Can eating a cheeseburger make you want to break a store window? Even though a 2012 study found a link between trans fat and aggression, not exactly.
Here's the deal: Researchers from the University of California, San Diego (UCSD) School of Medicine studied nearly 1,000 men and women, looking at their self-reported eating habits and asking them about their behavior. For instance, one questionnaire asked participants about aggressive behavior over the past week. Other surveys asked them to rate their irritability and impatience on a scale of 1 to 10.
The result? There was a strong link between dTFA (dietary trans fatty acids) and aggression/irritability. (Analyses were adjusted for sex, age, race and education).
So why was this? Trans fats stop the body from producing omega-3 fatty acids, which have already been shown to reduce aggression, notes lead study author Beatrice A. Golomb, M.D., Ph.D., a professor of medicine at the UCSD School of Medicine.
"The idea of a relationship wasn't foreign. But I have to admit, I was a bit surprised at how statistically strong the relationship was, and how consistent across tests of aggression, and groups tested," Golomb says in an e-mail interview.
So does that mean that if someone has a Big Mac and a large order of french fries, they're more likely to hit a rude order taker? Or could it be that when someone's upset, they're more likely to crave some junk food? Golomb says the study was cross-sectional (meaning it analyzed collected data), so it didn't look at causality. "But the finding fits with a body of literature that speaks to the likelihood of a causal relationship," she says.
Consumers encounter trans fats in margarine, packaged cookies, ready-made frostings and fried fast foods like cheeseburgers. They're created when hydrogen is added to vegetable oil — that's how you get partially hydrogenated oil. Manufacturers add the stuff to food products to improve their shelf life, texture and flavor stability. (Some trans fat is found naturally in meat and dairy, but the main product is the artificial variety).
Eating a lot of trans fat raises your level of low-density lipoprotein or LDL (the "bad" cholesterol) in your blood, which can lead to your developing heart disease.
But trans fat's days seem to be numbered: On June 16, 2015, the U.S. Food and Drug Administration (FDA) announced that food companies must phase out the use of artificial trans fat in their products within three years. If they want to continue using it after that, they must petition the FDA.