Ultra-processed food linked with increased risk of dementia

People who eat the highest amounts of ultra-processed foods like soft drinks, chips and cookies may have a higher risk of developing dementia than those who eat the lowest amounts, according to a new study published in the medical journal of the American Academy of Neurology.

Researchers also found that replacing ultra-processed foods in a person’s diet with unprocessed or minimally processed foods was associated with a lower risk. The researchers were keen to stress that the study does not prove that ultra-processed foods cause dementia – it only shows an association.

The research defines ultra-processed foods are high in added sugar, fat and salt, and low in protein and fibre.

“Ultra-processed foods are meant to be convenient and tasty, but they diminish the quality of a person’s diet,” said study author Huiping Li, PhD, of Tianjin Medical University in China.

“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.”

For the study, researchers identified 72,083 people from the UK Biobank, a large database containing the health information of half a million people living in the UK. Participants were age 55 and older and did not have dementia at the start of the study. They were followed for an average of 10 years. By the end of the study, 518 people were diagnosed with dementia.

During the study, participants filled out at least two questionnaires about what they ate and drank the previous day. Researchers determined how much ultra-processed food people ate by calculating the grams per day and comparing it to the grams per day of other foods to create a percentage of their daily diet. They then divided participants into four equal groups from lowest percentage consumption of ultra-processed foods to highest.

On average, ultra-processed foods made up nine percent of the daily diet of people in the lowest group, an average of 225 grams per day, compared to 28 percent for people in the highest group, or an average of 814 grams per day. One serving of items like pizza or fish sticks was equivalent to 150 grams. The main food group contributing to high ultra-processed food intake was beverages, followed by sugary products and ultra-processed dairy.

In the lowest group, 105 of the 18,021 people developed dementia, compared to 150 of the 18,021 people in the highest group.

After adjusting for age, gender, family history of dementia and heart disease and other factors that could affect risk of dementia, researchers found that for every 10 percent increase in daily intake of ultra-processed foods, people had a 25 percent higher risk of dementia.

Researchers also used study data to estimate what would happen if a person substituted 10 percent of ultra-processed foods with unprocessed or minimally processed foods, like fresh fruit, vegetables, legumes, milk and meat. They found that such a substitution was associated with a 19 percent lower risk of dementia.

“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 three percent decreased risk of dementia,” said Li.

“It’s encouraging to know that small and manageable changes in diet may make a difference in a person’s risk of dementia.”