The damage worsens as time passes and is impossible to reverse, says researcher Stella Daskalopoulou, MD, of the McGill University Health Centre.
The study found that smoking just one cigarette increases the stiffness of the arteries in 18- to 30-year-old smokers by 25 percent after a treadmill exercise test. It was presented at the Canadian Cardiovascular Congress 2009 in Edmonton, Alberta.
As arteries stiffen, she says, the heart must work harder, increasing the risk for heart disease or stroke.
"Our results are significant because they suggest that smoking just a few cigarettes a day impacts the health of the arteries," Daskalopoulou says in a news release. "This was revealed very clearly when these young people were placed under physical stress, such as exercise."
She tells WebMD that the study compared the arterial stiffness of 10 young smokers, who puffed five to six cigarettes a day, to 10 nonsmokers. The median age of the participants was 21 years. Researchers, who included R.J. Doonan and other medical students under her supervision, measured arterial stiffness at rest and after exercise.
Arterial stiffness in all participants was measured using a method called applanation tonometry.
An initial arterial stiffness measurement was performed at rest for each subject to establish a baseline measure for all the participants. Smokers were instructed not to smoke for 12 hours prior to the test.
After the first meeting, the smokers completed two more tests on different days. For one test, they smoked a single cigarette and then repeated a treadmill exercise test. For the other test, smokers were asked to chew a piece of nicotine gum prior to the exercise test.
Daskalopoulou found that after exercise:
- Arterial stiffness levels in nonsmokers dropped by 3.6 percent.
- Arterial stiffness in smokers increased by 2.2 percent.
- After one cigarette, it increased by 24.5 percent in the smokers.
- After nicotine gum, stiffness increased by 12.6 percent in the smokers.
What the study means is that even light smoking in otherwise healthy people damages the arteries, compromising the ability to cope with physical stress, such as climbing stairs.
"The people tested were young and healthy," she said. "We found there was no significant difference at rest between smokers and nonsmokers, but then we got them to exercise, and the difference was clear."
Cherry Wongtrakool, a pulmonary specialist at the Emory University School of Medicine in Atlanta, tells WebMD there's no doubt that even one or two cigarettes impair blood vessel function.
The question is "how much of that change is going to be persistent," which she says isn't answered by the study.
"We know if you have any smoking in your personal history, that puts you at risk for a number of diseases, even if you are a former smoker," Wongtrakool says.
Daskaloupoulou is working on another study now examining whether former smokers who recently stopped can recover some lung function, and if so, how long it takes.
"This study is very exciting," Daskalopoulou tells WebMD. "The earlier you stop, my belief is, the faster some recovery will be, but I don't believe the [arterial] system ever goes back to normal. If you stop early, the damage will be much smaller, but there will still be damage."
She also says that young people who believe that a little smoking doesn't hurt are wrong.
Beth Abramson, MD, spokeswoman for the Heart and Stroke Foundation of Canada and director of the Cardiac Prevention Center at St. Michael's Hospital in Toronto, tells WebMD the study is stunning in that it shows clearly that "harmful effects of smoking show up immediately. This is more evidence to prove that smoking is horrendous to one's health."
Any smoking is bad, she says, because "it does the opposite of what nitroglycerin does, which is helps increase blood flow to the heart."
She says even people who have smoked for decades can benefit from quitting, though "it's going to take longer to take your risk down."
By Bill Hendrick
Reviewed by Louise Chang
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