Heart disease health centre

No link between heart disease and foods fried in olive oil

By Sophie Ramsey

BMJ Group News

What do we know already?

Frying foods increases their calorie count, because they absorb cooking oil as part of the cooking process. Studies show that frequently eating fried food can raise your risk of high blood pressure, high cholesterol and obesity - all risk factors for heart disease. However, few studies have explored whether eating lots of fried food directly raises your risk of heart disease.

To learn more, researchers looked at more than 40,000 men and women in Spain, who filled out detailed questionnaires about their diet, health, and lifestyle. They were then followed for up to 12 years, to see if they developed heart disease. The participants ranged in age from 29 to 69.

What does the new study say?

People who ate the most fried food daily (250 grams, on average) were no more likely to develop heart disease during the study than those who ate the least amount (47 grams, on average). The researchers also found no link between how much fried food people ate and their chances of dying during the study, of any cause.

These results remained the same after researchers accounted for several factors that can affect a person’s risk of heart disease, including their age, how much they exercised, whether they smoked, and whether they had high blood pressure.

More than 6 in 10 people in the study used olive oil for frying, with the rest using sunflower oil or another type of vegetable oil. The researchers found no difference between the oils in people’s risk of developing heart disease or dying.

How reliable is the research?

This was a large and well-conducted study, but we need to be cautious about its findings for a few reasons.

First, the researchers used questionnaires to assess people’s diets. This isn’t the most reliable approach, as some people may have misrepresented what they ate - particularly if they thought fried food would be viewed as unhealthy. Also, the researchers asked people about their diets only at the start of the study, so they didn’t take into account any changes to eating habits that happened over time.

Most importantly, we can’t be certain that these findings apply to people outside of Spain, where a Mediterranean-style diet is common. This features plenty of fruit and vegetables, not too much red or processed meat, and olive oil instead of fats such as butter, margarine, and lard.

So the fried food people ate in the study - for example, lots of fish - was different to the fried food consumed in many other countries. And even if the oils used were similar, the types of frying (for example, deep frying versus pan frying) might have produced different results.

What does this mean for me?

These findings suggest that eating foods fried with olive or sunflower oils may not raise your risk of heart disease, which is good news. However, eating lots of fried food, which is high in fat and calories, can lead to other health problems, including weight gain and high cholesterol. For good overall health, it’s best to limit high-fat foods, and balance these out with plenty of whole grains, fruit, and vegetables. Also, it’s important to remember that the results don’t apply to foods fried in solid fats, such as animal fat or butter.