People who eat more processed foods may be at higher risk of developing dementia, a study has indicated.
Researchers found that replacing such foods with minimally processed options were associated with a lower risk of the condition.
Academics at Tianjin Medical University in China found that consuming more unprocessed foods - equalling to half an apple a day - while reducing consumption of ultra-processed foods - equating to a chocolate bar a day - is associated with three per cent decreased risk of dementia.
Ultra-processed are defined as those high in added sugar, fat and salt, and low in protein and fibre. Such foods include soft drinks, crisps, chocolate, ice cream, sausage, deep-fried chicken, canned baked beans, pre-packaged white bread, ketchup and flavoured cereals.
The study, published in the Neurology Journal, highlighted no proof was found that ultra-processed foods cause dementia, rather their findings only show an association.
Study author Huiping Li said: "Ultra-processed foods are meant to be convenient and tasty, but they diminish the quality of a person's diet.
"These foods may also contain food additives or molecules from packaging or produced during heating, all of which have been shown in other studies to have negative effects on thinking and memory skills.
"Our research not only found that ultra-processed foods are associated with an increased risk of dementia, it found replacing them with healthy options may decrease dementia risk."
Research suggests that for every 10 per cent increase in daily intake of ultra-processed foods, people had a 25 per cent higher risk of dementia.
Findings also showed that substituting just 10% of ultra-processed foods with unprocessed or minimally processed foods, like fresh fruit, vegetables, legumes, milk and meat, was associated with a 19 per cent lower risk of dementia
Researchers identified 72,083 people from the UK Biobank study, a large database containing the health information of half a million people.
They were aged 55 and older and did not have dementia at the start of the study. After being followed for an average of 10 years, 518 were diagnosed with dementia.
They determined how much ultra-processed food people ate by calculating the grams per day and comparing it with grams per day of other foods to create a percentage of their daily diet.
The participants were divided into four equal groups from lowest percentage consumption of ultra-processed foods to highest.
Researchers found that on average, ultra-processed foods made up 9 per cent of the daily diet of people in the lowest group, an average of 225 grams per day, compared with 28 per cent for people in the highest group, or an average of 814 grams per day.
They say the main food group contributing to high ultra-processed food intake was drinks, followed by sugary products and ultra-processed dairy.
Huiping Li added: "Our results also show increasing unprocessed or minimally processed foods by only 50 grams a day, which is equivalent to half an apple, a serving of corn, or a bowl of bran cereal, and simultaneously decreasing ultra-processed foods by 50 grams a day, equivalent to a chocolate bar or a serving of fish sticks, is associated with 3 per cent decreased risk of dementia.
"It's encouraging to know that small and manageable changes in diet may make a difference in a person's risk of dementia."
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