Background: Sensitization to pet dander allergens has been increasing globally, however, its clinical relevance to allergic disease exacerbation remains underexplored. Objective: We aimed to determine the prevalence of serum-specific IgE (SSIgE) response to the major dog allergen Canis familiaris 1 (Can f 1), and to evaluate its association with asthma-related symptom severity and exacerbation in a Singapore/Malaysia population. Patients and Methods: A comprehensive serological profiling of specific IgE responses to 38 common inhalant and seafood allergen sources was performed in 736 young adults from the Singapore/Malaysia Cross-sequential Genetics and Epidemiology Study (SMCGES) sub-cohort. SSIgE levels were analyzed in relation to asthma diagnosis, symptom frequency, and exacerbation history. Results: Detectable Can f 1-specific IgE was present in 13.5% of participants, predominantly at low-grade Class 1-2 levels (0.35-3.49 IU/mL). Individuals with pre-existing sensitization to common inhalant and seafood allergen sources, including house dust mites (HDM), cat dander (Felis domesticus 1, Fel d 1), pollen, fungi, crustaceans, mollusks, and fish, showed a significantly higher rate of Can f 1-specific IgE response. Among asthmatic subjects, elevated Can f 1 SSIgE levels were significantly associated with recent (past 12 months) wheezing (p=0.005), daytime (p=0.019) and nighttime asthma attacks (p=0.033), and asthma exacerbations (p=0.001). These associations remained to be significant and consistent in trend among asthmatic patients sensitized to HDM allergen sources. Conclusion: Sensitization to Can f 1 is associated with increased asthma-related symptom burden and exacerbation risk, particularly in individuals with pre-existing atopy among young adults in Singapore and Malaysia. These findings highlight Can f 1-specific IgE as a potential molecular marker for identifying higher-risk asthma phenotypes in the tropical environment.

Atopy (66.1%) and HDM sensitisation (63.5%) were highly prevalent in the SMCGES cohort. In this tropical Singapore–Malaysia cohort, HDM sensitisation demonstrated high concordance with atopic status.

Pro‐inflammatory diets were associated with higher odds of atopic dermatitis (AD), but not non‐atopic dermatitis, suggesting specificity to atopic mechanisms. Directionally consistent associations observed using both a nutrient‐based (Dietary Inflammatory Index) and a food‐based (Mediterranean‐like) dietary score support the potential robustness of diet‐AD relationships.

Background: Asthma is a chronic respiratory condition that poses significant public health challenges worldwide, including Singapore. Objective: Associations between dietary intake and asthma outcomes were assessed in two independent cohorts: the Singapore/Malaysia Cross-Sectional Genetics Epidemiology Study (SMCGES; n = 12,172) and the Singapore Multi-Ethnic Cohort Phase 2 follow-up (MEC2_T2; n = 12,353). Methods: 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. Asthma status was determined through self-reported physician diagnosis, with recent asthma attacks and inhaler requirements analyzed as clinically relevant phenotypes. Multivariable logistic regression models adjusted for demographic and lifestyle factors were applied with Bonferroni correction, and meta-analyses across 16 food groups were conducted to derive pooled effect estimates and assess between-cohort heterogeneity. Results: Asthma prevalence was 19.7% in SMCGES and 9.83% in MEC2_T2. Among patients with asthma, 18.8% (SMCGES) and 18.7% (MEC2_T2) experienced recent asthma attacks, while inhaler requirement was lower in SMCGES (5.9%) than MEC2_T2 (18.4%). Fruit (pooled odds ratio [pOR] = 0.65; 95% confidence interval [CI], 0.57-0.74; P < .001) and nuts (pOR = 0.90; 95% CI, 0.85-0.95; P < .001) intake lowered the odds of asthma, while seafood intake increased the associated odds (pOR = 1.13; 95% CI, 1.07-1.20; P < .001). Fruit intake showed moderate heterogeneity (I2 = 63%; P = .10), with no heterogeneity for nuts (I2 = 0; P = .69) or seafood (I2 = 0, P = .56). Conclusion: Pooled findings across two independent cohorts highlight specific food groups that may influence asthma outcomes.

