Open AccessInteraction of vitamin C with the relation between smoking and obstructive airways disease in EPIC Norfolk
Author(s) -
Sargeant L.A.,
Jaeckel A.,
Wareham N.J
Publication year - 2000
Publication title -
european respiratory journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.021
H-Index - 241
eISSN - 1399-3003
pISSN - 0903-1936
DOI - 10.1034/j.1399-3003.2000.016003397.x
Subject(s) - medicine , odds ratio , vital capacity , confidence interval , vitamin , vitamin c , population , vitamin d and neurology , disease , environmental health , lung function , lung , diffusing capacity
Previous studies have reported an association between plasma vitamin C levels and respiratory function, but have not examined the role of vitamin C as an effect modifier of the relation between cigarette smoking and obstructive airways disease (OAD). This question was investigated in a cross‐sectional analysis of a population‐based study of 3,714 males and 4,256 females aged 45–74 yrs. Undiagnosed OAD was defined as a forced expiratory volume in one second (FEV1) of <80% of the predicted value and FEV1/forced vital capacity of <70% without self‐reported OAD. An increase of 20 μmol·L ‐1 (or 1 sd ) in plasma vitamin C concentration was associated with a 13% reduction in the risk of having OAD (adjusted odds ratio (OR) (95% confidence interval) 0.87 (0.77–0.98)). The OR for current smokers relative to never smokers within the lowest quintile of plasma vitamin C concentration was 5.93 (3.03–11.61). The risk in the upper four quintiles was 2.84 (1.92–4.19). Within the lowest quintile of plasma vitamin C concentration, the risk in former smokers was strongly related to the time since quitting (interaction significant, p=0.001). These findings support a protective role for vitamin C against the risk of obstructive airways disease and support the hypothesis that vitamin C may be an effect modifier for the adverse effects of smoking on the risk of obstructive airways disease.