Tuesday Nov 18, 2008 (foodconsumer.org) -- Ingredients derived from corn such as corn oil are present in almost all types of fast foods, according to a new study published in the proceedings of National Academy of Sciences.

The study led by A. Hope Jahren, a professor of geography and geophysics at the University of Hawaii and Rebecca A. Kraft found that of the hundreds of servings of fast-fast meals purchased nationwide, only about 12 servings of food could potentially be traced back to something besides corn.

For the study, the researchers sampled 480 servings of hamburgers, chicken sandwiches and fries from McDonald’s, Burger King, and Wendy’s chains in Los Angeles, San Francisco, Denver, Detroit, Boston, and Baltimore.

Results of the study suggested that 100 percent and 93 percent of the cows responsible for the hamburgers and chicken sandwiches were fed exclusively corn-based diets.    And only 12 Burger King burgers bought on the West Coast used meat from cows that did not exclusively eat corn-based diets.

The researchers also found that the frying oil used by Wendy's seemed to be corn oil only although the restaurant claims it uses more than one type, media reported.    In contrast, McDonald's and Burger King fries seemed to be made using other types of vegetable oils.

What does the study mean?   For one thing, the results may concern some people who know how coin oil affects their health.   Not all cooking oils are the same and some types boost cancer growth while others inhibit cancer, according to a report published in the Oct 2007 issue of Molecular Nutrition & Food Research.

The report by Escrich E and colleagues from Universitat Autònoma de Barcelona in Barcelona, Spain says that epidemiologic and experimental studies have found that dietary lipids play a role in cancer particularly breast, colorectal and prostate cancers.

Escrich says incidence of cancer in Mediterranean countries where olive oil is commonly used is lower than other regions of the world. This observation prompts researchers to believe dietary fat may have something to do with cancer.  

Although previous studies are not conclusive, evidence suggests that the influence of dietary fats depends on the quantity and the type of lipids. High intake of omega-6 and saturated fat have been found to promote tumor while omega-3, conjugated linoleic acid and gamma-linolenic acid inhibit cancer growth.

Olive oil full of monounsaturated fatty acids is found to have inhibitory effects on cancer, Escrich says probably due to oleic acid, the main component of olive oil and some minor ingredients like squalene and phenolic compounds.

Nutritionists believe the ratio of omega-6 to omega-3 in American diets is too high.   That is, they use too much Omega-6 fatty acids which are commonly found sunflower oil, soybean oil, safflower oil in addition to corn oil.