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Table 1 Studies assessing effect of antioxidant supplementation on lung function associated with controlled air pollutant exposures in intact humans

From: Modification by antioxidant supplementation of changes in human lung function associated with air pollutant exposure: A systematic review

First author, Year, Country Study design Conditions* Pollutant exposure duration Additional stresses during exposure Population
(N)
Age range Inclusion / Exclusion criteria Outcome
Hackney, 1981, USA Randomized
(non-crossover); supplement double-blinded; exposure nominally single-blinded
a) 800 IU Vitamin E (9 to 10 weeks); air then next-day ozone (0.5 ppm) 2 hr Heat and "light exercise" Healthy
(34)
20-27 Not Specified. No significant effect of antioxidants on ozone-attributable decrease in FEV1 and FVC. (i.e. statistical significance of supplementation effect: p > 0.05).
   b) Placebo (9 to 10 weeks);air then next day ozone (0.5 ppm)       
Hackney, 1981, USA Randomized
(non-crossover); supplement double-blinded, exposure nominally single-blinded
a) 1600 IU Vitamin E (11 to 12 weeks); air then ozone (0.5 ppm, for 2 subsequent days) 2 hr Heat and "light exercise" Healthy males
(22)
22-28 Not Specified. No significant effect of antioxidants on ozone-attributable decrease in FEV1, FVC, TLC, FEF25%, FEF50% (i.e. statistical significance of supplementation effect: p > 0.05).
   b) Placebo (11 to 12 weeks); air
then ozone (0.5 ppm, for 2
subsequent days)
      
Chatham, 1987, USA Randomized (crossover); double-blinded a) Vitamin C (1 gm, one hour before exposure) and Vitamin E (800 IU daily for unspecified duration); ozone (0.3 ppm) 2 hr Exercise Medical students
(9)
21-29 Normal baseline pulmonary function, non-smokers, refrained from any drugs, including vitamin supplements. Ozone-induced decrements in FVC were attenuated by vitamin C and vitamin E (p < 0.05), but no significant effect was observed in FEV1, FEF25-75 and SGaw (p > 0.05).
   b) Placebo; Ozone (0.3 ppm)       
Mohensin, 1987, USA Randomized (crossover); double-blinded a) Vitamin C (2000 mg/day for 3 days); NO2 (2.0 ppm) 1 hr   Healthy subjects
(11)
18-36 Not Specified. Airway hypersensitivity induced by NO2 was attenuated by pre-treatment with ascorbic acid, relative to placebo (p < 0.04).
   b) Placebo (3 days); NO2 (2.0 ppm)       
   c) Vitamin C (2000 mg/day for 3 days); air       
   d) Placebo; air       
Peters, 2001,
The Netherlands
Double-blinded;
cross over;
a) Placebo; ozone (0.4 ppm) 2 hr Intermittent exercise Mild atopic asthmatics
(7)
19-26 Required a measurable plateau of the dose-response curve to methacholine, non smokers, no NSAID or vitamin use during study. Airway hypersensitivity induced by O3 was attenuated by pre-treatment with apocynin, relative to placebo (p = 0.025).
   b) Apocynin (12 mg); ozone (0.4 ppm)       
Samet, 2001, USA Randomized
(non-crossover); double-blinded
a) Vitamin C-restricted diet + placebo (2 weeks); ozone (0.4 ppm) 2 hr Exercise Healthy on a low ascorbate diet
(31)
18-35 Non-smokers. Ozone-induced decrements in FEV1 and FVC were attenuated (p = 0.046 and p = 0.055 respectively), by vitamin C and vitamin E.
   b) Vitamin C-restricted diet +
250 mg of vitamin C, 50 IU of
alpha-tocopherol, and 12 oz. of
vegetable cocktail (2 weeks);
ozone (0.4 ppm)
      
   c) Vitamin C-restricted diet
(1 week); air
      
Trenga, 2001, USA Randomized (crossover);
double-blinded
a) Placebo; ozone (0.12 ppm) 45 min Intermittent exercise Adults with asthma
(17)
18-39 Significant decrease (at least 8%) in FVC1 from baseline with SO2 challenge, non-smokers. SO2-induced decrements in FEV1 and peak expiratory flow (PEF), and FEF25-75 were attenuated by vitamin C and vitamin E (p < 0.05).
   b) 400 IU vitamin E and 500 mg
Vitamin C daily (4 weeks);
ozone (0.12 ppm)
      
   c) Placebo; air       
   d) 400 IU Vitamin E and 500 mg Vitamin C daily (4 weeks); air       
Mudway, 2006, Sweden Randomized (crossover);
double-blinded
a) Placebo; ozone (0.2 ppm) 2 hr Intermittent exercise Healthy ozone-sensitive
(14)
21-27 Normal lung function, negative skin prick test, non-smokers, no history of allergy and/or lung disease. No significant effect of antioxidants on ozone-attributable decrease in FEV1 (p > 0.05).
   b) 500 mg
Vitamin C with 100 mg Vitamin E
(7 days); ozone (0.2 ppm)
      
   c) air       
  1. * For crossover studies, each individual subjected to each condition; in non-crossover, the conditions were distributed between subjects.