Researchers at the University of Toronto are sounding the alarm about the high consumption of ultra-processed foods among preschool-aged children in Canada and its association with obesity development.
"We saw that ultra-processed foods contributed to almost half of a child's total daily energy intake," says Kozeta Miliku, assistant professor of nutritional sciences at U of T's Temerty Faculty of Medicine .
The findings, published today in JAMA Network Open, are the first to describe sex-driven differences in the effects of ultra-processed food on obesity risk among Canadian children, with stronger effects seen in males.
Ultra-processed foods are those that have been industrially produced and contain ingredients not typically found in a home kitchen, like emulsifiers, preservatives and artificial colours and flavours. The broad category includes items like soda, instant noodles and chips, as well as less obvious foods like flavoured yogurts and commercially prepared whole-grain breads.
To examine the link between ultra-processed food consumption and obesity development, the researchers used data from over 2,200 kids enrolled in the CHILD Cohort Study , one of the largest prospective pregnancy cohort studies in Canada. The study collects information from families starting in pregnancy and at key developmental stages to track the impact of genetic and environmental factors on children's long-term health.
The work was led by Zheng Hao Chen, a PhD student in Miliku's lab, who notes that Canada is among the top consumers of ultra-processed foods worldwide.
For the study, the researchers looked at data from detailed food frequency questionnaires caregivers completed when the child was three years old and compared it to physical measurements taken of the same child at age five, including their height, weight, waist circumference and skinfold thickness.
Miliku notes that early childhood is a critical developmental window because food preferences and habits established during this time can carry into adulthood.
The researchers found a link between increased ultra-processed food consumption at age three and higher body fat measurements — such as BMI, waist-to-height ratio, skinfold thickness — and a greater risk of living with overweight or obesity at age five. Interestingly, these associations were primarily seen in males and remained significant after accounting for other factors like parent education and whether the child was breastfed.
In ongoing follow-up studies, the researchers are looking at whether replacing some of the ultra-processed foods with minimally processed whole foods can help reduce the negative effects on body composition and obesity risk. They are also trying to understand why males seem to be especially vulnerable to the health harms related to ultra-processed foods and what role the gut microbiome might play in these adverse health outcomes.
As a mom to a three-year-old who also can't completely avoid ultra-processed foods, Miliku understands firsthand the challenges parents face in trying to feed their child a well-balanced diet.
"Ultra-processed foods are very accessible and a handy solution for busy days. We are all doing our best to make sure our children are fed, but there are opportunities for us to improve their diet."
She hopes that the study will spur regulators to adopt public health policies, like front-of-package nutrition labelling, to make it easier for families to choose healthier, less processed options.
"Ultra-processed foods are common in today's retail market, but they are not all easy to spot," says Chen.
Miliku and Chen point to the Nutri-Score label used in France — a colour-coded scale ranging from A to E — and food-specific taxes as measures that have worked in other countries to encourage people to eat less ultra-processed foods. Miliku also acknowledges that with an increasing number of Canadian households experiencing food insecurity, broader policy supports are needed to ensure the affordability and accessibility of fresh whole foods.
"Canada is falling behind in this area. With overweight and obesity affecting nearly one in three children in this country, it's scary that we are not taking more action."