Summary A ubiquitin D (UBD) promoter haplotype was identified to confer protection against atopic dermatitis (AD). The rs362513‐G allele suppresses UBD transcription and downstream NF‐κB–regulated cytokine production, independent of the AD‐risk SNP rs995185.

Acne vulgaris is a common chronic inflammatory skin disorder that begins in adolescents and often persists into adulthood, with substantial psychosocial impact. Tea tree oil (TTO) has been explored as a topical treatment for acne, but clinical evidence for its efficacy and safety remain limited and inconsistent. This systematic review and meta-analysis synthesizes available clinical data to evaluate TTO's therapeutic effects and safety profile in acne management. PubMed, Embase, and Web of Science were systematically searched for clinical studies published up to August 2025 that evaluated TTO for acne treatment. Study selection, data extraction, and risk-of-bias assessment were independently conducted by trained reviewers. Pooled estimates were calculated using fixed- or random-effects models according to heterogeneity, quantified using the I 2 statistic. Seven studies comprising 445 patients were included. The use of TTO was associated with a reduction in acne severity compared with control groups (pooled odds ratio [pOR] = 0.74, 95% confidence intervals [CI]: 0.63-0.88). Adverse events were predominantly local and mild. An exploratory pooled analysis indicated a lower incidence of mild itching with TTO compared to the corresponding control treatments in the included studies (pOR = 0.09, 95% CI: 0.03-0.23), with similar trends observed for dryness, burning sensation, erythema, and scaling. Publication bias was not evident based on Egger's test and the trim-and-fill analysis, and overall risk of bias was assessed as low. Current evidence suggests that TTO is associated with a modest reduction in acne severity and generally acceptable short-term tolerability. Larger, high-quality trials with standardized formulations and long-term follow-up are needed to define its clinical role.

BackgroundIndoor allergen sensitization to cockroach (CR) is clinically relevant and exhibits substantial geographic heterogeneity. However, its relationship with pre-existing atopy and allergic symptom burden in tropical urban environments remains uncertain considering the overwhelming influence of house dust mite (HDM) sensitization. This study aimed to characterize sensitization to the major indoor CR allergens-Periplaneta americana and Blattella germanica-and to evaluate its association with allergic disease prevalence, symptom severity, and exacerbation.MethodsA total of 5350 young adults from the Singapore-Malaysia Cross-sequential Genetics and Epidemiology Study (SMCGES) were assessed for sensitization to common indoor allergens, including HDM and CR, using skin prick testing. Associations between sensitization and clinical allergic outcomes were analyzed. In a sub-cohort (n = 736), serum specific IgE (SSIgE) profiling against 40 aeroallergens and seafood allergens was performed to assess co-sensitization patterns.ResultsCR sensitization was identified in 23.1% of participants, with 19.7% sensitized to both HDM and CR. CR sensitization was associated with higher prevalence of asthma (OR 1.59; 95% CI 1.31-1.93), allergic rhinitis (AR; OR 1.42; 95% CI 1.22-1.65), atopic dermatitis (AD; OR 1.55; 95% CI 1.33-1.80), and atopic multimorbidity (OR 1.91; 95% CI 1.61-2.28). CR sensitization was also associated with higher frequencies of rhinitis symptoms, greater rhinitis symptom severity (OR 1.26; 95% CI 1.07-1.48), and higher total nasal symptom scores (OR 1.32; 95% CI 1.07-1.63). While HDM monosensitization was strongly associated with allergic outcomes, concurrent HDM and CR sensitization conferred additional risk and symptom burden. Polysensitized individuals also exhibited higher likelihood of developing CR-specific IgE responses.ConclusionCR sensitization is prevalent in the tropical Singapore-Malaysia population and is strongly associated with polysensitization, higher allergic disease prevalence, and increased symptom burden. These findings emphasize the clinical significance of CR allergy and support targeted strategies for indoor allergen avoidance and environmental control.

