And that's because of the flavanols that are in dark chocolate has been linked to increasing blood circulation, antioxidant activity, anti-inflammatory activity.

Source: https://www.cbc.ca/news/health/dark-chocolate-lead-1.6744120?cmp=rss

However, describing the level of evidence supporting the claim that consumption of cocoa flavanols in high flavanol cocoa powder reduces risk of CVD as “supportive but not conclusive” or “not conclusive” is not accurate.

Source: https://www.poynter.org/reporting-editing/2023/is-cocoa-healthy-good-for-you/