A U.S.-based study team analyzed diet and disease data collected from more than 100,000 men and women. Compared to people who ate fried food less than once a week, those who gobbled things like fries, fried chicken, or other deep-fried snacks four to six times a week saw their risk for Type 2 diabetes and coronary heart disease jump 39% and 23%, respectively. The risks rose even more for people who ate fried food on a daily basis.
Cooking oil tends to break down during the frying process—a chemical transformation that changes the oil’s fatty acid composition, explains study co-author Leah Cahill, a research fellow in nutritional sciences at the Harvard School of Public Health. Foods simmering in that degraded oil absorb fatty acids and other unhealthy compounds. That’s a problem, because those acids and compounds contribute to ballooning waist lines, unhealthy cholesterol and blood pressure changes, and higher levels of oxidative stress—all of which could explain the links between fried food consumption and higher rates of Type 2 diabetes and heart disease, Cahill says.
Still, there may be a light at the end of the tunnel for fried-food fans. Cahill says past research has hinted that trans fat-free cooking oils may not pose the same health risks. Cooking at home with fresh oils might also limit your exposure to unhealthy compounds, she adds.
Unfortunately, at this point Cahill says it’s impossible to say which fried foods are safe and which are not. “I wish I could give more-specific recommendations when it comes to healthy cooking oils. But our study is really a first take, and we need to know more before we can say what’s safe.”
While Cahill and other nutrition scientists sort things out, her research suggests you’re better off limiting your fried food intake—especially away from home, where oils are more likely to be reused.
Originally Published: TIME