Diets worldwide that are rich in fried and salty foods increase heart attack risk, while eating lots of fruit, leafy greens and other vegetables reduces that risk, a groundbreaking study showed.
The study, called INTERHEART, looked at 16,000 heart attack patients and controls between 1999 and 2003 in countries on every continent, marking a shift from previous studies which have focussed on the developed world.
The patients and controls filled in a "dietary risk score" questionnaire based on 19 food groups, which contained healthy and unhealthy items and were tweaked to include dietary preferences of each country taking part in the study.
People who ate a "Prudent Diet", high in leafy green vegetables, other raw and cooked vegetables, and fruits had a 30 percent lower risk of heart attack than those who ate little or no fruit and veg, the study showed.
The third dietary pattern, called the "Oriental Diet" because it contained foods such as tofu and soy sauce which are typically consumed in Asian societies, was found to have little impact on heart attack risk.
Although some items in the Oriental diet might have protective properties such as vitamins and anti-oxidants, others such as soy sauce have a high salt content which would negate the benefits, the study said.
The study was groundbreaking in its scope and because previous research had focussed mainly on developed countries, according to Salim Yusuf, a senior author of the study.
"We had focussed research on the West because heart disease was mainly predominant in western countries 25-30 years ago," Yusuf, who is a professor of medicine at McMaster University in Canada, told AFP.
"But heart disease is now increasingly striking people in developing countries. Eighty percent of heart disease today is in low- to middle-income countries" partly because more people around the world are eating western diets, he said.
"This study indicates that the same relationships that are observed in western countries exist in different regions of the world," said Yusuf, who is also head of the Population Health Research Institute at Hamilton Health Sciences in Ontario.
Patients who had been admitted to coronary care units in 262 centers around the world, and at least one control subject per patient, took part in the study.
The INTERHEART results were published Monday in Circulation, the journal of the American Heart Association.
The main countries in the study were Argentina, Brazil, Chile and Colombia in South America; Canada and the United States in North America; Sweden in western Europe; Croatia, Poland and Russia for eastern Europe; and Dubai, Egypt, Iran, Kuwait and Qatar for the Middle East.
In sub-Saharan Africa, the main countries were Cameroon, Kenya, Mozambique, South Africa and Zimbabwe; while nearly all the South Asian countries, India, Pakistan, Bangladesh, Nepal and Sri Lanka took part, as did Southeast Asian countries including the Philippines and Singapore, Yusuf told AFP.