Ultra-processed foods have gone through a certain amount of industrial processing.
Their labels often have laundry lists of ingredients, many of which you won’t find in your kitchen, like emulsifiers and artificial flavorings and sweeteners.
They tend to be high in salt, unhealthy fats, and refined sugar. They're also generally low in fiber and don't contain whole food ingredients.
Many packaged snacks, sweets, processed meats, ice creams, microwave meals, breakfast cereals, and sodas, for example, are ultra-processed.
In the United States and United Kingdom, we consume a great deal of ultra-processed food. In fact, more than half of our calories come from these products.
In recent years, research into the relationship between ultra-processed foods and chronic diseases has produced sobering results.
But in this article, we’ll investigate the possible links between ultra-processed foods and brain health in later life. In particular, we’ll concentrate on cognitive decline and dementia.
So far, this topic has received less attention than some of the other health effects, so we don't have firm answers yet. But as you’ll see, links are becoming apparent.
What’s cognitive decline?
As we age, we may find that our mental abilities aren’t quite as sharp. Everyone is different, but on average, some aspects of our thinking abilities become less acute.
You may have slightly more difficulty remembering things or feel like you can’t think quite as quickly. This is a normal part of aging.
"Cognition" is the collection of brain processes that includes your ability to learn, remember, and make judgments. In people with cognitive decline, these abilities are slowly impaired.
But cognitive decline exists on a spectrum — our brain powers decline at different rates. Some people barely notice a difference, while others struggle to do everyday tasks.
We mentioned that cognitive decline is a normal part of aging. Dementia, however, is not.
Most people with cognitive decline don’t later develop dementia. But for people who do develop dementia, cognitive decline is often the first sign that something is up.
There are different types of dementia, and Alzheimer’s disease is the most common. All the types affect the ability to think, reason, and do everyday tasks.
Worldwide, dementia affects an estimated 55 million people. Various treatments can help manage the symptoms, but at the moment, there’s no cure.
Nutrition, cognitive decline, and dementia
Many lifestyle factors might increase the risk of dementia and cognitive decline.
In the case of dementia, they may include how active you are, your education level, and your alcohol and tobacco use.
It's tricky to separate out the effects of these factors, which may nearly span a lifetime, while cognitive decline and dementia tend to develop late in life.
Meanwhile, scientists are increasingly interested in the impact of food on health, including its role in cognitive decline and dementia. And they’ve made some headway.
Another study investigated the MIND diet, a Mediterranean-style diet with a focus on vegetables, nuts, berries, beans, whole grains, seafood, poultry, olive oil, and a glass of wine every day.
They found that cognitive decline was slowest in people who followed this diet most closely.
So, healthy foods in combination over the years might offer some protection.
But can ultra-processed foods, which are already linked to poorer health outcomes, increase the risk of significant cognitive decline and dementia?
Next, we’ll take a look at what the research says so far.
The findings aren’t conclusive, but it's looking more likely that ultra-processed foods do affect our brain health as we age.
Join the community
Be the first to know about ZOE’s breakthrough research, content from the world’s leading scientists, and more.
Ultra-processed food and cognitive decline
Overall, the team tracked 10,775 people for 6–10 years. Each participant gave detailed information about their diet and other factors that might influence their brain health later in life.
These factors included age, sex, monthly income, self-reported race and ethnicity, body mass index, existing health conditions, physical activity levels, calorie intake, smoking, and alcohol consumption.
Up to three times every 4 years, the participants also completed cognitive tests.
After analyzing their data, the scientists concluded: “Participants who reported consumption of [ultra-processed foods] of more than 19.9% of daily calories had a 28% faster rate of global cognitive decline, compared with those who reported consumption of [ultra-processed foods] up to 19.9% of daily calories.”
In other words, those who ate the least ultra-processed foods experienced slower cognitive decline.
The scientists also found that higher intakes of ultra-processed foods in people under 60 were linked to swifter cognitive decline.
According to the authors, this “suggests the importance of preventive interventions in middle-aged adults.”
