Washington: A minimum drinking age of 21 can actually save lives, a new US study has confirmed.
Researchers in the US found that studies done since 2006 - when a new debate over age-21 laws flared up - have continued to demonstrate that the mandates work.
The laws, studies show, are associated with lower rates of drunk-driving crashes among young people.
"The evidence is clear that there would be consequences if we lowered the legal drinking age," said lead researcher William DeJong, of Boston University School of Public Health.
The legal-drinking age in the US has had a winding history. In the early 1970s, 29 states lowered their legal drinking age to 18, 19 or 20, researchers said.
But after a rise in drunk-driving crashes among young people, many states began to reverse course. A change in federal law eventually pushed all states to adopt a minimum drinking age of 21 by 1988.
But in recent years, the benefits of the age-21 law have been challenged.
In one study, researchers found that, in 2011, 36 per cent of college students said in the past two weeks they had engaged in heavy episodic drinking (five or more drinks in a sitting, sometimes called "binge" drinking).
That compared with 43 per cent of students in 1988, the first year that all US states had an age-21 law. There was an even bigger decline among high school seniors - from 35 per cent to 22 per cent.
DeJong said that education can help discourage underage drinking. He said tougher enforcement of the age-21 law, rather than a repeal, is what's needed.
"Just because a law is commonly disobeyed doesn't mean we should eliminate it," DeJong said.
Clinical trials have found that when college towns put more effort into enforcing the law - and advertise that fact to students - student drinking declines.
"Some people assume that students are so hell-bent on drinking, nothing can stop them. But it really is the case that enforcement works," DeJong said.
The study was published in the Journal of Studies on Alcohol and Drugs.