Ultra-processed foods tied to greater dementia odds: researchers warn

A new long-term study suggests diets high in industrially processed foods are tied to quicker declines in memory and reasoning—a finding that matters as many Western diets are dominated by these products. Researchers tracked more than 10,000 adults and found measurable differences in cognitive decline when a sizeable share of daily calories came from ultra-processed items.

The analysis, published in JAMA Neurology and presented at the 2022 Alzheimer’s Association International Conference, focused on changes in overall thinking ability and the brain skills involved in planning, decision-making and problem-solving. Participants averaged roughly 51 years old and were followed for up to a decade while completing standardized cognitive tests and diet questionnaires.

People who derived more than about 20% of their daily calories from ultra-processed foods experienced notably faster decline: a roughly 28% greater drop in measures of global cognition and about a 25% faster deterioration in executive function, compared with those whose intake of such foods was lower.

Study authors categorized ultra-processed foods as industrial formulations made mostly from extracted ingredients—oils, refined starches, sugars and protein isolates—that contain little intact food and commonly include flavorings, colorants and emulsifiers. Examples are ubiquitous in modern diets.

• Common examples: hot dogs, hamburgers and sausages; french fries and other deep-fried sides; soda and other sweetened drinks; cookies, cakes, candy, doughnuts and ice cream.
• Study size and scope: more than 10,000 Brazilian adults, average age 51, followed up to 10 years.
• Testing: immediate and delayed word recall, recognition tasks and verbal fluency administered at baseline and follow-up.
• Key numbers: >20% of calories from ultra-processed foods associated with ~28% faster global cognitive decline and ~25% faster executive-function decline.

The researchers noted that the prevalence of ultra-processed calories is high across many countries: roughly three in five calories in the United States, more than half in the U.K., and close to half in Canada come from these products, making the findings broadly relevant.

These cognitive results add to a growing body of evidence linking highly processed diets to other risks—obesity, cardiometabolic disease, certain cancers and shorter life expectancy. The tests used in the study tapped memory and language skills as well as the mental flexibility needed to plan and make decisions, providing a multidimensional view of cognitive change rather than a single measure.

Study co-authors urged practical changes: increasing whole foods, fruits, vegetables and whole grains, and reducing reliance on packaged, ready-made items. Preparing meals at home was recommended as an effective way to lower intake of ultra-processed ingredients and increase dietary quality.

What this means for readers now: because consumption of ultra-processed foods is common and modifiable, even modest reductions—swapping a packaged snack for a whole-food alternative or cooking more meals at home—could help protect both heart and brain health over time.

For quick steps to reduce ultra-processed intake:

• Cook simple meals from whole ingredients at least several times per week.
• Choose whole fruit over sweetened snacks and whole grains over refined breads.
• Limit sugar-sweetened beverages and replace with water or unsweetened options.
• Read labels: favor products with short ingredient lists and recognizable foods.

Researchers caution that the observational nature of the study cannot prove cause-and-effect, but the consistency with prior findings on metabolic and cardiovascular harm strengthens the case for policy and personal actions to shift diets toward less-processed, nutrient-dense foods.