We are all aware how important our diet is when it comes to our health. Regularly eating certain foods is known to increase your risk for things such as being obese or overweight, as well as having high cholesterol, high blood pressure, cardiovascular disease and fatty liver disease.

Perhaps less known is the fact that your diet can also influence your likelihood of developing dementia. Dementia is a syndrome, or group of symptoms, related to the ongoing decline of the brain.

More common among people over the age of 65, it can lead to problems with memory, speech, understanding and mobility, as well as personality and behavioural changes.

Currently there are around 55 million people living with dementia worldwide. But it is estimated that this number will rise to 139 million by 2050.

Now scientists are warning that eating certain popular foods could be increasing our chances of the devastating condition.

Alarming new research has revealed that foods cooked in reused oil could cause degeneration in the brain.

This applies to pretty deep-fried foods from takeaways and restaurants which will be cooked in oil that is used again and again.

Two popular foods that could therefore be considered risky are French fries and fried chicken.

As part of the study, which was presented at an annual meeting of the American Society for Biochemistry and Molecular Biology, scientists discovered higher levels of neurodegeneration among rats consuming reused deep fried cooking oils in comparison to other rodents following a healthier diet.

The same problems were found among the rats’ offspring. 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.

One of the researchers, Kathiresan Shanmugam – an associate professor from Central University of Tamil Nadu, explained: “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.

“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.

As part of the research, 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.

Professor Shanmugam continued: “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.”