Acne vulgaris is a common chronic inflammatory skin disorder with a substantial genetic contribution. However, replication of findings from genome-wide association studies across diverse populations remains limited. In this study, we evaluated 88 previously reported acne-associated variants in 2741 acne cases and 2235 controls from the Singapore/Malaysia Cross-sequential Genetic Epidemiology Study. Two association signals were replicated at Bonferroni-corrected significance: rs1159268 near TGFB2 at 1q41 and rs738409 in the PNPLA3 coding region at 22q13.31, with consistent directions of effect. Functional annotation and transcriptomic evidence supported the involvement of these loci in pathways related to pilosebaceous unit biology, including epithelial differentiation, tissue homeostasis, retinoid regulation, and lipid metabolism. Gene-environment interaction analyses further identified 12 variants whose associations with acne risk were modified by screen-time exposure. These findings suggest that screen-associated exposures may act as contextual modifiers of genetic susceptibility, potentially through lifestyle-related metabolic factors, circadian endocrine regulation, and oxidative stress responses. Together, these findings emphasize the importance of considering environmental exposures alongside genetic susceptibility to refine our understanding of acne pathogenesis.

Introduction Asthma is a chronic respiratory disease characterized by chest tightness, coughing, shortness of breath, and wheezing. Results from the Global Burden of Diseases Study 2021 have shown that asthma poses a notable burden on patients in Malaysia and Singapore (age-standardized prevalence rates of 2461.83 and 3352.79 per 100,000 individuals, and age-standardized disability-adjusted life year rates of 189.06 and 139.99 per 100,000 individuals, respectively). The current study aimed to compare the patterns of asthma symptoms and exacerbations between participants from Malaysia and Singapore, using data from the Singapore/Malaysia Cross-Sectional Genetic Epidemiological Study (SMCGES). Methods The SMCGES has been ongoing since August 2005 at the National University of Singapore; Universiti Tunku Abdul Rahman; and Sunway University. Data on asthma status, symptoms, and exacerbations were obtained via a standardized and validated protocol established by the International Study of Asthma and Allergies in Childhood. Participants who indicated having ever had asthma were classified as recognized asthma cases. Results Participants recruited in Malaysia (henceforth referred to as "Malaysian subset", n = 4028) and Singapore (henceforth referred to as "Singaporean subset", n = 11,473) were analyzed. Compared to participants from Singapore, those from Malaysia were younger (mean age ± standard deviation: 21.1 ± 4.6 vs 22.8 ± 5.7, P < .001) and more likely to be female (65.0% vs 58.1%, P < .001). The prevalence of recognized asthma was higher among subjects recruited in Singapore than in Malaysia (22.7% vs 12.0%, P < .001). However, asthma symptoms were significantly more prevalent among respondents from Malaysia than from Singapore. These included ever-wheezing (20.8% vs 18.9%, P = .01), wheezing in the past 12 months (15.8% vs 9.2%, P < .001), experiencing a wheezy chest after exercise (11.6% vs 4.0%, P < .001), and experiencing a dry nocturnal cough (13.2% vs 11.4%, P = .004). Participants recruited in Malaysia experienced more daytime asthma attacks (fewer than once a month: 26.1% vs 13.3%, at least once monthly: 3.3% vs 2.6%, P < .001) and nighttime asthma attacks (fewer than once a month: 25.6% vs 10.5%, at least once monthly: 6.1% vs 2.3%, P < .001) than their Singaporean counterparts. As compared to the Singaporean subset, more individuals from the Malaysian subset missed school or work at least once in the past 12 months due to wheezing or asthma (8.0% vs 2.8%, P < .001), visited the general practitioner or specialist for asthma (1–3 visits: 14.2% vs 9.5%, at least 4 visits: 3.4% vs 1.2%, P = .002), visited the emergency department for asthma (at least once: 6.0% vs 1.6%, P < .001), or had been admitted to the hospital for asthma (at least once: 8.1% vs 1.1%, P < .001). Conclusion The prevalence of recognized asthma was higher in the Singaporean subset than in the Malaysian subset. However, there was a greater proportion of the Malaysian subset than that of Singapore that exhibited higher frequencies of wheezing, wheezing after exercising, and dry nocturnal coughing. Additionally, asthma exacerbations were more frequent in Malaysia than in Singapore. These results suggest that asthma is under-recognized and undermanaged in Malaysia.

