Are ultra-processed foods linked to cognitive decline and dementia?

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 recent years, research into the relationship between ultra-processed foods and chronic diseases has produced sobering results.

There’s growing evidence that consuming lots of these products is linked to heart disease, cancer, and an increased risk of death.

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.

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.

What’s dementia?

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.

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.

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Ultra-processed food and cognitive decline

One of the most recent studies was published in late 2022. The scientists took data from the ELSA-Brasil study, which recruited public servants aged 35–74 from six Brazilian cities.

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.”

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.

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.

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.

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.

Many challenges

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. 

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.

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.

Shrinking hippocampus

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.

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.

Salt?

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.

Hormones?

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.

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.

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.