The 2008-2011 study of almost 1,100 children aged three to five found those with poor eating behaviours had higher blood-cholesterol readings than children who had healthier eating habits.
"It shows that we should pay attention to how children eat, not just what they eat," said Dr. Nav Persaud, a family physician and researcher at St. Michael's Hospital in Toronto, who led the study.
"We should be paying close attention to these young children, preschoolers aged three to five, because the early changes that may lead to serious problems later on are occurring in this age group and it's an opportunity for us to intervene early and get kids on the right track," he said.
The study, published Monday in the Canadian Medical Association Journal, involved 1,076 preschoolers enrolled in the TARGet Kids! practice-based research network in Toronto.
Researchers looked at the link between eating habits and blood-serum levels of so-called "bad" cholesterol like LDL and triglicerides, which can be markers of later cardiovascular risk.
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Researchers found that "the less healthy the eating behaviours, the higher the cholesterol level," said Persaud.
Those behaviours include eating while watching TV — and likely when engaged with other screens, such as computers and tablets — and snacking on fluids like juice that can leave kids feeling full at mealtime.
"The other issue related to (avoiding) the TV is it gets kids to pay attention to what they're eating, which may make them more interested in variety and having a balanced diet," Persaud said. "It also gets kids to focus on internal cues about when they're full.
"(Food) variety isn't valued as much when you're in front of the TV because you're distracted by the TV, so your food doesn't have to be as interesting."
Persaud said previous research has suggested that "responsive feeding," in which kids are presented with a selection of nutritious foods and allowed to choose when and how much they eat, "is healthier."
"The idea (is) to give kids control over when they eat, but to only provide them with the healthy foods, not to give them a choice between the unhealthy and the healthy foods," he said.
Other research has shown that modelling — in other words, parents or caregivers exhibiting good dietary habits like consuming lots of vegetables — can also promote healthy eating in children.
Persaud also advises parents to "try to make mealtimes fun for kids."
Creative presentation of food, such as cutting vegetables into interesting shapes, can encourage healthier eating habits, he said.
Dr. Guido Filler, chief of pediatrics at Children's Hospital, London Health Sciences Centre, said the study has some limitations, including the fact that researchers did not measure the kinds of foods children were ingesting but relied on parents' reports.
However, he lauded the researchers for investigating cholesterol levels in preschoolers, saying it is an issue that has been understudied in young children, "and in my opinion it should be."
"This study sort of augments the data and the growing evidence that diseases that we used to have only in adults is now moving into childhood — diabetes, heart disease, hypertension," said the kidney specialist, adding that almost half of the adolescents he sees on referral have high blood pressure, mostly because of being overweight.
"So targeting preschool children is a very, very good idea. And it would make sense that behaviour and nutritional intake are causing new problems that are potentially modifiable."
Persaud said it's known that in older children, elevated cholesterol levels are associated both with the later risk of heart attacks and strokes, based on studies that followed children into adulthood.
However, comparatively few studies are done on three- to-five-year olds, and that needs to be remedied, he said.
"This age group is usually neglected, so we're trying to draw attention to the importance of focusing on this age group, where it might be possible to intervene and promote healthy eating behaviours that would have implications later on."