The effects of increasing fruit and vegetable intake in children with asthma: A randomized controlled trial

Background A high fruit and vegetable (F&V) diet reduces asthma exacerbations in adults; this has not been examined in children to date. Objective To investigate the effect of a 6-month, high F&V diet on the time to first asthma exacerbation in children with asthma, in a parallel-group, randomized, controlled trial. Methods Children (aged 3-11 years) with asthma, history of exacerbations and usual low F&V intake (<= 3 serves/day) were randomized to the intervention (high F&V diet) or control group (usual diet) for 6 months. The primary outcome was time to first exacerbation requiring medical intervention. Secondary outcomes included exacerbation rate, lung function, plasma TNF-alpha, CRP, and IL-6, faecal microbiota and peripheral blood mononuclear cell (PBMC) histone deacetylase (HDAC) activity and G-protein coupled receptor (GPR) 41/43 and HDAC (1-11) expression. Results 67 children were randomized between September 2015 and July 2018. F&V intake (difference in change ( increment ): 3.5 serves/day, 95% CI: [2.6, 4.4] p < 0.001) and plasma total carotenoids ( increment : 0.44 mu g/ml [0.19, 0.70] p = 0.001) increased after 6 months (intervention vs control). Time to first exacerbation (HR: 0.81, 95% CI: [0.38, 1.69], p = 0.569) and exacerbation rate (IRR: 0.84, [0.47, 1.49], p = 0.553) were similar between groups. In per-protocol analysis, airway reactance z-scores increased (X-5 increment : 0.76 [0.04, 1.48] p = 0.038, X-20 increment : 0.93 [0.23, 1.64] p = 0.009) and changes in faecal microbiota were observed, both in the intervention versus control group, though there was no difference between groups in systemic inflammation or molecular mechanisms. In the control group, CRP and HDAC enzyme activity increased, while GPR41 expression decreased. No adverse events attributable to the interventions were observed. Conclusion & Clinical Relevance A high F&V diet did not affect asthma exacerbations over the 6-month intervention, though warrants further investigation as a strategy for improving lung function and protecting against systemic inflammation in children with asthma.