What’s the opposite of brain food?
Trans fat, finds a new study presented at the American Heart Association’s Scientific Sessions 2014. Eating a lot of the compound that magically rejuvenates junk food that should have expired long ago is linked to higher rates of memory impairment.
After analysis of food questionnaires and memory tests from about 1,000 adult men, trans fat intake was linked to worse memory in people under age 45, even after controlling for mind-influencing factors like age, depression and education. Every gram of trans fat eaten per day was linked to 0.76 fewer words recalled. Put another way? Those who ate the most trans fat remembered 11 fewer words.
MORE: 7 Foods That Wouldn’t Be The Same If Trans Fats Are Banned
That relationship eased when researchers adjusted for BMI and blood pressure, and a study like this can’t prove cause and effect. But the study author believes trans fat may be contributing to oxidative stress, a cell-damaging process. Trans fat appears to be a pro-oxidant: the opposite of an antioxidant. And indeed, prior research from the study’s lead author, Beatrice A. Golomb, MD, PhD, professor of medicine at the University of California-San Diego, found that antioxidant-rich chocolate is linked to better word recall.
We’re not eating as much trans fat as we used to: a recent study found that between 1980-2009, we cut down on trans fats about 35% thanks to regulations and reformulations. Still, trans fat is the bane of every health nut’s label-reading experience—it travels under sneaky ingredient adjectives like “partially hydrogenated” and can even creep into foods labeled “0 grams of trans fat.”
But as hard as it is to figure out whether or not your snack contains trans fat, what the compound does to your brain is even more cognitively complex. “From a health standpoint, trans fat consumption has been linked to higher body weight, more aggression and heart disease,” Golomb said in a press release. “As I tell patients, while trans fats increase the shelf life of foods, they reduce the shelf life of people,” Golomb said.
Read next: The Surefire Way To Eat Healthier
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Write to Mandy Oaklander at mandy.oaklander@time.com