Scientists have claimed that men benefit most from eating dark chocolate as it protects them against heart diseases and stroke.
The benefits include anti-clotting effects which are activated within two hours in both sexes, and with greater impact in men, the Daily Mail reported.
Having a piece of chocolate a day - not just at Christmas - could be the secret to staying heart healthy, according to scientists at the University of Aberdeen Rowett Institute of Nutrition and Health.
Lead researcher Dr Baukje de Roos, from the Rowett Institute, said: "It's an acute effect in the body that men and women both benefit from, but it's more diluted in women."
"These findings are not a carte blanche to eat chocolates as they are extremely rich in fat and sugar.
"But probably eating a little bit of dark chocolate containing at least 70 per cent cocoa every day is going to do more good than harm," she added.
The scientists from the Rowett, who joined together with the Institute of Food Research in Norwich, studied what happened in the blood of 42 healthy volunteers, 26 women and 16 men, after they ate dark chocolate specially boosted with cocoa extract.
They were investigating the effect on blood clotting, the result of over-activity of platelets that stick together blocking blood vessels that can lead to heart attacks and strokes.
Compounds called flavanols which are found in cocoa, tea and apples, appear have a beneficial effect on platelet function - and they are higher in cocoa-rich chocolate.
Long associated as a woman's favorite treat, epitomized by the famous Milk Tray ads, chocolate has been found to reduce the risk of deadly blood clots
The platelet function of people eating the enriched dark chocolate was compared with platelet function in those who had eaten dark chocolate - with a lower cocoa and flavanol content - and white chocolate.
Blood and urine samples were taken and then analyzed two hours and six hours after chocolate consumption.
The scientists were looking at a range of platelet function tests such as platelet activation - a reversible process where platelets are starting to get stressed and sticky - and platelet aggregation - an irreversible process when sticky platelets clump together.
They discovered the specially enriched dark chocolate significantly decreased both platelet activation and aggregation in men, but only cut platelet aggregation in women. The strongest effects were seen two hours after the chocolate had been eaten, the report said.
Researchers also measured bleeding time - which shortens as platelets become stickier.
They found that the specially enriched dark chocolate significantly increased bleeding time after six hours in both men and women, possibly caused by the metabolites that our bodies produce from flavanols.
The findings are published in Molecular Nutrition Food Research.