" ... trans fatty acids can be "formed by the high temperatures of frying, so you may be making them yourself." High heat can cause the formation of minuscule amounts of trans fatty acids over extended lengths of time. But temperatures for traditional frying (300 to 350 degrees) and relatively short cooking times (5 to 10 minutes) would have a negligible effect on the formation of trans fat in cooking oil.
"... a recent [nb: the article was published in 2003] study conducted to determine the levels of trans fat isomers formed by heat found that in canola oil heated to 500 degrees for 30 minutes, trans fat levels were increased by only 1 percent. Traditional frying at lower temperatures for shorter lengths of time would produce significantly fewer trans fats."