Associations of fruit intake and lung function in middle-age are modified by obesity

Abstract

Background: Results from studies of fruit intake and lung function are inconsistent.

Aim: To investigate associations between fruit intake, lung function and bronchial responsiveness in middle-age.

Methods: A subsample (n=836) of the 1961-born Tasmanian Longitudinal Health Study (TAHS) cohort was assessed by questionnaire, pre-bronchodilator (pre-BD) spirometry and methacholine challenge. Participants reported serves of fruit and vegetables consumed daily (none to ≥ 4). Regression was used to model respiratory outcomes adjusting for gender, smoking, education, occupation and asthma. Obesity measures (body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR)) were examined as effect modifiers.

Results: Associations between fruit intake and pre-BD FEV₁, FEV₁/FVC and methacholine dose response slope (mDRS) were modified by BMI (p_interaction = 0.01, 0.004 and 0.01 respectively) and WC (p_interaction=0.08, 0.07 and 0.02 respectively) but not WHR.

Fruit intake was associated with better lung function for those with a healthy weight and worse lung function in overweight or obese participants. Worse lung function was observed for those with BMIs > 30, 26 and 25 for pre-BD FEV₁, FEV₁/FVC and mDRS respectively. Worse lung function was also seen with WC > 102cm, 90cm and 88cm for pre-BD FEV₁, FEV₁/FVC and mDRS respectively.

Conclusion: The association between fruit intake and lung function was modified by obesity. Fruit intake was associated with higher lung function in healthy weight persons and lower lung function in those overweight or obese.

Grant Support: NHMRC, Clifford Craig Medical Research Trust.