The association between fruit and vegetable consumption and cigarette smoking: Initiation, cessation, and possible explanatory mechanisms
Haibach, Jeffrey P.
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Cigarette smoking is the leading preventable cause of death in the United States and smoking prevalence has declined more slowly in the last decade than previously. This dissertation explored two interrelated factors that might reduce smoking initiation and promote cessation to re-accelerate declines in smoking prevalence: fruit and vegetable consumption (FVC) and depressive symptomatology. Three observational cohort studies were conducted with the first two assessing direct FVC-smoking associations using generalized linear modeling to estimate risk ratios. The third study tested for FVC moderation of depressive symptomatology and smoking associations using the Johnson-Neyman technique. All three studies included covariates of demographics and general health behavior orientation variables for statistical adjustment. Study 1 found that adult smokers (age range = 25-105 years; Mage = 45.6 years) in the highest quartile of FVC at baseline, compared to the lowest, were 3.05 times more likely to quit smoking and remain abstinent from all tobacco products for ≥ 30 days at 1-year follow-up (p < .01; n = 751). Study 2 found longitudinally, through secondary data analysis of National Longitudinal Survey of Youth 1979: Child and Young Adult (NLSY79-CYA) data, that baseline older adolescents (aged 14-18 years in the year 2004) who consumed fruit at least weekly had a lower level of smoking progression at 4-year follow-up than those who typically did not consume fruit ( p < .05; n = 388). Study 3 found FVC moderation of the association between depressive symptomatology and smoking cross-sectionally among both older adolescents (aged 14-18 years; n = 534; NLSY79-CYA data) and younger adults (aged 19-33 years; n = 2164; NLSY79-CYA data). Longitudinally among baseline adolescents, FVC moderated the association between baseline smoking frequency and 4-year follow-up depressive symptomatology. Among baseline young adult smokers, FVC moderated the inverse association between baseline depressive symptomatology and quitting smoking by 4-year follow-up. The results of the three studies suggest that FVC may be protective against cigarette smoking and promote smoking cessation. However, current results remain limited in their generalizability due to survey and analysis methodology paired with the complexity of both dietary and smoking behaviors. Further research is warranted to inform the consistency of the associations, to examine possible explanatory mechanisms, and to assess the efficacy of increasing FVC for smoking prevention and cessation.