Eating High Amounts of Ultra-Processed Foods Associated with Increased Risk of Dementia

People who eat high amounts of ultra-processed foods, such as soft drinks, chips, and cookies, may have a higher risk of developing dementia than people who eat low amounts, according to a study recently published in Neurology.

Replacing ultra-processed foods in a person’s diet with unprocessed or minimally processed foods was found to be associated with a lower risk.

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

Researchers identified 72,083 people from the UK Biobank, a large database containing the health information of half a million people living in the United Kingdom, to be participants in the study. Participants were 55 years of age and older and did not have dementia at the start of the study. Researchers followed the patients for an average of 10 years.

Participants filled out at least 2 questionnaires about what they ate and drank the previous day during the study. Researchers measured the amount of ultra-processed food participants ate by calculating the grams per day and comparing it to the grams per day of other foods to determine a percentage of their daily diet.

Participants were then divided into 4 equal groups from lowest to highest percentage consumption of ultra-processed foods. Ultra-processed foods were defined as those high in added sugar, fat, and salt, and low in protein and fiber. Such foods include soft drinks, salty and sugary snacks, ice cream, sausage, deep-fried chicken, yogurt, canned baked beans and tomatoes, ketchup, mayonnaise, packaged guacamole, packaged hummus, packaged breads, and flavored cereals.

The study found that eating high amounts of these ultra-processed foods was associated with a higher risk of developing dementia; however, the authors emphasize that this study shows an association, not a causal relationship.

Ultra-processed foods made up 9% of the daily diet of people in the lowest group, an average of 225 grams per day. For people in the highest group, ultra-processed foods made up 28% of their daily diet, an average of 814 grams per day.

Beverages were the main food group contributing to high ultra-processed food intake, followed by sugary products and ultra-processed dairy.

A total of 518 participants were diagnosed with dementia by the end of the study. Researchers found that in the lowest group, 105 of the 18,021 people developed dementia. For the highest group, 150 of 18,021 people developed dementia.

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

They also estimated what would happen if a person substituted 10% of ultra-processed food with unprocessed or minimally processed food. Such substitutions were found to be associated with a 19% 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 3% decreased risk of dementia,” Li said. “It’s encouraging to know that small and manageable changes in diet may make a difference in a person’s risk of dementia.”

Although the findings suggest an association between the risk of dementia and diet, the study authors assert that further research is needed to confirm the findings.

They also note a limitation of their study in the potential that milder cases of dementia may have been overlooked, given that cases were determined by looking at hospital records and death registries rather than primary care data.

Author of an accompanying editorial, Maura E. Walker, PhD, of Boston University in Massachusetts, concluded, “While nutrition research has started to focus on food processing, the challenge is categorizing such foods as unprocessed, minimally processed, processed and ultra-processed. For example, foods like soup would be classified differently if canned versus homemade. Plus, the level of processing is not always aligned with diet quality. Plant-based burgers that qualify as high quality may also be ultra-processed. As we aim to understand better the complexities of dietary intake, we must also consider that more high-quality dietary assessments may be required.”

Reference

Eating more ultra-processed foods associated with increased risk of dementia [press release]. Minneapolis, MN: EurekAlert; July 27, 2022. https://www.eurekalert.org/news-releases/959815. Accessed July 27, 2022.