It's common knowledge that smoking is extremely bad for your health, but for those still clinging onto the habit by telling themselves one or so a day can't really do any harm, a new BMJ study has shown the negative effects are still significant. Meta-analysis of 141 cohort studies revealed that by smoking just one cigarette per day, the chances of heart disease rise by 48 percent for men and 57 percent for women when compared to someone who never smokes. Likewise, the risk of suffering a stroke go up by 25 percent for men and 31 percent for women.