The fruit appears to thin the blood, reducing the risk of clots, and lower fat in the blood that can cause blockages, without negatively affecting cholesterol levels. Such effects are similar to those of a daily dosage of aspirin, recommended by doctors to improve heart health.

"Platelet inhibitory drugs, such as aspirin, have been shown to reduce the incidence of myocardial infarction, stroke and death from cardiovascular disease," said lead researcher Professor Asim Duttaroy of the Institute for Basic Medical Sciences at the University of Oslo.

Aspirin, a member of the non-steroidal anti-inflammatory drug (NSAID) class, is one the most commonly used medications - taken by 14 million people in the US alone on a daily basis - and has recently been recommended as a means of protecting against cardiovascular events. But all drugs in this class can cause inflammation and ulcers in the GI tract and this massive exposure takes its toll. Each year, around 100,000 people are hospitalised and 10,000-20,000 die each year from NSAID-related complications.

Dr Duttaroy's team stops short of recommending kiwifruit as a replacement for aspirin by cardiovascular patients. But he said: "The results of our study are quite promising and are an indication that kiwifruit is an excellent choice for people trying to improve heart health through diet."

Heart disease is the leading cause of death in the world, killing nearly 17 million people annually.

The Oslos researchers still do not know which components in kiwifruit bring about the benefits to heart health however. Writing in the August 2004 issue of Platelets (vol 15, no 5, pp287-292), Dr Duttaroy explains that many of the polyphenolic compounds found in fruits and vegetables have antioxidant as well as anti-thrombotic properties, which help prevent blood clotting.

But although kiwifruit contains very significant amounts of polyphenols as well as the antioxidant vitamins C and E, these were not included in the study.

"There is something in kiwifruit which creates an anti-platelet effect," said Dr Duttaroy. He added that the mode of action by which kiwifruit elicits this response appears to be quite different from that of aspirin.

"Further research on identification of the active compound is required for a more definitive conclusion."

A recent study by the UK's Rowett Research Institute shows that eating kiwifruit daily can provide substantial protection against the kind of DNA damage that can trigger cancer and, more significantly, kiwifruit greatly speeds the repair of DNA damage.

Kiwifruit is one of the most nutrient-dense fruits, containing more vitamins and minerals than 27 of the most commonly consumed fruits.