Image Credit: Heart UK
We have always praised dark chocolate for its antioxidant effects, but the new research reveals that it works for more than that.
There are compounds in cocoa called flavan-3-ols, including epicatechin, that can influence blood vessel activity. These compounds may improve the function of the blood vessels’ inner lining, called the endothelium, partly by influencing nitric oxide production and signalling. Nitric oxide helps relax and widen blood vessels, which can improve blood flow.
In the year 2019, a systematic review of randomised trials was conducted, and the authors found that cocoa flavonoids show a significant change in flow-mediated dilation (FMD), which happens to be the endothelial function. This review consisted of a total of 15 published studies with 18 intervention groups. The final result indicated an improvement of around 1.17% in FMD.
Recent data have allowed us to understand even more. The meta-analysis of 2025, involving 145 trials with 5,205 participants, has found that consumption of flavanol-3-ols positively affects endothelial function and leads to a modest reduction in blood pressure.
The most crucial point here is that cocoa may be more than the above-mentioned antioxidant. flavan-3-ols seem to have an influence on vascular activity through vascular signalling pathways.
Nonetheless, it does not mean that chocolate consumption can lead to treatment of hypertension or heart diseases. Researchers often make use of controlled cocoa or flavanol-rich products, and ordinary chocolate may contain a significant quantity of sugar and calories.
References:
Sun Y, et al. (2019). Cocoa flavanols and endothelial function. https://doi.org/10.1039/C9FO01747J
Lagou V, et al. (2025). Flavan-3-ols, blood pressure and endothelial function. https://doi.org/10.1093/eurjpc/zwaf173
