Pediatric investigation study links dietary preferences to childhood asthma in Shanghai

Childhood asthma, a chronic inflammatory condition affecting millions worldwide, may be shaped not only by genetics and environment but also by what children prefer to eat. A new study published on 4 September 2025 in Pediatric Investigation has found that dietary preferences for pickled, smoked, and fried foods are linked to an elevated risk of asthma among first-grade children in Shanghai.

Researchers surveyed 8,412 children aged about 6.6 years across 42 public schools in Minhang District, Shanghai. Parents provided detailed reports on dietary preferences and medical history, while trained personnel conducted physical examinations. Logistic regression analyses were applied to assess associations between food preferences and asthma. “Pickled and smoked foods contain compounds that can trigger oxidative stress and airway inflammation, while seafood may offer protective effects through omega-3 fatty acids and vitamin D,” explained corresponding author Dr. Zengliang Ruan.

After adjusting for confounders, children who preferred pickled and smoked foods were nearly twice as likely to have asthma compared with those who disliked them (odds ratio [OR] 1.81; 95% CI 1.16–2.82). Subgroup analyses revealed striking sex-specific patterns: girls with a preference for fried foods showed a markedly higher asthma risk (OR 14.72), while boys with a preference for pickled and smoked foods were especially vulnerable (OR 2.01). Interestingly, seafood preference in normal-weight children appeared to reduce asthma risk (OR 0.60).

The study underscores a broader trend: the rising prevalence of childhood asthma in China, which climbed from 0.98% in 1990 to over 3% in 2010, with some recent surveys reporting even higher rates. The Minhang study recorded a prevalence of 4.66% in first-grade children, consistent with this escalating public health concern. The researchers also noted a clear sex imbalance, with boys showing more than double the prevalence of asthma compared to girls, echoing earlier studies that attribute differences to hormonal factors, airway size, and exposure patterns. This trend not only reflects increasing diagnostic awareness but also hints at changing lifestyle and environmental factors, including dietary habits, urbanization, and indoor air quality. Together, these influences are converging to create new risks for children’s respiratory health.

While the cross-sectional design means causality cannot be confirmed, the large sample size and careful adjustment for confounders strengthen the findings.

The research team highlights that pickled and smoked foods often contain nitrites, polycyclic aromatic hydrocarbons, and high levels of salt, all of which are known to contribute to oxidative stress and airway inflammation. The research also details how high salt intake may activate epithelial sodium channels, dehydrate airway surfaces and trigger bronchoconstriction, while other compounds can disrupt airway barriers or enhance Th2-mediated inflammation. These mechanisms could plausibly explain the observed associations with asthma. In contrast, seafood is rich in omega-3 fatty acids, which have anti-inflammatory properties, and vitamin D, which is linked to immune regulation. These protective nutrients may account for the reduced asthma risk seen among seafood-preferring children. “These findings suggest that seemingly simple food choices may lead to long-term respiratory consequences,” Dr. Ruan further elaborated.

The study’s Implications extend beyond Shanghai. As children worldwide are increasingly exposed to processed and fried foods, the findings raise concerns about how early-life dietary habits may shape the global burden of asthma. The researchers recommend that future longitudinal studies incorporating metabolomic profiling should be conducted to better understand biological pathways. Such research could help identify biomarkers that predict risk and clarify how dietary exposures interact with genetic and environmental factors.

Ultimately, these findings point toward actionable strategies. Public health authorities, schools, and parents may need to re-examine dietary recommendations for children, not just in terms of overall nutrition but also with respect to respiratory health. By promoting healthier food choices, such as seafood and balanced diets rich in fruits and vegetables, it may be possible to reduce asthma risk and improve long-term outcomes for children.

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Reference
DOI:  10.1002/ped4.70021

About Associate Professor Zengliang Ruan
Dr. Zengliang Ruan is an Associate Professor at the Department of Epidemiology and Biostatistics, Key Laboratory of Environmental Medicine and Engineering of the Ministry of Education, School of Public Health, Southeast University, Nanjing, China. Dr. Ruan’s research focuses on environmental and lifestyle risk factors for chronic diseases, including the impact of air pollution and other exposures on respiratory, cardiovascular, and metabolic health, with an emphasis on epidemiological approaches that guide public health interventions and policy.