A cheap, single pill taken once a day that combines four common drugs is safe and reduces the risk of events such as heart attacks, strokes and sudden death in people over the age of 50, research has found.

The study, the first large-scale trial to date, looked at the effectiveness of a so-called polypill – a four-in-one therapy containing drugs to lower cholesterol and blood pressure that was first proposed more than 15 years ago. The researchers found those taking the polypill had a more than 30% lower risk of serious heart problems than those just offered advice.

While different formulations have been studied, previous trials have only been conducted in small groups of people and over short periods of time. These studies have primarily looked at the impacts of cholesterol on blood pressure, relying on models to predict the impact on cardiovascular events such as strokes – meaning the full potential of the polypill has remained unclear.

The latest study tackled both of these problems. “There has been a lot of talk about using this simple, fixed-dose combination drug for prevention of cardiovascular disease and I think we have shown that as a strategy it can work,” said Prof Tom Marshall, a co-author of the study from the University of Birmingham, adding that the pills might cost as little as a few pence per day.

The new study involved more than 6,800 participants aged 50-75 from rural Iran – an area where almost 34% of premature deaths are down to coronary heart disease, and 14% are caused by strokes.

Writing in the Lancet, researchers from the UK, US and Iran reported that 3,417 people were given only minimum care, such as help with controlling blood pressure or cholesterol if needed, as well as lifestyle advice on topics such as diet, exercise and smoking. A similar number of people were, in addition to this, also given the polypill. More than 90% of those involved in the study did not have cardiovascular disease at the outset.

Participants were followed up for five years. Over that time, 202 people taking the polypill had a major cardiovascular event, such as heart attack, heart failure, or stroke, compared with 301 in the “advice” group.

The authors say that translated as a 34% lower risk of having such an event, compared with the “advice” group, once factors including age, sex, diabetes and high blood pressure were taken into account.

There were also signs that, at least early on, the polypill reduced some aspects of high blood pressure, while it also led to a small fall in “bad” cholesterol. Both groups showed similar low levels of problematic events including internal bleeding and peptic ulcers.

Overall, the results suggested that two major cardiovascular events would be avoided for every 69 people taking the tablet for 5 years.

The polypill includes aspirin, which the team acknowledge is controversial as it can increase the risk of bleeding: the latest trial did not include people who were at high risk of such problems.

The researchers said the polypill could be particularly beneficial in low and middle income countries, with the study showing that simply giving it to people over a certain age, without the need for blood tests or complicated assessments, helps to prevent heart attacks, stroke and other such conditions.

The authors added that an additional benefit of the polypill was that patients did not have to take four separate tablets. That said, they stressed that a healthy lifestyle remained important for cardiovascular health.

Scientists in the field welcomed what they called a “robust” study, but they noted there were limitations.

Prof Jeremy Pearson, an associate medical director at the British Heart Foundation, cautioned that the situation in Iran was very different to countries such as the UK. In high-income countries there is good preventive medical care and lower rates of cardiovascular disease than in rural Iran. This means the benefits of rolling out a polypill might be smaller in high-income countries.