Melbourne, Vic, Australia. Daily consumption of dark chocolate over 10 years can can reduce cardiovascular events in people with metabolic syndrome, says a new study.

Cardiovascular disease is the leading cause of death worldwide. Dark chocolate (containing at least 60% cocoa solids) is rich in flavonoids — known to have heart protecting effects — but this has only been examined in short term studies.


What is already known on this topic

Dark chocolate has antihypertensive, anti-inflammatory, antithrombotic, and metabolic effects.

Short term trials have shown that dark chocolate consumption can potentially reduce systolic blood pressure by 5 mm Hg (interquartile range 2-8 mm Hg) and total cholesterol concentration by 0.21 mmol/L (0.05-0.36 mmol/L).

What this study adds

A modelling analysis predicted that dark chocolate consumption in populations at high risk of cardiovascular disease could potentially avert cardiovascular events over the long term owing to its antihypertensive and metabolic effects.

The model also suggested that $A40 (£25; €31; $US42) could be cost effectively spent per person per year on prevention strategies using dark chocolate.

This best case analysis suggests that dark chocolate/cocoa consumption with a polyphenol content of 500-1000 mg would be an effective and cost effective primary prevention strategy for those with multiple cardiovascular disease risk factors.

—  Adapted from the research articlePeople with metabolic syndrome, a cluster of factors that increases the risk of developing heart disease and diabetes, are at high risk of heart attacks and strokes. So a team of researchers at Monash University used a mathematical model to predict the long-term health effects and cost effectiveness of daily dark chocolate consumption in 2,013 people that meet this risk profile. The findings appear in the journal BMJ.

All of the study participants had high blood pressure and met the criteria for metabolic syndrome, but had no history of heart disease or diabetes, and were not on blood pressure lowering therapy.

• With 100% compliance (best case scenario), the researchers show that daily dark chocolate consumption could potentially avert 70 non-fatal and 15 fatal cardiovascular events per 10,000 people treated over 10 years.
  
  
• Even when compliance levels were reduced to 80%, the number of non-fatal and fatal events potentially averted was 55 and 10 per 10,000 people treated over 10 years, and could still be considered an effective intervention strategy.
  
  
• The model also suggested that $A40 (£25; €31; $US42) could be cost effectively spent per person per year on dark chocolate prevention strategies and could be used for advertising, educational campaigns, or subsidising dark chocolate in this high risk population.

The authors stress that only non-fatal stroke and non-fatal heart attack were assessed in their analysis, and that the potential effects on other cardiovascular events, such as heart failure, are yet to be tested.

Also important, they say, is that these protective effects have only been shown for dark chocolate (at least 60-70% cocoa), rather than for milk or white chocolate, probably due to the higher levels of flavonoids found in dark chocolate.

Nevertheless, they conclude that the blood pressure and cholesterol lowering effects of plain dark chocolate "could represent an effective and cost effective strategy for people with metabolic syndrome (and no diabetes)."