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Eating at fast food chains ‘could raise your risk of brain damage’

Scientists fed lab rats diets with frying oil with worrying findings

WE all know fried food is bad for the old waistline.

But new research suggests scoffing chips and other fast food might also cause long-lasting brain damage - for you and your unborn children.

Many restaurants and fast food chains deep fry food. They may reuse this oil over days or even weeks
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Many restaurants and fast food chains deep fry food. They may reuse this oil over days or even weeksCredit: Alamy

Scientists from the University of Chicago studied the effect of food fried in large vats of old cooking oil, which is often how food is made in restaurants.

They discovered that old oil - that which is used to cook food and then reheated to use again - contains brain-damaging properties, which seeps into the food we eat.

Rats fed diets high in reused oils showed more signs of inflammation in the liver which is believed to speed cognitive decline, a precursor for dementia.

Researchers also detected more signs of brain damage in rats fed diets high in reheated oils compared to a control group.

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The same brain damage appeared to pass down to children of rats who ate the dangerous diets.

The scientists from the University of Chicago said: "Deep-frying at high temperatures has been linked with several metabolic disorders.

"To our knowledge, we are the first to report that long-term deep fried oil supplementation increases neurodegeneration."

Fast food chains usually reuse oil over a day, a few days or even weeks.

Deep frying food is commonplace for many cuisines across the world, and in some households, too.

In the study, rats were divided into five groups.

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Each were given standard food to eat, or food supplemented with unheated or reheated sesame or sunflower oil.

The reheated oils were used to simulate the effects of reused frying oil.

The rats that consumed reheated sesame or sunflower oil had elevated oxidative stress and inflammation in the liver. They also had significant damage to the colon, reported

The researchers said that changes in the liver meant the transport of the omega-3 fatty acid DHA to the brain decreased.

Omega-3 fatty acids are thought to be important for brain health and are found in seafoods like salmon and sardines.

This led to higher levels of neurodegneration in the rats and their offspring, the researchers said.

Additional human studies are needed to verify the effects seen in rats.

But the researchers said they were keen to study the effects of deep-frying oils on neurodegenerative diseases like Alzheimer's and Parkinson's.

It's not the first time a link has been made between poor diet and declining brain health.

For example, highly processed foods, crisps, and deli meats containing preservatives were linked with abrupt memory loss in older brains after scientists at America’s Ohio State University Institute for Behavioural Medicine Research did tests on lab rats in 2021.

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Dr Ruth Barrientos called the results “alarming”, adding: “Consumption of a processed diet can produce significant and abrupt memory deficits.”

6 ways you're damaging your brain

Not socialising enough

Feeling lonely has long been linked with cognitive decline and the development of Alzheimer’s. 

One US study looking at the brains of healthy adults found those who reported feelings of loneliness had higher cortical amyloid levels - a marker used to help diagnose dementia and Alzheimer’s.

Participants with increased amyloid were seven and a half times more likely to identify as lonely, the Harvard Medical School said. 

You don't have a sense of purpose

Would you agree or disagree with the following statement: “I have a sense of direction and purpose in life"?

People who agreed tended to have a considerably less likely risk of developing Alzheimier’s disease, according to a four-year study of 900 people from Chicago.

Studies have shown that older adults with hobbies or who try and engage in social activities may age slower.

Not getting enough sleep

A lack of sleep is linked with dementia in later life.

It could be that not getting enough good quality rest causes more of the protein amyloid in the brain, which is a hallmark of Alzheimer’s.  

Alzheimer’s Society says that problems such as struggling to get to sleep, stay asleep or napping are associated with many forms of dementia - but says the topic is "complicated".

Not exercising

One study at the University of British Columbia found that regular aerobic exercise boosts the size of the hippocampus - a brain region involved in verbal memory and learning. 

Aerobic exercise is the kind that gets your heart pumping and sweaty, as opposed to muscle or weight training. 

Similarly, high intensity workouts keep blood flowing to the brain, Researchers at the University of Queensland have found.

Poor diet

Kkeeping your diet healthy and weight managed can indirectly help the brain by banishing diseases like high blood pressure.

Studies have shown that a typical “Western” diet of highly processed food is linked to higher depression rates than those that are healthier, such as Mediterranean and Japanese.

Some foods are considered optimal for brain health - salmon (high in omega-3), dark chocolate, berries, nuts and eggs are just examples.

Listening to loud music

Loss of hearing is linked with dementia, studies have suggested - and listening to loud music can cause damage to the eardrums.

The NHS says to protect your hearing, do not listen to music at more than 60 per cent of the maximum volume.

Do not use earphones or headphones for more than an hour at a time – take a break for at least five minutes every hour.

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