Photo by Shalaco.

When New York City banned trans fats from local restaurants in 2006, it was trying to make its citizens healthier. Trans fatty acids — which, you’ll recall, are a type of unsaturated fat almost exclusively found in processed food — have a number of proven health effects, including raising bad cholesterol and lowering good cholesterol simultaneously. But, unbeknownst to municipal government, the ban may have also helped crime rates (and taken the edge off New Yorkers’ legendary surliness). According to a new study by researchers at the University of California, San Diego, trans fats are connected with aggressive behavior.

This sounds like a made-up story — like, really? Eating trans fats is connected with aggression? But eating regular fats is connected with so much serenity! But I looked up the original paper, which was published in the journal of the Public Library of Science on March 5, and it actually looks reasonably robust. I’m not about to do a statistical analysis but they seem to have studied lots of subjects, found correlations with low p-values, and worked to rule out confounding factors like high cholesterol and diabetes.

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And as the researchers point out, it’s biologically plausible — trans fats are linked with other behavioral effects, including depression, and they limit absorption of natural fatty acids that reduce aggressive behavior. (Your brain is mostly fat, so the fat you eat can have big psychological effects. I wasn’t kidding about the serenity.) The scientists haven’t established that trans fats cause aggressive behavior, just that it’s correlated, but they can see how the causation would work.

So if you try to tell a friend, coworker, or stranger to cut out the trans fats, and he or she chews you out — well, you deserved that, mind your own business. But you can also rest assured that you are not talking to a psychopath. It’s probably the trans fats yelling, or throwing things, or hitting you. Don’t you feel better?

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