Skin ageing is influenced by genetics, chronological age, and Sun exposure. Nasolabial folds are wrinkles prevalent among young ethnic Chinese participants in the Singapore/Malaysia Cross-sectional Genetics Epidemiology Study (SMCGES). We analysed data from 4421 SMCGES ethnic Chinese young adults. Collected data included demographics, Sun exposure, Fitzpatrick Skin Type, and nasolabial fold presence, assessed using validated questionnaires and photo-numeric scales. Genetic data were obtained through SNP genotyping, imputation, and whole transcriptome sequencing. Buccal cell samples from 2776 participants across three sites (National University of Singapore [NUS], University of Tunku Abdul Rahman [UTAR], and Sunway University [SU]) were used for SNP genotyping, and peripheral blood mononuclear cell samples from 658 participants at NUS and UTAR for sequencing. Analyses were performed using HaploView, RStudio, and PLINK, integrating data from the Genotype-Tissue Expression (GTEx) portal, eQTLGen consortium, and NCBI Gene Expression Omnibus. Our GWAS identified SAMD5 as associated with nasolabial folds among individuals with regular Sun exposure. SAMD5 SNPs might modulate binding of microRNAs hsa-miR-216a and hsa-miR-485-5p, suppressing SAMD5 expression and promoting nasolabial folds. rs844607 increased odds of nasolabial folds (AOR = 2.67 [1.89–3.77], p = 2.27 × 10−8) and forms a risk haplotype with 3′-end SNPs predicted as miRNA binding sites. The likely causal SNP, rs702344, strengthens miRNA binding (hsa-miR-216a: score 151, ΔG = − 19.64 kcal/mol; hsa-miR-485-5p: score 157, ΔG = − 22.36 kcal/mol), suppressing SAMD5 expression. eQTL data from GTEx (NES = − 0.72, p = 2.79 × 10−52) and eQTLGen (Z = 6.16, p = 6.59 × 10−6) supported this model. Lower SAMD5 expression was observed among chronologically aged individuals (GEO GSE200002, logFC = − 0.639, adj. p = 7.57 × 10−3) and in untreated photo-aged dermal fibroblasts relative to retinoid-treated ones (GEO GSE294121, adj. p = 3.00 × 10−2). SAMD5 promotes melanogenesis and UV protection; t-allele carriers showed 1.6-fold higher odds of melanin-poor burning skin types (95

