Effects of Menthol Flavor Cigarettes or Total Urinary Menthol on Biomarkers of Nicotine and Carcinogenic Exposure and Behavioral Measures

Assessing the Evidence on the Differential Impact of Menthol versus Non-menthol Cigarette Use on Smoking Dependence in the US Population: A Systematic Review and Meta-analysis

Background: Menthol's effect on cigarette smoking behaviors is an intensely scrutinized US public health issue. This systematic review and meta-analysis examined the question: Does menthol cigarette use have a differential impact on smoking dependence compared with non-menthol cigarette use? Methods: We consulted 6 databases from inception to October 15, 2021. We included articles comparing menthol versus non-menthol cigarette smokers against predefined smoking dependence outcomes. Risk of bias was assessed using the AHRQ Evidence-Based Practice Center approach. We applied a random-effects model to pool adjusted odds ratios. Results: We synthesized 37 demographically adjusted studies. Meta-analytic results suggested non-menthol smokers were equally/more likely to report daily versus non-daily smoking; menthol use was associated with needing a cigarette within one hour; cigarettes per day was not associated with menthol use; menthol use was associated with a low (vs high) Heaviness of Smoking Index score; and results were either non-significant or associated menthol use with lower TTFC. Conclusions: Despite consistently good or fair quality adjusted studies across several measures, results were discordant depending on measures used and means of measurement. Overall, the evidence is insufficient to draw clear conclusions on a differential association between menthol (vs non-menthol) cigarette use and smoking dependence.

Differences in Smoking Topography and Subjective Responses to Smoking Among African American and White Menthol and Non-Menthol Smokers

INTRODUCTION

It has been suggested that menthol increases exposure to harmful elements of smoking and makes smoking more rewarding, easier to initiate, and harder to quit. Isolating the direct effects of menthol is challenging as African American (AA) race and menthol preference are highly overlapping. This study evaluated smoking behavior and subjective responses among a balanced sample of AA and white menthol and non-menthol smokers. In addition, smoking topography (ST) was compared to naturalistic smoking (NS) and interactions with menthol and race were explored.

AIMS AND METHODS

Smokers (N = 100) smoked and rated their preferred brand of cigarettes via ST or NS during two laboratory visits (counterbalanced).

RESULTS

Controlling for baseline differences among the groups (eg, nicotine dependence), menthol smokers took shorter and smaller puffs and AA smokers took longer puffs, but there were no differences in total puff volume, carbon monoxide, or other ST parameters. Menthol smokers reported greater urge reduction and lower sensory stimulation. The smoking method (ST vs. NS) had no effects on smoking behavior or exposure. Cigarettes smoked via ST were rated stronger. Differences in satisfaction based on the smoking method interacted with race and menthol status. Ratings of aversion differed by race and menthol status.

CONCLUSIONS

Menthol was not associated with increased smoke exposure or reward (except for urge reduction). ST caused minimal experimental reactivity relative to NS. Additional research that isolates the effects of menthol and examines potential interactive effects with race and other variables is needed to better understand its role in smoking-related health disparities.

IMPLICATIONS

Menthol and non-menthol smokers differed on some demographic variables and menthol preference was associated with greater nicotine dependence and greater urge reduction after smoking. Menthol was not associated with greater smoke exposure. Future research that investigates the unique risks associated with menthol and examines potential interactive effects with race and other related variables is warranted to better understand the role of menthol in smoking-related health disparities.

Measures of dependence in menthol and nonmenthol smokers - A comprehensive narrative review

Introduction. More than a decade ago, concerns were raised that menthol in cigarettes might enhance addiction to smoking. This article provides a comprehensive review of published studies examining cigarette dependence among menthol and nonmenthol smokers. The purpose of the review is to evaluate the scientific evidence to determine if menthol increases cigarette dependence. Materials and Methods. The published literature was searched in 2019 for studies that provide evidence on cigarette dependence among menthol compared to nonmenthol smokers. Included in this review are published studies that compare menthol and nonmenthol smokers based on widely accepted and validated measures of dependence, or other established predictors of dependence (age of smoking initiation [first cigarette]/age of progression [regular/daily smoking]) and indicators of dependence (smoking frequency, cigarettes smoked per day, time to first cigarette after waking, night waking to smoke, smoking duration). Results and Conclusion. Based on a review of the available studies, including those with adjusted results and large representative samples, reliable and consistent empirical evidence supports a conclusion that menthol smokers are not more dependent than nonmenthol smokers and thus menthol in cigarettes does not increase dependence.

Inhalation exposure to cigarette smoke induces endothelial nitric oxide synthase uncoupling and enhances vascular collagen deposition in streptozotocin-induced diabetic rats

Smoking is an acknowledged risk factor for vascular disorders, and vascular complication is a main outcome of diabetes. Hence, we investigated the impact of cigarette smoke on blood vessels in diabetes, postulating that smoking might aggravate diabetic vascular impairment. Sprague-Dawley rats were divided into four groups: control, cigarette smoke-exposed, diabetic, and cigarette smoke-exposed diabetic groups. Streptozotocin-induced diabetic rats were exposed to cigarette smoke by inhalation at total particulate matter concentration of 200 μg/L for 4 h/day, 5 day/week for a total of 4 weeks. Diabetes caused structural change of aorta, but additional cigarette smoke exposure did not induce further alteration. Collagen, a marker for fibrosis, was increased in media of diabetic aorta, and this increase was augmented by cigarette smoke. Cigarette smoke induced endothelial nitric oxide synthase (eNOS) uncoupling in the diabetic group. Malondialdehyde was increased and glutathione was decreased in blood from diabetes, but these effects were not exaggerated by cigarette smoke. Cigarette smoke caused NADPH oxidase (NOX) 2 expression in diabetic aorta and enhanced diabetes-induced NOX4 expression in aorta. Taken together, cigarette smoke exposure can aggravate vascular fibrosis and induce eNOS uncoupling in diabetes under experimental condition, suggesting that smoking might exacerbate diabetic vascular impairments.

Cigarette smoke inhalation aggravates diabetic kidney injury in rats

Diabetic kidney disease (DKD) is the leading cause of end-stage kidney disease. Epidemiological studies have demonstrated that cigarette smoke or nicotine is a risk factor for the progression of chronic kidney injury. The present study analyzed the kidney toxicity of cigarette smoke in experimental rats with DKD. Experimental diabetes was induced in 7-week-old Sprague-Dawley rats by a single intraperitoneal injection of streptozotocin (60 mg kg^-1). Four weeks after the induction of diabetes, rats were exposed to cigarette smoke (200 μg L^-1), 4 h daily, and 5 days per week for 4 weeks. Cigarette smoke did not affect the levels of plasma glucose, hemoglobin A1c, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol or non-esterified fatty acids in both control and diabetic rats under the experimental conditions. Cigarette smoke, however, significantly increased diabetes-induced glomerular hypertrophy and urinary kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) excretion, suggesting exacerbation of diabetic kidney injury. Cigarette smoke promoted macrophage infiltration and fibrosis in the diabetic kidney. As expected, cigarette smoke increased oxidative stress in both control and diabetic rats. These data demonstrated that four weeks of exposure to cigarette smoke aggravated the progression of DKD in rats.