UMass Amherst food scientists reported that feeding frying oil to mice exaggerated colonic inflammation, enhanced tumor growth, and worsened gut leakage, spreading bacteria or toxic bacterial products into the bloodstream. Their results were published in Cancer Prevention Research today.
According to the team, "it's not our message that frying oil can cause cancer." Rather, the new research suggests that eating fried foods may exacerbate and advance conditions of the colon. "In the United States, many people have these diseases, but many of them may still eat fast food and fried food," says Guodong Zhang. "If somebody has IBD or colon cancer and they eat this kind of food, there is a chance it will make the diseases more aggressive."
For their experiments, the researchers used canola oil, in which falafel had been cooked at 325 F in a standard commercial fryer at local eatery. A combination of the frying oil and fresh oil was added to the powder diet of one group of mice. The control group was fed the powder diet with only fresh oil mixed in. "We tried to mimic the human being's diet," lead author Jianan Zhang adds.
The researchers then looked at the effects of the diets on colonic inflammation, colon tumor growth, and gut leakage, finding that the frying oil diet worsened all the conditions. "The tumors doubled in size from the control group to the study group," Guodong Zhang says.
To test their hypothesis that the oxidation of polyunsaturated fatty acids, which occurs when the oil is heated, is instrumental in the inflammatory effects, the researchers isolated polar compounds from the frying oil and fed them to the mice. The results were "very similar" to those from the experiment in which the mice were fed frying oil, suggesting that the polar compounds mediated the inflammatory effects.
"For individuals with or prone to inflammatory bowel disease," Guodong Zhang says, "it's probably a good idea to eat less fried food."
Image: For their research, food scientists used samples of canola oil in which falafel had been deep-fried. Image courtesy of UMass Amherst