Ultra-Processed Food and the Ageing Brain: What a Nine-Year Study Suggests

Look at the label on a packet of biscuits, a ready meal or a fizzy drink and you will often find a long list of ingredients we would not keep in our own kitchen. Foods like these are known as ultra-processed, and they make up a large share of what many of us eat. A study published in the American Journal of Public Health this summer asked whether they might be linked to how our thinking holds up later in life.

What the researchers did

The team used the Health and Retirement Study, a large survey of older adults in the United States. They looked at 5,370 people aged 50 and over, with an average age of 64. At the start, everyone filled in a questionnaire about what they usually ate. People who already had dementia or memory problems at that point were left out.

Over the next nine years or so, the participants took standardised tests of memory and attention every two years. Based on the results, the researchers sorted people into three groups: thinking that stayed within the normal range, mild cognitive impairment without dementia, and dementia. They then compared people by how much ultra-processed food they had reported eating at the start.

What they found

Compared with the fifth of people who ate the least ultra-processed food, the fifth who ate the most had a 58 percent higher risk of dementia and a 46 percent higher risk of mild cognitive impairment. These are relative differences, not the chance that any one person will develop dementia.

The picture also worked the other way round. The fifth of people who ate the most whole or minimally processed food, such as fresh fruit, vegetables and plain grains, had a 41 percent lower risk of dementia and a 24 percent lower risk of mild cognitive impairment than the fifth who ate the least. The researchers took age, gender, race, education, wealth, physical activity and smoking into account. Among the types of food they examined, processed meat stood out as the one linked to higher risk across the outcomes.

What this does and does not mean

This is an association, and it should be read as one. People who eat a lot of ultra-processed food may differ in many other ways that no questionnaire fully captures, such as income, time to cook, mood, sleep or how much company they have at meals. The study cannot say that these foods cause dementia, or that changing what you eat will prevent it.

The researchers suggest some possible routes, for example effects on gut bacteria, on oxidative stress or on inflammation, but these were not tested in this study. They remain ideas for future work.

The honest limits

The authors name several limits themselves. Diet was reported from memory, which is never exact, and was recorded only once at the start, so it may not reflect how people ate in the following years. The questionnaire was not designed to measure industrial processing, so the true amounts may have been underestimated. Thinking was assessed with survey-style tests rather than a full examination by a specialist, so some people may have been placed in the wrong group.

There is also the possibility of reverse causation. Very early changes in thinking, too small to notice, could shift what people choose to eat. The researchers left out people who were already affected in the first two years, but that may not remove the problem entirely.

A gentle way to use this

Nobody needs to feel guilty about a biscuit or a pizza. What the study invites is a small, curious look at the balance of the shopping basket. Some people find it easier to add than to cut: a piece of fruit with the morning coffee, a vegetable soup made from scratch once a week, plain yoghurt or nuts instead of a packaged snack. Others start with drinks, since sweetened drinks were one of the biggest sources of ultra-processed food in the study. Cooking with a friend or a grandchild can make the change feel like a pleasure rather than a rule. These are ideas to try, not findings of the study.

A small, steady habit

Brain health tends to come from many small things done regularly, at the table, on a walk and in the mind. Treeny is built around that same idea. The daily exercises are short and meant to be enjoyed, and Flo, the coach inside the app, adjusts them to how you are doing each day. It is one gentle way to keep your mind busy alongside everything else that matters. Treeny was not part of this study and does not treat or prevent any disease.

A note on how to read this

This article describes research and is not medical or dietary advice. The study shows an association and cannot show that ultra-processed food causes dementia, or that eating less of it prevents it. If you have a health condition, take regular medication or are thinking about changing your diet in a big way, talk to your doctor or a dietitian first. If you are worried about your memory, speak to your doctor, who knows your situation in a way no article can.