Longitudinal association between healthy diet and change in asthma symptom in elderly women

Abstract

<b>Background:</b> In adulthood, a healthy diet evaluated by the Alternative Healthy Eating Index 2010 (AHEI-2010) has been associated with less asthma symptoms, but evidence remains limited among elderly women. Furthermore, one may hypothesize that obesity could acts as a mediator rather than a confounder in the diet–asthma association. <b>Aim:</b> To investigate the association between the AHEI-2010 and change in asthma symptom over time, and the potential mediating role of body mass index (BMI). <b>Methods:</b> Using data from 5,941 elderly women (mean age 70 years) from the French Asthma-E3N study, we assessed the averages of the AHEI-2010 assessed in 1993 and in 2005 (unhealthy (quintiles 1-2-3) vs. healthy diet (quintiles 4-5)), changes in the asthma symptom score from 2011 to 2018 (worsening vs no symptom), and BMI (kg/m²) in 2008. Mediation analysis based on counterfactual framework was used to estimate the total, direct, and indirect effect mediated through BMI, after adjustment for age, smoking, energy intake, physical activity, education, marital status, and having had farmer parents. <b>Results:</b> Asthma symptoms worsened in 20% of the women. After adjustment, we found borderline, close to significance, protective associations between the AHEI-2010 score and asthma worsening (total effect: ORs(95%CI)= 0.86(0.73-1.02); direct effect: 0.87(0.74-1.04)), with a significant protective indirect association mediated by BMI (0.98(0.97-0.99), accounting 13% of the total effect. <b>Conclusions:</b> A healthy diet was associated with a reduced risk of asthma worsening over time, partly through an indirect effect mediated by BMI. Our results highlight that both diet and obesity are important contributors of pulmonary health.