A study published online in the journal Heart found that regular consumption of chocolate may be associated with a lower risk of developing irregular heart rhythm, atrial fibrillation (heart flutter).
The findings suggested that the associations seem to be the strongest for 1 weekly chocolate serving in women (21 percent lower risk) and between 2 and 6 weekly servings in men (23 percent lower risk).
Globally 33 million people are affected by atrial fibrillation, with 1 in 4 adults developing it at some point in their life span. The causes are not clear exactly, however, there are no cures at present and no obvious ways of prevention either.
Given that regular consumption of chocolate, in particular, dark chocolate, has been related to improvements in various heart health indicators, the researchers wanted to see if it might also be connected with a lower atrial fibrillation rate.
From the population-based Danish Diet, Cancer and Health Study, the current study drew 55,502 participants (26,400 men and 29,100 women) in the age group between 50 and 64.
The participants provided information on their usual weekly consumption of chocolate, with one serving categorized as 1 ounce or 30 g. However, they were not asked to specify the type of chocolate they have consumed. However, in Denmark, mostly milk chocolate is consumed which has minimum 30 percent cocoa solids.
When the participants were recruited for the study, information about the lifestyle such as diet, smoking habits (roughly one in three participants smoked), and risk factors of heart diseases were obtained. Using national registry data, their health, such as episodes of hospital treatment and deaths were tracked.
Participants who are at the higher end of the chocolate consumption scale were likely to consume more calories daily—with chocolate contributing to higher proportion, and tend to be more highly educated when compared with those at the lower end of the scale.
The mean of the monitoring period was 13.5 years and, during this period, 3,346 new atrial fibrillation cases were diagnosed. After adjusting other factors connected with heart disease, the rate of atrial fibrillation that was newly diagnosed was 10 percent lower for 1–3 chocolate servings in a month than it was for less than a single serving in a month.
This difference was also noticeable at other consumption levels. The rate was 17 percent lower for a single serving in a week, 20 percent lower for 2-6 servings a week, and 14 percent lower for 1 or more servings in a day.
When the data were scrutinized by gender, the frequency of atrial fibrillation in women was lower when compared with men irrespective of intake. However, the associations between higher consumption of chocolate and lower risk of heart flutter remained even after adjusting for possible influential factors.
The nature of the study is observational and so no firm conclusions can be drawn about cause and effect. In addition, the milk—thought to have a role in the favorable associations found between chocolate and heart health, may lower the beneficial compound levels in chocolate. Most often, chocolate is consumed in high-calorie products containing fat and sugar, which are generally not considered good for the health of the heart.
Nevertheless, the researchers said: "Despite the fact that most of the chocolate consumed in our sample probably contained relatively low concentrations of the potentially protective ingredients, we still observed a robust statistically significant association."
However, a linked editorial sounds a word of caution. Doctors from the Duke Center for Atrial Fibrillation in North Carolina, USA, highlighted that the factors associated with better general health might have influenced the findings as the study participants were healthier and more highly educated.
Secondly, the researchers were not able to consider other risk factors for atrial fibrillation, such as kidney disease and sleep apnoea (breathing problems at night). The editorials suggested that the study included only diagnosed cases of atrial fibrillation, making it difficult to find out if chocolate is associated with a lower risk of atrial fibrillation or only with evident symptoms.
Finally, the levels of cocoa solids vary across different parts of the world and so they added that the findings might not be applicable in countries with lower cocoa solids levels.
Nevertheless, Drs Sea Pokorney and Jonathan Piccini said: "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.