Key is Healthy Oils
Eating Fried food may not be hard on the heart or clog the arteries, as long as the frying is done in healthier oils, such as olive oil, according to a 12 year study of 40,000 Spaniards.
The hazard ratio for coronary heart disease was a nonsignificant 1.08 for the highest intake versus the lowest, they reported online in BMJ.
All-cause mortality likewise showed no impact from even the highest intake of fried foods in the study (adjusted HR 0.93, P=0.98 for trend).
"This result may seem surprising because frying is generally considered an unhealthy way of preparing food," an accompanying editorial acknowledged.
But that's an assumption that has largely gone unchallenged, with only sparse and inconsistent data on hard outcomes, explained Michael F. Leitzmann, MD, DrPH, of the University of Regensburg, Germany and Tobias Kurth, MD, ScD, of Université Bordeaux Segalen in Bordeaux, France.
"However, this does not mean that frequent meals of fish and chips will have no health consequences," they warned.
Negative Health Effects of Eating too Much Fried Foods
Instead of a blanket conclusion on fried food, the type of oil used, whether it's used to deep fry or pan fry, and how many times the oil is reused may be relevant, Leitzmann and Kurth concluded.
Fried Foods Health Study
The fried foods health study dug into one aspect, the type of oil used. The study used the Spanish cohort of the ERIC study (European Prospective Investigation into Cancer and Nutrition).
Detailed dietary interviews analyzed for 40,757 adults, ages 29 to 69, without baseline coronary heart disease indicated that about 7% of food eaten was fried for a total of roughly 5 oz each day (the equivalent of a medium serving of french fries).
Consumption was higher among younger, more educated individuals who smoked more and didn't sit as much at work.
After adjusting for energy intake, body mass index, hypertension, and other factors, the risk of incident coronary heart disease during 12 years of follow-up was not elevated significantly at any level of fried food intake.
The hazard ratio was 1.15 for the second quartile averaging 106 g (3.7 oz) of fried food each day, compared with the lowest intake at an average 47 g (1.6 oz) per day (95% CI 0.91 to 1.45). Other hazard ratios were:
• 1.07 for the third quartile averaging 158 g (5.6 oz) compared with the lowest intake group (95% CI 0.83 to 1.38)
• 1.08 for the top consumers averaging 250 g (8.8 oz) versus the bottom quartile (95% CI 0.82 to 1.43)
The results were the same for the 62% of people who used olive oil to fry food as for the rest who used sunflower or other vegetable oil (P=0.22 for interaction).
Nor was there any difference across genders (P=0.19 for interaction).
None of the most commonly fried foods -- fish, meat, potatoes, and eggs -- were linked individually to either heart disease or all-cause mortality.
The researchers cautioned that their findings came from a population that followed the traditional Mediterranean diet with greater use of olive oil, which is less prone to degradation during frying.
"Frying with other types of fats may still be harmful," the researchers warned.
While large amounts of fried foods are eaten both at and away from home in Spain, fried foods aren't a proxy for fast food or for high salt content in Spain, unlike in the U.S., the group pointed out.
Limitations of the study included dietary assessment only at baseline, which didn't account for changes over time, and inability to separate out the effect of the method of cooking from that of the food cooked.
The study was funded by research grants from FIS and the Instituto de Salud Carlos III and by funds from the Spanish regional governments of Andalusia, Asturias, Basque Country, Murcia, and Navarra, and the Catalan Institute of Oncology.