A third of the world's adult population -- more than one billion people -- will suffer from high blood pressure by 2025, scientists predicted.

About a billion people around the globe were afflicted with high blood pressure or hypertension, the most important preventable risk factor for heart disease and stroke, in 2000.

But in the next 20 years the number is expected to soar by about 60 percent and three-quarters of cases will be in developing countries.

"By 2025 we project that the number of adults with hypertension will be 1.56 billion," Dr Jiang He, of Tulane University School of Public Health and Tropical Medicine in New Orleans stated.

Cardiovascular disease is already one of the top killers in most countries and accounts for 30 percent of all deaths worldwide.

In the first study to estimate the total burden of hypertension in the world, the Tulane scientists compiled published research on regional and national figures from 1980 to 2002 to estimate the current worldwide and future prevalence.

In 2000, 333 million adults in developed countries and 639 million in poor nations had hypertension. The report estimates prevalence in developing states -- where it is set to rise by 80 percent -- will account for most of the predicted increase.

BRUNT OF BURDEN IN POOR COUNTRIES

"More than half of hypertension patients are living in developing countries now. By 2025 an even higher proportion will be in economically developing countries," He, an epidemiologist, explained.

"Cardiovascular disease will become the most serious public health challenge in developing countries."

Latin America and the Caribbean had particularly high prevalence of hypertension, according to the research published in The Lancet medical journal.

During recent decades, cases of high blood pressure have remained stable or decreased in wealthy nations, but have risen in poor nation because of lifestyle changes and the fact that people are living longer.

He and his team said developing countries consider infectious diseases as their most important health problem and do not focus prevention efforts on chronic illnesses.

Research has shown that reducing weight, salt and alcohol consumption, eating more fruits and vegetables and increasing exercise can reduce hypertension.

The researchers believe developing countries should follow the example of wealthy nations which have established national programs to prevent and treat high blood pressure.

"Our study gives a serious warning to health policy makers in developing countries and world organizations. They have to pay serious attention to hypertension and hypertension-related chronic diseases such as cardiovascular disease," said He.

"They have to pay attention now."