Indulging in a little chocolate each week maybe be linked with a lower risk of developing the heart rhythm irregularity atrial fibrillation, according to new Danish research.

Also known as a heart flutter, atrial fibrillation affects more than 33 million people worldwide, and one in four adults are likely to develop the condition at some point in their life. However, it's not clear what causes it or how to prevent it, and there is no known cure.

As regular chocolate consumption, especially of dark chocolate, has been shown to be beneficial for other heart conditions, the team behind the new research wanted to see if chocolate could also help reduce the risk of atrial fibrillation.

The researchers looked at data from 55,502 (26,400 male and 29,100 female) participants, aged between 50 and 64, who were taking part in the Danish Diet, Cancer and Health Study.

Participants reported on their usual weekly chocolate consumption, with one serving classified as 1 ounce (30 g). Although they were not asked to specify what type of chocolate they consumed, most chocolate eaten in Denmark is milk chocolate, which has a minimum 30 per cent cocoa solids.

The team also gathered information on participants' diet and lifestyle at the beginning of the study, including information on heart disease risk factors such as smoking. Participants were then monitored for an average of 13.5 years.

The results showed that the diagnosis rate of atrial fibrillation rate was 10 per cent lower for those who are 1-3 servings of chocolate a month than it was for those who ate less than 1 serving a month.

Those who ate one serving of chocolate a week benefited from a 17 per cent lower risk of atrial fibrillation, and those who increased this to 2-6 weekly servings benefited from a 20 per cent lower risk. Those who ate one or more servings daily showed a 14 per cent lower risk.

When they looked at any sex differences between the results, the findings showed that the association seemed to be strongest for women when they ate 1 weekly serving of chocolate (21 per cent lower risk), and strongest for men when they consumed between 2 and 6 weekly servings (23 per cent lower risk).

As an observational study, no firm conclusions can be made, and certain factors could affect the health benefits of the chocolate, for example adding milk.

However the team still concluded, "Regardless of the limitations of the Danish chocolate study, the findings are interesting and warrant further consideration, especially given the importance of identifying effective prevention strategies for [atrial fibrillation]," which have so far proved elusive.

The findings can be found published online in the journal Heart.