In experiments on mice, researchers at the University of California in Los Angeles found that eating high-fructose diets -- such as cakes, cookies, jams, jellies, crackers and carbonated soft drinks -- for as little as six weeks can make one stupid.
But, a diet high in omega-3 fatty acids can counteract this IQ loss, the researchers suggested.
"Our findings illustrate that what you eat affects how you think," study researcher Fernando Gomez-Pinilla said.
"Eating a high-fructose diet over the long term alters your brain's ability to learn and remember information. But adding omega-3 fatty acids to your meals can help minimise the damage," Gomez-Pinilla was quoted as saying by LiveScience.
The study, published in Journal of Physiology, was done on rats, but the researchers believe their brain chemistry is similar enough to humans to extend the findings.
For the study, the researchers zeroed in on high-fructose corn syrup, an inexpensive liquid six times sweeter than cane sugar, that is commonly added to processed foods, including soft drinks, condiments, applesauce and baby food.
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Before starting the experiment, the rats were taught to navigate their way through a maze using visual landmarks to remember the way.
Then the rats were divided into two groups, both consumed a fructose solution as their water, but one half of them also received omega-3 fatty acids, which are thought to protect against damage to the synapses -- the chemical connections between brain cells that enable memory and learning.
After six weeks of their new diet, the researchers tested the rats' recall of the maze route. "The second group of rats navigated the maze much faster than the rats that did not receive omega-3 fatty acids," Gomez-Pinilla said.
"Their brains showed a decline in synaptic activity. Their brain cells had trouble signalling each other, disrupting the rats' ability to think clearly and recall the route they'd learned six weeks earlier." (More)