Study explores diet–asthma relationship in Asians

Certain food groups may influence the risk of asthma in Asians, with a study suggesting a protective benefit with fruit and nuts and a potential risk increase with seafood.

In a pooled analysis of data from the Singapore/Malaysia Cross-Sectional Genetics Epidemiology Study (SMCGES) and the Singapore Multi-Ethnic Cohort Phase 2 follow-up (MEC2-T2), the odds of asthma were lower by 35 percent among participants with higher vs no/occasional intake of fruit (pooled odds ratio [pOR], 0.65, 95 percent confidence interval [CI], 0.57–0.74; p<0.001; I2=63 percent) and by 10 percent among those with higher vs no/occasional intake of nuts (pOR, 0.90, 95 percent CI, 0.85–0.95; p<0.001; I2=0). [J Allergy Clin Immunol Glob 2026;doi:10.1016/j.jacig.2026.100648]

Meanwhile, participants with increased intake of seafood had 13-percent greater odds of asthma relative to those who abstained from eating or only occasionally consumed seafood (pOR, 1.13, 95 percent CI, 1.07–1.20; p<0.001; I2=0).

No consistent associations were observed between asthma and intake of fast food, pasta, meat, probiotic, and vegetables. The remaining food groups (ie, potatoes, rice, milk, cereals, eggs, butter, and margarine) had no significant associations with asthma.

“These findings provide valuable insights into diet–asthma relationships, supporting the need for longitudinal research and refined dietary assessments to inform public health strategies for asthma prevention,” the investigators said.

Plausibility of associations

Vegetables did not show the same association with asthma as fruits, possibly owing to the higher bioavailability of bioactive compounds in fruits than vegetables, they explained.

“Fruits such as oranges are rich in vitamin C and anti-inflammatory flavonoids, which may reduce oxidative stress and airway inflammation, thereby alleviating asthma symptoms. Beyond fruits, the inclusion of more plant-based foods, such as vegetables and whole grains, may also contribute to lower asthma risk by improving diet quality and reducing the intake of proinflammatory foods,” the investigators said.

Nuts, on the other hand, are common allergens for some individuals, they noted. The protective effect of this food group on asthma “may be attributed to their rich antioxidant content and potential synergistic effects when incorporated into a Mediterranean-style dietary pattern.”

For the association between asthma and seafood, the investigators advised caution when interpreting this finding.

While evidence from prior epidemiologic studies is mixed, specific seafood subtypes, particularly shellfish, contain allergenic proteins such as tropomyosin that can trigger respiratory symptoms in hypersensitized individuals or those with occupational exposure, they explained.

“Ongoing work within a subset of SMCGES participants is currently examining seafood-specific IgE responses to clarify the contribution of shellfish and other seafood subtypes to asthma risk,” they said.

Reliable habitual dietary intake data

“A critical strength of this study is the detailed quantification of dietary exposures using frequency-based data across both cohorts, harmonized into weekly servings to reflect habitual dietary intake rather than single-point dietary intake,” the investigators pointed out.

Dietary intake was assessed using a 16-food-group food frequency questionnaire (FFQ) in SMCGES and a validated 163-item population-specific FFQ in MEC2-T2. FFQs capture habitual dietary intake over several months, and the data reflect long-term exposure rather than short-term dietary variation, according to the investigators.

“The associations observed [in this study] therefore reliably represent habitual dietary intake related to asthma activity,” they said.

The analysis included 12,172 participants from the SMCGES cohort and 12,353 from the MEC2-T2 cohort. SMCGES participants were predominantly young adults (mean age ∼22 years), while MEC2-T2 included mainly older adults (mean age ∼50 years).

Asthma prevalence was 19.7 percent in SMCGES and 9.83 percent in MEC2-T2, of whom 18.8 percent and 18.7 percent, respectively, had a recent attack. Inhaler requirement was lower in SMCGES (5.9 percent) than in MEC2-T2 (18.4 percent).

In both cohorts, asthmatic patients were younger than nonasthmatic controls (SMCGES: 20.7 vs 22.8 years; MEC2-T2: 44.1 vs 49.6 years). Significant ethnic differences were observed, with a higher proportion of Malays and Indians among patients with asthma. Additionally, patients with asthma were more likely to be overweight. In MEC2-T2, patients with asthma were more likely to be ever or current smokers, while no significant differences in smoking status were observed in SMCGES.