The BMJ has published a paper of 40,000 Spanish patients followed for 12 years. They compared people who ate the most fried food versus those who ate the least and concluded no increase in the risk of heart attack. The wrinkle is that the foods were fried in olive or sunflower oil. Before you celebrate, MedPage Today points out a couple of limitations. First, frying foods increases the calorie content, which could be bad for your health. Deep frying versus pan frying may have an effect and so could the number of re-uses of the oil.
As with the vast majority of these studies, this is observational, ie: someone tracked their habits and then ran the statistics to guess about risks. This is different from the scientific "gold standard", a randomized trial, but you can imagine how hard it would be to randomly assign some people to eat olive oil fried foods and others to eat, say, peanut oil fried foods. Besides, no one eats the same thing every day.
My take home point would be: if you are going to fry, use a healthy oil, but try to avoid it and bake or broil the majority of your food.
See the accompanying editorial for more opinion on the study.