Unhealthy diet raises heart attack risk by 35 percent

Medical Tribune December 2008 SFXIV

David Brill

Eating a diet high in salt and fried foods can increase the risk of acute myocardial infarction (AMI) by as much as 35 percent, according to a large-scale study conducted across 52 countries worldwide.

The analysis of 5,761 AMI cases and 10,646 controls from the INTERHEART study also highlighted the benefits of eating fruit and vegetables – a dietary pattern that reduced AMI risk by 30 percent.

The chairman of the Singapore Heart Foundation, Dr. Terrance Chua, said that the findings should serve as a warning to Singaporeans, who are increasingly moving towards the unhealthy diet described in the paper.

"This is a message that all the various health promotion bodies in Singapore have been advocating all along, but knowledge is one thing and actual practice is another. Changing behavior is a real challenge," he said.

Chua hailed the global scale of the study as "very significant" since most previous research in this area had been limited to Western countries.

"This allows us to extend those results to different populations and different ethnic groups," he said.

"In a way it’s confirmed our understanding that high fat, salty snacks and dairy products are associated with an increased risk. Unfortunately that’s the diet that everyone in the world is tending to develop because it’s seen as the diet of successful societies."

The National Nutrition Survey of 2004 showed that although Singaporeans are eating more fruit and vegetables they are also consuming more fat, an increasingly high proportion of which is saturated.

Dr. Seow Swee Chong, a consultant cardiologist at National University Hospital, agreed that the findings from the INTERHEART study are a concern for Singaporeans but was more cautious in his appraisal of the research.

"This study is hypothesis-generating but not conclusive," he said, adding that the exact extent to which diet influences risk remains unclear since there are several limitations to the paper.

"The type of diet is undoubtedly influenced by the region that the study subject is from and also his ethnicity. Thus the findings may reflect more of a difference in propensity towards AMI due to genetic, racial or geographical factors rather than the diet. Indeed, there was a significant interaction between diet and region in the study," he said.

Participants in the case-control study were enrolled at 262 centers between February 1999 and March 2003. Dietary patterns were assessed using a 19-item food frequency questionnaire. [Circulation 2008 Nov 4;118(19):1929-37]

The international research team, led by McMaster University and Hamilton Health Sciences, Ontario, Canada, divided diet into three types: ‘prudent’ – high in fruit and vegetables, ‘Western’ – rich in fats, meat and salt, and ‘Oriental’ – high in tofu, soy and other sauces.

The adjusted odds ratios for AMI were 1.35 and 0.70 for those in the highest quartile
of adherence to the Western and prudent diets, respectively, compared to those in the lowest quartile (P for trend <0.001).>

Chua and Seow, however, both expressed reservations about the arbitrary classification system employed by the authors, preferring instead to focus on the components of the diet.

"It’s important not to be confused by the labeling and think that a Western diet is unsafe but it’s fine to eat nasi lemak and chicken rice," said Chua, noting that Asian food often contains just as much fat as Western food.