title: Prospective study of fruit and vegetable consumption and risk of lung cancer among men and women.
abstract: BACKGROUND
  Diets high in fruits and vegetables have been shown to be associated with a lower risk of lung cancer. beta-Carotene was hypothesized to be largely responsible for the apparent protective effect, but this hypothesis was not supported by clinical trials.
  
  
  METHODS
  We examined the association between lung cancer risk and fruit and vegetable consumption in 77 283 women in the Nurses' Health Study and 47 778 men in the Health Professionals' Follow-up Study. Diet was assessed with the use of a food-frequency questionnaire that included 15 fruits and 23 vegetables. We used logistic regression models to estimate relative risks (RRs) of lung cancer within each cohort. All statistical tests were two-sided.
  
  
  RESULTS
  We documented 519 lung cancer cases among the women and 274 among the men. Total fruit and vegetable consumption was associated with a modestly lower risk of lung cancer among the women but not among the men. The RR for the highest versus lowest quintile of intake was 0.79 (95% confidence interval [CI] = 0.59-1.06) among the women and 1.12 (95% CI = 0.74-1.69) among the men after adjustment for smoking status, quantity of cigarettes smoked per day, time since quitting smoking, and age at initiation of smoking. However, total fruit and vegetable consumption was associated with a lower risk of lung cancer among never smokers in the combined cohorts, although the reduction was not statistically significant (RR = 0.63; 95% CI = 0.35-1.12 in the highest tertile).
  
  
  CONCLUSIONS
  Higher fruit and vegetable intakes were associated with lower risks of lung cancer in women but not in men. It is possible that the inverse association among the women remained confounded by unmeasured smoking characteristics, although fruits and vegetables were protective in both men and women who never smoked.
authors.affiliation: Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA. diane.feskanich@channing.harvard.edu
authors.forename: D
authors.initials: D
authors.lastname: Feskanich
authors.forename: R G
authors.initials: RG
authors.lastname: Ziegler
authors.forename: D S
authors.initials: DS
authors.lastname: Michaud
authors.forename: E L
authors.initials: EL
authors.lastname: Giovannucci
authors.forename: F E
authors.initials: FE
authors.lastname: Speizer
authors.forename: W C
authors.initials: WC
authors.lastname: Willett
authors.forename: G A
authors.initials: GA
authors.lastname: Colditz
mesh_terms: D000328:Adult; D000368:Aged; D004034:Diet Surveys; D005247:Feeding Behavior; D005260:Female; D005500:Follow-Up Studies; D005638:Fruit; D006282:Health Personnel / Q000706:statistics & numerical data; D006801:Humans; D016015:Logistic Models; D008175:Lung Neoplasms / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012306:Risk; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D014481:United States / Q000453:epidemiology; D014675:Vegetables