Eating fried foods at your favorite fast-food restaurants can cause serious damage your brain health. Deep frying, a popular cooking method worldwide, involves submerging food entirely in hot oil. While it may add flavor and texture to our favorite dishes, a new study has revealed that consuming reused deep frying oil could have detrimental effects on health, particularly in the brain.
The study, presented at Discover BMB (the annual meeting of the American Society for Biochemistry and Molecular Biology), found higher levels of neurodegeneration in rats that consumed reused deep fried cooking oils, as well as in their offspring, compared to rats on a normal diet. These findings suggest that the increased neurodegeneration may be connected to the oil’s impact on the liver–gut–brain axis, a bidirectional communication network that plays a crucial role in regulating various physiological functions.
“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 study lead author Kathiresan Shanmugam, an associate professor from Central University of Tamil Nadu in Thiruvarur, 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.”
Reusing oil for frying, a common practice in both homes and restaurants, not only adds calories but also removes many of the oil’s natural antioxidants and health benefits. Reused oil can also contain harmful components such as acrylamide, trans fat, peroxides, and polar compounds.
To investigate the long-term effects of reused deep frying oil, the researchers divided female rats into five groups. Each group received either standard chow alone or standard chow with 0.1 milliliters per day of unheated sesame oil, unheated sunflower oil, reheated sesame oil, or reheated sunflower oil for 30 days. The reheated oils were used to simulate reused frying oil.
Compared to the other groups, the rats that consumed reheated sesame or sunflower oil exhibited increased oxidative stress and inflammation in the liver. They also showed significant damage in the colon, which led to changes in endotoxins and lipopolysaccharides – toxins released by 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 study co-author Sugasini Dhavamani, a research collaborator from the University of Illinois at Chicago.
In additional studies, researchers used MSG to induce neurotoxicity in the offspring. They found that the offspring that consumed the reheated oils were more likely to show neuronal damage than the control group receiving no oil or those that received unheated oil.
While more studies are needed, researchers suggest that supplementation with omega-3 fatty acids and nutraceuticals such as curcumin and oryzanol might help reduce liver inflammation and neurodegeneration. However, they emphasize that clinical studies in humans are necessary to evaluate the adverse effects of consuming fried foods, particularly those made with repeatedly used oil.
The next step for the research team is 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. They also aim to further explore the relationship between gut microbiota and the brain to identify potential new ways to prevent or treat neurodegeneration and neuroinflammation.
As consumers, it is crucial to be aware of the potential health risks associated with fried foods and to make informed choices about our dietary habits. While indulging in the occasional fried treat may not cause significant harm, regularly consuming foods prepared in reused deep frying oil could have serious consequences for our health and the health of future generations.
