They placed 38 volunteers on the diet, in which protein accounted for 10% of daily energy intake, carbohydrate 60% and fat for 30%.

It included nuts, sunflower seeds, fruit and vegetables, millet and corn. Sesame milk provided a daily source of calcium.

A further 28 volunteers followed a healthy diet with approximately the same proportions of protein, carbohydrate and fat.

Saturated fats were not to make up more than 10% of daily energy intake, and wholegrain products were to be chosen as often as possible.

Those on the vegan diet showed a decrease in the total level of cholesterol and specifically a reduction in the amount of low-density lipoprotein (LDL), also known as "bad cholesterol".

In contrast, those on the non-vegan diet showed no significant variations in these levels.

The researchers pointed to a "large body of evidence" suggesting that these changes were beneficial when it comes to preventing blockage of the arteries and cardiovascular disease.

The vegan volunteers also had a lower Body Mass Index (BMI) at the end of the 12 month period, while the control group remained the same.

The Arthritis Research Campaign, which is currently looking into how statins may reduce cardiovascular risks for sufferers, said the study was of interest but said the role of diet could be exaggerated.

"However we do know that, for example, eating oily fish can reduce inflammation, and risk factors for developing the condition include high consumption of red meat and low consumption of fruit and vegetables, so diet does play a role - however limited," a spokeswoman said.

But the charity also sounded a note of warning: "A vegan diet may be helpful in reducing cholesterol, but it is difficult to get enough of some important nutrients on a vegan diet."