title: A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E and beta carotene for age-related cataract and vision loss: AREDS report no. 9.
abstract: BACKGROUND
  Experimental and observational data suggest that micronutrients with antioxidant capabilities may retard the development of age-related cataract.
  
  
  OBJECTIVE
  To evaluate the effect of a high-dose antioxidant formulation on the development and progression of age-related lens opacities and visual acuity loss.
  
  
  METHODS
  The 11-center Age-Related Eye Disease Study (AREDS) was a double-masked clinical trial. Participants were randomly assigned to receive daily oral tablets containing either antioxidants (vitamin C, 500 mg; vitamin E, 400 IU; and beta carotene, 15 mg) or no antioxidants. Participants with more than a few small drusen were also randomly assigned to receive tablets with or without zinc (80 mg of zinc as zinc oxide) and copper (2 mg of copper as cupric oxide) as part of the age-related macular degeneration trial. Baseline and annual (starting at year 2) lens photographs were graded at a reading center for the severity of lens opacities using the AREDS cataract grading scale.
  
  
  METHODS
  Primary outcomes were (1) an increase from baseline in nuclear, cortical, or posterior subcapsular opacity grades or cataract surgery, and (2) at least moderate visual acuity loss from baseline (>/=15 letters). Primary analyses used repeated-measures logistic regression with a statistical significance level of P =.01. Serum level measurements, medical histories, and mortality rates were used for safety monitoring.
  
  
  RESULTS
  Of 4757 participants enrolled, 4629 who were aged from 55 to 80 years had at least 1 natural lens present and were followed up for an average of 6.3 years. No statistically significant effect of the antioxidant formulation was seen on the development or progression of age-related lens opacities (odds ratio = 0.97, P =.55). There was also no statistically significant effect of treatment in reducing the risk of progression for any of the 3 lens opacity types or for cataract surgery. For the 1117 participants with no age-related macular degeneration at baseline, no statistically significant difference was noted between treatment groups for at least moderate visual acuity loss. No statistically significant serious adverse effect was associated with treatment.
  
  
  CONCLUSIONS
  Use of a high-dose formulation of vitamin C, vitamin E, and beta carotene in a relatively well-nourished older adult cohort had no apparent effect on the 7-year risk of development or progression of age-related lens opacities or visual acuity loss.
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D000975:Antioxidants / Q000008:administration & dosage*; D001205:Ascorbic Acid / Q000008:administration & dosage*; D002386:Cataract / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D019587:Dietary Supplements; D018450:Disease Progression; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007908:Lens, Crystalline / Q000187:drug effects / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010781:Photography; D011446:Prospective Studies; D012307:Risk Factors; D014786:Vision Disorders / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D014792:Visual Acuity / Q000187:drug effects; D014810:Vitamin E / Q000008:administration & dosage*; D019207:beta Carotene / Q000008:administration & dosage*
chemical_list: D000975:Antioxidants; D019207:beta Carotene; D014810:Vitamin E; D001205:Ascorbic Acid