But, interestingly, they only found links between ultra-processed foods and cognitive decline in people with a generally unhealthy diet.
So, for people with an overall healthy diet, there was no association between ultra-processed foods and cognitive decline.
The study did have some limitations, and we’ll talk about them later on, but their findings align with some other recent studies.
For instance, a study published in July 2022 used data from 3,632 people aged 60 or older. It didn’t find links between ultra-processed food intake and cognitive performance overall.
But it did find that people without preexisting chronic health conditions who consumed the most ultra-processed foods performed worse on one cognitive test. This assessed verbal fluency and executive function.
Executive function includes cognitive skills that are necessary to self-regulate your behavior. Some examples of these skills are working memory, flexible thinking, and self-control.
What about dementia?
There has been less research into links between ultra-processed foods and dementia.
A 2022 study followed 118,528 people with an average age of 56.2 years. Each participant provided detailed information about their diet.
Over the study's average 10-year follow-up period, 566 participants developed dementia.
After taking into account a range of variables, the researchers concluded:
“Higher consumption of [ultra-processed foods] was associated with higher risk of dementia, whereas substituting unprocessed or minimally processed foods [for ultra-processed foods] was associated with lower risk of dementia.”
Specifically, they found that if you replace 10% of the ultra-processed food in your diet with an equivalent amount of unprocessed or minimally processed food, there’s a 17% lower risk of dementia.
Although the studies we’ve outlined above start to paint a picture, they do have limitations.
First, because of the nature of the research, these studies haven't proved that ultra-processed foods cause swifter cognitive decline or dementia. They can only point to an association.
And although the researchers accounted for a range of factors, it’s impossible to account for them all.
Also, these studies only captured information about what people ate over a certain period. Dietary patterns can change a great deal over a lifetime.
What people eat in their 20s and 30s might be very different from what they eat in their 60s and 70s, for instance.
Also, in the case of dementia, there’s a long "preclinical stage." In other words, the symptoms may begin at an earlier age, but they’re not significant enough to be diagnosed as dementia yet. And this stage can last for more than a decade.
So, some people in the dementia study we covered above might have been experiencing early stages, but because they didn't have a diagnosis yet, the researchers didn't include them in the "dementia group" of participants.
This muddies the waters of the analysis. Overall, scientists need to do much longer studies to capture more accurate information.
How might these foods affect brain health?
Right now, the evidence that ultra-processed foods might affect brain health isn’t watertight. But scientists have some theories about how these foods might impact our brains over the years.
We’ll cover some of these theories below.
Blood vessels in the brain
Previous research has shown that consuming ultra-processed foods is linked to an increased risk of cerebrovascular disease. This affects the blood vessels in your brain.
So, if ultra-processed foods damage blood vessels in the brain, this might help explain reduced cognitive abilities.
Other studies have found links between diets low in nutrient-dense foods and decreased volume in a part of the brain called the hippocampus. The hippocampus is important for learning and memory.
So, in this theory, it’s not ultra-processed foods themselves that are causing damage, it’s that they’re replacing more healthy foods.
This theory aligns nicely with the Brazil study, which found links between ultra-processed foods and cognitive decline only in those with less healthy diets.
The authors of the 2022 dementia study also have some theories. For example, they suggest that the high salt content of ultra-processed foods might be key.
The researchers refer to a review that found some evidence that high salt intake is associated with cognitive decline.
The team floats another theory, which concerns the packaging of ultra-processed foods. This can contain chemicals like bisphenol A, which may disrupt hormone levels.
The researchers also note, “Experimental studies suggest that bisphenol A could increase DNA damage in brain cells and impair cognitive function.”
But, to reiterate, we don’t know if ultra-processed foods truly do increase the risk of cognitive decline and dementia. The theories above are just speculative at this point.
What should you do?
As we’ve seen, there’s growing evidence that a healthy diet supports brain health as you age.
And there’s some evidence that ultra-processed foods might be linked to increased rates of cognitive decline and perhaps dementia. But much more research is needed.
