More evidence dark chocolate is cardioprotective

Pauline Anderson

June 01, 2012

Melbourne, Australia - The blood-pressure-lowering and lipid effects of dark chocolate could be an effective—and cost-effective—strategy for preventing cardiovascular events in high-risk patients, a new study suggests [1].

"The findings of this study suggest that the blood-pressure-lowering and lipid effects of plain dark chocolate could represent an effective and cost-effective strategy for the prevention of cardiovascular disease in people with metabolic syndrome (and diabetes)," Dr Christopher M Reid (Monash University, Melbourne, Australia) and colleagues conclude.

"Chocolate benefits from being by and large a pleasant and hence sustainable treatment option," they write. "Evidence to date suggests that the chocolate would need to be dark and of at least 60% to 70% cocoa or formulated to be enriched with polyphenols."

Dark chocolate, derived from cocoa beans, is rich in polyphenols, specifically flavonoids that exhibit antihypertensive, anti-inflammatory, antithrombotic, and metabolic effects, all of which may contribute to cardioprotection.

The study was published online yesterday in BMJ.

Long-term effects

Previous studies have shown that dark-chocolate consumption may lower blood pressure, but they have been relatively short—only to a maximum of 18 weeks. Studies have also shown that dark chocolate may decrease total and LDL cholesterol and increase HDL cholesterol, but again, these changes have been explored only in short-term trials.

To determine potential long-term effects of consuming dark chocolate every day, as well as the cost-effectiveness of this strategy, Australian researchers used statistical modeling techniques (Markov model) to which health states ("alive without cardiovascular disease," "alive with cardiovascular disease," "dead from cardiovascular disease," "dead from other causes") and decision analysis (no dark chocolate [control] or with dark chocolate [treatment]) were added.

With each annual cycle, the researchers used risk-prediction algorithms and population life tables to estimate the impact of eating dark chocolate every day for 10 years on patients with metabolic syndrome.

The study used data on 2013 participants from the Australian Diabetes, Obesity, and Lifestyle study who had metabolic syndrome, but not a diagnosis of cardiovascular disease or frank diabetes, and who were not receiving antihypertensive medications.

Patients were relatively young (mean age 53.6 years) and considered at high risk: they had a mean systolic blood pressure of 141.1 mm Hg, mean total cholesterol of 6.1 mmol/L, mean glycated hemoglobin of 34.4 mmol/mol, and mean waist circumference of 100.4 cm.

The researchers concluded that under the best-case scenario—in which all patients ate dark chocolate daily for a decade—70 nonfatal cardiovascular events, including nonfatal stroke and nonfatal MI per 10 000 population, as well as 15 cardiovascular-related deaths per 10 000 population, could be prevented.

The estimated incremental cost-effectiveness ratio was $52 500 per years of life saved when $42 per person per year was assumed to have been spent on a prevention strategy using dark chocolate.

Even if only 80% of individuals with metabolic syndrome were compliant with daily consumption of dark chocolate over 10 years, preventing only 55 nonfatal and 10 fatal events per 10 000, it would still be considered an efficacious and cost-effective intervention strategy, the authors write.

Prevention strategy

A dark-chocolate prevention strategy of $42 per person per year in a high-risk population would be cost-effective "based on the commonly accepted, albeit arbitrary, threshold of $50 000 per years of life saved," said the authors.

The $42 per person per year could be devoted to advertising, educational campaigns, or potentially subsidization of dark chocolate in this high-risk population, they said.

The authors point out that the potential effectiveness of dark-chocolate consumption on cardiovascular events other than nonfatal stroke and nonfatal MI, such as heart failure, were not assessed.

They also stressed that the effects of dark-chocolate consumption on blood pressure and total cholesterol, although beneficial, are not as profound as those of drug interventions.

The authors declared no relevant conflict s of interest.


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