Using ultrasounds to monitor children's blood vessels, doctors from Hong Kong and Sydney's Royal Prince Alfred Hospital found some of the children's arteries had thickened to look like those of adult smokers.
"It means these children are at risk of heart attack or stroke in their 40s or 50s, rather than their 70s or 80s. This has terrible implications for later in life," said Royal Prince Alfred Hospital cardiologist and director David Celemajer said Tuesday.
Even chubby children were at risk, Celemajer said. The research will be published in next month's issue of the International Journal of Obesity.
RPA director Kate Steinbeck said a study has found that with a healthy low-fat diet and sustained exercise over one year, the children's blood vessels returned to normal, however.
About 60 percent of Australian adults are overweight, and Steinbeck said children were increasingly starting preschool "significantly overweight."