The arteries of teenagers who drink alcohol and smoke, even occasionally, are already beginning to stiffen by the age of 17, according to research.
The University College London (UCL) study also showed that a combination of high alcohol intake and smoking was linked to even greater arterial damage compared with drinking and smoking separately.
But the findings, published in the European Heart Journal, showed that if teenagers stopped smoking and drinking during adolescence, their arteries returned to normal.
Arterial stiffness indicates damage to the blood vessels, which predicts heart and blood vessel problems in later life such as heart attacks and stroke.
Researchers analysed data from 1266 adolescents from the UK's Children of the 90s, the Avon Longitudinal Study of Parents and Children (ALSPAC), over a five-year period between 2004 and 2008.
Participants provided details of their smoking and drinking habits at 13, 15 and 17.
A man lighting a cigarette Source: Jonathan Brady/PA Wire
Aortic stiffening was then assessed using a Vicorder device to measure carotid-femoral pulse wave velocity - the speed at which the arterial pulse propagates through the circulatory system.
Teenagers in the high intensity smoking group had a relative increase of 3.7 per cent in the stiffening of their arteries - measured by mean increase in pulse wave velocity - compared with those in the low smoking intensity group.
Participants also reported the age they started drinking alcohol and the frequency and intensity of alcohol consumption per month.
Heavy, medium, and light intensity drinkers were defined as consuming more than 10 drinks, between three and nine drinks and fewer than two drinks respectively on a typical day that they were drinking alcohol.
One drink equated to 8 grams of alcohol - roughly a third of a pint of beer.
Teenagers showed a preference for beer over wine or spirits, and those who tended to binge drink - more than 10 drinks in a typical drinking day, with the aim of becoming drunk - had a relative increase of 4.7 per cent in the stiffening of their arteries compared with light intensity drinkers.
