Poster Presentation Joint Annual Scientific Meeting of the Nutrition Society of NZ and the Nutrition Society of Australia

Dietary intervention reduces markers of neutrophil activity in obese adults with asthma in a fourteen week RCT (#P62)

Megan E Jensen 1 , Peter G Gibson 1 , Manohar L Garg 2 , Lisa G Wood 1
  1. Centre for Asthma & Respiratory Diseases, University of Newcastle, Newcastle, NSW, Australia
  2. Neutraceuticals Research, University of Newcastle, Newcastle, NSW, Australia

Background: Overweight and obesity is prevalent in adults with asthma and associated with neutrophilic airway inflammation and oxidative stress. The effect of dietary carotenoids in overweight/obese adults with asthma is unknown.

Aims: (1) To compare airway neutrophil markers, systemic inflammation and carotenoid levels in healthy-weight versus overweight/obese adults with asthma. (2) To examine the effects of a high, versus low, fruit and vegetable diet on these markers in overweight/obese asthmatic adults.

Methods: In a cross-sectional analysis, sputum neutrophil elastase activity, toll-like receptor (TLR)-4 gene expression and IL8 levels, plasma carotenoids and systemic inflammation were compared between healthy-weight (BMI <25kg/m2) and overweight/obese (BMI ≥25kg/m2) adults with asthma. Changes in these biomarkers were then compared between overweight/obese asthmatic adults randomised to a high (HFV) versus low (LFV) fruit and vegetable diet for 14 weeks.

Results: Baseline sputum neutrophil elastase, TLR4 expression and IL8 were higher in the overweight/obese (n=106) versus the healthy-weight (n=27) adults; conversely, plasma carotenoids were reduced. Following the 14-week RCT, neutrophil elastase decreased in the HFV (n=33) versus LFV (n=63) group (-28.5 (-350.4, 64.6) vs. 211.5 (-15.4, 1508.7) ng/mL, p=0.045), as did CRP (-0.2 (-2.8, 0.8) vs. 0.8 (0.1, 4.9) mg/L, p=0.014). Lutein and alpha-carotene increased in the HFV versus LFV group. 

Conclusion: Markers of airway neutrophils were raised in overweight/obese adults with asthma; however, neutrophil activity reduced following a 14-week high fruit and vegetable diet, while circulating carotenoids increased. Dietary intervention may be beneficial in obese adults with asthma.

Funding source: NHMRC