One cigarette a day increases cardiovascular risk

Smoking just one cigarette a day carries a much higher risk of developing coronary heart disease and stroke than expected - about half the risk of smoking 20 per day - concludes a UCL-led review of the evidence. The researchers say their findings, published today in the BMJ , have important consequences for many smokers and health professionals who believe that smoking only a few cigarettes per day bears little or no harm.  "What this tells us is that people who smoke shouldn't just cut down - they should aim to stop smoking altogether. There is no safe level of smoking," said the study's lead author, Professor Allan Hackshaw (UCL Cancer Institute). Individual studies have reported that smoking only one to five cigarettes per day is associated with a higher than expected risk of heart disease. To investigate this further, the researchers analysed the results of 141 studies and estimated the relative risks for smoking one, five, or 20 cigarettes per day. They found that men who smoked one cigarette per day had 46% of the excess risk of heart disease and 41% of the excess risk of stroke associated with smoking 20 cigarettes per day (much higher than the expected one 20th, or 5%). For women, those who smoked one cigarette per day had 31% of the excess risk of heart disease and 34% of the excess risk of stroke associated with smoking 20 cigarettes per day.