Recent research has unveiled startling findings that the consumption of reused deep-fried cooking oil could significantly increase neurodegeneration levels in rats and their offspring. This revelation is particularly concerning given the widespread practice of reheating the same batch of oil for cooking multiple meals in both domestic kitchens and restaurants around the globe, potentially posing serious risks to human health.
Deep-frying, a method that involves immersing food in hot oil, is a highly favored cooking technique used to prepare a variety of foods, from doughnuts to falafel. Despite the undeniable appeal of the foods it produces, deep-frying has been associated with various health issues, including cancer and diabetes. The risks are believed to escalate when oils are reused. Reheating oil multiple times can destroy its antioxidants and other beneficial components, while also creating harmful compounds such as trans fats and peroxides. Until now, the specific effects of consuming reused oil had not been thoroughly examined.
“Deep-frying at high temperatures has been connected to several metabolic disorders, yet there has been a lack of long-term studies on the impact of consuming deep-fried oil and its adverse effects on health,” stated Kathiresan Shanmugam, the study’s lead author. “To our knowledge, this is the first report that long-term supplementation with deep-fried oil leads to increased neurodegeneration in the first-generation offspring.”
In their 30-day study, researchers fed female rats a diet of either standard chow or food enriched with either fresh or reheated oils. By the end of the study, it was evident that rats fed with reused oil had higher liver enzyme levels, a marker of increased inflammation and oxidative stress within this crucial organ.
“As a consequence, there was a significant alteration in liver lipid metabolism, and the transport of the vital brain omega-3 fatty acid DHA was reduced,” Shanmugam explained. “This resulted in neurodegeneration, observable in the brain histology of the rats fed reheated oil and their offspring.”
These findings underscore the critical role of the liver-gut-brain axis and how its disruption can lead to neurological damage. Moreover, rats on the reheated oil diet exhibited higher cholesterol levels and increased markers of inflammation, such as high-sensitivity C-reactive protein (hs-CRP), which is associated with a higher risk of heart attacks and strokes.
The study also noted cellular damage in the colon of these rats, alongside the degeneration of glial cells, which support neurons. Further experiments revealed that exposure to monosodium glutamate (MSG), a common food additive, exacerbated neurological damage in rats raised on reused oil.
These alarming results were presented at Discover BMB, the annual meeting of the American Society for Biochemistry and Molecular Biology, which took place from March 23 to 26 in San Antonio, highlighting the urgent need for further research into the health implications of consuming reused deep-fried cooking oil.