Effects of combustible tobacco smoking and novel tobacco products on oxidative stress: Different sides of the same coin?

Oxidative stress is the result of the imbalance between reactive oxygen species (ROS) production and antioxidant cellular systems. Smoking is one of the most important contributing factors to increased oxidative stress. Free radicals (ROS) after cigarette smoking are generated through an exogenous pathway from inhaled toxic gases in cigarette vapor or particulate phases of cigarette smoke, activation of macrophages and neutrophils in situ, platelet activation as well as from an endogenous pathway (nitric oxide synthase, xanthine oxidase and mitochondrial electron transport chain). Furthermore, cigarette smoking weakens intracellular antioxidant mechanisms. This review focuses on the effects of conventional smoking and medically aided smoking cessation on oxidative stress and the effects the new smoking-like devices: HNBC (heat-not-burn tobacco cigarettes) and ENDS (electronic nicotine delivery system) on oxidative burden.