If you haven’t heard that trans fats are bad for you, you probably live under a rock, and don’t have Internet access. But then I guess you wouldn’t be reading this blog…

But last week a new study about trans fats was published (first reported back in 2014) which suggests that consuming trans fats may directly harm your ability to learn a language!

How the study was done

Participants were presented 104 word flash cards. 22 of the words were duplicates, the other 82 were unique in the deck. Participants were asked to judge whether the word on each card was new, or had been previously seen. The number of correct answers is their score.

Hopefully, you can see how this simple memory test might be relevant to recognizing new vocabulary terms–or countless other daily activities!

When they tested people who ate different amounts of trans fats, ranging from absolutely no trans fat, up to 28 grams (1 ounce!) of trans fat per day, they found that for every 1 gram of trans fat consumed per day, participants scored an average of 0.76 points worse on the memory test.

The researchers did what they could to eliminate other possible explanations of the reduced memory performance, such as age and mood. As a result, they concluded that trans fats were the apparent culprit. The study shows this effect exists for men ages 20-45. The study authors believe the same to hold true for women, but there wasn’t enough information available on women to prove it. The study also doesn’t explain why older men weren’t affected, but one possibility is that dietary effects may show more clearly in younger adults.

Let me try to put that into perspective.

Half a letter grade

Imagine you show up to Spanish class and the teacher gives you a sheet of brand new vocabulary words, asks you to read the list, then immediately gives you a pop quiz over the new vocabulary.

If you’re an average student, according to the study, you’ll walk away with a solid B grade–a score of 85%.

If, on the other hand, you’re the type of person who eats one large order of fries every day, and an icing-covered cupcake at the convenience store for a snack (for a combined 7 grams of daily trans fat), you’re likely to lose more than half a letter grade, and walk away with only a C+–a score just below 80%!

And this is just a recognition test! You aren’t even asked to define the vocabulary terms! If junk food can cause you not to recognize new words at this level, what can it do to your ability to remember definitions and your long-term recall? I guess we don’t know, but I don’t imagine it’s going to have a beneficial effect!

Now to be fair, not all fried foods, including French fries, are fried in trans fat. In fact, fewer and fewer are all the time, as the health problems associated with trans fats become more known. But many cakes you’ll buy at the store, especially those with icing, come packed with trans fats, as do many salad dressings and other processed foods.

Remember to check your nutrition labels!

Aside from the obvious “Trans fat” item on the nutrition label, you should also look for, and avoid, anything with partially-hydrogenated vegetable oils, as this is where most trans fats come from. It’s common to see food items labeled as “0g Trans Fat” but tout partially-hydrogenated vegetable oils (this is possible if the designated serving size is small enough that the trans fat per serving rounds down to 0 grams).