A WORLD-FIRST trial of a low-cost combination "polypill" to prevent heart attacks is about to begin in Sydney, in a move that could eventually see all people from middle age onwards medicated to reduce their chance of disease - even if they do not have high blood pressure, raised cholesterol or other obvious risk factors.

The pill could cost as little as $40 for a year's supply and combines aspirin with off-patent cholesterol-lowering and blood pressure medicines. Organisers of the pilot study have started recruiting people who are apparently healthy but have an increased chance of developing heart disease over the next five years because of their age, smoking or weight.

The initiative is the first time a cheap combination heart pill has gone into a large trial and marks a step towards the goal - advocated by some doctors - of offering preventive heart drugs to all people above a certain age.

Medicating people who were not ill was a confronting idea, said Anushka Patel, director of the cardiovascular division of Sydney University's George Institute for International Health.

A common fear was that "people will see this as an instant cure and say, 'Now I can just take a pill with my Big Mac'," said Associate Professor Patel, who is leading the Australian arm of the New Zealand-led international trial. But it was also possible the pills might prompt people to think about their health and adopt lifestyle changes. "They're not mutually exclusive," she said.

All the component drugs had a strong safety record, "so you can treat very low levels of cardiovascular risk without the side-effects outweighing the risks."

The 400-person study will establish whether the pill - made by Dr Reddy's Laboratories in Hyderabad - lowers participants' blood pressure and cholesterol over a three-month period, compared to a placebo. The researchers then hope to follow 5000 people for five years to see whether the pill prevents disease and death.