The gradual loss of ability to perform everyday tasks: remembering dates, doing basic math, planning a meal.
Across three Brazilian universities and nearly 15,000 lives tracked over a decade, a quiet alarm has been raised: the modern diet's most convenient offerings may be quietly eroding the mind. Those who drew more than a fifth of their daily calories from ultraprocessed foods showed cognitive decline nearly 28 percent faster than their peers — a finding that places the humble slice of commercial bread within a much larger conversation about how what we eat shapes who we are able to remain. The mechanisms are not yet fully understood, and experts debate even the definition of 'ultraprocessed,' but the pattern is consistent enough to demand attention.
- A decade-long study of 15,000 Brazilians found that heavy ultraprocessed food consumption accelerates cognitive decline by 28% — the mental equivalent of aging faster than your years.
- The damage is not abstract: people lose the ability to remember dates, calculate, plan, and complete ordinary tasks — the quiet infrastructure of a functioning life.
- Researchers suspect small strokes, inflammation, nutritional deficiency, and harmful additives as possible culprits, but no single mechanism has been confirmed.
- Ultraprocessed foods already carry links to obesity, diabetes, heart disease, and depression — all known pathways toward dementia — compounding the urgency of these findings.
- A fault line runs through the science itself: some experts argue that nutritional quality, not processing level, is the true measure of harm, leaving the field without a unified framework.
- The path forward requires more research, clearer definitions, and a reckoning with whether it is the processing, the emptiness of nutrients, or both that quietly dims the mind.
Scientists from three major Brazilian universities tracked roughly 15,000 people over a decade and found that those consuming more than 20 percent of their daily calories from ultraprocessed foods experienced cognitive decline 28 percent faster than their peers. To make that concrete: it is the equivalent of eating three slices of commercial bread every day on a standard 2,000-calorie diet. The findings were published in JAMA and presented at a neuroscience conference in Florianópolis in June 2023.
Cognitive decline is not a distant abstraction — it erodes the ability to remember dates, do basic arithmetic, plan a meal, or carry a simple project through to completion. Claudia Suemoto, a geriatrics professor at the University of São Paulo, suggested that small strokes triggered by these foods may be one mechanism at work, while cautioning that further studies are still needed to confirm the link.
Co-author Renata Levy noted that the precise biological pathways remain unclear, but ultraprocessed foods are already firmly associated with obesity, high blood pressure, diabetes, heart disease, and depression — all established risk factors for dementia. Compared to whole foods, these products tend to carry higher glycemic loads, more trans fats and sodium, and far fewer micronutrients and fiber. A parallel study of nearly 11,000 Brazilians reached similar conclusions, and American research involving more than 10,000 adults found that heavier ultraprocessed food consumption correlated with greater rates of mild depression and anxiety.
Not everyone agrees on the terms of the debate. Mario Marostica Junior of the University of Campinas argues that Brazil's official definition of ultraprocessed is too broad, pointing out that some products made from such ingredients — infant formula among them — have strong nutritional profiles. The real harm, he contends, lies in nutritional quality and caloric density, not processing level alone. What remains clear is that the science is still settling: the correlation is consistent, the mechanisms are contested, and the definitions are unresolved — leaving researchers with more work ahead before the full picture comes into focus.
A team of researchers from three major Brazilian universities has found evidence that ultra-processed foods may be accelerating cognitive decline at an alarming rate. The study, conducted by scientists at the University of São Paulo, the Federal University of Minas Gerais, and the Federal University of Bahia, tracked roughly 15,000 people over time and discovered that those consuming more than one-fifth of their daily calories from ultra-processed items experienced cognitive decline 28 percent faster than their peers. To put that in concrete terms: it's the equivalent of eating three slices of commercial bread every single day, based on a 2,000-calorie diet.
The research builds on a decade of health monitoring that began in 2008, part of the Brazilian Longitudinal Study of Adult Health. The findings were published in the journal JAMA and presented at the Brain Behavior and Emotions conference in Florianópolis in June, where neuroscience specialists gathered to discuss the implications. Cognitive decline itself is not abstract—it manifests as the gradual loss of ability to perform everyday tasks: remembering dates, doing basic math, planning a meal, executing a simple project.