Background:CYP4V2 is involved in lipid metabolism, but its contribution to asthma is poorly understood. This study aimed to investigate genetic polymorphisms and regulatory features of CYP4V2 in asthma development. Methods:We performed an integrative multi-omics analysis combining transcriptomic, genetic, and epigenetic data from peripheral blood mononuclear cells (PBMCs) of individuals in the Singapore/Malaysia Cross-Sectional Genetics and Epidemiological Study (SMCSGES) cohort. The influence of CYP4V2 expression on asthma risk and expression of genes involved in arachidonic acid (AA) pathway were evaluated, followed by expression quantitative trait locus (eQTL) analysis to identify regulatory variants. DNA methylation analyses were conducted to assess epigenetic regulation of CYP4V2, and promoter reporter assays were used to functionally validate candidate regulatory CpG sites. Results:The upregulation of CYP4V2 in PBMCs was associated with an increased risk of asthma and inversely associated with PTGER2 and ALOX5AP in the AA pathway. The SNP rs2276921 was identified as the only expression quantitative trait locus (eQTL) associated with both increased CYP4V2 expression and asthma risk (FDR-adjusted p < 0.05; OR = 1.24, 95% CI = 1.10-1.40). The minor allele G of rs2276921 was associated with low methylation at cg23232844 (p = 3.94 × 10-3) and cg11969330 (p = 4.25 × 10-2), located in the promoters of the protein-coding and non-coding CYP4V2 isoforms respectively. Promoter assays indicated that these two CpG sites inhibited CYP4V2 expression, supporting the regulatory effect of rs2276921 on CYP4V2 expression may be mediated through methylation. Conclusion:This study identified rs2276921 and CpG sites cg23232844 and cg11969330 that regulate CYP4V2 expression. CYP4V2 potentially modulates the AA metabolism and contributes to asthma susceptibility. These findings suggest CYP4V2 as a potential biomarker and therapeutic target in asthma.

Summary Box 8p21.3 polymorphisms associate with lower BMP1 expression, lower skin hydration and increased AD susceptibility. Regulatory variants at 8p21.3 reduce BMP1 promoter activity in dermal fibroblasts, mediating its downregulation.

Background:Asthma is a chronic respiratory condition affecting 3,340 cases per 100,000 individuals globally. The significant global health burden of asthma necessitates the development and use of valid diagnostic tools for epidemiological purposes. Objective:This study evaluated the diagnostic accuracy of the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire among participants from the Singapore/Malaysia Cross-sequential Genetic Epidemiology Study (SMCGES). Methods:Investigators administered the ISAAC survey questionnaire to SMCGES participants. Symptoms related to asthma were compared against diagnosed asthma, which was characterized by a questionnaire-reported history of asthma and exhibiting a positive skin prick reaction to allergen extracts from 2 dust mite species. Diagnostic accuracy was assessed via sensitivity (Se), specificity (Sp), positive and negative predictive values, and Youden's Index (J). Results:This study analyzed data from 4,028 participants from Malaysia and 11,473 participants from Singapore. Asthma symptom prevalence differed between Malaysia and Singapore, with ever wheeze being the most prevalent in both populations. Diagnosed asthma was more prevalent in Singapore (17.3%, 95% confidence interval [CI]: 16.6-18.1%) than in Malaysia (9.7%, 95% CI: 8.8-10.7%). Ever wheeze showed the best diagnostic performance for diagnosed asthma in Malaysia (Se = 0.548, Sp = 0.831, J = 0.379) and Singapore (Se = 0.679, Sp = 0.888, J = 0.566). Combining symptoms or asthma medication usage improved accuracy slightly, with the most valid combinations being ever wheeze or exercise-induced wheeze in Malaysia (Se = 0.557, Sp = 0.824, J = 0.381) and usage of bronchodilators, beta-agonists, inhaled steroids, or leukotriene modifiers in Singapore (Se = 0.771, Sp = 0.871, J = 0.642). Conclusion:The modified ISAAC questionnaire used by the SMCGES showed good Se and Sp for diagnosed asthma, especially when combining various symptom indicators or usages of different asthma medications. These findings substantiate the continued use of the ISAAC questionnaire as a valuable survey tool in epidemiological studies across diverse populations.