Links between a healthy diet and a healthy brain aren’t well defined. But experts know that a diverse diet rich in plant foods is key to good overall health.
You don’t need to stop eating ultra-processed foods entirely. And it would be nearly impossible to do this.
But if you eat lots of these foods, consider swapping them out for less processed foods whenever possible.
Here are some swaps you could try:
Switch packaged snacks for a handful of nuts.
Swap flavored, high-sugar yogurt for natural full-fat yogurt.
Buy minimally processed cheeses, like cheddar, instead of processed cheese slices.
Replace breakfast cereals with homemade oats, natural yogurt, or eggs.
Swap processed meats for white meat or fish.
Making changes like these might not reduce your risk of cognitive decline and dementia, but they’ll likely improve your health in the long run.
If you’d like to learn more about how to eat well for your body, you can start by taking our free quiz.
About dementia. (2019). https://www.cdc.gov/aging/dementia/index.html
Association between ultra-processed food consumption and cognitive performance in US older adults: A cross-sectional analysis of the NHANES 2011–2014. European Journal of Nutrition. (2022). https://link.springer.com/article/10.1007/s00394-022-02911-1
Association between ultraprocessed food consumption and risk of mortality among middle-aged adults in France. JAMA Internal Medicine. (2019). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6450295/
Association of ultraprocessed food consumption with risk of dementia. Neurology. (2022). https://n.neurology.org/content/99/10/e1056
Brazilian Longitudinal Study of Adult Health (ELSA-Brasil): Objectives and design. (2012). American Journal of Epidemiology. https://pubmed.ncbi.nlm.nih.gov/22234482/
Can a healthy diet reduce your dementia risk? (n.d.). https://www.bhf.org.uk/informationsupport/heart-matters-magazine/nutrition/dementia-diet
Cognitive profile of subcortical ischaemic vascular disease. Neurology, Neurosurgery & Psychiatry. (2006). https://jnnp.bmj.com/content/77/1/28
Consumption of ultra-processed foods and cancer risk: Results from NutriNet-Santé prospective cohort. The BMJ. (2018). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5811844/
Dementia. (2023). https://www.who.int/news-room/fact-sheets/detail/dementia
Early-stage signs and symptoms of dementia. (2021). https://www.alzheimers.org.uk/about-dementia/symptoms-and-diagnosis/how-dementia-progresses/early-stages-dementia
Link between dietary sodium intake, cognitive function, and dementia risk in middle-aged and older adults: A systematic review. Journal of Alzheimer’s disease. (2020). https://pubmed.ncbi.nlm.nih.gov/32675410/
Mediterranean diet and risk for Alzheimer's disease. Annals of Neurology. (2006). https://onlinelibrary.wiley.com/doi/10.1002/ana.20854
Mediterranean diet and risk for dementia and cognitive decline in a Mediterranean population. Journal of the American Geriatrics Society. (2021). https://agsjournals.onlinelibrary.wiley.com/doi/abs/10.1111/jgs.17072
MIND diet slows cognitive decline with aging. Alzheimer’s & Dementia. (2015). https://www.sciencedirect.com/science/article/abs/pii/S1552526015001946
Normal cognitive aging. Clinics in Geriatric Medicine. (2014). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4015335/
Risk factors for dementia. Journal of the Formosan Medical Association. (2009). https://www.sciencedirect.com/science/article/pii/S0929664609604022
Subjective cognitive decline — a public health issue. (2019). https://www.cdc.gov/aging/data/subjective-cognitive-decline-brief.html
Ultra-processed food intake and obesity: What really matters for health – processing or nutrient content? Current Obesity Reports. (2018). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5787353/
Ultra-processed food intake and risk of cardiovascular disease: Prospective cohort study (NutriNet-Santé). The BMJ. (2019). https://www.bmj.com/content/365/bmj.l1451
Western diet is associated with a smaller hippocampus: a longitudinal investigation. BMC Medicine. (2015). https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-015-0461-x