Eating Foods Fried In Olive Or Sunflower Oil Not Tied To Heart Disease Or Earlier Death, BMJ Study

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Main Category: Nutrition / Diet
Also Included In: Heart Disease;  Public Health
Article Date: 25 Jan 2012 - 2:00 PST

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In a new study published in BMJ on Tuesday, researchers find that consuming fried food is not linked to heart disease or earlier death, as long as the frying is done in in olive or sunflower oil. But they also note that the people they studied live in Spain, where like other Mediterranean countries they use olive or sunflower oil for frying, so this result would most likely be different in countries where people fry with solid and re-used oils.

Professor Pilar Guallar-Castillón from Autonomous University of Madrid, and colleagues set out to do the study because while high consumption of fried food has been tied to higher risk factors for heart disease, such as high blood pressure, high cholesterol and obesity, the link to heart disease itself had not been fully investigated.

People in Western countries use frying more than any other way of cooking food. Frying changes the nutritional content of food: it loses water and takes up fat, increasing its calorie content. Another thing that happens is that frying degrades oils, especially when re-used, creating more unhealthy trans fats and losing the healthier unsaturated fats. These unhealthier fats end up in the food that is eaten.

For the study, Guallar-Castillón and colleagues used data covering 40,757 adults aged 29 to 69 in the Spanish cohort of EPIC study.

EPIC (the European Prospective Investigation into Cancer and Nutrition study) is a large study of diet, health and lifestyle that has recruited in total about half a million participants in ten European countries.

None of the participants they studied had heart disease at the start of the study. Through trained interviewers, the participants gave information about their diet and cooking methods. Fried food was defined as being where frying was the only method used to prepare the food, and the participants were also asked whether the food was fried, battered, crumbed or sautéed.

Data about coronary heart disease events and deaths came from hospital discharge registers, population based registers of heart attacks and death registers.

When they analyzed the data, Guallar-Castillón and colleagues found that over the median follow-up of 11 years (up to 2004), there were 606 coronary heart disease events and 1,135 deaths (from all causes).

They then sorted the participants according to how much fried food was in their diet, so the ones who ate the least fried food were at the bottom of the list and the ones who ate the most were at the top.

They then compared the results in quartiles, for instance comparing the 25% who ate the least fried food (the first, or bottom quartile) with the next 25%, (the second quartile) and the third 25%, and lastly the fourth 25% (the ones who ate the most fried food).

When they did this they found, after adjusting for energy intake, BMI, high blood pressure and other risk factors, that the risk of coronary heart disease events was not significantly higher in the second, third and fourth quartiles compared to the first. (Eg the the multivariate hazard ratio of coronary heart disease in the fourth quartile was 1.08 (95% confidence interval 0.82 to 1.43; P for trend 0.74) compared to the first).

They also found the results did not vary between those who used olive oil and those who used sunflower oil to fry their food.

And there was no link between fried food cosumption and death (from any cause).

The authors conclude:

"In a Mediterranean country where olive and sunflower oils are the most commonly used fats for frying, and where large amounts of fried foods are consumed both at and away from home, no association was observed between fried food consumption and the risk of coronary heart disease or death."

In an accompanying editorial, Michael Leitzmann, a professor from the University of Regensburg in Germany, and Tobias Kurth, director of research at the Université Bordeaux in France, write that the study dispels the myth that "frying food is generally bad for the heart".

However, they also caution this "does not mean that frequent meals of fish and chips will have no health consequences".

They also note, as do the authors, that specific aspects of frying food, such as the type of oil used, could make a difference.

Written by Catharine Paddock PhD
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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