French Fries on the Corny Side

A study in the Proceedings of the National Academy of Sciences found that French fries from national chain restaurants tend to be fried in corn oil, which is a less healthful alternative than other vegetable oils. Karen Hopkin reports

Illustration of a Bohr atom model spinning around the words Science Quickly with various science and medicine related icons around the text

Join Our Community of Science Lovers!


On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.


Ever wonder what your French fries were fried in? Like bumbling burglars who leave fingerprints at a crime scene, cooking oils leave their own clues. And by measuring the carbon isotopes in French fries, University of Hawaii researchers found that one oil tops all others as the choice to fry fries in: corn oil. That’s according to a report in the Proceedings of the National Academy of Sciences.

National chain restaurants typically reveal only that fries may contain one or more of the following oils: corn, canola, soybean, cottonseed, sunflower and palm. But consumers might like a little more info: in a meal of burger, fries and soda, 20 percent of the total calories come from the oil that fried the potatoes.

Analyzing fries from nearly 200 Hawaiian restaurants, the scientists found that 69 percent of the national chain outlets used corn oil, compared with just 20 percent of independent eateries.

Corn oil is probably the least healthy of the oils mentioned, with more harmful saturated fats than canola or sunflower and fewer heart-healthy compounds than soybean. Of course, regardless of what they’re fried in, French fries probably aren’t on your diet. Then again, you’re probably not on your diet either.

—Karen Hopkin

[The above text is an exact transcript of this podcast.]

It’s Time to Stand Up for Science

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.

I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.

If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.

In return, you get essential news, captivating podcasts, brilliant infographics, can't-miss newsletters, must-watch videos, challenging games, and the science world's best writing and reporting. You can even gift someone a subscription.

There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.

Thank you,

David M. Ewalt, Editor in Chief, Scientific American

Subscribe