Hamilton, ON - A new, retrospective analysis of the worldwide INTERHEART case-control study conducted in 52 countries has found that a so-called "Western" diet—high in fried foods, salty snacks, eggs, and meat—increases the risk of acute MI globally and accounts for about 30% of the population-attributable risk [1]. Meanwhile, a prudent diet, rich in fruits and vegetables, appears protective and an Oriental diet neutral, Dr Romaina Iqbal (McMaster University, Hamilton, ON) and colleagues report online October 20, 2008 in Circulation.

It's pretty easy: the more bad things you eat and the less of the good things, the higher your risk of MI.

"Although the message might not seem novel—ie, that fruits and vegetables are protective and that fried and salty foods and meat, are harmful—the beauty here is twofold," coauthor Dr Sonia Anand (McMaster University) told heartwire. "First, this is a global study, and the results are very consistent from region to region. Second is the simplicity of the message, because dietary advice—especially around heart-disease prevention—has often been muddied by the complexity of the information, which is often lost on the individual.

"We hope this will allow policy makers to try to think of creative ways of making the good foods more easily accessible and affordable and the bad foods less accessible and maybe not as affordable," she added. "Because the greatest gains in changing what people eat—by country, by region, and by community—will come from those policy-level changes. It's pretty easy: the more bad things you eat and the less of the good things, the higher your risk of MI. From a public-health perspective, having a simple message is very important."

In the present analysis, Iqbal and colleagues included 5761 AMI cases and 10 646 control subjects. Individuals were excluded if they had known preexisting risk factors, such as diabetes or high blood pressure—"which adds noise to the analysis," Anand noted—but not if they were overweight.

They identified three dietary patterns in the world: Western, prudent, and a new pattern they termed "Oriental," categorized by a high intake of tofu and soy. Trained medical personnel interviewed the MI patients and controls regarding their eating habits and filled in dietary questionnaires consisting of a simple 19-item, one-page assessment tool that was adjusted for dietary preferences in each country, with a higher score indicating a worse diet.

"In general," Anand explains, "people eat some good things and some bad things, so we wanted to see whether we could create a simple score that can easily indicate in a clinic, to a family doctor, or to the individuals themselves whether they are eating the right things."

For someone in Canada, fried food might be pizza or French fries while in India it might be samosas.

"And we gave options to individuals related to the country they live in," she noted, "so for someone in Canada, fried food might be pizza or French fries, while in India it might be samosas."

After adjusting for known risk factors, the researchers found that those who consumed the prudent diet had a 30% lower risk of heart attack compared with people who ate little or no fruits and vegetables, those who ate a "Western" diet had a 35% greater risk of MI compared with those who ate little meat or fried foods, and those who followed an Oriental diet showed no relationship with MI risk.

The researchers believe that some components of the Oriental diet may be protective, such as tofu, but that the higher sodium content of some soy sauces may be harmful, thereby creating a neutral effect overall.

There was also a graded and positive association between the dietary risk score and risk of AMI. Compared with the lowest quartile, the odds ratio (OR) for the second quartile was 1.29, for the third quartile 1.67, and for the highest quartile 1.92 (95% CI 1.74-2.11; p for trend <0.001).

The results, the researchers say, are consistent with findings from several other studies in Western populations using different study design—that is, they illustrate the protective effects of fruits and vegetables and the harmful effects of fried foods and meats.

"The present study extends these findings and indicates that the same relationships that are observed in Western countries exist in different regions of the world," they note in their paper. "Our standardized case-control approach is the only feasible one to obtain evidence on the relationship of diet to cardiovascular disease from multiple populations in a relatively short period of time and at an affordable cost."

You come out as a specialist who can treat a patient with a heart attack, but when it comes to prevention, there is not much training.

Simply put, an unhealthy diet, as assessed by a straightforward dietary risk score, increases the risk of AMI significantly, whereas consumption of a prudent diet is associated with lower risk, they note. And "the population-attributable risk for AMI worldwide associated with poor dietary intake is substantial," they add.

Anand says she hopes the results will help cardiologists and others who treat such patients. "When I think of my own training—which was fairly recent—there was very little information on nutrition or dietary advice. So you come out as a specialist who can treat a patient with a heart attack, but when it comes to prevention, there is not much training.

"I believe physicians will welcome this advice. If the family doctor and other specialists embrace a holistic but simple approach, this could lead to a reduction in heart attacks and is very consistent with cancer-prevention guidelines. And I think the results are broadly applicable to the population at large," she concludes.