Protective role of omega-3 polyunsaturated fatty acids supplementation in children and adolescents with bronchial asthma: a 6-month randomized, double-blind, placebo-controlled trial

Abstract

Background

Non-compliance with inhaled corticosteroids in pediatric asthmatics is common and can lead to worsening airways and even systemic inflammation. Therefore, complementary strategies alongside pharmacological treatment, such as certain nutrients and dietary patterns, may offer easy and acceptable approaches to mitigate inflammation and alleviate asthma manifestations. The current work aimed to explore the protective effects of omega-3 polyunsaturated fatty acid supplements in asthmatic children and adolescents.

Methods

The current longitudinal, prospective, double-blind, controlled study included 116 children and adolescents with asthma, ranging in age from 6 to 17.6 years, randomly assigned into two age- and sex-matched groups. Over 6 months, in addition to their regular controller medications, 56 participants received 1200 mg of omega-3 supplement, while 60 received a placebo. The participants were evaluated at the beginning of the study, after 6 months of supplementation, and 6 months after discontinuation, using asthma severity grading, a childhood asthma control test (C-ACT), and pulmonary function tests (PFTs), in addition to measurements of antioxidant and inflammatory markers (glutathione reductase [GR], malondialdehyde [MDA], matrix metalloproteinase-9 [MMP-9], and interleukin-17 [IL-17]).

Results

In the omega-3 group, asthma severity grades, C-ACT scores, PFTs, and serum levels of GR, MDA, MMP-9, and IL-17 significantly improved after 6 months of supplementation in comparison to the placebo group (p < 0.001 vs. baseline; p < 0.001 vs. placebo). Specifically, moderate and severe asthma cases declined from 76.7 to 26.7%, while not well-controlled and very poorly controlled asthma decreased from 100 to 17.8%. Improvements were significantly maintained, albeit to a lesser extent, for 6 months after discontinuation, with moderate and severe asthma cases remaining at 37.5% and not well-controlled and very poorly controlled asthma at 33.9% (p < 0.001 vs. baseline; p < 0.001 vs. placebo). Adverse effects were reported in 32.1% of the omega-3 group, primarily fishy burping (26.8%) and mild gastrointestinal symptoms (5.4%).

Conclusion

Omega-3 supplementation may serve as a promising adjunct therapy in asthma management, potentially reducing severity, enhancing control, improving lung function, and lowering inflammatory markers in pediatric asthma patients.

Introduction

Asthma is a prevalent chronic illness associated with significant morbidity and mortality, often resulting in emergency visits and hospitalizations [1]. The underlying reasons for the rising incidence and severity of asthma and its dramatic increase in prevalence over the last two decades remain poorly understood [2]. However, they are believed to involve a complex interaction of genetic factors, along with ecological, socioeconomic, and dietary influences [3, 4].

Oxidative stress arises from an imbalance between free radicals and antioxidants, playing a role in the development of asthma. This imbalance results in tissue damage, inflammation of the airways, abnormal immune responses, and a worsening of asthma symptoms [5, 6]. The antioxidant defense system of the body includes endogenous antioxidant enzymes and exogenous agents derived from the diet [7].

In recent years, the link between asthma and nutrition has been the subject of extensive research. Various nutrients, foods, and nutritional strategies have been demonstrated to boost lung function, improve asthma management, and lower inflammatory markers, thereby reducing the occurrence of asthma exacerbation [8].

Among the dietary components, omega-3 polyunsaturated fatty acids (PUFAs), primarily sourced from marine oils, have gained significant attention [9]. The polyunsaturated fatty acids integrate into cell membranes, influencing cellular signaling, membrane protein function, and gene expression [10]. Omega-3 also suppresses the leukotrienes and prostaglandins synthesis from arachidonic acid, and emerging evidence suggests they may help manage asthma [11]. However, findings across studies remain inconsistent, with some reporting limited or no benefit, particularly in pediatric populations [12, 13, 14–15]. This conflicting evidence underscores the need for more targeted research.

Dietary modifications and micronutrient supplementation are promising strategies to reduce oxidative stress and manage asthma symptoms [16]. Such approaches may represent a cost-effective complement to conventional pharmacologic therapies for asthma management. Yet, the role of long-term omega-3 supplementation in children and adolescents with asthma, particularly its impact on both clinical severity and inflammatory/oxidative markers, remains insufficiently explored. Therefore, we aimed in this work to explore the protective effects of omega-3 PUFAs in preventing and alleviating the severity of asthmatic attacks in children and adolescents. This study uniquely contributes by including a long-term follow-up after supplementation discontinuation and a detailed biomarker profile, providing new insight into the sustainability of clinical and biochemical improvements.

