Research published in a peer-reviewed journal has found that diets heavy in ultra-processed foods are tied to neurological alterations that may raise a person's likelihood of experiencing stroke or cognitive decline in later years. Across a growing body of research, regular consumption of heavily processed foods has shown associations with elevated body fat, type 2 diabetes, and cardiovascular disease.
Brain imaging data from the study points to the organ undergoing measurable changes well before the onset of old age. Among those whose diets leaned most heavily on packaged snacks, fizzy drinks, sugary cereals, and convenience meals, the rate of small lesions in brain tissue ran roughly 40% higher than among those who ate less of such foods.
All participants fell within the 35-to-69 age range, reported no symptoms at the time, and posted cognitive assessment results that placed them in line with the broader group. Heading the research effort at Hamilton, Ontario's Population Health Research Institute, associate scientist Russell de Souza partnered with Sonia Anand to bring the study to completion. A partnership between McMaster University and Hamilton Health Sciences governs how the institute operates.
Because the research collected measurements from every participant at one moment rather than across time, the team could identify a link between eating habits and biological indicators of brain damage but had no way to establish which factor — if either — was responsible for the other; one member of the research group noted the finding ran contrary to what the team had expected.
De Souza noted that the research drew on imaging data and dietary records gathered from 8,783 Canadian adults who had no prior history of heart disease and reported themselves to be in good cardiovascular health — a population in which this variety of cardiac damage would ordinarily be expected only at considerably later stages of life. Each of them had been enrolled in one of two health studies that had been running for a number of years.
Two distinct research efforts fed into the data: the Canadian Alliance for Healthy Hearts and Minds, focused on cardiovascular health, and PURE-MIND's Canadian arm, a neurological study nested within the broader international PURE project. Dietary habits across the preceding twelve months were captured through a questionnaire completed by every person taking part. The brain scans were assessed by neurologists who had been kept unaware of each participant's dietary habits throughout the process.
Researchers narrowed their focus to two neurological markers: tiny strokes that had passed without any outward symptoms, and patches of white matter — the brain's connective tissue — that had begun to break down. Both instances qualified as harm. Roughly one in eleven members of the overall group carried the condition.
Of those in the lowest quartile for ultra-processed food consumption, a rate of 8.1% was recorded. Within that top-consumption quartile, the rate stood at 11.3%. Even after the research team controlled for variables including age, income, smoking habits, physical activity, and pre-existing health conditions such as high blood pressure and diabetes, the disparity remained.
Those who consumed the most food also tended to accumulate greater amounts of abdominal fat, the data showed. Compared with those who ate the least, this group carried body fat readings roughly 1.7 percentage points above that baseline. Visceral fat — the kind that accumulates in the abdominal cavity, nestled around internal organs — registered roughly 5.7 millilitres (about 0.2 fluid ounces, or just over a teaspoon) higher on those imaging scans. Hepatic fat levels showed no variation between groups.
Among those with obesity, the association held consistently, whereas no such link turned up in individuals whose weight fell within the typical range. Visceral fat tissue — the variety stored deep around the abdomen — is thought by researchers to drive both arterial damage and chronic inflammation, two pathways that may partly account for the observed link between eating patterns and cognitive wellbeing.
When body-fat measurements were folded into the analysis, the association held nearly steady — pointing to the possibility that properties inherent to the food itself carry some independent weight.
Two brief assessments covering memory, attention, and processing speed were administered to all study participants. Testing across the full intake range showed no meaningful gap between the highest-volume eaters and those at the lower end of consumption. Elevated baseline performance across the entire group may have compressed the tests' capacity to detect meaningful variation. Those short assessments, the team noted, may lack the precision needed to detect the earliest neurological shifts in people approaching middle age.
The study's lead author, Anand, noted that the data point to a detectable connection between diet and brain health that may appear before any memory or cognitive difficulties become apparent to the individual.
The study's sex-based breakdown revealed that dietary patterns across middle adulthood — spanning the 30s through the 60s — showed a stronger association with markers of brain damage in women than in men. Among women in the study, those whose diets contained the highest levels of ultra-processed food were roughly 80% more likely to show signs of silent brain damage than those whose diets contained the lowest levels — a statistical association, not a proven cause.
Food intake data were split into four equal groups, and the team drew comparisons between those at the upper end and those at the lower end of consumption. Among male participants, no meaningful difference emerged between the two cohorts. Those comparisons were not part of the original study design and were characterised by the team as exploratory in nature. Hormonal influences and other potential explanatory factors fell outside the scope of what the study's design allowed researchers to examine.
Among those whose diets fell into the highest consumption tier, nearly half of all servings — 45 percent — came from ultra-processed foods. That income tier accounted for 16.5 percent of the total.
Foods handled with minimal processing — whole grains, fresh produce, and their counterparts — painted a notably different picture. In the group consuming the least ultra-processed food, whole or minimally processed options made up 68.6% of servings, a share that dropped to 41.5% among those at the opposite end of the consumption spectrum.
Those consuming the largest quantities of food were not reducing their vegetable intake. Daily intake of vegetables, whole grains, and dairy products edged upward by modest amounts, according to the recorded data. Their total caloric intake ran roughly 300 units higher across the day. People who ate larger amounts of ultra-processed foods tended to see other food categories shrink in their diets, with those items taking up a reduced share of total intake rather than simply being pushed aside by added calories alone.
De Souza noted that those food items appeared to take the place of more nutritious whole-food options in people's diets. Those who consumed the greatest quantities of ultra-processed food tended to fall into lower income brackets and had, on average, fewer years of formal education — a pattern that one researcher attributed to the relative cost and convenience such products offer many Canadians.
The research points to a connection between diets heavy in those foods and brain alterations that may raise the likelihood of memory decline and stroke as people age, Anand noted. Data from that single visit captured everything measured, and the dietary questionnaire reached back only one year, even though harm of this nature tends to accumulate across a considerably longer span of time.
How the team tallied consumption turned out to shape the brain-related outcome in their analysis. When the calculation shifted to servings per 2,000 calories, the figure remained unchanged. When assessed against either total calorie share or total serving count, the figure declined — a pattern the researchers noted warrants careful interpretation.
The findings, published in JAMA Network Open, leave open the question of whether cutting back on ultra-processed foods would alter what brain imaging detects, with de Souza noting that longitudinal research using repeated MRI scans will be needed to determine whether dietary changes can slow or head off those neural patterns — work that, according to de Souza, is already underway.
