The Common Food Ingredient That's Making You Stupid

Lab studies show fructose, a component of sugar and high-fructose corn syrup, can actually sabotage your smarts in just 6 weeks.

Leah Zerbe May 16, 2012

Brain-harming high-fructose corn syrup hides out in unexpected places. Be sure to read the label.

Foods that appear to be nutritious could actually be destroying your brainpower. The culprit? A common ingredient slipped into many "healthy" foods, including baby food, applesauce, and oatmeal, a breakfast favorite. Researchers at UCLA found that ingesting foods and drinks containing fructose, a component of the ingredient high-fructose corn syrup and sugar, for just six weeks caused troubling changes in brain function. "Our findings illustrate that what you eat affects how you think," says Fernando Gomez-Pinilla, PhD, a professor of neurosurgery and integrative biology and physiology at UCLA. "Eating a high-fructose diet over the long term alters your brain's ability to learn and remember information."


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While high-fructose corn syrup and added sugar is rampant in soda and candy products, it also hides out in some seemingly innocuous items like bread, juices, ketchup, and instant oatmeal. (Previous studies have found high-fructose corn syrup is sometimes contaminated with mercury.) Most often associated with obesity and diabetes, this latest study, appearing in the Journal of Physiology, shows that too much fructose can harm the brain, too.

Read More: 9 Disturbing Side Effects of Soda

This could be leading to an all-out American brain drain, given that the average citizen downs about 35 pounds of high-fructose corn syrup every year.

The Experiment
To find out how high-fructose intake affects brain function, researchers studied two groups of rats: One group downed fructose in water for six weeks; another dined on it but also received doses of brain-protecting omega-3 fatty acids.

Before the high-fructose diet began, the rats were all trained to navigate a maze. After eating the sweetener for six weeks, researchers put the rats to the maze test again. The animals that didn't receive the omega-3 brain protection were slower and experienced problems with brain signaling, which disrupts critical skills like memory and thinking. Researchers also witnessed signs of insulin resistance in the group without omega-3s; this could hamper normal energy processing, which could impact thoughts, emotions, memory, and learning, according to Gomez-Pinilla. "Our study shows that a high-fructose diet harms the brain as well as the body," he adds. "This is something new."

3 Rules for Avoiding a High-Fructose Corn Syrup-Derived Brain Drain
#1: Eat organic. If you don't feel like reading fine-print ingredient labels every time you reach for a product in the supermarket, just look for the organic seal. High-fructose corn syrup and many other harmful food additives are banned. And whatever you do, don't ditch real fruit, which contains a natural form of fructose, not the dangerous processed type. "We're less concerned about naturally occurring fructose in fruits, which also contain important antioxidants," explains Gomez-Pinilla, who is also a member of UCLA's Brain Research Institute and Brain Injury Research Center. "We're more concerned about the fructose in high-fructose corn syrup, which is added to manufactured food products as a sweetener and preservative."

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#2: Find safer sweet treats. Gomez-Pinilla, a native of Chile and an exercise enthusiast who practices what he preaches, advises people to keep fructose intake to a minimum and swap sugary desserts for fresh berries and Greek yogurt, which he keeps within arm's reach in a small refrigerator in his office. An occasional bar of dark chocolate that hasn't been processed with a lot of extra sweetener is fine, too, he adds.

#3: Eat for brain protection. Be sure to eat foods containing naturally robust levels of omega-3 fatty acids, especially if you'll be indulging in food containing high-fructose corn syrup. Omega-3–rich foods include eggs from pastured hens, wild-caught Alaskan salmon, flaxseed, and walnuts. DHA, the type of omega-3 that comes from omega-3–rich animal products, helps protect against damage to brain synapses. These synapses are critical to tasks like memory and learning—the very functions that high-fructose corn syrup or sugar could damage.

Read More: 10 Suspect Causes of Autism & Learning Disabilities

Correction: UCLA originally incorrectly reported that scientists used high-fructose corn syrup in the study, when in fact they used fructose, a component of high-fructose corn syrup and sugar. This updated article reflects the correction.

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