Patients and methods

This prospective interventional longitudinal controlled study involved 116 asthmatic children and adolescents aged between 6 and 17.6 years. Participants of both sexes were recruited from the Chest Outpatient Clinic, Pediatric Department, Tanta University Hospital, Egypt, and were randomly assigned to two age- and sex-matched groups in a 1:1 ratio, determined using a computer-generated randomization process.

Participants were enrolled after obtaining written consent from their parents or caregivers. Over 6 months, in addition to their regular controller medications, 56 participants, having a mean age of 9.73 (± 2.65) years received 1200 mg of omega-3 PUFA supplements, while 60 participants, with a mean age of 9.60 (± 3.23) years, received a placebo. A double-blind design was employed in the study, ensuring that both the participants and researchers, engaged in data gathering and interpretation, were unaware of the treatment assignments. The research ran from May 2021 through June 2024.

Inclusion criteria

• Children and adolescents aged 6 to 18 years with varying degrees of persistent asthma, including mild, moderate, and severe forms.

• According to GINA 2021 guidelines, asthma was diagnosed based on symptoms like recurrent cough, chest tightness, wheezing, and breath shortness, which typically resolve spontaneously or with bronchodilators. The diagnosis was confirmed by demonstrating a significant improvement of 12% or more in forced expiratory volume in one second (FEV1) after short-acting bronchodilator administration in children over 6 years [17].

Exclusion criteria

Exclusions included children whose parents refused participation or those with the following conditions:

• Clinical evidence of heart diseases, renal or hepatic insufficiency

• Cystic fibrosis or congenital respiratory diseases

• Chronic diarrhea or malabsorption

• Clinical evidence of malnutrition

• Children who received any nutritional supplements in the last 6 months before the study and those who were incompliant with the intervention

All participating children and adolescents underwent the following assessments:

1. Clinical assessment:

   1. A complete medical history was obtained, focusing on age and sex, bronchial asthma course and duration, history of systemic diseases, and family history of bronchial asthma or any atopic diseases.

   2. Thorough clinical examination

   3. Grading of the severity of bronchial asthma

      Bronchial asthma severity in the participating children was assessed using the GINA 2024 classification, which considers symptom frequency, nighttime awakenings, and lung function [FEV1 or FEV1 to the forced vital capacity ratio (FEV1/FVC ratio)] [18]. Assessments were performed at the beginning of the study, after 6 months of regular supplemental therapy, and 6 months following discontinuation. According to GINA 2024, asthma severity, based on symptoms over the past week, is classified into intermittent and persistent types, with persistent asthma further categorized by severity into mild, moderate, and severe [18].

   4. Childhood asthma control test (C-ACT)

      Patients were categorized according to their asthma control level. A questionnaire was designed with five questions using Nathan et al.’s 2004 as a reference [19]. It assessed patients’ views of their asthma control during the past 4 weeks, and each question was rated on a scale of one to five. Based on the total score of this questionnaire, the patients were classified into three subgroups: Controlled for scores of > 19, not well-controlled for scores between 16 and 19, and very poorly controlled for scores < 16 [20]. The evaluation of the C-ACT scores took place monthly.

   5. Pulmonary function test (PFT)

      The test monitors changes in lung health [21]. It was performed at baseline, after 6 months of treatment, and 6 months post-discontinuation. The Spirostik Complete spirometer (Geratherm Medical AG, Germany) was used for direct patient assessments, employing single-use flow sensors to prevent cross-contamination. The data were processed through a touchscreen PC and printed for further analysis. All spirometry procedures were conducted in accordance with the American Thoracic Society/European Respiratory Society (ATS/ERS) 2019 guidelines, ensuring quality control through standard criteria for acceptability, repeatability, and calibration [21].

      • FEV1: The highest value from three maneuvers was used and represented as a percentage of the predicted value, which varies according to age, sex, height, and ethnicity [18, 22]. A FEV1 > 80% is considered normal. Bronchial obstruction is classified as follows: For ages 6–11 years: Mild (FEV1 > 80% predicted); moderate (FEV1 60–80% predicted; and severe (FEV1 < 60% predicted). For ages ≥ 12 years: mild (FEV1 ≥ 80% predicted), moderate (FEV1 > 60% and < 80% predicted), and severe (FEV1 ≤ 60% predicted) [22].

