A new study suggests that all most all fast foods contain chemical elements or ingredients derived from corn either in forms of meat, oil or others.

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.

In the United States, as much as 70 percent is genetically modified and has drawn criticism from opponents.   The study did not tell whether trans fat was found in the samples, but it's very likely as trans fat is often used to prepare fries.

Another thing some consumers may be concerned about is the way the cows are raised.   Cows and chicken feeding on corn meals or other grains are likely to produce high proportions of omega-6 fatty acids, which are not good for health.   Meat from cows grazing on grass tends to contain higher levels of omega-3 fatty acids, which are good for health.

The study was published in www.pnas.org