Smoking one cigarette a day is as bad as having half a pack – so is vaping the answer?
Smoking just one cigarette a day carries the same risk as smoking 10 when it comes to heart disease and strokes. Also in the news: vaping could encourage youngsters to smoke cigarettes, but also helps adult quit smoking
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Just a single cigarette a day carries nearly half the risk for heart attack and stroke as smoking a full pack of 20, according to a large-scale study.
“If someone smokes one cigarette instead of 20 per day, intuitively we’d think that the risk drops to one in 20, or five per cent,” says lead author Allan Hackshaw, a professor at University College London, whose paper analysed 141 previous studies.
“This seems to be the case for lung cancer, but is not true for heart attacks and stroke, where one cigarette per day carries around 50 per cent of the risk of a pack a day,” he says.
Smokers should not be fooled, in other words, into thinking that a few cigarettes a day – or even just one – carries little or no long-term harm.
“While it is great that smokers try to cut down – and they should be positively encouraged to do so – to get the big benefits on cardiovascular disease they need to quit completely,” he says.
The findings were published in the medical journal BMJ.
Tobacco kills about seven million people worldwide every year, according to the World Health Organisation.
About two million of those deaths are due to cardiovascular disease, mainly coronary heart attacks and stroke.
Earlier research suggested that smoking a few cigarettes a day was linked to a higher-than-expected risk of heart disease, but findings were inconclusive.
To probe deeper, a team of scientists led by Hackshaw analysed the results of 141 studies, estimating the relative risk of one, five or 20 cigarettes a day.
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They found that men who lit up once a day had 46 per cent of the excess risk of heart disease associated with smoking a full pack a day, much higher than expected. For strokes, the excess risk was 41 per cent.
For reasons that are not fully understood, the risk for women was somewhat lower – 31 per cent and 34 per cent, respectively.
“It could be a mixture of biological difference and differences in lifestyle,” says Hackshaw.
Overall, long-term smoking shortens life expectancy by 12 to 15 years.
“This well conducted study confirms what epidemiologists have suspected but few among the public have,” says University of Oxford professor Paul Aveyard, who was not involved in the research.
“The implication is obvious – anyone who smokes should stop.”
At the same time it would be wrong to conclude that cutting down is useless.
“There is more reason to believe that lower cigarette consumption will reduce the risk of chronic lung disease and lung cancer, the other two big causes of early death from smoking,” he says.
Vaping can encourage young people to smoke, but helps adults quit
Vaping, or smoking battery-powered devices known as e-cigarettes, may encourage youths to start smoking, but may also help adults quit, according to a US review of scientific research.
The report by the US National Academies of Sciences, Engineering, and Medicine is based on more than 800 peer-reviewed scientific studies on the health effects of electronic cigarettes.
It was compiled at the US Congress’s request, amid a growing international debate over whether e-cigarettes are safe or harmful.
E-cigarettes, which have gained popularity in the last decade, are hand-held devices that heat up a nicotine-containing liquid so users can inhale the vapour.
They contain “fewer numbers and lower levels of toxic substances than conventional cigarettes,” says the report. But they are also addictive.
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The amount of nicotine they deliver can vary, but experienced adult e-cigarette users tend to get “a comparable level of nicotine as conventional cigarettes” – leading to “symptoms of dependence” in those who use them.
Reviewed evidence suggests that e-cigarettes are “likely to be far less harmful than tobacco products,” says David Eaton, chair of the committee that wrote the report.
“In some circumstances, such as their use by non-smoking adolescents and young adults, their adverse effects clearly warrant concern,” says Eaton, dean of the graduate school of the University of Washington, Seattle.
Young people are more likely than adults to use e-cigarettes, and the report found “substantial evidence” that vaping increases the risk of smoking conventional cigarettes.
Switching from regular cigarettes to e-cigarettes also “results in reduced short-term adverse health outcomes in several organ systems.”
But when adult smokers use e-cigarettes to quit smoking, “they offer an opportunity to reduce smoking-related illness,” says Eaton.
The report found “conclusive evidence” that substituting e-cigarettes for conventional cigarettes “reduces users’ exposure to many toxicants and carcinogens present in conventional cigarettes.”
In some circumstances, such as their use by non-smoking adolescents and young adults, their adverse effects clearly warrant concern.
But their long-term effects remain unknown.
The report found “no available evidence whether e-cigarette use” is associated with cancer in people. Animal studies however suggest that long-term e-cigarette use “could increase the risk of cancer.”
Researchers also declined to categorise e-cigarettes as a positive or negative influence on public health.
“More and better research on e-cigarettes’ short- and long-term effects on health and on their relationship to conventional smoking is needed to answer that question with clarity,” says the report.
Flu increases risk of heart attack by six times
People who get the flu may face a six-fold higher risk of heart attack in the week following infection, according to a study that reinforces the importance of vaccination.
The risk of heart attack – or myocardial infarction – is particularly acute in older adults, says the report in the New England Journal of Medicine.
The study was based on nearly 20,000 adult cases of laboratory-confirmed influenza infection in Ontario, Canada from 2009 to 2014.
Of those, 332 patients suffered a heart attack within one year of their flu infection.
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The risk appeared highest in the first week, particularly for older people, those with influenza B infections, and patients experiencing their first heart attack.
Other respiratory viruses were also seen to raise the risk of heart attack, though not as much as the flu.
Previous studies have also pointed to a link between the flu and cardiac crises and death.
Kwong urges new “international guidelines that advocate for influenza immunisation in those at high risk of a heart attack.”
He also calls on people at risk of heart disease to “take precautions to prevent respiratory infections, and especially influenza, through measures including vaccinations and hand washing.”
