Chocolate may have heart-healthy effects

Eating chocolates at least once a week may reduce the risk of coronary artery disease (CAD), a meta-analysis has shown.

“Our study suggests that chocolate helps keep the heart’s blood vessels healthy,” said study author Dr Chayakrit Krittanawong from the Baylor College of Medicine in Houston, Texas, US, in a press release.

“In the past, clinical studies have shown that chocolate is beneficial for both blood pressure and the lining of blood vessels … I wanted to see if it affects the … coronary arteries or not [and] if it does, is it beneficial or harmful?” he continued.

Six prospective studies (n=336,289) were included in the analysis. During a median follow-up of 8.78 years, 14,043 individuals developed CAD and 4,667 had MIs. [Eur J Prev Cardiol 2020;doi:10.1177/2047487320936787]

Compared with chocolate intake of <1 time/week, consuming chocolate >1 time/week was associated with an 8 percent reduction in CAD risk (pooled risk ratio [RR], 0.92; p<0.001).

The findings were consistent even after excluding one study that used a cutoff of 3.5 times/month (pooled RR, 0.90) and another study presented as an abstract (pooled RR, 0.94; p<0.001 for both).

“Chocolate contains heart-healthy nutrients such as flavonoids, methylxanthines, polyphenols, and stearic acid, which may reduce inflammation and increase good cholesterol,” said Krittanawong.

Flavanols* apparently reduce infarct size and platelet aggregation, and improve endothelial function, while methylxanthines are noted for their beneficial effects on cardiovascular function. [Vasc Pharmacol 2015;71:70-78; Proc Natl Acad Sci USA 2006;103:1024-1029; Am J Clin Nutr 2017;105:352-360] Polyphenols have been shown to facilitate nitric oxide synthesis, while stearic acid may reduce mean platelet volume. [Pflugers Arch 2010;459:853-862; Eur J Clin Nutr 2001;55:88-96]

However, the type or ideal portion of chocolate that could render heart benefits remain unclear. “Moderate amounts of chocolate seem to protect the coronary arteries, but it’s likely that large quantities do not,” he stressed. “[As such,] the unfavourable effects of supplemental calories** from chocolate products commercially available need to be taken into account … particularly in [individuals with diabetes and obesity].”

The findings may have also been limited by potential dietary confounders*** and the lack of adjustment for lifestyle factors (eg, exercise, physical activity). The predominant US and European populations may also limit the external validity of the findings.

“[Nonetheless,] the benefits of nutrients in chocolate appear promising, and chocolate consumption at least once a week may be beneficial for CAD prevention,” said Krittanawong and colleagues. The team called for longer randomized trials to establish the underlying physiologic mechanisms that could elucidate the cardioprotective effects of chocolate.

The type and ideal portion of chocolate that can generate a cardioprotective effect should also be determined in future trials. The role of genetic potential may also be worth looking into, they added.