The researchers were also interested in which components of the lifestyle intervention had the greatest impact of plasma lipids.
"The LDL cholesterol concentration of children from families who participated in the lifestyle intervention was slightly reduced during the two-year follow-up, whereas no similar change was observed in children in the control group," said study researcher Aino-Maija Eloranta from the University of Eastern Finland.
"The lifestyle intervention did not have an impact on other plasma lipids," Eloranta added.
During the two-year follow-up, families participated in six individualised dietary and physical activity counselling sessions. The sessions were individually tailored to each family and they focused on improving the quality of the family's diet, increasing physical activity and reducing screen time.
In addition, children were encouraged to participate in weekly after-school exercise clubs. Children's plasma lipids were analysed at the beginning and at the end of the study.
The study showed that increasing the consumption of high-fat vegetable oil-based spreads and decreasing the consumption of butter-based spreads played the most important role in decreasing the LDL cholesterol concentration.
Replacing high-fat milk with low-fat milk, and doing more physical activity, also explained some of the decreases in the LDL cholesterol concentration.
Having an elevated LDL cholesterol concentration in childhood may predict artery wall thickening in adulthood, the researchers said. The results of the findings thus suggest that a family-based dietary and physical activity intervention may prevent the development of atherosclerosis in adulthood.