coffee without added sugar, syrups or cream. And take note: whilst no risks are evident with up to five cups of coffee a day, exceeding this limit (even with the help of energy drinks and energy ‘shots’) can have harmful effects on the heart.

The key point of the statement is precisely that it is the quantity that makes the difference – and not always in the way one might expect. Drinking between 1 and 3 cups a day, in people with normal blood pressure, is associated with an increased risk of high blood pressure, whilst drinking more than 3 cups a day appears to be associated with a reduced risk. Conversely, high doses of caffeine, such as those found in energy drinks, can significantly raise blood pressure, particularly in those who are already hypertensive.

When it comes to type 2 diabetes, too, the relationship between coffee and heart health is not clear-cut: in the short term, caffeine (found in coffee) may reduce insulin sensitivity, but regular consumption of black coffee, without added sugar or flavourings, has been linked to a lower risk of developing diabetes in the long term. The authors caution, however, that this benefit may depend on other bioactive compounds found in coffee and not necessarily on caffeine itself.

The results of randomised trials suggest that coffee consumption is associated with a reduced risk of atrial fibrillation, but also with an increased risk of ventricular premature beats – ‘premature’ heartbeats originating in the ventricles. Very high doses of caffeine, such as those found in energy drinks, are, on the other hand, inexorably linked to the onset of arrhythmias, even in young people (under 30) with a low cardiovascular risk. In short, at the recommended doses, caffeine appears to have a protective effect against atrial fibrillation (one of the most feared arrhythmias because it exposes the patient to the risk of pulmonary thromboembolism), whilst causing a few extrasystoles; but be careful not to overdo the doses, or you risk developing a serious arrhythmia even at a young age.