Eating dark chocolates may boost heart health

Scientists conducted a systematic review and meta-analysis of 19 randomised controlled trials (RCTs) of cocoa consumption.

The meta-analysis focused on whether consumption of flavanol-rich cocoa products was associated with improvements in specific circulating biomarkers of cardiometabolic health as compared to consuming placebos with negligible cocoa flavanol content. In all, 1,139 volunteers were involved in these trials.

 "Our meta-analysis of RCTs characterises how cocoa flavanols affect cardiometabolic biomarkers, providing guidance in designing large, definitive prevention trials against diabetes and cardiovascular disease in future work," said Simin Liu, professor at Brown University in the US.

"We found that cocoa flavanol intake may reduce dyslipidemia (elevated triglycerides), insulin resistance and systemic inflammation, which are all major subclinical risk factors for cardiometabolic diseases," said Liu.

The team's research summarising data from 19 trials found potential beneficial effects of flavanol-rich cocoa on cardiometabolic health.

There were small-to-modest but statistically significant improvements among those who ate flavanol-rich cocoa product vs those who did not.

The greatest effects were seen among trial volunteers who ate between 200 and 600 milligrammes of flavanols a day (based on their cocoa consumption).

They saw significant declines in blood glucose and insulin, as well as another indicator of insulin resistance called HOMA-IR. They also saw an increase in HDL, or "good," cholesterol.

Those consuming higher doses saw some of the insulin resistance benefits and a in triglycerides, but not a significant increase in HDL. Those with lower doses of flavanols only saw a significant HDL benefit.

In general, where there were benefits they were evident for both women and men and did not depend on what physical form the flavanol-rich cocoa product was consumed in - dark chocolate vs a beverage, for example.

"The treatment groups of the trials included in our meta-analysis are primarily dark chocolate - a few were using cocoa powder-based beverages," said graduate student Xiaochen Lin.