Eating chocolate at least once a week is linked to reducing the risk of heart disease, a large-scale study suggests.

Analysis of over 330,000 participants found that eating chocolate more than once a week reduced the risk of developing coronary heart disease by 8% when compared to those who indulged less often.

Researchers combined six studies to examine the association between chocolate consumption and coronary heart disease, a condition where the arteries become blocked by a build up of fatty substances.

This narrows the arteries and reduces the supply of blood to the heart, leading to a heart attack in severe cases.

Author Dr Chayakrit Krittanawong, of Baylor College of Medicine in Houston, Texas, said: “Our study suggests that chocolate helps keep the heart’s blood vessels healthy.”

Some 336,289 participants, from the United States, Sweden and Australia, reported their chocolate consumption for the six separate studies.

Participants had an average follow-up time of around nine years in the studies, which spanned the past five decades.

The meta-analysis, published in the European Journal of Preventive Cardiology Research on Wednesday, found that 14,043 of the participants had developed coronary heart disease.

Compared with consumption less than once a week, eating chocolate regularly, more than once a week, was associated with an 8% decreased risk of the condition, the authors report.

Moderate amounts of chocolate seem to protect the coronary arteries but it’s likely that large quantities do not

Researchers suggest that nutrients in chocolate, such as flavonoids, methylxanthines, polyphenols and stearic acid, may reduce inflammation and increase good cholesterol.

Limitations noted by the authors include different types of chocolate being consumed by participants, while lifestyle factors, such as exercise, were not adjusted for the studies.

The analysis did not examine whether any particular type of chocolate is more beneficial, or whether there is an ideal portion size.

But Dr Krittanawong added: “Moderate amounts of chocolate seem to protect the coronary arteries but it’s likely that large quantities do not.

“The calories, sugar, milk, and fat in commercially available products need to be considered, particularly in diabetics and obese people.”