Canadian preschoolers get nearly half their calories from ultra-processed foods, study says

A grocery store aisle in Montreal on Oct. 9, 2024. THE CANADIAN PRESS/Graham Hughes

MONTREAL — Canadian preschoolers are getting nearly half their calories from ultra-processed foods and it’s putting them at risk of obesity, according to a new study.

Researchers at the University of Toronto’s faculty of medicine found that nearly one in five of the more than 2,000 children they followed over a years-long study was overweight or obese by age five.

Dr. Kozeta Miliku, one of the study’s authors, said the results aren’t surprising, given that Canada is among the top five countries for the sale of ultra-processed foods. But seeing such high consumption among young children is “worrisome,” she said in an interview.

Ultra-processed foods, which include sweetened breakfast cereals, frozen meals, fast food, chips and candy, are often high in added sugar, salt and saturated fats, Miliku said. They often contain artificial flavours, preservatives, sweeteners and emulsifiers, and lack many essential nutrients.

“These are often designed to be convenient, to be tasty, to have ... a long shelf life,” she said, adding that a long list of unfamiliar ingredients is a common sign of an ultra-processed food.

The study, which followed 2,200 children in Toronto, Vancouver, Edmonton and Manitoba between 2011 and 2018, was published Friday in JAMA Network Open. The researchers collected data about the children’s diets when they were three years old, and then took body measurements at age five.

They found that the three-year-olds were getting 45 per cent of their daily energy from ultra-processed foods. Moreover, high consumption of those foods at age three was linked to higher body fat and obesity risk at age five, especially among boys. The researchers used the World Health Organization definition of obesity.

Zheng Hao Chen, a PhD student at the University of Toronto, said it’s unclear exactly how ultra-processed foods are linked to obesity. One possible explanation is simply that many of these foods are high in calories. Another is that they can be “hyperpalatable,” the study says, meaning it can be difficult to control how much you eat.

Chen pointed to research that has found the combination of saturated fat and refined carbohydrates promotes the reward centres of the brain. Another study showed the over-consumption of ultra-processed foods “is comparable to addictive behaviours,” he said. “So this means they have a neurological effect and should be examined further, particularly in children.”

The researchers also suggested that emulsifiers and additives in ultra-processed foods can change the gut microbiome, and could have different effects in men and women. For example, Miliku said, the lack of fibre in these foods can disturb the balance between good and bad bacteria in the gut.

Whatever the reason, the study points out that obesity rates are increasing along with the rise of ultra-processed foods. It cites statistics showing that 7.3 million Canadian adults were living with obesity in 2018, rising to 8.3 million — more than one in four adults — in 2020. One third of Canadian children and youths were living with obesity in 2023.

Miliku pointed to a number of policy measures that could help reduce consumption of ultra-processed foods in children, including mandating healthier school meals, requiring nutrition quality information on the front of food packages and restricting marketing to children. She also said it’s important to improve accessibility to healthy foods, including through community gardens and farmers markets.

“I’m a mother of a three-year-old myself, and with a busy lifestyle ... it is so difficult to skip over processed foods. They are such a handy solution to make sure our children are fed,” she said.

“But trying to give our children more whole fruits, whole veggies, minimally processed foods, grains and lean proteins can support them for better health.”

This report by The Canadian Press was first published Jan. 31, 2025.

Maura Forrest, The Canadian Press