      • FEV1/FVC ratio: This ratio indicates the fraction of FVC exhaled in the first second and is a critical marker for identifying airflow limitations in asthma [18]. The interpretation of the FEV1/FVC ratio is as follows: normal airflow (> 85%); mild airflow limitation (> 80% for ages 6 to 11 years and > 85% for ages twelve and older); moderate airflow limitation (75–80% for ages 6 to 11 years and reduce 5% for ages twelve and older); and severe airflow limitation (< 75% for ages 6 to 11 years and reduce > 5% for ages twelve and older) [22].

2. Laboratory investigations:

   Laboratory tests were conducted at three stages: at the baseline, after 6 months of treatment, and 6 months post-treatment. These assays provided valuable insights into oxidative stress and inflammatory markers throughout the research. Blood samples were obtained under aseptic conditions, processed by centrifugation at 3000 rpm for 10 min, and serums were preserved at − 20 °C prior to analysis. Following manufacturers’ protocols, the following tests were performed using the sandwich enzyme-linked immunosorbent assay (ELISA) principle:

   • Serum glutathione reductase (GR): Levels were assessed using the Human GR ELISA Kit (Catalog No. GR-101) from BioAssay Systems (Hayward, California, United States), with absorbance readings taken at 450 nm [23].

   • Serum malondialdehyde (MDA): Levels were evaluated using the Human MDA ELISA Kit (ab213801) (Abcam, Cambridge, UK), where color changes were proportional to MDA concentration [24]. Owing to assay kit availability constraints caused by import issues, MDA levels were measured in a subset of 30 participants from each group.

   • Serum matrix metalloproteinase-9 (MMP-9): Levels were determined using the Human MMP-9 Quantikine ELISA Kit (R&D Systems, Inc., Minneapolis, MN, United States, with color changes indicating MMP-9 concentrations [25].

   • Serum interleukin-17 (IL-17): Levels were quantified using the Human IL-17 Quantikine ELISA Kit (R&D Systems, Inc., Minneapolis, MN, United States) [26].

Details of the medical interventions

The participants in the supplement group received 1200 mg of omega-3 PUFAs once daily in two soft gelatin capsules (Zandros capsules, manufactured by Egyptian Group for Pharmaceutical Industries (EGPI), Egypt), each containing 1200 mg of fish oil, with 50% active omega-3 PUFAs, providing 360 mg of eicosapentaenoic acid (EPA), 240 mg of docosahexeanoic acid (DHA), and 19 mg alpha tochopherol acetate, equivalent to 19 IU of vitamin E, consumed with a meal for 6 months. The placebo group received identical soft gel capsules filled with vegetable glycerin (which had a neutral taste and gentle digestive effects) manufactured in the Pharmaceutics Laboratory, Faculty of Pharmacy, Tanta University. The omega-3 capsules (Zandros) used were fresh and of high quality, and according to manufacturer and user reports, they are nearly odorless under proper storage conditions, making both the active and placebo capsules comparable in appearance and odor.

After the supplementation period, participants were monitored for an additional 6 months. Both groups continued their prescribed controller medications during the study period, with reliever treatments provided as needed.

Follow-up

The monthly follow-up involved checking supplement compliance, confirming dosages, assessing side effects, and evaluating the asthma control test score. The 6-month follow-up included these same checks, evaluating asthma severity, conducting pulmonary function tests, and measuring serum levels of GR, MD, MMP-9, and IL-17.

Sample size calculation

We calculated sample size using online OpenEpi [27], assuming a power of 80%, a 95% confidence level, and a 1:1 ratio of exposed to unexposed groups. Based on data from Lorensia et al. (2018), the proportion of participants with partial asthma control was estimated at 17.2% before treatment and 44.8% after treatment [28]. These parameters yielded a minimum required sample size of 50 participants per group. To account for an anticipated 10% loss to follow-up, the sample size was increased to 55 participants per group.

