The Dangers Of Reusing Cooking Oil: Study Finds Link To Neurodegeneration

💡What To Know:

  • Reusing cooking oil to fry foods affected the brain health of rats and their offspring.
  • Reused cooking oil can contain trans fat and other harmful compounds.
  • Omega-3 fatty acid supplements may reduce liver inflammation tied to this problem.

CHICAGO — Deep-fried foods can be a delicious treat once in a while, but alarming new research is serving up a sobering reminder that these foods should be reserved for special occasions only. Scientists have discovered higher levels of neurodegeneration among rats consuming reused deep fried cooking oils in comparison to other rodents following a healthier diet. The team also found the same problems among the rats’ offspring.

Deep-frying refers to completely submerging food in hot oil. It is a very common method of food preparation around the world, producing tasty albeit unhealthy foods like fried chicken and French fries, just to name a couple.

Researchers also found that the increased neurodegeneration appears tied to the oil’s effects on the bidirectional communication network between the liver, gut, and brain. This liver–gut–brain axis is crucial to the regulation of various physiological functions, and its impairment shows an association with neurological disorders.

“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,” says Kathiresan Shanmugam, an associate professor from Central University of Tamil Nadu, in a media release. “To our knowledge we are first to report long-term deep-fried oil supplementation increases neurodegeneration in the first-generation offspring.”

Besides adding empty calories, deep frying foods usually entails reusing the same oil for frying. This is a common practice in both homes and restaurants, despite reuse removing many of the oil’s natural antioxidants and health benefits. Reused oil may also contain harmful components, including acrylamide, trans fat, peroxides, and polar compounds.

French fries frying basket
Reusing the same oil for frying is a common practice in both homes and restaurants despite reusing oil removing many of the oil’s natural antioxidants and health benefits. (Photo by Wine Dharma from Unsplash)

To explore the long-term effects of reused deep-fried frying oil, the study authors divided a collection of female rats into five groups. Each group received either standard food alone or food with 0.1 ml per day of unheated sesame oil, unheated sunflower oil, reheated sesame oil, or reheated sunflower oil for 30 days. The reheated oils served to simulate reused frying oil.

In comparison to other groups, rodents provided with reheated sesame or sunflower oil showed increased oxidative stress and inflammation in the liver. Those same rodents also displayed notable damage in the colon that sparked changes in endotoxins and lipopolysaccharides, which are toxins released from certain bacteria.

“As a result, liver lipid metabolism was significantly altered, and the transport of the important brain omega-3 fatty acid DHA was decreased. This, in turn, resulted in neurodegeneration, which was seen in the brain histology of the rats consuming the reheated oil as well as their offspring,” explains Prof. Shanmugam, formerly of Madurai Kamaraj University.

Additional experiments involving the addition of MSG to induce neurotoxicity in the offspring showed that offspring eating the reheated oils showed a higher risk of neuronal damage than the control group receiving no oil or those receiving unheated oil.

While more research is necessary, study authors say supplementation with omega-3 fatty acids and nutraceuticals like curcumin and oryzanol may help lower liver inflammation and neurodegeneration. They add that clinical studies in humans are urgently needed in order to evaluate the adverse effects of eating fried foods, particularly those made with reused oil.

Next, the research team wants to study the effects of deep-frying oil on neurodegenerative diseases like Alzheimer’s and Parkinson’s, as well as on anxiety, depression, and neuroinflammation. Moreover, they want to conduct more research exploring the relationship between gut microbiota and the brain with an eye toward identifying new ways to prevent or treat neurodegeneration and neuroinflammation.

The scientists presented their findings at Discover BMB, the annual meeting of the American Society for Biochemistry and Molecular Biology.

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John Anderer

Born blue in the face, John has been writing professionally for over a decade and covering the latest scientific research for StudyFinds since 2019. His work has been featured by Business Insider, Eat This Not That!, MSN, Ladders, and Yahoo!

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    1. The study is rather flawed, including continuing the long debunked notion that MSG causes neurodegeneracy.

      That said, have you looked at Democrats lately? The ones who aren’t skin and bones vegans are often land whales of epic proportions. Pretty sure eating fried food is not a politically segregated in the way you claim.

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