Researchers in eastern England have set themselves an easy challenge: finding 150 women prepared to eat a bar of chocolate every day.

The chocolate is free, and made specially for the study by a Belgian chocolatier. The intention is to see whether it improves the women’s health.

The volunteers must be past menopause, must suffer from type 2 diabetes, and must already be taking statins to reduce their cholesterol levels. They will also need the approval of their doctors.

Postmenopausal women with type 2 diabetes are usually advised to avoid chocolate. Rich in sugar and fat, it is not part of their recommended diet.

Chocolate is also rich in flavonoids, compounds that have been linked to a reduced risk of heart disease. Chocolate companies are set to take advantage of the research — some of which they have funded themselves — to encourage the belief that chocolate can be good for you.

Until now, few of the trials have met the highest standards of scientific validity. A team from the University of East Anglia plans to put that right.

The volunteers, all postmenopausal women who are not taking hormone replacement therapy, will be divided into two groups. Half will eat the special chocolate, the other half a normal bar as a placebo. The women will be checked at the start of the one-year trial, and five times during it.

Ultrasound scans will measure the thickness of the wall of the carotid artery, and the total volume of plaque, the material that blocks the arteries in heart disease.

“The chocolate has three times the amounts of flavonoids you would find in a normal high cocoa chocolate. This has been achieved by a special extraction process that retains the chemicals we think are the important ones,” said study coordinator Peter Curtis.

It tastes, he says, “quite nice” with a flavor of caramel. Soy has been added to provide an even greater dose of flavonoids.

Aedin Cassidy, Professor of Diet and Health at the university, who is heading the project, said: “We hope to show that adding flavonoids to their diets will provide additional protection from heart disease and give women the opportunity to take more control over reducing their risk of heart disease in the future.”

Ketan Dhatariya, consultant in diabetes at the Norfolk and Norwich University Hospital, added: “If the trial confirms that flavonoids improve the level of protection against heart disease, it could have a far-reaching impact on the advice we give.”

Iain Frame, director of research at Diabetes U.K., which is funding the trial, said: “We certainly don’t advise people to start eating a lot of chocolate as it’s very high in sugar and fat. We would always recommend that people with diabetes eat a diet low in fat, salt and sugar with plenty of fruit and vegetables.”

He said that older women with diabetes were five times more likely to develop heart disease.