Abstract
Individual nutrients and bioactive compounds have been implicated in the expression of microRNAs (miRNAs), which are related to inflammation and asthma. However, evidence about the impact of diet is scarce. Therefore, we aimed to assess the association between dietary acid load and asthma-related miRNA in the exhaled breath condensate (EBC) of school-aged children. This cross-sectional analysis included 150 participants aged 7 to 12 years (52% girls) from a nested case–control study, which randomly selected 186 children attending 71 classrooms from 20 public schools located in city of Porto, Portugal. Dietary data were collected by one 24 h-recall questionnaire. Dietary acid load was assessed using the potential renal acid load (PRAL) and net endogenous acid production (NEAP) scores. Based on previous studies, eleven asthma-related miRNAs were chosen and analyzed in EBC by reverse transcription-quantitative real-time PCR. PRAL, NEAP and miRNAs were categorized as high or low according to the median. Logistic regression models were performed to assess the association between dietary acid load scores and miRNAs. Children in high dietary acid load groups (PRAL ≥ 14.43 and NEAP ≥ 55.79 mEq/day) have significantly increased odds of having high miR-133a-3p levels. In conclusion, higher dietary acid loads possibly modulate asthma-related miRNAs of school-aged children.
Highlights
The increased prevalence of asthma from the middle of the 20th century has led to the hypothesis that changes in lifestyle and environmental exposures could be the causes [1]
This association remained significant after controlling for confounders
This is the first study to assess the effects of diet on exhaled breath condensate miRNAs associated with asthma in children, demonstrating that higher net endogenous acid production (NEAP) and potential renal acid load (PRAL) scores might upregulate the expression of miRNAs related to asthma
Summary
The increased prevalence of asthma from the middle of the 20th century has led to the hypothesis that changes in lifestyle and environmental exposures could be the causes [1]. The lower intake and diversity of fruits and vegetables have been associated with asthma in children [3,4]. These foods are important sources of dietary fiber, micronutrients and phytochemicals, which participate in antioxidant and anti-inflammatory metabolic activities, possibly modulating asthma development or progression. The dietary balance between base-inducing (e.g., fruits and vegetables) and acid-inducing foods (e.g., eggs, cheese, and cereal grains) may be associated with childhood asthma [5]. Experimental models showed after fish oil [7] or EPA and DHA exposure [8] a decreased expression of microRNAs (miRNAs), which have been measured in EBC from individuals and associated with asthma [9,10]. Other experimental studies showed that bioactive compounds, such as quercetin and isorhamnetin treatment of macrophages, downregulated the levels of miRNAs [12] involved in inflammation and asthma [9,10]
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