Jan. 19, 2010 -- A new study shows corn oil is the most popular frying oil used for cooking french fries at major fast food outlets. Researchers found that 69% of national fast food restaurant chains serve french fries containing corn oil, compared to only 20% of small-business restaurants.
Researchers say french fries are often described by national fast food chains as being "prepared" or "cooked" in vegetable oil and may contain one or more of several oils, such as corn, canola, soybean, cottonseed, sunflower, and palm. But there are several nutritional reasons why it might be important for the consumer to know what type of oil is used in frying.
"Corn oil, although initially hailed as a highly polyunsaturated fat that could lower cholesterol, contains considerably more heart-harmful saturated fat than canola, sunflower, or safflower oils, and less heart-protective alpha-linolenic acid than soybean oil, making it the least healthy choice of the five," write researcher A. Hope Jahren of the University of Hawaii in Honolulu and colleagues in the Proceedings of the National Academy of Sciences.
They say nearly a quarter of the total calories in a typical fast food meal of a hamburger, fries, and soda and most of the meal's fat comes from the oil in which the french fries are cooked.
Figuring Out French Fry Fats
In the study, researchers analyzed the oil used in french fries purchased from 68 of the 101 national fast food chain outlets in Oahu, Hawaii, and compared it to the frying oil used in a similar number of small businesses.
The results showed 80% of the French fries purchased from small businesses had no evidence of corn oil in the frying oil composition, compared to only 31% of the national fast food chains.
Although the percentage of restaurants using more than 50% corn oil in their frying oil mixture was similar among the major chains and small restaurants (7% and 11% respectively), the study shows corn oil accounts for at least some of the mix in all the fast food chains, with the exception of Jack in the Box.
Researchers say corn oil is more expensive to purchase from small business suppliers than other oils, like soybean oil, which suggests that large-scale corporate agreements are needed to make frying in corn oil cost effective for fast food restaurants.