Serum carotenoids, vitamins A and E, and 8 year lung function decline in a general population

Background: Oxidative stress is thought to have a major role in the pathogenesis of airway obstruction. A study was undertaken to determine whether subjects with low levels of antioxidants ( serum beta-carotene, alpha-carotene, vitamins A and E) would be at a higher risk of accelerated decline in forced expiratory volume in 1 second (FEV1) as their lungs would be less protected against oxidative stress. Methods: 1194 French subjects aged 20 - 44 years were examined in 1992 as part of the European Community Respiratory Health Survey (ECRHS); 864 were followed up in 2000 and 535 (50% men, 40% lifelong non-smokers) had complete data for analysis. Results: During the 8 year study period the mean annual decrease in FEV1 ( adjusted for sex, centre, baseline FEV1, age, smoking, body mass index and low density lipoprotein cholesterol) was 29.8 ml/ year. The rate of decrease was lower for the subjects in tertile I of beta-carotene at baseline than for those in the two other tertiles (236.5 v 227.6 ml/ year; p = 0.004). An increase in beta-carotene between the two surveys was associated with a slower decline in FEV1. No association was observed between alpha-carotene, vitamin A, or vitamin E and FEV1 decline. However, being a heavy smoker (>= 20 cigarettes/day) in combination with a low level of beta-carotene or vitamin E was associated with the steepest decline in FEV1 (-52.5 ml/ year, p = 0.0002 and 250.1 ml/ year, p = 0.010, respectively). Conclusions: These results strongly suggest that beta-carotene protects against the decline in FEV1 over an 8 year period in the general population, and that beta-carotene and vitamin E are protective in heavy smokers.