Just one smoked cigarette a day increases the risk of cardiovascular diseases and stroke by about 50 percent, a British study has shown, concluding that there is no harmless number of cigarettes.
The scientific team analyzed data from 141 smaller studies to assess the risks for heart disease and stroke among people who smoked one, five, or 20 cigarettes a day.
“Reducing the number of cigarettes is certainly better than staying at the old number,” says Hackshaw.
Reducing the number of cigarettes results in a significant reduction in the risk of cancer and other disorders, so it is important for people, if they cannot quit smoking, to try to reduce.
Men who smoked one cigarette a day had a 74 percent higher chance of heart disease and a 30 percent higher chance of stroke than men who have never smoked, according to a paper published in the journal BMJ.
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Women who smoked one cigarette a day had double the risk of developing heart disease and a 46 percent higher risk of stroke than women who have never smoked.
“People who have always smoked a little will have a higher risk of cardiovascular diseases than many of them expect,” says study leader Allan Hackshaw from the British Institute for Cancer at University College London.
Although their risk is lower than that of heavy smokers, the results offer them a new incentive to quit smoking completely, says Hackshaw.
The research shows that heavy smokers can also benefit from reducing the number of cigarettes smoked.
“Reducing the number of cigarettes is certainly better than staying at the old number,” says Hackshaw. “Reducing the number of cigarettes results in a significant reduction in the risk of cancer and other disorders, so it is important for people, if they cannot quit smoking, to try to reduce.”
“With cigarettes, it’s like with matches – you only need one, not a whole box, to start a fire,” says Johnson. “Even passive smoking seems to trigger these harmful processes resulting in 80 to 90 percent of the effects associated with active smoking.”
For example, men who smoked a pack a day had double the risk of heart disease compared to non-smokers, while that risk was 58 percent higher for those who smoked five cigarettes a day and 48 percent higher for those who smoked only one cigarette a day.
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Similarly, women who smoked five cigarettes a day had a 43 percent higher risk of heart disease compared to those who smoked a pack a day, while women who smoked one cigarette a day had a 31 percent higher risk.
Compared to non-smokers, men who smoked 20 cigarettes a day had a 64 percent higher chance of stroke, while women had more than double the risk of stroke.
Scientists emphasize that the study was not a controlled trial aimed at determining how a certain number of cigarettes can affect the risks of cardiovascular diseases and that they did not have data on other factors that may have explained the higher risk for cardiovascular diseases among smokers, such as obesity or diabetes.
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Despite this, the results can serve as a reminder that there is no safe smoking, says Kenneth Johnson from the School of Epidemiology and Public Health at the University of Ottawa in Canada, who did not participate in the research. Smoking can result in irregular heart rhythms, clots, thickening of blood vessel walls, and increased blood pressure, says Johnson.
“With cigarettes, it’s like with matches – you only need one, not a whole box, to start a fire,” says Johnson. “Even passive smoking seems to trigger these harmful processes resulting in 80 to 90 percent of the effects associated with active smoking.”