Abstract Background Skin ageing is influenced by complex genetic factors. Various phenotypes such as wrinkling, pigmentation changes, and skin cancers have been linked to specific genetic loci. However, the underlying genetic mechanisms and pathways remain poorly understood. This systematic review and meta-analysis aims to summarise the genetic loci found to be associated with skin ageing phenotypes by published genome-wide association studies (GWAS) and candidate gene studies. We also evaluated the overall association of loci via meta-analysis and identified the association patterns to explore potential biological pathways contributing to skin ageing. The Web of Science, Embase, and PubMed databases were searched on January 2024 using specific exclusion criteria (e.g., study of non-human subjects, focus on skin diseases, or treatments) to identify relevant articles. There did not appear to be any significant publication bias observed across the all phenotypes. Main body A total of 48 studies were included, revealing 30 loci that were confirmed to be associated with skin ageing by multiple studies (e.g., AFG3L1P: odds ratio 1.133 95% confidence interval [1.044, 1.222]; BPIFA3: 1.859 [1.567, 2.151]; CLPTML1: 1.164 [1.0.99, 1.229]; CPNE7: 0.905 [0.852–0.958]; DEF8: 1.186 [1.042, 1.331]; IRF4: 1.260 [1.025, 1.495]; MYO16: 2.303 [1.697, 2.908]; PRDM16: 1.105 [1.084, 1.127]; RORA: 1.391 [1.206, 1.577]; SPG7: 0.922 [0.897, 0.947]; SPON1: 2.214 [1.204, 3.225]; SPTLC1: 1.464 [1.432, 1.495]; TYR: 1.175 [1.007, 1.343]). The lack of significance for many loci may be due to studies analysing different SNPs within the same locus, weakening the overall associations. Several loci were associated with specific phenotypic categories (e.g., skin colour related, skin cancer related, wrinkling and sagging related), suggesting shared biological pathways are involved in the pathogenesis of different skin ageing phenotypes. This pattern was also observed in several of the loci that do not have a significant overall association with skin ageing. Conclusion Despite significant heterogeneity among the included studies and the use of subjective visual methods for phenotype assessment, our review highlights the critical role of fundamental biological processes, such as development and cellular organisation, in skin ageing. Future research that targets the same SNP across multiple populations could strengthen the association of additional loci with skin ageing. Further investigation into these underlying biological processes would significantly advance our understanding of the pathogenesis of skin ageing phenotypes.

INTRODUCTION:TXK regulates IFN-γ expression and T-helper (Th)1 cell-mediated inflammation that underlies the development of neutrophilic asthma; however, its implication in asthma remains uncertain. This study aimed to functionally characterize the role of TXK single nucleotide polymorphism (SNP) in the development of asthma. METHODS:This study is part of an ongoing Singapore/Malaysia Cross-Sectional Genetics and Epidemiological Study (SMCSGES). In a SMCSGES sub-cohort (n = 658), we assessed the associations of TXK mRNA expression with asthma phenotype, SNP genotype, and the mRNA expression of IFN-γ and IL23A in peripheral blood mononuclear cell (PBMC). Genetic associations between TXK variants and asthma were investigated in a case-control sub-cohort of SMCSGES (n = 2,407). The functional roles of asthma-associated TXK variants in regulating promoter activity were evaluated by in vitro promoter luciferase assay in THP-1 cells. RESULTS:We identified significant associations of upregulated TXK transcript expression with increased asthma risk (p < 0.05) and the increased transcript expressions of both IFN-γ (p < 0.0001) and IL23A (p < 0.0001) in PBMC. The major allele "T" of tag-SNP rs2661532 was significantly associated with increased TXK mRNA expression compared to the "C" allele (false discovery rate-adjusted p < 0.05). The "T" allele of rs2661532 was also significantly associated with a higher risk of asthma (p = 0.0346, odds ratio = 1.171, 95% confidence interval = 1.011-1.357). The in vitro promoter luciferase assay showed the major alleles of rs6819804 and rs74513879 (tagged by rs2661532) resulted in higher promoter activity of the TXK gene (p < 0.05). CONCLUSION:This study identified multiple TXK functional variants associated with asthma by regulating the transcript expression of TXK and downstream Th1 and Th17 cell-mediated inflammatory pathways. These findings suggested that TXK functional variants might be involved in the development of neutrophilic asthma.

