If you want to keep your cool, you might want to pass up those greasy wings and gooey dessert. A new study from the University of California, San Diego, suggests that people whose diets are higher in trans fats are more prone to aggression.

Trans fats, or hydrogenated oils, have made the news in recent years because studies have strongly linked them to heart disease and cancer, and some locales have passed laws restricting their use. They are still common, however, in restaurant food and many grocery items.

Beatrice Golomb, a physician and associate professor of medicine at U.C. San Diego, wondered if trans fats might affect behavior, after noting how they interact with a type of healthy fat. Past studies found that docosahexaenoic acid—or DHA, a long-chain omega-3 fatty acid—has a calming, antidepressant effect. Trans fats disrupt the chemical process that leads to the conversion of fatty acids into DHA, which led Golomb to suspect that trans fats might be linked to aggression.

Her study, which was published in March in PLoS ONE, involved 1,018 men and women older than 20 who filled out a food questionnaire and several other surveys that measure impatience, irritability and aggression. Even after considering other influences, Golomb's team found a strong link between the intake of trans fats and aggression. “Trans-fatty acids were a more consistent predictor of aggression than some traditional risk factors such as age, male sex, education and smoking,” Golomb says. The findings were consistent across both sexes and across all ages, ethnicities and socioeconomic groups.

Although the correlation was strong, the study does not prove that trans fats are causing the aggressive behavior. It is possible that naturally aggressive people tend to eat less healthy food. Or perhaps other ingredients found in processed foods, such as added sugars, are the real culprit. “We like to think we're in charge of our behaviors, but in fact there are many factors that influence us, food being one of them,” Golomb says.