Reused Deep-Frying Oil May Cause Neurodegeneration

Picture: a deep-fryer in use and, inset, a human brain. Reused cooking oil may increase our risk of neurodegenerative disease, a new study suggests.

Deep fried food is a staple for many American diets. But new research has found that these foods could also be frying our brains.

Between 1 in 3 and 1 in 4 American adults consumes food from fast food restaurants every single day, the National Institutes of Health reports. And, in most cases this food is fried. Deep frying is a common method of food preparation around the world and involves completely submerging foods in hot oil.

Due to the amount of oil used in this process (and to reduce food waste) restaurants and food vendors usually reuse their frying oil. However, according to new research, this not only removes many of the oil’s natural antioxidants and health benefits, but can also increase its content of harmful compounds such as acrylamide, trans fat and peroxides.

Not only are these harmful compounds thought to increase our risk of various cancers and metabolic disorders, but they may also increase our risk of neurodegeneration.

“Deep-frying at high temperatures has been linked with several metabolic disorders, but there have been no long-term investigations on the influence of deep-fried oil consumption and its detrimental effects on health,” Kathiresan Shanmugam, an associate professor from Central University of Tamil Nadu in Thiruvarur, India, said in a statement. “To our knowledge we are first to report long-term deep-fried oil supplementation increases neurodegeneration in the first-generation offspring.”

To explore these effects, Shanmugam and colleagues from the University of Illinois at Chicago divided a group of female rats into five groups, each receiving a different diet for 30 days. One group received standard chow alone while the others received standard chow with 0.1 milliliter of either unheated sesame oil, unheated sunflower oil, reheated sesame oil, or reheated sunflower oil. The reheated oils simulated reused frying oil.

Compared to the other groups, the rats receiving the reheated oils showed significantly more toxin accumulation and inflammation in their livers, as well as colon damage.

“As a result, liver lipid metabolism was significantly altered, and the transport of the important brain omega-3 fatty acid DHA was decreased,” Shanmugam said. “This, in turn, resulted in neurodegeneration, which was seen in the brain [anatomy] of the rats consuming the reheated oil as well as their offspring.”

Of course, these results have only been seen in animals, but the research raises important questions about the health impacts of consuming deep fried food beyond their calorie content.

Moving forward, the team hope to explore the effects of deep-frying oil on neurodegenerative diseases in humans such as Alzheimer’s and Parkinson’s, as well as on anxiety and depression.

The results will be presented at the annual meeting of the American Society for Biochemistry and Molecular Biology in San Antonio between March 23 and 26.

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