This was only a ‘sign’, however, and not proof because of the flawed nature of the study, said Steffen Desch from the University of Leipzig Heart Centre in Germany.
He said a more conclusive trial could be difficult because the real thing would have to be tested against a ‘dummy’ substance that looked and tasted like chocolate.
Some small studies have claimed that chocolate lowers blood pressure and reduces inflammation in the body.
But Desch is unconvinced, the Daily Mail reports.
“Despite the studies, I couldn’t yet recommend dark chocolate as a prevention or treatment in cardiovascular disease,” he said.
“There’s no strong evidence of a benefit and no clear explanation of an effective mechanism.”
The calories contained in chocolate are likely to offset any protection to the heart, he said.
His reservations came as Dutch researchers dampened down speculation about the benefits of red wine on the heart. Any benefit from moderate consumption of red wine is likely to be small and outweighed by the adverse effects of drinking too much, scientists say.
Even though it is also supposed to help heart health, there is no single ingredient which appears to work, they said.
They have tested resveratrol, which is found in the skin of red grapes touted as having a range of life-enhancing properties.
Eric Sijbrands of Erasmus University Medical Centre in Rotterdam led a series of studies which failed to replicate the findings of heart benefits from taking resveratrol.
Using it in capsules for four weeks did not lower blood pressure in patients with hypertension, he said.
“Certainly, I would never actively prescribe red wine for a heart condition and, even if I was asked about it, I would be cautious,” he added.
If red wine does work, the explanation is likely to be ‘complex’, he said.
Any benefit from moderate consumption is likely to be small and outweighed by the adverse effects of drinking too much.
These findings were presented at the European Congress of Cardiology in Munich.