Recent research suggests that eating ultra-processed foods does not accelerate cognitive decline in older adults over a 10-year period. This study european nutrition journalprovides evidence that overall diet quality may be more important than specific levels of food processing in maintaining brain health as we age. These findings help uncover the complex relationship between what people eat and how their brains change over time.
As the world’s population ages, the number of people living with dementia is expected to increase dramatically in the coming decades. There is currently no cure for dementia, so it is critical to identify lifestyle factors that can prevent or slow cognitive decline. Scientists are particularly interested in the role of diet, as healthy dietary patterns are consistently associated with improved brain function.
Ultra-processed foods are products made from raw materials that have been significantly modified through chemical processes. These are usually assembled using artificial flavors, colors and cosmetic additives into ready-to-eat products with a very appealing taste. Common examples include packaged cookies, ice cream, sugary drinks, hot dogs, and mass-produced bread.
In recent years, the amount of these highly processed items in the average daily diet has increased significantly around the world. The effects of these foods on brain health remain unclear, so scientists conducted a new study. Some previous studies have linked a diet high in ultra-processed foods to a higher risk of dementia and memory loss, while others have found no such link.
“Our study was motivated by growing concerns about the health effects of ultra-processed foods. Increased intake of these foods is associated with a variety of chronic diseases, but evidence on cognitive aging remains limited and inconsistent, particularly in European populations. used several validated cognitive tests in a large sample of older adults in the Netherlands to investigate whether consumption of ultra-processed foods is associated with cognitive decline over time,” said study author Haneke Weinhoven, assistant professor at the Faculty of Health Sciences at Vrije Universiteit Amsterdam.
Because an overall healthy diet tends to protect the brain, the scientists wanted to test whether the degree of food processing itself plays a distinct role in cognitive aging. To answer this question, researchers examined data from 1,371 older adults participating in the Amsterdam Long-Term Aging Study.
All participants were over 55 years old, with an average age of approximately 67 years. The researchers analyzed data from detailed dietary questionnaires administered to these people from 2014 to 2015 as part of a broader ongoing study. The study asked participants to recall how often and for how much they ate 238 specific foods over the past four weeks.
The scientists then classified all the foods from the study based on their level of processing using a standard system called the NOVA classification. The system classifies foods into four categories, ranging from completely unprocessed items such as fresh vegetables to heavily processed and ultra-processed foods. They calculated each person’s total daily intake of ultra-processed foods by weight in grams rather than calories.
This approach allowed the researchers to consider zero-calorie items such as processed additives and artificially sweetened beverages with no nutritional value. Participants were divided into four equal groups based on the proportion of ultra-processed foods in their daily diet. On average, ultra-processed products accounted for approximately 20% of the total food weight consumed by participants each day.
To track brain health, researchers looked at cognitive test scores collected from participants on four different occasions over a 10-year period. The original ongoing project used five separate tests to assess different areas of brain function. These areas include global cognition, a common measure of overall brain health assessed through common screening tools.
This dataset also includes scores for information processing speed using coding tasks. Coding tasks track how quickly a person can understand and react to new information by matching symbols to letters. The recording also included tests of episodic memory, including the ability to recall specific past events and learn a list of new words. To measure this, participants in the original project were asked to memorize a list of 15 words and then recall them after a short delay.
Finally, the dataset includes measures of executive function, including mental skills such as planning, focusing attention, and handling multiple tasks simultaneously. This was tested by asking participants to list as many animals as they could think of in one minute and then repeating the sequence of numbers backwards. Scientists today used statistical models on all the information they collected to look for patterns over time.
During this analysis, the researchers adjusted for various lifestyle factors that can influence brain health. These factors include age, gender, education, partner status, total energy intake, physical activity, BMI, alcohol intake, smoking, depression, and the presence of chronic diseases. They also took into account scores representing overall diet quality in a separate analysis to ensure they could isolate the specific effects of ultra-processed foods on the brain.
Researchers found no long-term association between ultra-processed food intake and a person’s cognitive performance. They also found no link between highly processed diets and faster cognitive decline as participants aged.
People in the group who ate the highest percentages of ultra-processed foods experienced mental aging at the same rate as those who ate the lowest percentages. Because Dutch adults eat large amounts of mass-produced bread, the researchers conducted additional tests to exclude bread from the ultra-processed category. This secondary analysis yielded exactly the same results.
“In this group of older adults, we found no clear evidence that increased intake of ultra-processed foods according to the NOVA classification was associated with accelerated cognitive decline over a 10-year period,” Weinhoven told PsyPost. “A possible explanation is that overall diet quality may be more important for cognitive health than the level of food processing. Previous analyzes within the same cohort found that higher adherence to healthy dietary patterns, including the EAT-Lancet reference diet, was associated with less cognitive decline.”
As with all research, this study has some limitations. The main limitation is that dietary habits are measured using self-report surveys that rely heavily on human memory. People can forget exactly what they ate or underreport less-healthy food choices, which can affect the accuracy of the data.
Another potential misconception is the idea that all ultra-processed foods have equal nutritional value. Some processed foods are fortified with vitamins and minerals, while others consist entirely of empty calories.
“NOVA’s classification has been criticized for not distinguishing between nutritionally inferior foods (such as sugary drinks and processed meats) and more desirable ultra-processed foods (such as some whole-wheat breads and certain fortified breakfast cereals), which may partially explain the largely null results, Weinhoven noted.
Future research could focus on investigating the precise nutritional profile of different ultra-processed foods over time. Scientists might also be able to track how specific types of processed ingredients, rather than broad categories, affect brain health over a person’s lifetime. By looking more closely at these individual components, researchers can gain a clearer understanding of how modern diets affect the aging brain.
The study, “Ultra-processed food intake and cognitive decline in older adults,” was authored by Chantal Buis, Mary Nicolaou, Marjolein Visser, Margreet R Olthof, and Hanneke AH Wijnhoven.
