The conclusions, published in the journal Clinical Nutrition, come on the back of a body of research pointing to the positive impact of flavonoids in chocolate.
And the authors, including researchers based at the Harvard Medical School and the Boston University School of Medicine, argue that their findings are consistent with a recent study in the German Heart Journal which showed dark chocolate intake was associated with a 39 per cent lower risk of myocardial infarction and stroke combined.
Dark chocolate belongs to the flavonoid-rich foods such as fruit and vegetables, tea, and red wine, with epidemiologic evidence indicates that beneficial effects of these on CHD are partly mediated through the effects of their polyphenolic compounds.
The authors hold that while interventional studies have demonstrated beneficial effects of dark chocolate on blood pressure and endothelial function, there is, in fact, limited data available on the effects of total chocolate intake on CHD.
And they decided to analyse data taken from the National Heart, Lung, and Blood Institute (NHLBI) Family Heart Study to evaluate this link.
The scientists explained that, using a cross-sectional design, they studied 4,970 participants aged 25 to 93 years, whose chocolate intake had been assessed through a semi-quantitative food frequency questionnaire. “We used generalized estimating equations to estimate adjusted odds ratios,” said the authors.
Of the total study cohort, 2,258 participants were men while 2,712 were women. The average age was 52.0 years and CHD prevalence was 10.9 per cent, added the researchers.
The researchers found that there was evidence for an inverse association between frequency of chocolate consumption and prevalent CHD in crude and adjusted models.
In the fully adjusted model, consumption of chocolate more than five times a week was associated with 57 per cent lower prevalent CHD compared with subjects who did not consume chocolate.
“Exclusion of subjects with prevalent diabetes and those who were on a weight loss diet made the association stronger,” they added.
They said that similar associations were observed in subjects who were 60 years of age or younger and those above the age of 60. Furthermore, they said, similar associations were seen among smokers and non-smokers.
The researchers admit, however, that the cross-sectional design of their study limits their ability to draw casual inference. “In addition, misclassification and reporting bias are inherent to self-reported data on chocolate consumption and we were not able to differentiate dark from milk or lighter chocolate,” they stated.
But the authors also stress that the inability to distinguish the different types of chocolate might have led to an underestimation of the true association between cocoa/chocolate polyphenol consumption and CHD in the study.
And they argue that large sample size (most of whom were from population-based studies), the availability on multiple CHD risk factors, and the multi-centre nature of the study are the strengths of the study.