A Detailed Characterization of Asthma Manifestations and Their Associations with Dietary Intakes in a Singapore Cohort of Young Chinese Adults: A Cross-Sectional Study

Jun Jie Lim,1,* Zong Xun Huang,1,* Evelyn Xiu Ling Loo,2 Mei Hui Liu,3 Fook Tim Chew1 1Department of Biological Sciences, National University of Singapore, Singapore, Singapore; 2Singapore Institute for Clinical Sciences (SICS), Agency for Science, Technology and Research (A*STAR), Singapore, Singapore; 3Department of Food Science & Technology, National University of Singapore, Singapore*These authors contributed equally to this workCorrespondence: Fook Tim Chew, Email [email protected]: Asthma is a heterogeneous disease with phenotypic variations potentially influenced by dietary factors. This cross-sectional study aimed to estimate the prevalence of current allergic asthma (AA), characterize its phenotypic variants, and examine dietary associations with asthma manifestations among young Chinese adults in Singapore.Patients and Methods: We assessed 10,544 young Chinese participants (mean age 22.3 ± 5.5 years; male: female = 0.74) using a standardized, investigator-administered questionnaire adapted from the International Study of Asthma and Allergies in Childhood. Current AA was defined as a history of doctor diagnosis with symptoms in the past 12 months and having allergic sensitization to common house dust mites. Dietary intake across 16 food groups was assessed using a semi-quantitative food frequency questionnaire. Multivariable logistic regression, adjusted for sociodemographic and lifestyle factors, examined dietary associations with AA outcomes.Results: The prevalence of current AA was 5.24%. Among those with current AA, 67.0% (370/552) had mild, 21.7% (120/552) moderate, and 11.2% (62/552) severe asthma. Asthma was well-controlled in 60.7% (319/552), partly controlled in 39.3% (217/552), and poorly controlled in 2.9% (16/552). Common phenotypes included cough-variant (57.6%), wheezy variant (55.1%), and exercise-induced asthma (31.5%), with overlapping symptoms. Frequent intake (most or all days) of pulses (Adjusted odds ratio [AOR]: 0.65; 95% confidence intervals [CI]: 0.47– 0.89; p < 0.001), probiotic drinks (AOR: 0.69; 95% CI: 0.50– 0.94; p < 0.001), fruits (AOR: 0.47; 95% CI: 0.31– 0.71; p = 0.001), and vegetables (AOR: 0.58; 95% CI: 0.35– 0.99; p = 0.003) was associated with protective odds of current AA. Pulses were also associated with reduced odds of exacerbated and wheezy AA, while occasional (once or twice per week) intake of probiotic drinks was associated with reduced odds of cough-variant and wheezy AA.Conclusion: While certain plant-based foods and probiotic drinks were associated with reduced odds of AA and its phenotypes, these findings should be interpreted with caution given the cross-sectional design. Longitudinal or interventional studies are needed to clarify causality and underlying mechanisms.Keywords: associations, asthma, asthma phenotypes, dietary intake, epidemiology