Could your everyday eating habits be connected to changes in your brain before you notice any problems with memory or thinking? A new study suggests there may be a link, even among middle-aged adults without known heart disease.
Researchers analyzed the diets and brain scans of 8,783 Canadian adults ages 35 to 69 and found that those who ate the most ultraprocessed foods had 40% higher odds of showing certain signs of injury to the brain's blood vessels compared with those who ate the least. The findings, published in JAMA Network Open, raise questions about how diet may relate to brain health long before symptoms appear, although they don't establish cause and effect.
"I would not have expected this finding, frankly," said Russell J. de Souza, the study's first author and an associate professor at McMaster University. "Usually, this kind of damage is associated with conditions we hear about and treat at a much older age."
Researchers looked for small areas of brain damage, including evidence of previous disruptions in blood flow and changes in the brain's white matter. These abnormalities often cause no noticeable symptoms but have been linked to a greater risk of stroke and cognitive problems later in life.
Signs of this damage appeared in 11.3% of participants who consumed the most ultraprocessed foods, compared with 8.1% of those who consumed the least. The 40% figure represents a difference in adjusted odds, not an absolute increase in risk.
Interestingly, researchers found no consistent relationship between ultraprocessed food consumption and performance on tests measuring memory, attention and other thinking abilities. In other words, the brain scans revealed an association that wasn't reflected in participants' cognitive performance.
"Our findings suggest that the link between diet and brain health may be detectable before people experience noticeable problems with memory or thinking," said senior author Sonia Anand of the Population Health Research Institute.
The researchers also examined body composition and found that participants with higher ultraprocessed food intake tended to have more overall body fat and more fat stored deep in the abdomen. These associations were more consistent than the findings involving brain injury. Abdominal fat is associated with metabolic problems that can affect blood vessel health, although this study couldn't establish whether it helped explain the brain changes.
The dietary patterns also revealed some complexity. People who consumed more ultraprocessed foods generally ate a smaller proportion of minimally processed foods, but they didn't necessarily eat fewer vegetables or whole grains. In fact, some nutritious foods were consumed more frequently among those with higher ultraprocessed food intake.
That matters because ultraprocessed foods aren't all nutritionally alike. The category includes everything from sugary drinks and packaged snacks to certain breads and cereals, making it difficult to separate the effects of processing from overall diet quality and other lifestyle factors.
The findings also come with important limitations. The association with brain injury was not statistically significant when researchers used alternative ways of measuring ultraprocessed food intake. And because participants' diets and brain health were assessed at a single point in time, the study cannot determine whether eating these foods contributed to the changes.
Researchers say longer-term studies are needed to determine whether changes in eating habits could help prevent or slow these early signs of brain injury.
The research drew on studies supported by the Canadian Institutes of Health Research, Canadian Partnership Against Cancer, Heart and Stroke Foundation of Canada, Public Health Agency of Canada and participating research institutions. The underlying PURE study also received unrestricted funding from pharmaceutical companies, including AstraZeneca, Sanofi and Boehringer Ingelheim, as well as support from Dairy Farmers of Canada and the National Dairy Council. Several authors reported financial relationships with pharmaceutical companies.