Statistical analysis

The analysis was carried out using the SPSS version 27 (IBM©, Chicago, IL, USA). The normality of distribution was evaluated using the Shapiro–Wilk test. Quantitative data were summarized by reporting the range (minimum and maximum), mean, standard deviation, median, and interquartile range (IQR). The independent t test was used to compare two independent groups with normally distributed data, while the Mann–Whitney U test was applied for data with abnormal distribution. The Chi-square test was used for categorical variables, with the Monte Carlo correction applied when more than 20% of the cells had expected counts below five. The analysis of variance (ANOVA) F test with repeated measures compared normally distributed data across multiple periods, using the Bonferroni-adjusted post hoc test for pairwise comparisons. For abnormally distributed data, the Friedman test was applied, with the Dunn test for pairwise comparisons. Pearson correlation assessed relationships between normally distributed variables, while Spearman rank correlation was used for non-parametric variables. P values of ≥ 0.05 were interpreted as non-significant, values < 0.05 were deemed significant, and those < 0.01 were considered highly significant [29].

Results

We assessed 164 patients for eligibility, but 29 did not meet the criteria: 13 had received nutritional supplements in the last 6 months, 10 were under 6 years old, four showed signs of malnutrition, and two had heart disease. Additionally, seven parents declined to participate. The remaining participants were randomly allocated to either the omega-3 group or the placebo group [30]. Eight patients from the omega-3 group (12.5%) and four from the placebo group (6.25%) were lost to follow-up, resulting in 116 participants (Fig. 1).

[See PDF for image]

Fig. 1

Flowchart of the enrolled participants

Demographics and participants’ characteristics

Table 1 presents the demographic data of the studied groups. No significant differences were found between the omega-3 and placebo groups regarding age, sex, residence, family history of atopy, and controller medications (p > 0.05).

Table 1. Demographic data of the studied groups

Demographic data	Omega-3 group (n = 56)		Placebo group (n = 60)		p
Age (years)
Min–Max	6.0–16.5		6.0–17.0		tp = 0.540
Mean ± SD	9.73 ± 2.65		9.60 ± 3.23
	N	%	N	%	χ2p
Sex
Male	39	69.6	36	60.0	0.627
Female	17	30.3	24	40.0
Residence
Urban	37	66.1	38	63.3	0.996
Rural	19	33.9	22	36.7
Family history of atopy
Positive	43	76.8	48	80.0	0.966
Negative	13	23.2	12	20.0
Controller medications
LABA, IC, and SABA	21	37.5	25	41.6	0.646
LABA, IC, LTRA, and SABA	30	53.6	32	53.3	0.979
IC, LTRA, and SABA,	4	7.1	2	3.3	0.355
IC with SABA	1	1.8	1	1.7	0.962
Intranasal steroids and oral antihistamines	45	80.6	43	71.7	0.274

N/n number, Min minimum, Max maximum, SD standard deviation, pp value for comparing the studied groups, t independent t test, χ² Chi-square test, LABA long-acting beta-agonist, IC inhaled corticosteroid, SABA short-acting beta-agonist, LTRA leukotriene receptor antagonist

Asthma severity grading

At baseline, there was no significant difference in the grades of asthma severity between the omega-3 and placebo groups (p > 0.05). After 6 months of supplementation, both groups showed significant improvements (p < 0.001), with a significant difference observed between the two groups (p < 0.001). In the omega-3 group, the percentage of children with moderate and severe asthma decreased significantly from 76.7 to 26.7%, while the placebo group showed a lesser yet significant decrease from 73.3 to 53.3%. Six months after the discontinuation of supplementation, these improvements were significantly sustained (p < 0.001) but to a lesser extent. The omega-3 group showed a reduction in moderate and severe asthma cases to 37.5%, while the placebo group exhibited a lesser reduction to 46.6%, with a significant difference noted between them (p < 0.001) (Table 2).

Table 2. Distribution of asthmatic patients in the studied groups according to the severity of bronchial asthma

Severity of bronchial asthma	Omega-3 group (n = 56)		Placebo group (n = 60)		χ2p
	N	%	N	%
At beginning
Mild persistent	13	23.2	16	26.7	MC P 0.993
Moderate persistent	26	46.4	30	50.0
Severe persistent	17	30.4	14	23.3
After 6 months of treatment
Intermittent	17	30.4	4	6.7	MC P < 0.001*
Mild persistent	24	42.8	24	40
Moderate persistent	15	26.8	24	40
Severe persistent	0	0.0	8	13.3
After 6 months of stopping treatment
Intermittent	9	16.1	6	10.0	MCP < 0.001*
Mild persistent	26	46.4	26	43.3
Moderate persistent	15	26.8	20	33.3
Severe persistent	6	10.7	8`	13.3
Frp1	< 0.001*		0.001*
p2	< 0.001*		0.001*
p3	< 0.001*		0.001*
p4	0.053		0.056

