Ultra-processed foods linked to brain changes that could raise stroke, dementia risk

HAMILTON — People with the highest intake of ultra-processed foods may face an increased likelihood of brain changes that could serve as precursors for stroke, dementia and cognitive decline, a new Canadian study suggests.

The research, co-authored by two professors at Hamilton's McMaster University and published Thursday by JAMA Network Open, examined the diets and brain MRI scans of more than 8,700 Canadian adults with a median age of about 58.

"Fat tissue in the wrong places can be almost like a furnace spewing out a whole bunch of inflammatory proteins that then affect our brains," said co-author Dr. Sonia Anand, a professor of medicine and epidemiology at McMaster.

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The group with the highest consumption got nearly 45 per cent of their daily calories from ultra-processed foods, equal to 16 servings a day, which they self-reported in a survey.

By comparison, the group with the lowest consumption got 15 per cent of their daily calories from ultra-processed foods, equal to three servings.

Anand says the MRIs of the higher-risk group showed changes to the brain similar to silent strokes, a type of stroke that doesn't present any noticeable symptoms but damages the tissue.

"The more injuries you accumulate, the more likely you are to have neurological problems later in life, most commonly vascular dementia," said Dr. Michael Hill, a neurologist and professor at the University of Calgary who is not affiliated with the study.

While the damage a UPF-heavy diet may do can't be reversed, Hill says dietary changes can reduce further progression.

"Feed your brain," he said. "It's not just about your gut, right? It's about your whole body."

Study co-author Russell de Souza, an associate professor at McMaster's Mary Heersink School of Global Health and Social Medicine, says the findings could encourage people to shift their eating habits now, before experiencing serious consequences later in life.

He notes that not all processed foods are ultra-processed and that some degree of processing is necessary to keep food safe and shelf stable.

Foods are classified as ultra-processed if they are mostly or entirely made from substances derived from plant and animal sources and combined with additives like salt, sugar, fats, oils, preservatives, stabilizers, dyes and artificial flavours.

They also tend to be lower in fibre, vitamins and minerals that benefit overall health, de Souza says.

Hill says that while "one Snickers bar isn't going to hurt you," ultimately, ultra-processed food isn't going to benefit your health, especially if eaten regularly.

"Eat foods that will rot, but not rotten food," he said.

Anand and de Souza note their study doesn't provide the full picture and say more long-term research is needed to determine if dietary changes later in life can make a difference.

The next phase of their research will see 2,000 people who took part in the first round of scans receive a second round to determine if reducing ultra-processed foods results in improvements to brain health.

Anand notes that not everyone has the time or money to prepare high-quality food, which she says is a systemic issue that would require government intervention.

She says Canada could follow the lead of other countries, like Chile, which implemented mandatory front-of-package labels for ultra-processed foods high in sugar.

"We need both to happen to make Canadians healthier," Anand said.

With files from CBC News