Cutting processed foods from your diet, even in small amounts, slashes risk of dementia

It’s widely accepted that consuming excessive amounts of processed food is linked to poorer gut health and an increased likelihood of developing chronic diseases like heart disease and stroke. It’s lesser-known that doing so may also increase risk of developing dementia.

Scientists strongly suggest that people of all ages, but especially older adults, be more mindful of the types of foods they consume and how it can affect not only neurodegeneration risk, but mood and cognition overall. Their work shows that even slight changes to one’s diet, such as replacing processed foods like potato chips at lunch with just half an apple, reduces the chances of developing dementia.

For the study, researchers at Tianjin Medical University in China examined 72,083 people from the U.K. Biobank, which is a large database containing medical information of half a million British people. Participants were 55 or older and didn’t have dementia at the start, and were followed for 10 years. By the end, 518 people were diagnosed with dementia.

Throughout the study, participants filled out at least two questionnaires explaining what they ate and drank the previous day. From this, the researchers were able to determine how much ultra-processed food was eaten by calculating the grams per day and comparing it to the grams per day of whole foods to generate a percentage of their daily diet. They then divided participants into four groups from lowest percentage of processed food intake to highest.

Generally, ultra-processed foods made up around 9% of the daily diet of people in the lowest group, which is an average of 225 grams per day. In the highest group, they made up 28%, which is an average of 814 grams per day. The primary contributor was sugary beverages, with desserts and heavily-processed dairy coming second and third.

In the lowest group, just 105 of the 18,021 people developed dementia, but this jumped up 150 people in the highest group. Moreover, the results shined a light on the importance of adding whole foods to the diet and not just taking things away.

“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,” says study co-author Huiping Li. “It’s encouraging to know that small and manageable changes in diet may make a difference in a person’s risk of dementia.”

A strong limitation of this work is the complexity of nutrition research and the varying levels of what’s considered “processed” food.

“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,” explains Maura E. Walker, PhD, of Boston University, in an editorial that accompanies the study.

If more studies are to look into this in the future, it may be time to consider improving the quality of dietary assessments and food questionnaires.

This study is published in the journal Neurology.


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About the Author

Shyla Cadogan

Shyla Cadogan is a recent graduate from the University of Maryland, College Park with a Bachelor’s of Science in Nutrition and Food Science. She is on her way to becoming a Registered Dietitian, with next steps being completion of a dietetic internship at the University of Maryland Medical Center. Shyla has extensive research experience in food composition analysis and food resource management.

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