Heavy smoking of cigarettes is associated with an increased risk of cardiovascular disease (CVD) and stroke. However, how does low cigarette consumption impact the risk of CVD is not yet clear. The objective of this study is to derive a relationship between light smoking (1-5 cigarettes a day) and the risk of coronary heart disease and stroke.

This systematic review and meta-analysis included around 55 publications containing 141 cohort studies. For each study, the researchers determined the relative risk of CVD associated with smoking 1, 5, or 20 cigarettes per day using regression modeling. The primary outcome of the study was the risk of cardiovascular disease.

The findings suggested that smoking only one cigarette per day was associated with a significant risk of coronary heart disease (1.48). The relative risk of smoking 20 cigarettes per day was 2.04. Women were at a higher relative risk of coronary heart disease (1.57 for one cigarette per day, 2.84 for 20 cigarettes per day). Men who smoked one cigarette per day had a 46% higher relative risk of smoking 20 cigarettes per day, as compared with 53% relative risk in women.

The research concluded that smoking, even one cigarette per day, was associated with a significant risk of developing coronary heart disease in both men and women.

Ref: https://www.bmj.com/content/360/bmj.j5855