Fish consumption and respiratory symptoms among young adults in a Norwegian community

The aim of this study was to investigate the relationship between dietary fish consumption and self-reported respiratory symptoms among young adults. A random sample of 4,300 subjects, aged 20-55 yrs, living in Bergen, Norway, received a postal questionnaire on respiratory symptoms, of whom 80% responded. Mean fish consumption was assessed in a food-frequency questionnaire by asking how often the subject consumed units of fish (150 g) during the last year. Average fish consumption was 1.8 units.week(-1). Fish intake of <1 unit.week(-1) was reported by 24%, 41% reported consumption of 1 unit.week(-1) and 35% intake of >1 unit.week(-1). A high fish intake was significantly associated with increasing age after adjusting for smoking. Adjusted for smoking habits, the prevalence of "cough at night" and "chest tightness" showed a decreasing trend with increasing fish consumption (p < 0.05), while such a trend for "wheeze" was demonstrated only in smokers (p = 0.008 for interaction). In logistic regression models (adjusting for age, sex, body mass, smoking habits and occupational exposure) fish consumption (three categories) was not significantly associated with "wheeze","chest tightness", "breathless at night" or "asthma attack", although the odds ratios (OR) were consistently less than 1 (except for "asthma attack"). Fish consumption was of borderline significance as a protective factor of "cough at night", OR = 0.86 (95% confidence interval: 0.76-097) but in stratified analyses only in smokers. Subjects reporting very high levels of fish consumption (>14 units.week(-1)) did not have lower prevalences of respiratory symptoms. In conclusion, among young Norwegian adults, with a relatively low prevalence of asthma and an overall high fish intake, fish consumption was not a significant predictor of four out of five respiratory symptoms.