N number

*Statistically significant at p ≤ 0.05; χ²: Chi square test; MC: Monte Carlo Exact test; Fr: Friedman test, significance between periods were done using post hoc test (Dunn’s test). p₁: p value for comparing between the three studied periods; p₂: p value for comparing between at beginning and after 6 months of treatment; p₃: p value for comparing at the beginning and after 6 months of stopping treatment; p₄: p value for comparing after 6 months of treatment and 6 months of stopping it

Asthma control test scores

At baseline, no significant difference in asthma control test (ACT) scores was noted between the groups (p > 0.05). After 6 months of treatment, both the omega-3 and placebo groups showed significant improvements in their scores (p < 0.001 for omega-3 and < 0.05 for the placebo groups), with the omega-3 group exhibiting significantly a higher ACT score than the placebo group (p < 0.001). Six months after discontinuation, the omega-3 group’s score decreased significantly (p < 0.001) but remained significantly higher than the baseline score (p < 0.001). The placebo group’s score did not show significant change compared to the treatment phase (p > 0.05) but remained significantly higher than the baseline value (p < 0.05) (Table 3).

Table 3. The asthma control test (ACT) score in the studied groups

ACT score	Omega-3 group (n = 56)	Placebo group (n = 60)	UP
At beginning
Min–Max	13.0–19.0	14.0–20.0	0.137
Median (IQR)	16.0 (15.0–18.0)	17.0 (16.0–18.0)
After 6 months of treatment
Min–Max	20.0–27.0	14.0–25.0	> 0.001*
Median (IQR)	22.50 (21.0–24.0)	18.50 (17.5–19.0)
After 6 months of stopping treatment
Min–Max	17.0–24.0	14.0–25.0	> 0.001*
Median (IQR)	20.0 (19.0–21.0)	18.0 (17.0–19.0)
Fp1	< 0.001*	0.02*
p2	< 0.001*	0.03*
p3	< 0.001*	0.04*
p4	< 0.001*	> 0.05

n number, Min minimum, Max maximum, IQR inter quartile range, U Mann-Whitney U test, pp value for comparing the studied groups

*Statistically significant at p ≤ 0.05; F: F test (ANOVA) with repeated measures was used to assess significance between periods, with pairwise comparisons performed using the post hoc test (Bonferroni); p₁: p value for comparing the three studied periods; p₂: p value for comparing baseline and after 6 months of treatment; p₃: p value for comparing baseline and after 6 months of stopping treatment; p₄: p value for comparing after 6 months of treatment and 6 months after stopping treatment

Asthma control grades

At baseline, the distribution of asthma control grades did not differ significantly between the omega-3 and placebo groups (p > 0.05). However, after 6 months of supplementation, a significant difference was observed (p < 0.001). The percentage of children with not-well-controlled and very poorly controlled asthma decreased significantly in both groups: in the omega-3 group, it decreased from 100% to 17.8% (p < 0.001), and in the placebo group, from 96.6 to 56.6% (p < 0.001). Six months after the discontinuation, improvements remained significant in both groups, with the omega-3 group showing 33.9% of children in not-well-controlled and very poorly controlled categories (p < 0.001), and the placebo group showing 53.3% (p < 0.001) with a significant difference observed between the two groups (p < 0.001) (Table 4).

Table 4. Distribution of asthmatic patients in the studied groups according to asthma control grades

Asthma control	Omega-3 group (n = 56)		Placebo group (n = 60)		χ2p
	N	%	N	%
At beginning					0.993
Very poorly controlled	17	30.36	18	30.00
Not well controlled	39	69.64	40	66.67
Well controlled	0	0	2	3.33
After 6 months of treatment					MCp< 0.001*
Very poorly controlled	4	7.14	10	16.66
Not well controlled	6	10.71	24	40.00
Well controlled	46	82.14	26	43.33
After 6 months of stopping treatment					MCp< 0.001*
Very poorly controlled	4	7.14	12	20.00
Not well controlled	15	26.79	20	33.33
Well controlled	37	66.07	28	46.66
Frp1	< 0.001*		0.001*
p2	< 0.001*		0.001*
p3	< 0.001*		0.001*
p4	0.053		0.056

n/N number, χ² Chi-square test, MC Monte Carlo exact test, pp value for comparing the studied groups

