February 3, 2023

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Qualified food specialists

Ultra-processed foods may accelerate cognitive decline

6 min read

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New research shows that people who consume large amounts of ultra-processed foods have a 28% faster rate of cognitive decline. Xvision/Getty Images
  • Ultra-processed foods are commonplace in the United States — an estimated 73% of the U.S. food supply is ultra-processed.
  • Almost all food is processed for preservation, but ultra-processed “ready-to-eat” foods are often nutritionally poor and may lead to overconsumption.
  • Prior research has linked ultra-processed food intake to a range of negative health outcomes.
  • A new study shows people who consume more ultra-processed foods are at greater risk of cognitive decline.

Ultra-processed food consumption has been linked to a higher risk of cardiovascular disease, metabolic syndrome, and obesity, among various other negative health outcomes.

One study using machine learning has estimated that over 73% of the food supply in the United States is ultra-processed. The findings of this study have yet to be evaluated by experts through peer review but are in line with other evidence that shows ultra-processed food consumption is very common in the United States.

In addition, the Centers for Disease Control and Prevention (CDC) National Health and Nutrition Examination Survey found that calories obtained from ultra-processed foods increased from 53.5% to 57% from 2001–2018. The data show that whole-food consumption also decreased during the survey period.

As such, a growing body of research shows that eating too much ultra-processed food is dangerous for human health. Now, a new study shows more evidence that ultra-processed foods have a negative effect on cognitive health.

Lead study author Natalia Gomes Gonçalves, Ph.D., of the University of Sao Paulo Medical School in Sao Paulo, Brazil, told Medical News Today:

“Our results together with these other two studies provide evidence that the consumption of ultra-processed food is related to poorer cognitive performance, cognitive decline, and dementia in different samples”

The study was recently published in JAMA Neurology.

Not all processed foods are created equal, as many foods are processed to preserve their flavor, texture, and freshness.

But ultra-processed foods are typically ready to eat or drink but contain little to no nutritional value.

The NOVA food classification system categorizes foods based on the amount of processing used to preserve, extract, modify, or create them. The system describes four groups:

  • Minimally processed foods: Unprocessed or minimally processed foods such as seeds, fruits, eggs, and milk.
  • Processed culinary ingredients: These include salt, sugar, honey, and oils — foods in this group are processed by being pressed, milled, or ground.
  • Processed foods: From bread to cheese to canned foods, processed foods are made simply by adding sugar, oil, or salt to food. Processes include cooking and fermentation.
  • Ultra-processed food and drink products: These are industrial formulations with ingredients such as stabilizers and preservatives, including foods like chocolate, candies, ice cream, cookies, pastries, cakes, pizza, and fast food.

Cognitive decline is often the first noticeable sign of dementia, the general term which describes the impaired ability to remember, think or make decisions that can impact everyday life and activities.

Cognitive decline affects 1 in 9 adults in the U.S.

Ultra-processed food consumption has been previously linked to a reduction in verbal fluency in older adults and has been associated with worsening cognition in older individuals with type 2 diabetes.

The current study provides more evidence linking ultra-processed food consumption to an increased risk of cognitive decline.

The multicenter prospective study included three different time periods between 2008 and 2017. Overall, 10,755 participants aged between 35 and 74 years were included — 5880 of the participants were women and 53.1% were white.

At the start of the study, the participants completed a food frequency questionnaire. During set time points throughout the study, they completed cognitive tests that analyzed word recall, recognition, and fluency.

Follow-up data an average of 8 years later, showed people with the highest intake of ultra-processed foods had a 28% faster rate of cognitive decline and a 25% faster rate of decline in executive function compared to people who had the lowest ultra-processed food intake.

Dr. Gonçalves explained the findings to MNT:

“At this time we cannot say if the consumption of ultra-processed foods is associated with accelerated decline in people who already have cognitive decline. These findings support the role of healthy dietary choices in delaying decline in cognitively healthy people.”

Large population-based studies have shown that a healthy, balanced diet is associated with larger brain volume.

Research has also shown that the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet — a combination of the Mediterranean and DASH diets — has been successful in slowing cognitive decline.

Dr. Gonçalves agreed that proper diet and nutrition can help protect cognitive health.

“The MIND diet has been linked to better cognitive performance and decreased risk of cognitive decline […] healthy foods included in the MIND diet are whole grains, green leafy and other vegetables, nuts, beans, berries, poultry, fish, and olive oil.”

She added that the most exciting part of her research is to show people that they can make choices about what they eat to maintain healthy cognition.

“Dietary choices are a powerful way in helping maintain a healthy brain function. It is possible to make healthier food choices within our means in order to maintain overall health as we age. In addition, middle age is an important period of life to adopt preventive measures through lifestyle changes since the choices we make at this age will influence our older years.”

– Natalia Gomes Gonçalves, Ph.D., lead author of the study

The occasional serving of processed food is unlikely to cause harm — but ultra-processed foods should be limited as much as possible.

The 2020–2025 Dietary Guidelines for Americans provides nutrition recommendations from birth to older adults: “Focus on nutrient-dense foods and beverages, limit those higher in added sugars, saturated fat, and sodium, and stay within calorie limits.”

Dr. Scott Kaiser, a geriatrician and director of Geriatric Cognitive Health for the Pacific Neuroscience Institute at Providence Saint John’s Health Center in Santa Monica, CA, not involved in the study, explained to MNT that in clinical practice, healthcare professionals encourage a healthy diet to manage cognitive health.

“Within our practice, we’ve long been encouraging patients to avoid highly processed foods and supporting them in adopting and maintaining healthier diets,” Dr. Kaiser said.

“This guidance was based upon the well-established links between ultra-processed food consumption and increased risk of cardiovascular disease, metabolic syndrome, and obesity as clear evidence of direct impacts on cognition have been limited.”

Dr. Kaiser added that around 40% of all dementia cases could “theoretically be prevented, or significantly delayed” if the risk for comorbid health conditions for which dietary and lifestyle factors play a role were eliminated. These conditions include:

“This study makes important contributions to what is now mounting evidence in support of the negative impacts of ultra-processed foods on cognition and brain health; including, the fact that this was done in a large, ethnically diverse cohort with about a decade of follow-up. It is also important that this study evaluated the impacts of diet on cognition in middle-aged people, as more evidence is needed in support of dementia prevention strategies.”

– Dr. Scott Kaiser, geriatrician

Focus on nutrient-dense whole foods

The Heart and Stroke Foundation suggests cooking more at home to cut back on ultra-processed foods.

When shopping for groceries, a practical way to identify an ultra-processed food is to check its list of ingredients.

Does it contain substances never or rarely used in kitchens (i.e., high-fructose corn syrup, hydrogenated, interesterified oils, or hydrolyzed proteins), or classes of additives designed to make the final product more appealing (i.e., flavors, enhancers, colors, or, sweeteners)?

As a rule of thumb, stick with real, whole foods that have gone through minimal processing whenever possible.