That's the encouraging news of two studies first published last year. And considering that smoking claims the lives of 400,000 Americans each year, according to federal statistics, it's a message that bears repeating.

"You can undo some of the harm of smoking, but it's not immediate," said Donald Taylor Jr., an assistant research professor at Duke University Medical Center's Center for Health Policy, Law and Management, and a co-author of one of the reports. "The point is: the earlier the better," he added.

Taylor teamed up with Dr. Truls Ostbye, a professor of community and family medicine at Duke, to measure the effects of smoking in middle-aged and older Americans. The study examined "years of healthy life," a measure of quality of life that combines risk of death and indicators of health status.

The researchers analyzed data on smoking and health from two studies -- one involving 12,652 men and women 50 to 60 years old and another focusing on 8,124 people 70 and older. The participants in each study were asked every two years to rate their health as excellent, very good, good, fair or poor.

"The idea that smoking's bad for you has hardly stopped the presses," Taylor said. "What we were trying to do is to develop estimates of the negative harm of smoking and, sort of, the positives of quitting in a way that could try to motivate people to quit."

Quitting yielded significant health benefits, indeed, after 15 years of having kicked the habit. At that point, the number of healthy years remaining in a former smoker's life is about the same as people who never smoked, according to the study, published in the journal Health Services Research.

The results suggest that a smoker who quits before turning 35 is likely to live as long and as well as someone who never took up the habit.

Researchers at the University of Oxford in England came to a similar conclusion in a prospective study involving 34,439 British doctors. Begun a half century earlier, it is the longest study ever into the effects of smoking.

While smokers die 10 years sooner, on average, than nonsmokers, quitting at 30 almost erases the risk of dying, and stopping at 50 cuts the risk in half, the researchers found.

Taken together, the two studies convey a potentially life-saving lesson: quitting works and it can greatly improve people's lives, especially in old age.

But some anti-tobacco experts fear that cautionary advice isn't reaching the smoking public.

Dr. Michael Siegel, an associate professor at Boston University School of Public Health, blames a shift within the tobacco control community. Instead of framing smoking broadly as a public health problem, some anti-smoking groups are focusing on stopping kids from lighting up. As a consequence, millions of adults already hooked on cigarettes are being left to "die off," as he put it.

"One of our priorities needs to be to get adult smokers to quit, even elderly people," he said.

As evidence of the shift, Siegel points to legislation introduced in the last session of Congress that would put the Food and Drug Administration in charge of regulating tobacco products. While imposing certain restrictions on marketing to kids, he insists the measure is riddled with loopholes benefiting the tobacco industry.

What's more, he said, it fails to enhance the public's perception of the inherent risks of smoking.

Sens. Mike DeWine (R-Ohio) and Edward Kennedy (D-Mass.), introduced the bill, which received the endorsement of several public health groups, including the Campaign for Tobacco-Free Kids, a leading tobacco control group, as well as Philip Morris USA, the world's largest tobacco company.

"We supported this legislation because it granted the FDA enormous new authority to regulate both current and new tobacco products and restrict tobacco product marketing," explained Vince Willmore, a spokesman for the Washington, D.C.-based Campaign for Tobacco-Free Kids. He contends the measure would better inform consumers about the health risks of smoking while strictly regulating any health claims.

As for whether tobacco control efforts should be focused on kids or the public at large, Willmore says prevention and cessation are not an either-or choice: "We must do both to reduce tobacco use and its terrible toll in health, lives and health care bills."

Emphasizing improvements in quality of life and health from quitting may be the ticket to getting adults to finally nip their habit in the bud.

"The hard part is getting people's attention and convincing them to quit before they have something really bad happen to them," Duke's Taylor said.

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