Effect of antioxidant supplementation on ozone-induced lung injury in human subjects

To determine whether antioxidants can influence human susceptibility to ozone (O-3)-induced changes in lung function and airway inflammation, we placed 31 healthy nonsmoking adults (18 to 35 yr old) on a diet low in ascorbate for 3 wk. At 1 wk, subjects were exposed to filtered air for 2 h while exercising (20 L/min/m(2)), and then underwent bronchoalveolar lavage (BAL) and were randomly assigned to receive either a placebo or 250 mg of vitamin C, 50 IU of alpha -tocopherol, and 12 oz of vegetable cocktail daily for 2 wk. Subjects were then exposed to 0.4 PPM O-3 for 2 h and underwent a second BAL. On the day of the O-3 exposure, supplemented subjects were found to have significantly increased levels of plasma ascorbate, tocopherols, and carotenoids as compared with those of the placebo group. Pulmonary function testing showed that O-3-induced reductions in FEV1 and FVC were 30% and 24% smaller, respectively, in the supplemented cohort. In contrast, the inflammatory response to O-3 inhalation, as represented by the percent neutrophils and the concentration of interleukin-6 recovered in the BAL fluid at 1 h after O-3 exposure was not different for the two groups. These data suggest that dietary antioxidants protect against O-3-induced pulmonary function decrements in humans.