Ultra-Processed Foods and Brain Health: What a New MRI Study Found
Updated: 3 days ago
Written and medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 19, 2026
Quick Answer
Ultra-processed foods were linked to silent blood-vessel damage in the brain in a study published October 15, 2026. Among 8,783 Canadian adults aged 35 to 69 without heart disease, those who ate the most had 40% higher odds than those who ate the least, but did not score worse on memory tests. The study shows a link, not proof [1].
A new study published on October 15, 2026, adds to the evidence on ultra-processed foods and brain health. Researchers scanned the brains of 8,783 Canadian adults aged 35 to 69 with no heart disease. Those who ate the most ultra-processed food had 40% higher odds of small, silent areas of blood-vessel damage in the brain than those who ate the least. They did not score worse on memory and thinking tests. The study shows a link, not proof that these foods cause brain damage. [1]
What the research says
Ultra-processed food is linked to many health problems. A 2024 umbrella review in the BMJ pooled 45 analyses covering almost 9.9 million people. Higher intake was linked to higher risk in 32 of the health outcomes studied (71%), including a 50% higher risk of death from cardiovascular disease and, in dose-response analyses, a 12% higher risk of type 2 diabetes. (Lane et al., BMJ, 2024) [2]
Earlier brain studies point the same way. In a US study of more than 20,000 adults, every 10% increase in the share of the diet from ultra-processed foods was linked to a 16% higher risk of cognitive impairment and an 8% higher risk of stroke. These links were independent of how closely people followed Mediterranean, DASH or MIND eating patterns. (Bhave et al., Neurology, 2024) [3]
A randomized trial suggests processing itself matters. In an 8-week crossover trial, 55 adults ate two diets that both met UK healthy-eating guidelines. They lost about 2.06% of their body weight on the minimally processed diet and about 1.05% on the ultra-processed diet. (Dicken et al., Nature Medicine, 2025) [4]
Key takeaways
People who ate the most ultra-processed food had 40% higher odds of "vascular brain injury" on MRI. This means tiny silent strokes or extensive white-matter changes. [1]
They also had about 1.7 percentage points more body fat and 5.7 mL more deep belly (visceral) fat. [1]
Memory and thinking test scores were not different between high and low eaters. [1]
The study took one snapshot in time (it was cross-sectional), so it cannot show which came first or prove cause and effect. [1]
Swapping some packaged snacks, sugary drinks and processed meats for whole or minimally processed foods is a reasonable step that fits existing healthy-eating advice. [5]
What did the new study on ultra-processed foods and brain health find?
The study was led by researchers at McMaster University in Canada and published in JAMA Network Open. It used data from two large Canadian research programs: the Canadian Alliance for Healthy Hearts and Healthy Minds (CAHHM) and PURE-MIND. [1]
Participants filled in detailed food questionnaires, and researchers counted servings of ultra-processed food per 2,000 calories. People then had body-fat measurements, an MRI of the brain and abdomen, and two standard thinking tests: the Montreal Cognitive Assessment (MoCA) and the Digital Symbol Substitution Test (DSST). [1]
On average, ultra-processed foods made up about a quarter of what participants ate, according to news reports on the study. [6]
Measure | Highest vs. lowest ultra-processed food intake | What it means |
|---|---|---|
Body fat | 1.7 percentage points higher | More overall body fat |
Visceral (deep belly) fat | 5.7 mL more | More fat around internal organs |
Liver fat | No significant difference | No clear link found |
Vascular brain injury on MRI | 40% higher odds | More silent small-vessel damage |
Memory and thinking scores | No significant difference | No measurable effect on test results |
Source: de Souza et al., JAMA Network Open, 2026. [1]
What is "vascular brain injury," and should you worry?
Vascular brain injury means damage linked to the brain's small blood vessels, and finding it on a scan does not mean someone will develop dementia. In this study it included:
Covert brain infarcts: tiny strokes that cause no obvious symptoms and are only seen on a scan.
High white matter hyperintensities: bright spots on MRI that often reflect wear and tear in small blood vessels.
Researchers pay attention to these changes because they reflect the health of the brain's small blood vessels, even when a person feels fine. Finding them on a scan does not mean someone will develop dementia.
In this study, people who ate the most ultra-processed food did not perform worse on thinking tests. Some headlines connected the study to dementia, but the study did not measure dementia. [1]
Were the results different for women?
News coverage reported that the link appeared stronger in women. Women with the highest intake were described as about twice as likely to show this brain damage as women with the lowest intake. [6] This subgroup result is not part of the study's main summary, so it should be treated as preliminary until it is confirmed by other research.
How strong is the evidence on ultra-processed foods and brain health?
The evidence linking ultra-processed foods and brain health comes from a large, carefully measured study, but it is a snapshot with important limits.
It is a snapshot. Diet and brain scans were measured around the same time, so the study cannot show that ultra-processed food came first. The authors say longer-term studies are needed. [1]
The result depended on definitions. The link with brain injury changed depending on how ultra-processed food intake was defined. [1]
Diet was self-reported. Food questionnaires rely on memory and can be inaccurate.
