A glass of tomato juice a day keeps blood clots away, says a study into heart disease.

After drinking 250ml of tomato juice a day for three weeks, a group with diabetes experienced much reduced clotting activity, University of Newcastle dietetics PhD student Sherri Lazarus found.

"We looked at how susceptible the platelets were to clotting before and after the daily tomato juice," she said.

"Platelet activity decreased following supplementation with tomato juice compared with the placebo group."

Platelets are responsible for blood clotting, which is necessary to stop bleeding.

Although Lazarus examined only the anti-clotting effect in people with diabetes, she said tomato juice would benefit anybody at risk of cardiovascular disease.