Introduction: Despite the high prevalence of acne vulgaris and its impact on affected individuals, few studies have provided a detailed characterization of acne phenotypes and their associated risk factors. This study aimed to comprehensively evaluate the prevalence, severity, scarring, and phenotypes of acne, along with their associated risk factors, in a cohort of young Chinese adults, as part of the Singapore and Malaysia Cross-Sectional Genetic Epidemiology Study (SMCGES). METHODS:Participants were randomly and consecutively recruited from universities in Singapore and Malaysia. Data on sociodemographic, familial medical histories of atopic diseases and acne, and lifestyle habits were collected using a validated investigator-administered questionnaire from 6,225 young Chinese adults (mean age = 22.8 ± 5.7 years). A subset of participants underwent clinical assessment for acne severity (n = 2,345), scarring grade (n = 2,345), and phenotypes (n = 1,191) by dermatologically trained personnel. RESULTS:The prevalence of acne was 56.0%. Among acne cases (n = 3,504), 38.5% had moderate-to-severe acne, 52.8% had scarring, 95.7% presented with blackhead and/or whitehead, and 55.8% had inflammatory phenotypes (e.g., papules, pustules, cysts, and nodules). A parental history of acne emerged as the strongest risk factor associated with all acne phenotypes. Pet ownership (adjusted odds ratio [AOR]: 1.403, 95% confidence interval [CI]: 1.131-1.744, p < 0.05) and occasional alcohol consumption (AOR: 1.328, 95% CI: 1.090-1.617, p < 0.05) were associated with a higher odd for blackhead and/or whitehead. Protective factors included higher parental education levels for acne scarring (AOR: 0.650, 95% CI: 0.459-0.904; p < 0.05), male gender (AOR: 0.365, 95% CI: 0.298-0.446; p < 0.05), and birthplace (AOR: 0.674, 95% CI: 0.555-0.819; p < 0.05) for non-inflammatory phenotypes. CONCLUSIONS:This study, conducted in a well-defined cohort of young Chinese adults from the SMCGES, reinforces familial history as a key risk factor for acne onset, severity, scarring, and phenotype manifestation. The identification of modifiable and environmental factors associated with acne phenotypes offers valuable insights for targeted interventions to improve acne management and control. .

High-fat food intake is associated with atopic dermatitis (AD), but the role of habitual dietary habits related to the frequency of high-fat food intake remains unclear. To address this, we developed a frequency-based dietary index, Diet Quality based on Dietary Fat Score, to assess high-fat food intake and examined its association with AD in 13 561 young Chinese adults (mean age = 22·51 years, (sd 5·90)) from Singapore and Malaysia. Using an investigator-administered questionnaire aligned with the validated International Study of Asthma and Allergies in Childhood protocol, we conducted multivariable logistic regression analysis, adjusting for demographics, body mass index, genetic predisposition and lifestyle factors, with false discovery rate correction for multiple comparisons. Frequent high-fat food intake was associated with higher odds of AD (adjusted OR (AOR): 1·53; 95 % CI: 1·31, 1·77; P< 0·001). The association remained significant regardless of total fat intake (AOR: 1·45; 95 % CI: 1·05, 1·80; P< 0·001) and among individuals with high fruit and vegetable intake (AOR: 1·49; 95 % CI: 1·19, 1·86; P< 0·001) or low energy intake (AOR: 1·40; 95 % CI: 1·05, 1·86; P< 0·05). No synergistic effects were observed between dietary factors. These findings highlight that frequent intake of high-fat foods is independently associated with AD, emphasising the potential of dietary moderation in AD risk management.

This cross-sequential study found that frequent intake of high-fat and high-protein foods was associated with higher odds of atopic dermatitis (AD). However, occasional intake across all three macronutrients significantly lowered AD odds, suggesting that moderation-not strict avoidance-may benefit AD management in allergic populations.