May 23, 2017

expert reaction to paper on chocolate and heart flutter

In a new study, published in Heart, scientists investigate the association between moderate chocolate intake and atrial fibrillation or flutter risk.

Dr Gavin Sandercock, Reader in Clinical Physiology (Cardiology) and Director of Research in Sport & Exercise Science at the University of Essex, said:

“The paper states ‘Participants with higher levels of chocolate intake had a lower rate of clinically apparent incident AF or flutter’ – but this is not true.  The people who ate chocolate 1-6 times per week had lower risk than people who hardly ever did (less than once a month), but there was no difference to those who ate chocolate every day.  If chocolate was ‘causing’ less atrial fibrillation/flutter then eating more should lower the risk more – but it didn’t.

“The group with the lowest chocolate consumption was a strange group.  They had the highest blood pressure, were most likely to have hypertension, most likely to have high cholesterol and were twice as likely to already have heart disease. They were fatter than all the other groups despite eating the least calories overall, which tells us they were the least active as well.

“In short, they were the unhealthiest group in the whole study – which means that almost any other group will seem healthier than them.  So it is somewhat misleading to compare everyone else to this group!

“Only one in five people in the survey ate chocolate less than once per month.  The study doesn’t say why they ate chocolate only very occasionally, but it’s worth noting that there were five times more people with diabetes in the is category compared with the 2-6 times per week group.  So it’s likely that these people only ate chocolate very rarely BECAUSE they have diabetes and have to follow a special diet.

“In short, the study shows that people who eat chocolate 1-6 times per week – which is nearly everyone in the study – do have a slightly lower chance of atrial fibrillation,  but only if you compare them with a small group of rather unhealthy individuals who don’t (or can’t) eat chocolate more regularly.

“AF (or flutter as it is known) is not a particularly serious problem, and is often benign so it’s strange to focus just on chocolate and its ‘benefits’ to AF, especially in a study designed to look at cancer risk, like this one.”

Dr Tim Chico, Reader in Cardiovascular Medicine & consultant cardiologist, University of Sheffield, said:

“Some studies have suggested eating chocolate may have benefits for the heart, but when a health story seems too good to be true, it sadly usually is.

“This study finds that Danish people who eat chocolate have a lower risk of a common heart rhythm disorder called atrial fibrillation. However, they show a benefit of eating chocolate once a month or more, compared with people who eat chocolate less often than this, so the benefit is seen with very infrequent chocolate intake, with little or no benefit of eating it more often. In addition, in this study the people eating more chocolate were actually thinner and healthier overall, both of which reduce the risk of atrial fibrillation. I suspect that the reduced risk of atrial fibrillation is more to do with these factors than their chocolate intake directly.

“One in four of us will develop atrial fibrillation by the age of 80, which is a major cause of strokes, so it is important to do what we can to reduce our chance of developing this heart rhythm problem. The best way to do this is to maintain a healthy weight and blood pressure, perform moderate exercise regularly, and reduce alcohol intake all of which also reduce the chances of other diseases as well.”

* ‘Chocolate intake and risk of clinically apparent atrial fibrillation: the Danish Diet, Cancer, and Health Study’ by Elizabeth Mostofsky et al published in Heart  on Tuesday 23 May 2017.

Declared interests

None to declare