In a recent study published in Scientific Reports, researchers explored the connection between a Western-style dietary pattern and the prevalence of asthma and its symptoms among children and adolescents in Yazd, Iran.
Background
Asthma, a chronic inflammatory disease influenced by both genetic and environmental factors, is increasingly burdening patients and healthcare systems worldwide. Annually, asthma accounts for about 15 million disability-adjusted life years lost. The condition affects around 300 million people globally, with its prevalence on the rise. Although more common in high-income countries, low-income nations are also experiencing significant impacts. Childhood asthma rates vary, with 10.1% in Brazil, 5.35% in India, 10.6% in Oman, and 6% in Iran. Contributing risk factors include lack of breastfeeding, socioeconomic status, infections, and dietary habits. Further investigation is needed to confirm the link between Western dietary patterns and childhood asthma, particularly in the Middle East, where dietary practices are rapidly changing.
About the Study
This cross-sectional study, conducted in early 2020 as part of the Global Asthma Network (GAN), involved 7,214 children (ages 6-7) and 3,026 adolescents (ages 13-14) from 36 elementary and 48 high schools in Yazd, achieving response rates of 71.3% and 83.5%, respectively. Due to the COVID-19 pandemic, data collection included online questionnaires about asthma symptoms, risk factors, and dietary intake, supplemented by pre-pandemic paper questionnaires.
The GAN questionnaire, adapted from the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire, assessed asthma symptoms and dietary intake over the previous 12 months. The questionnaire’s reliability was confirmed with a Cronbach’s alpha of 0.862. Participants were categorized into tertiles based on a Western dietary pattern score derived from the consumption of nine food groups.
Data on height, weight, ethnicity, and screen time were also collected, with body mass index (BMI) calculated from weight and height. Statistical analyses using STATA software involved chi-square tests, t-tests, and logistic regression to explore associations between Western dietary patterns and asthma outcomes, adjusting for confounders. The study adhered to ethical guidelines, with approval from Shahid Sadoughi University’s ethics committee and informed consent from participants.
Study Results
The study included 7,667 participants, examining asthma-related characteristics confirmed by a doctor and those requiring prescribed medication. Among the 324 participants with doctor-confirmed asthma, 58.02% were boys, and 61.7% of those with medication-prescribed asthma were also boys. Children with doctor-diagnosed asthma were older than those without asthma, a trend also seen in those with medication-prescribed asthma. Significant differences in ethnicity distribution were observed between children with and without medication-prescribed asthma. Children with doctor-diagnosed asthma had a lower history of wheezing and fewer recent wheezing episodes compared to those without asthma, with these differences also significant in children with medication-prescribed asthma.
Nine food items assessed the Western dietary pattern score, revealing higher intake frequencies of fast foods, soft drinks, and sauces among children with doctor-diagnosed asthma compared to those without. Similarly, children using asthma medication had higher intake frequencies of margarine, fast foods, and sauces compared to those not using medication.
The study investigated the association between adherence to a Western dietary pattern and doctor-confirmed asthma, finding a decreasing trend but no significant association across girls, boys, and the entire population. No significant association was found between adherence to a Western dietary pattern and the odds of current asthma in girls or the entire population. However, a significant negative trend was observed in boys, which remained significant after adjusting for BMI, television watching, and computer use.
Adherence to a Western dietary pattern was not significantly related to the use of asthma medications in the entire population or in subgroup analyses by sex. In boys and the whole population, higher adherence to a Western dietary pattern was associated with an increased risk of wheezing in the past 12 months compared to those with lower adherence. After adjusting for age and sex, this relationship remained significant for the whole population, with children in the top adherence tertile having a 24% higher chance of developing wheezing in the past 12 months compared to those in the lower tertile. However, this association disappeared for boys after adjusting for age and sex.
Conclusions
This study found a significant positive association between adherence to a Western dietary pattern and wheezing in the past 12 months among all participants and boys. However, it remained significant only in boys after adjusting for confounders. These results align with other studies linking Western diets to wheezing. No association was found between adherence to a Western diet and wheezing in girls. Additionally, the study found no significant association between a Western dietary pattern and current asthma, doctor-confirmed asthma, or the use of asthma medication.