Impact of Smoking Cessation and γ-Tocopherol to Restore Vascular Endothelial Function

Study Summary

Cigarette smoking is a significant risk factor for cardiovascular disease (CVD) and is the leading cause of premature mortality in the US. The detrimental effects of smoking on vascular dysfunction are attributed to the effects of smoke itself and the inflammatory responses it induces. Smoking cessation restores vascular function by alleviating these stress responses. However, smoking cessation with nicotine replacement therapy (NRT), the prevailing approach to mitigate tobacco dependence, fails to allow full restoration of vascular function. Thus, a critical public health problem exists to understand how NRT prevents restoration of vascular function and how these NRT-mediated impairments can be overcome by using gamma-tocopherol (g-T) as an innovative co-therapy. The objective of this study is to conduct a clinical intervention trial that aims to reduce CVD risk by defining how smoking cessation and g-T restore vascular function. The hypothesis is that smoking cessation and dietary g-T supplementation will synergistically restore smoking-induced impairments in vascular function by ameliorating oxidative/nitrosative stress responses, and that g-T will facilitate full restoration of vascular function otherwise precluded by NRT. A placebo-controlled, g-T intervention study will be conducted in cigarette smokers undergoing nicotine-free or NRT smoking cessation. Prior to and after 24 h and 7 days of placebo or g-T administration, vascular function will be evaluated using a non-invasive ultrasound technique and an array of antioxidants and biomarkers for vascular inflammation and oxidative/nitrosative stress responses will be assessed. Collectively, these studies will help identify how vascular function is regulated in individuals undergoing smoking cessation, and whether g-T can be used as a strategy to better improve vascular function during smoking cessation.

Primary Outcome

Flow-mediated dilation (FMD) of the brachial artery is measured to assess vascular endothelial function. FMD is obtained by monitoring change in vessel diameter before and after brachial artery occlusion with a blood pressure cuff. The unit of FMD is % and is calculated using the following equation: FMD = \[(peak dilation at post occlusion - vessel diameter at preocclusion)/vessel diameter at preocclusion\]\*100.

Interventions

• OTHER Placebo
• BEHAVIORAL Smoking cessation
• OTHER Nicotine Replacement Therapy (NRT)
• DIETARY_SUPPLEMENT Gamma-Tocopherol