Polyunsaturated fatty acid intake and lung function in a regional Australian population: A cross-sectional study with a nested case-control analysis

Chronic obstructive pulmonary disease (COPD) is a progressive disease of the airways, underpinned by inflammation and worsening lung function. Omega-3 polyunsaturated fatty acids (n-3PUFA) can modulate inflammatory mechanisms and may therefore impact lung function in people with COPD. This observational, cross-sectional study of 577 adults in the Whyalla Intergenerational Study of Health (WISH), conducted during 2008–09 in regional South Australia, explored associations between fish and PUFA intakes (from food frequency questionnaires) and lung function (spirometry). It also included a nested case-control study which compared fish and PUFA intakes and plasma phospholipid PUFA levels between 40 people with COPD and 80 age-sex matched controls. In the whole population, linear regression models adjusted for age, sex, smoking status and education demonstrated a weak negative association between lung function (FEV₁% predicted) and consumption of fried fish (OR -0.12, 95% CI -0.22, −0.01, P = 0.026) but not fish prepared by other cooking methods or estimated intakes of PUFA. There was no association between fish or PUFA intakes and COPD risk. Compared to age and sex matched controls, cases had poorer lung function and a higher rate of smoking prevalence but did not differ in their intakes of fish or PUFA or their PUFA levels in plasma phospholipids. In this sub-population, we found a marginally significant association between COPD risk and total long chain n-3PUFA levels in plasma phospholipids (OR 1.22 95% CI 1.00–1.49, P = 0.046). Given the relatively small number of cases in this analysis, this finding should be interpreted with caution, especially given the lack of association with other markers of n-3PUFA intake or status. Taken together, our data suggest that n-3PUFA intake and status are not determinants of improved lung function in this regional Australian population.