*Statistically significant at p ≤ 0.05; Fr: Friedman test for comparing among periods (pairwise comparisons between periods performed using the post hoc test (Dunn’s); p₁: p value for comparing the three studied periods; p₂: p value for comparing baseline and after 6 months of treatment; p₃: p value for comparing baseline and after 6 months of stopping treatment; p₄: p value for comparing after 6 months of treatment and 6 months after stopping treatment

Pulmonary function tests

FEV1%

At baseline, FEV1% did not differ significantly between the groups (p > 0.05). After 6 months of treatment, both omega-3 and placebo groups exhibited significant improvements in FEV1% (p > 0.001 for omega-3 and < 0.05 for placebo), with the Omega-3 group showing significantly higher FEV1% value than the placebo group (p < 0.001). Six months after discontinuing supplementation, FEV1% in the omega-3 group decreased significantly (p < 0.001) but remained significantly higher than baseline (p < 0.001) and control group (p < 0.001) values. In the placebo group, FEV1% did not differ significantly from the post-treatment value (p > 0.05) but remained significantly higher than the baseline (p < 0.05) (Table 5).

Table 5. Forced expiratory volume in first second (FEV1) % in the studied groups

FEV1 %	Omega-3 group (n = 56)	Placebo group (n = 60)	Up
At beginning
Min–Max	53.0–82.0	53.0–83.0	0.708
Median (IQR)	75.0 (59.0–78.0)	76.0 (63.0–80.0)
After 6 months of treatment
Min–Max	76.0–107.0	59.0–90.0	> 0.001*
Median (IQR)	83.50 (81.0–89.0)	79.0 (72.0–80.0)
After 6 months of stopping treatment
Min–Max	57.0–90.0	59.0–87.0	> 0.022*
Median (IQR)	81.0 (75.0–83.0)	77.0 (70.0–80.0)
Fp1	< 0.001*	0.03*
p2	< 0.001*	0.04*
p3	< 0.001*	0.04*
p4	< 0.001*	> 0.05

n number, Min minimum, Max maximum, IQR inter quartile range, U Mann-Whitney U test, pp value for comparing the studied groups

*Statistically significant at p ≤ 0.05; F: F test (ANOVA) with repeated measures was used to assess significance between periods, with pairwise comparisons performed using the post hoc test (Bonferroni); p₁: p value for comparing the three studied periods; p₂: p value for comparing baseline and after 6 months of treatment; p₃: p value for comparing baseline and after 6 months of stopping treatment; p₄: p value for comparing after 6 months of treatment and 6 months after stopping treatment

FEV1/FVC ratio

The baseline FEV1/FVC ratio was comparable between the groups (p > 0.05). After 6 months of supplementation, both groups showed significant improvements in their FEV1/FVC ratios (p < 0.001 for omega-3 and < 0.05 for placebo), with the omega-3 group showing a significantly higher ratio compared to the placebo group (p < 0.001). Six months after discontinuation, the omega-3 group’s FEV1/FVC ratio decreased significantly (p < 0.001) but remained significantly higher than baseline (p < 0.001) and control group ratios (p < 0.05). The placebo group’s ratio did not differ significantly from the post-treatment value (p > 0.05) but remained significantly higher than the baseline value (p < 0.05) (Table 6).

Table 6. Forced expiratory volume in first second/ forced vital capacity (FEV1/FVC) ratio in the studied groups

FEV1/FVC %	Omega-3 group (n = 56)	Placebo group (n = 60)	Up
At beginning
Min–Max	53.0–83.0	51.0–83.0	0.753
Median (IQR)	76.0 (59.0–79.0)	74.0 (63.0–80.0)
After 6 months of treatment
Min–Max	76.0–97.0	59.0–90.0	> 0.001*
Median (IQR)	83.50 (79.0–87.0)	79.0 (71.0–80.0)
After 6 months of stopping treatment
Min–Max	59.0–87.0	59.0–87.0	0.006*
Median (IQR)	81.0 (76.0–84.0)	78.0 (70.0–80.0)
Fp1	< 0.001*	0.04*
P2	< 0.001*	0.04*
P3	< 0.001*	0.04*
P4	< 0.001*	> 0.05

n number, Min minimum, Max maximum, IQR inter quartile range, U Mann-Whitney U test, pp value for comparing the studied groups

