Abstract
BackgroundA commonly held public belief is that cow’s milk products increase mucus production and respiratory symptoms. Dietary milk elimination is often attempted despite lack of evidence. Our objective was to investigate whether a single exposure to cow’s milk is associated with respiratory symptoms and changes in pulmonary functions in asthmatic and non-asthmatic children.MethodsWe conducted a prospective double blind, placebo-controlled trial on non-asthmatic and asthmatic children aged 6–18 years evaluated at a pediatric pulmonology unit.The children were randomly challenged with cow’s milk or soy milk substitute. Symptoms, spirometry, fractional-exhaled nitric-oxide (FeNO), and pulse oximetry findings were obtained at baseline and at 30, 60, 90, and 120 min following challenge.A two-way ANCOVA (with repeated measures when required) was used to compare the performances of all groups and subgroups over time. The outcome measures of each participant were compared to his/her own variables over time and in relation to his/her baseline values. In case of missing data points, missingness analysis was performed using Little’s missing completely at random (MCAR) test.ResultsFifty non-asthmatic children (26 assigned to the cow’s milk group and 24 to the soy substitute group), and 46 asthmatic children (22 in the cow’s milk group and 24 in the soy substitute group) were enrolled. Age, gender, and body mass index Z-score were comparable between the two groups. No changes in symptoms, spirometry, FeNO, or oxygen saturation measurements were observed following challenge in any of the participants in both groups, at any time point compared to baseline.ConclusionsA single exposure to cow’s milk is not associated with symptoms, bronchial inflammation, or bronchial constriction in both non-asthmatic and asthmatic children. Our findings do not support the strict elimination of dairy products from a child’s diet for the prevention of respiratory symptoms.Trial registrationThis study was approved by the Tel Aviv Sourasky Medical Center Institutional Review Board and the Israeli Ministry of Health review board (Helsinki Committee, NIH #NCT02745899). Registered April 2016 https://clinicaltrials.gov/ct2/show/NCT02745899?cond=milk+asthma&rank=1.
Highlights
A commonly held public belief is that cow’s milk products increase mucus production and respiratory symptoms
A 2003–2004 survey conducted by the Israeli Center of Disease Control (ICDC) showed that 12% of children in the 7-12th grades abstained from dairy products mostly due to general health considerations, family lifestyle, or veganism [2]
Study exclusion criteria were: (a) a known allergy to cow’s milk, (b) acute or recent respiratory infection at the time of testing, (c) use of systemic steroids during the month preceding study initiation, (d) asthma exacerbation that had been treated with short-acting beta-agonists or inhaled corticosteroids within the 48 h prior to the trial, and (e) an underlying disease that could affect clinical assessment, spirometry, or fractionalexhaled nitric-oxide (FeNO) measurements
Summary
A commonly held public belief is that cow’s milk products increase mucus production and respiratory symptoms. Our objective was to investigate whether a single exposure to cow’s milk is associated with respiratory symptoms and changes in pulmonary functions in asthmatic and non-asthmatic children. There is a commonly held belief that cow’s milk increases airway mucus production. A 2003–2004 survey conducted by the Israeli Center of Disease Control (ICDC) showed that 12% of children in the 7-12th grades abstained from dairy products mostly due to general health considerations, family lifestyle, or veganism [2]. In a 2015–2016 ICDC survey among 5,300 adolescents, 10–14% reported complete milk avoidance [3]. Balfour-Lynn recently reported that in their department, parents often claim that drinking milk increases mucus production and, they omit milk from their children’s diet. Balfour-Lynn recommended that this myth be refuted [6]
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