Other factors may play a role. People who eat more ultra-processed food may differ in other ways, such as income, activity or sleep, which statistics cannot fully remove.
Participants were middle-aged Canadians without heart disease. Results may not apply to everyone. [1]
Still, the finding fits with a larger body of research. Large reviews and long-term studies link ultra-processed food with heart disease, type 2 diabetes, stroke and cognitive decline. [2][3] One possible explanation the researchers suggest is that these foods worsen heart and metabolic risk factors that affect blood vessels, including those supplying the brain. [6] The lead author has said the exact reason for the link is still unknown. [6]
What counts as an ultra-processed food?
Not all processed food is the same. Washing, cutting, freezing or canning food is basic processing. Foods become "ultra-processed" when they are made mostly from industrial ingredients and additives, such as sweeteners, flavorings, preservatives and added fats, used for taste or shelf life. [5]
Usually minimally processed | Usually ultra-processed |
|---|---|
Fresh fruit and vegetables | Sweetened breakfast cereals |
Plain frozen fruit | Soda and energy drinks |
Canned fish | Chicken nuggets |
Unsweetened whole-grain cereal | Hot dogs |
Fruit or vegetables as a snack | Chips, crackers and cookies |
Examples based on guidance from Mayo Clinic Health System. [5]
How can you eat fewer ultra-processed foods?
Small, steady changes are easier to keep up than a complete overhaul. Practical steps include: [5]
Read ingredient lists. Long lists with additives such as high-fructose corn syrup, hydrogenated oils or food dyes are a sign of ultra-processing.
Make one swap at a time. For example, switch sugary cereal for an unsweetened whole-grain option.
Choose whole-food snacks. Reach for fruit or vegetables instead of chips, crackers or cookies.
Watch added sugar and salt. Adults should keep added sugars to about 10% of daily calories and sodium under 2,300 mg a day.
Get personal advice. A doctor or registered dietitian can help you build a plan that fits your health needs and budget.
These steps also fit general advice for heart health and weight control. While research on ultra-processed foods and brain health continues, they are sensible changes for most people.
Frequently asked questions
Do ultra-processed foods cause brain damage?
Not proven. The new study found that people who ate the most ultra-processed food had 40% higher odds of silent blood-vessel damage on brain MRI. Because it measured diet and brain scans at the same time, it cannot prove cause and effect. [1]
Does eating ultra-processed food lead to dementia?
The new MRI study did not measure dementia, and it found no difference in memory and thinking test scores. Other long-term research has linked higher intake with a higher risk of cognitive impairment, so the question is still being studied. [1][3]
How much ultra-processed food is too much?
There is no proven safe limit. In this study of ultra-processed foods and brain health, the strongest link was seen in the top quarter of eaters compared with the bottom quarter. [1] Eating less of these foods and more whole foods is a reasonable goal.
Are all processed foods bad for you?
No. Basic processing such as freezing, canning or cutting does not make food unhealthy. Fresh produce, plain frozen fruit and canned fish are fine choices. [5]
Should I get a brain MRI if I eat a lot of processed food?
No. MRI is not recommended as a screening test for diet. If you are worried about memory, stroke risk or blood pressure, talk to your doctor about checks that fit your situation.
Health information, not medical advice. This article explains new research for general education. It does not replace advice from your doctor or a registered dietitian. Talk to a healthcare professional before making major changes to your diet, especially if you have diabetes, heart disease, kidney disease or other medical conditions.
Sources
de Souza RJ, et al. Ultraprocessed Food Intake and Adiposity, Vascular Brain Injury, and Cognition in Middle-Aged Adults. JAMA Network Open. 2026;9(10):e2639118. PMID 42879154. https://doi.org/10.1001/jamanetworkopen.2026.39118
Lane MM, et al. Ultra-processed food exposure and adverse health outcomes: umbrella review of epidemiological meta-analyses. BMJ. 2024;384:e077310. PMID 38418082. https://doi.org/10.1136/bmj-2023-077310
Bhave VM, et al. Associations Between Ultra-Processed Food Consumption and Adverse Brain Health Outcomes. Neurology. 2024;102(11):e209432. PMID 38776524. https://doi.org/10.1212/WNL.0000000000209432
Dicken SJ, et al. Ultraprocessed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: a randomized, crossover trial. Nature Medicine. 2025;31(10):3297-3308. PMID 40760353. https://doi.org/10.1038/s41591-025-03842-0
Harguth A. Processed foods: What you should know. Mayo Clinic Health System. July 25, 2024. https://www.mayoclinichealthsystem.org/hometown-health/speaking-of-health/processed-foods-what-you-should-know
Laws J. Eating More Ultra-Processed Food Linked to Silent Brain Damage. Newsweek. October 16, 2026. https://www.newsweek.com/eating-more-ultra-processed-food-linked-silent-brain-damage-12571715
About the author
About the author: Dr. Baraa Alnahhal, MD, is a medical doctor and the founder of Rinnit. Dr. Baraa Alnahhal reviews new medical research and translates it into clear, evidence-based health information for everyday readers.
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