How Ultra-Processed Foods Affect Cognitive Performance, According to Science
In our guide to the best and worst foods for brain health, processed foods earned a slot on the "worst" list. A growing body of research has linked diets that are rich in ultra-processed foods with everything from cognitive impairment to worse memory and learning scores.
But some "processed" foods, like frozen vegetables and Greek yogurt, are undoubtedly health-promoting. So how can you tell which processed foods are the not-so-great ones—and how, exactly, do they impact cognitive performance?
A study published July 2022 in the European Journal of Nutrition was designed with just this purpose. After studying cognitive test data from a pool of people 60 and older, researchers found that people who consume high amounts of ultra-processed foods tend to perform worse in language and executive function cognitive tests.
What Are Ultra-Processed Foods?
Nearly every food we eat is processed in some way. Take that bottle of cinnamon in your spice cabinet. Bark from a cinnamon tree is transformed into a powder and placed into a jar to add anti-inflammatory qualities (and flavor!) to your recipes. Or the almond butter; which is often just a matter of blitzing up almonds (ideally just almonds, and maybe a little salt) and piping this spread into a jar. Or even that supermarket apple—it's sometimes coated in food-safe wax that extends its life and protects it from pests.
An item fits the "ultra-processed foods (UPF)" category if it contains zero whole foods, includes ingredients with flavors/colors/cosmetic additives and undergoes several industrial processes before it arrives in your kitchen. Breakfast cereals, candy bars, frozen pizza and "fruit" snacks are some of the foods that fall under this umbrella.
These foods are easily accessible, convenient and engineered to be delicious. And, for many in America, these types of ultra-processed foods are also essential and may be the only option at times. UPFs make up about 57% of the calories eaten by a typical American adult and 67% of the calories consumed by teens and kids.
Earlier research suggests that higher UPF consumption might lead to an overall lower-quality diet and increased risk for chronic health challenges, such as heart disease (the leading cause of death in America). And this study set out to see how these impact cognition.
What This Brain Health Study Found
The research team selected 2,713 people age 60 enrolled in the U.S. National Health and Nutrition Examination Survey (NHANES) 2011-2014, and asked them to:
- Share their dietary intake via two 24-hour diet journals
- Take a variety of cognitive tests, including exams that measure executive function (working memory), language skills and animal fluency (ability to recall and name as many animals as possible in a short period of time; a test that combines language and executive function skills in one)
There was no connection between UPF levels and overall cognitive test scores, but among those without pre-existing chronic health conditions (including heart disease and diabetes), higher UPF consumption was linked to lower scores on the animal fluency tests. While more research is needed to confirm this finding and cement exactly why it's the case, the scientists believe that frequent and high intake of UPFs might impact gut health in a way that disrupts the gut-brain axis in a way that, over time, may increase risk for Alzheimer's disease. They can also lead to low-grade chronic inflammation throughout the body—including around the brain.
Plus, the more UPFs a person consumes, the less real estate they have on their plate for health-boosting whole grains, lean proteins, fruits and vegetables. (ICYMI, this is the #1 food for boosting brain health, according to a dietitian.)
The Bottom Line
This new brain health study hints that eating a lot of ultra-processed foods may lead to cognitive decline in certain populations. There's not enough evidence yet to prove that this is a cause-and-effect relationship, though.
This new research appears to be the first to investigate the connection between UPFs and cognitive decline, and can act as the foundation for future longer and larger studies.
Until we know more, it certainly can't hurt to try to limit consumption of UPFs and lean into the MIND diet—a riff on the Mediterranean diet and the DASH diet that have been proven to reduce risk for Alzheimer's disease and dementia.