Claudia Suemoto, an associate professor of geriatrics at the University of São Paulo's medical school and member of the Brazilian Academy of Neurology, cautioned that while the results are suggestive, they require further confirmation. She pointed to one possible mechanism: small strokes triggered by the consumption of these foods. "Our study suggests the acceleration of cognitive functions, triggered by small strokes," she explained. "There is this possibility, but new studies are still necessary."
The exact biological pathways remain murky. Renata Levy, a researcher in preventive medicine at the University of São Paulo and co-author of the work, acknowledged that scientists don't yet fully understand how ultra-processed foods damage cognition. What is clear, she said, is that these foods are already strongly linked to obesity, high blood pressure, type 2 diabetes, heart disease, and depression—all established risk factors for dementia. Beyond that, ultra-processed items may harm brain function through their additives and contaminants, or through their nutritional deficiencies. Compared to whole foods like vegetables, fruits, fish, and eggs, ultra-processed products tend to have higher glycemic indices, more trans fats and sodium, and far fewer fiber and micronutrients.
A separate study by University of São Paulo researchers analyzing data from nearly 11,000 Brazilians aged 35 to 74 over a decade found similar results: a diet heavy in ultra-processed foods could accelerate cognitive decline by nearly 30 percent. American research involving more than 10,000 adults pointed in the same direction—the more ultra-processed food people ate, the more likely they were to report mild depression or anxiety. One researcher noted a significant jump in mentally unhealthy days among those deriving 60 percent or more of their calories from these foods.
Yet not all experts agree on what counts as ultra-processed in the first place. Mario Marostica Junior, a professor of food science and nutrition at the University of Campinas, argues that the definition used by Brazil's Health Ministry guidelines is too broad and potentially misleading. He points out that some products made from ingredients classified as ultra-processed—infant formula, for instance—actually have excellent nutritional profiles. The real issue, he contends, is nutritional quality, not processing level alone. The World Health Organization acknowledges diet as one factor among many in chronic diseases like Alzheimer's and cognitive decline, but obesity, driven by consuming more calories than the body expends, is equally important. Foods with high caloric density, regardless of how processed they are, can increase the risk of obesity and its related conditions, including cognitive decline.
The disagreement highlights a deeper uncertainty: researchers have identified a correlation between ultra-processed food consumption and faster cognitive decline, but the mechanisms remain incompletely understood, and the scientific community has not yet settled on a unified definition of what makes a food "ultra-processed" in the first place. What comes next is clearer: more research, more consensus-building among experts, and a closer look at whether it's the processing itself or the nutritional emptiness that does the damage.
Notable Quotes
Our study suggests the acceleration of cognitive functions, triggered by small strokes. There is this possibility, but new studies are still necessary.— Claudia Suemoto, associate professor of geriatrics, University of São Paulo
The exact mechanisms that make ultra-processed foods have this impact are still not clear, but they are already strongly linked to obesity, high blood pressure, type 2 diabetes, heart disease, and depression—all established risk factors for dementia.— Renata Levy, researcher in preventive medicine, University of São Paulo
The Hearth Conversation Another angle on the story
So we have this 28 percent figure—that's a significant jump. But what does it actually mean for someone's daily life?
It means the difference between someone at 70 staying sharp enough to manage their finances and remember their grandchildren's birthdays versus struggling with those same tasks five or ten years earlier. Cognitive decline isn't dramatic at first. It's the small forgetting that compounds.
The study tracked 15,000 people. That's a real sample size. But the researchers themselves seem cautious about their own findings.
They are, and that's honest science. They found a pattern, but they don't yet know why it's happening. Is it the additives? The lack of nutrients? Inflammation in the brain? They're pointing at something real but incomplete.
And then you have this other researcher saying the whole definition of ultra-processed is the problem.
Right. He's not wrong. If you can make infant formula from ultra-processed ingredients and it's nutritionally excellent, then maybe the label itself is misleading. Maybe the real culprit is just eating empty calories, whether they come from processed bread or something else.
So we're back to square one?
Not quite. We know these foods are linked to obesity, diabetes, heart disease, depression—all things that damage the brain. Whether it's the processing or the nutrition or both, the pattern is there. The question is just how to talk about it clearly.