Health campaigns targeted at teens could help reduce their risk of heart problems as adults, a study suggests.
Concerns have been raised that warning signs like high cholesterol are being seen in the young, laying the foundation for future health problems.
But the study of more than 500 people found those with high cholesterol at 15 could normalise it by their mid-30s.
The Australian research is published in Archives of Pediatrics and Adolescent Medicine.
Participants in the Australian study had levels of cholesterol and other blood fats measured in 1985 when they were aged 9, 12 or 15.
They were measured again between 2004 and 2006, an average of 20 years later.
High risk levels in this study were defined as a total cholesterol level of 240 miligrams per deciliter or higher (6.2mmol/l).
The average total cholesterol level in the UK is 5.5mmol/l for men and 5.6mmol/l for women.
Height, weight, waist circumference, skin-fold thickness, smoking habits and cardio-respiratory fitness were also measured in the study.
Good and bad
Of those participants who had high-risk cholesterol levels in their youth, those who stopped smoking or lost weight became low-risk in adulthood, while those who increased their body weight or who started smoking were more likely to maintain those high-risk levels 20 years later.
Costan Magnussen, lead study author from the University of Tasmania, said their findings were important.
"They suggest that beneficial changes in modifiable risk factors in the time between youth and adulthood have the potential to shift those with high-risk blood lipid and lipoprotein levels in youth to low-risk levels in adulthood," he said.
He added that prevention programmes targeted at the young could also benefit those who develop bad habits as they get older.
Dr John Coleman, chairman of the Association for Young People's Health, said: "This reseach gives a very clear example of why we need to invest more in adolescent health and make it a higher priority.
"It is clear that young people's lifestyle choices have a long term impact on their health and it is cost effective and sensible to work with them to encourage healthy habits."
Mike Knaptonof the Brtish Heart Foundation said: "All teenagers can do something to improve their cholesterol.
"We should all be eating five portions of fruit and veg a day. And, most importantly, the message is don't smoke."