Light smokers heavily at risk of heart attack
Women who smoke just three cigarettes a day, and men who smoke six, have double the risk of heart attack, a major Danish study shows. Even people who said they did not inhale had a dramatically increased heart attack risk.
"There is a general idea among smokers that if you keep to a few cigarettes a day or don't inhale it's okay," says Eva Prescott of the Institute of Preventative Medicine in Copenhagen. "Of course it's worse if you inhale and worse the more you smoke, but we've shown there is no safe way of smoking cigarettes," she told New Scientist.
The findings are based on data from more than 12,000 men and women taking part in the Copenhagen City Heart Study, which began in 1976. All participants were aged 20 or over when the study started.
Alison Shaw of the British Heart Foundation says the new results will not surprise researchers in the field: "The dangers of smoking and passive smoking are well known. Light smoking or smoking, whether someone inhales or not, should be avoided."
In 1976, 70 per cent of the men and nearly 60 per cent of the women studied were smokers. By 1998, almost 900 men and 500 women in the study had had a heart attack, 40 per cent of which were fatal. Over 5000 men and women died from other causes.
The researchers took into account other major risk factors for heart problems, such as weight and lifestyle. And they found that men who inhaled six to nine grams of tobacco each day - equivalent six to nine cigarettes, or one to two cigars - doubled their risk of heart attack. Consuming the same amount, but not inhaling, increased the risk by 13 per cent.
Women who consumed three to six cigarettes per day doubled their risk, not only of heart attack but also of death from all causes. Smoking the equivalent of six to nine cigarettes, but not inhaling, increased the risk by 60 per cent.
Although most people who reported smoking but not inhaling were cigar and cheroot smokers, many cigarette-smoking women also did not inhale, Prescott says. "This is particularly the case with the older generation of women in Denmark," she says.
There are several possible reasons for the bigger increase in heart attack for women smokers, Prescott thinks: "Oestrogen protects women from heart disease and heart attack, and we know smoking tobacco has an anti-oestrogenic effect."
Women are also more likely to suffer respiratory diseases, which could partly account for the increase in death from all causes.