title: The effect of vitamin E on common cold incidence is modified by age, smoking and residential neighborhood.
abstract: BACKGROUND
  We have previously found a 28% reduction in common cold incidence with 50 mg/day vitamin E supplementation in a subgroup of the Alpha-Tocopherol Beta-Carotene Cancer Prevention (ATBC) Study cohort: older city-dwelling men (> or =65 years) who smoked only 5-14 cigarettes/day.
  
  
  OBJECTIVE
  To carry out more detailed analyses to explore the modification of vitamin E effect by age, smoking, and residential neighborhood.
  
  
  METHODS
  We examined the effect of vitamin E on common cold risk in subjects consisting of the placebo and vitamin E arms (n = 14,573) of the ATBC Study, which recruited males aged 50-69 years who smoked > or =5 cigarettes/day at the baseline. The ATBC Study was conducted in southwestern Finland in 1985-1993; the active follow-up lasted for 4.7 years (mean). We modeled common cold risk as a function of age-at-follow-up in the vitamin E arm compared with the placebo arm using linear splines in Poisson regression.
  
  
  RESULTS
  In participants of 72 years or older at follow-up, the effect of vitamin E diverged. Among those smoking 5-14 cigarettes per day at baseline and living in cities, vitamin E reduced common cold risk (RR = 0.54; 95% CI 0.37-0.80), whereas among those smoking more and living away from cities, vitamin E increased common cold risk (RR = 1.58; 1.23-2.01).
  
  
  CONCLUSIONS
  Vitamin E may cause beneficial or harmful effects on health depending on various modifying factors. Accordingly, caution should be maintained in public health recommendations on vitamin E supplementation until its effects are better understood.
authors.affiliation: Department of Public Health, POB 41, University of Helsinki, Helsinki, FIN-00014, Finland. harri.hemila@helsinki.fi
authors.forename: Harri
authors.initials: H
authors.lastname: Hemilä
authors.forename: Jarmo
authors.initials: J
authors.lastname: Virtamo
authors.forename: Demetrius
authors.initials: D
authors.lastname: Albanes
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kaprio
mesh_terms: D000367:Age Factors; D000368:Aged; D003139:Common Cold / Q000453:epidemiology*; D016001:Confidence Intervals; D019587:Dietary Supplements; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D012423:Rural Health; D012907:Smoking; D014504:Urban Health; D014810:Vitamin E / Q000008:administration & dosage / Q000494:pharmacology*; D014815:Vitamins / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D014815:Vitamins; D014810:Vitamin E