Results from a systematic review and meta-analysis suggest that regular consumption of flavanol-rich cocoa powder or chocolate reduces blood pressure (BP) by a small but significant amount.
"Although we don't yet have evidence for any sustained decrease in blood pressure, the small reduction we saw over the short term might complement other treatment options and might contribute to reducing the risk of cardiovascular disease," commented lead researcher Karin Ried (University of Adelaide, Australia) in a press release.
These findings add to those from previous studies demonstrating the beneficial cardiac effects of flavanol consumption.
The team pooled data from 20 studies including 856 people in total. The studies lasted between 2-18 weeks (mean 4.4 weeks) and compared the effects of consumption of 3.6-105 g of cocoa products containing 30-1080 mg flavanols (mean 545.5 mg) per day with consumption of a control product (either flavanol-free or low flavanol concentration) on cardiac outcomes including BP.
Writing in the Cochrane Database of Systematic Reviews, Ried and colleagues found that individuals consuming flavanol-rich products had a mean reduction in systolic BP of 2.77 mmHg and in diastolic BP of 2.20 mmHg, both of which were statistically significant.
Notably, trial duration influenced the results and the significant effect was only present in trials of 2 weeks duration (n=9), but not in longer trials. However, most of these trials had control groups that did not consume flavanols, which may have influenced the results.
When the analysis was restricted to trials in which the controls consumed flavanol-free products only (n=12), the effects were more pronounced (3-4 mmHg).
"Long-term trials investigating the effect of cocoa products are needed to determine whether or not blood pressure is reduced on a chronic basis by daily ingestion of cocoa," write the authors
"Furthermore, long-term trials investigating the effect of cocoa on clinical outcomes are also needed to assess whether cocoa has an effect on cardiovascular events and to assess potential adverse effects associated with chronic ingestion of cocoa products," they conclude.
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