A growing body of research suggests that diet significantly impacts brain health, with a recent study indicating that ultra-processed foods may negatively affect cognitive abilities. The study, published in Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring, found a correlation between higher intake of these foods and declines in attention and mental processing speed.
Researchers analyzed data from over 2,100 Australian adults, finding that approximately 41% of their daily calories came from ultra-processed foods. These products, which include items like packaged cookies, soft drinks, and frozen ready-made meals, undergo extensive industrial processing and often contain additives, emulsifiers, artificial flavors, and preservatives not typically found in home kitchens.
The study indicated that for every 10% increase in ultra-processed food consumption, there was a measurable decrease in cognitive function and an increase in dementia risk factors. Experts note that the findings are particularly significant because the association persisted even among individuals who followed a generally healthy diet.
"Food processing itself may matter for brain health, not just the nutritional label," said Dr. Shaheen Lakhan, a neurologist not involved in the study. "What stood out most was that the association with attention persisted even among people who otherwise followed a Mediterranean-style diet." He suggests that factors beyond calories, fat, sugar, and protein, such as the effects of industrial processing, warrant attention.
Ultra-processed foods may impact the brain through several mechanisms. They are associated with conditions like obesity, hypertension, insulin resistance, and cardiovascular disease, all of which are known risk factors for cognitive decline. Processing can also alter food structures and introduce chemicals that may affect the gut microbiome, inflammation, and ultimately brain function.
Dr. Michael Stanley, a neurologist and assistant professor at Tufts University School of Medicine, pointed to high-temperature processing generating advanced glycation end-products (AGEs), which can damage blood vessels and nervous system tissues. Chemicals migrating from plastic containers, such as BPA, are also under investigation for potential neurotoxic effects. Stanley added that diets rich in ultra-processed foods might sustain a low-grade inflammatory state throughout the body, which over time could contribute to neuronal damage and accelerate brain aging.
Furthermore, the high sodium content in many ultra-processed foods can compromise vascular health essential for blood flow to the brain. A lack of fiber and nutrients can also impact blood flow and brain function. An association between diets high in these foods and insulin resistance highlights how metabolic disturbances can affect brain health.
"The gastrointestinal tract houses a vast microbial community whose activities influence immune function, metabolism, and even aspects of cognition and mood," Stanley noted. "By disrupting this microbial balance, ultra-processed foods may affect the intricate dialogue that exists between the gut and the brain."
Experts emphasize that diet is a modifiable factor for dementia risk. Lakhan recommends choosing foods that closely resemble their natural state, such as whole fruits and vegetables. Diets like the Mediterranean diet and the MIND diet, which emphasize fruits, vegetables, whole grains, fish, and healthy fats, have been linked to lower risks of cognitive decline.
Neuropsychologist Sanam Hafeez cautioned against drawing definitive causal conclusions from a single study, noting that the research shows an association rather than proof of cause and effect. She advised limiting highly processed foods rather than aiming for perfection, acknowledging that other factors could be involved.
The study's focus on attention is notable, as attention is considered a fundamental cognitive function. "Attention is the brain’s gateway function," Lakhan explained. "If attention falters, memory, learning, decision-making and problem-solving often suffer downstream."
While occasional lapses in attention are normal, persistent changes can signal deeper issues. Experts advise paying attention to increased distractibility, difficulty following conversations, or trouble completing familiar tasks. Tracking patterns over time and consulting a doctor for persistent concerns is recommended. Ultimately, maintaining overall lifestyle factors like sleep, exercise, and social engagement remains crucial for brain health.