title: Mortality associated with low plasma concentration of beta carotene and the effect of oral supplementation.
abstract: OBJECTIVE
  To examine the relationship between beta carotene plasma concentration and beta carotene supplementation and risk of death from major disease causes.
  
  
  METHODS
  Cohort study of plasma concentrations; randomized, controlled clinical trial of supplementation.
  
  
  METHODS
  Medical school-affiliated dermatology practices.
  
  
  METHODS
  A total of 1188 men and 532 women with mean age of 63.2 years, who had enrolled in a randomized clinical trial of beta carotene supplementation to prevent nonmelanoma skin cancer.
  
  
  METHODS
  Oral beta carotene, 50 mg per day for a median of 4.3 years.
  
  
  METHODS
  All-cause mortality and mortality from cardiovascular disease and cancer.
  
  
  RESULTS
  During a median follow-up period of 8.2 years, there were 285 deaths. Persons whose initial plasma beta carotene concentrations were in the highest quartile (>0.52 micromol/L [27.7 microg/dL]) had a lower risk of death from all causes (adjusted relative rate [RR], 0.52; 95% confidence interval [CI] 0.44 to 0.87) and from cardiovascular diseases (adjusted RR, 0.57; 95% CI, 0.34 to 0.95) compared with persons with initial concentrations in the lowest quartile (<0.21 micromol/L [11.2 microg/dL]). Patients randomly assigned to beta carotene supplementation showed no reduction in relative mortality rates from all causes (adjusted RR, 1.03; 95% CI, 0.82 to 1.30) or from cardiovascular disease (adjusted RR, 1.16; 95% CI, 0.82 to 1.64). There was no evidence of lower mortality following supplementation among patients with initial beta carotene concentrations below the median for the study group.
  
  
  CONCLUSIONS
  These analyses provide no support for a strong effect of supplemental beta carotene in reducing mortality from cardiovascular disease or other causes. Although the possibility exists that beta carotene supplementation produces benefits that are too small or too delayed to have been detected in this study, noncausal explanations should be sought for the association between plasma concentrations of beta carotene and diminished risk of death.
authors.affiliation: Dartmouth Medical School and Norris Cotton Cancer Center, Lebanon, NH, USA.
authors.forename: E R
authors.initials: ER
authors.lastname: Greenberg
authors.forename: J A
authors.initials: JA
authors.lastname: Baron
authors.forename: M R
authors.initials: MR
authors.lastname: Karagas
authors.forename: T A
authors.initials: TA
authors.lastname: Stukel
authors.forename: D W
authors.initials: DW
authors.lastname: Nierenberg
authors.forename: M M
authors.initials: MM
authors.lastname: Stevens
authors.forename: J S
authors.initials: JS
authors.lastname: Mandel
authors.forename: R W
authors.initials: RW
authors.lastname: Haile
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000401:mortality; D002338:Carotenoids / Q000008:administration & dosage* / Q000097:blood*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009026:Mortality; D012878:Skin Neoplasms / Q000517:prevention & control
chemical_list: D002338:Carotenoids