*Statistically significant at p ≤ 0.05; F: F test (ANOVA) with repeated measures was used to assess significance between periods, with pairwise comparisons performed using the post hoc test (Bonferroni); p₁: p value for comparing the three studied periods; p₂: p value for comparing baseline and after 6 months of treatment; p₃: p value for comparing baseline and after 6 months of stopping treatment; p₄: p value for comparing after 6 months of treatment and 6 months after stopping treatment

Serum glutathione reductase (GR) Levels

At baseline, there was no significant difference in serum glutathione reductase (GR) level between groups (p > 0.05). After 6 months of supplementation, the omega-3 group showed a significant increase in GR level (p < 0.001), which was significantly higher than that in the placebo group (p < 0.001). Six months after discontinuing treatment, the GR level in the omega-3 group decreased significantly (p < 0.001) but remained significantly higher than the baseline level (p < 0.001) and the placebo group (p < 0.001) levels. In contrast, the placebo group showed no significant change in GR levels across the study periods (p > 0.05) (Table 7).

Table 7. Serum glutathione reductase (GR) level in the studied groups

GR (pg/ml)	Omega-3 group (n = 56)	Placebo group (n = 60)	tp
At beginning
Min–Max	26.0–39.0	26.0–38.0	0.938
Mean ± SD	33.23 ± 4.25	33.50 ± 4.24
After 6 months of treatment
Min–Max	56.0–72.0	27.0–40.0	< 0.001*
Mean ± SD	64.17 ± 5.06	34.83 ± 3.12
After 6 months of stopping treatment
Min–Max	53.0–70.0	27.0–42.0	< 0.001*
Mean ± SD	60.63 ± 5.23	35.73 ± 2.66
Fp1	< 0.001*	0.900
P2	< 0.001*	> 0.05
P3	< 0.001*	> 0.05
P4	< 0.001*	> 0.05

n number, Min minimum, Max maximum, SD standard deviation, t independent t test, pp value for comparing the studied groups

*Statistically significant at p ≤ 0.05; F: F test (ANOVA) with repeated measures (the significance between periods was assessed using post hoc test (Bonferroni); p₁: p value for comparing the three studied periods; p₂: p value for comparing baseline and after 6 months of treatment; p₃: p value for comparing baseline and after 6 months of stopping treatment; p₄: p value for comparing after 6 months of treatment and 6 months of stopping treatment

Serum malondialdehyde, matrix metalloproteinase-9, and Interleukin-17 levels

At baseline, malondialdehyde (MDA), matrix metalloproteinase-9(MMP-9), and interleukin-17 (IL-17) serum levels were comparable between the omega-3 and placebo groups (p > 0.05). After 6 months of treatment, the omega-3 group demonstrated significant reductions in the levels of these markers (p < 0.001), which were significantly lower than those in the placebo group (p < 0.001). Six months post-discontinuation, although MDA, MMP-9, and IL-17 levels in the omega-3 group increased significantly (p < 0.001), surpassing the post-treatment levels, they significantly remained lower than both the baseline levels (p < 0.001) and those of the control group (p < 0.001). In the control group, the levels of these markers remained comparable across all time points: baseline, after 6 months of supplementation, and after 6 months of discontinuing it (p > 0.05) (Tables 8, 9, and 10).

Table 8. Serum malondialdehyde (MDA) level in the studied groups

MDA (nmol/ml)	Omega-3 group (n = 30)	Placebo group (n = 30)	tp
At beginning
Min–Max	4.80–6.30	4.90–6.30	0.601
Mean ± SD	5.52 ± 0.50	5.39 ± 0.46
After 6 months of treatment
Min–Max	2.60–3.90	4.10–6.10	> 0.001*
Mean ± SD	3.15 ± 0.30	4.83 ± 0.50
After 6 months of stopping treatment
Min–Max.	3.20–4.40	4.0–5.90	> 0.001*
Mean ± SD	3.64 ± 0.32	4.00 ± 0.35
Fp1	> 0.001*	0.186
p2	> 0.001*	0.07
p3	> 0.001*	0.06
p3	> 0.001*	0.08

n number, Min minimum, Max maximum, SD standard deviation, t independent t test, pp value for comparing the studied groups

*Statistically significant at p ≤ 0.05; F: F test (ANOVA) with repeated measures (the significance between periods was assessed using post hoc test (Bonferroni); p₁: p value for comparing the three studied periods; p₂: p value for comparing baseline and after 6 months of treatment; p₃: p value for comparing baseline and after 6 months of stopping treatment; p₄: p value for comparing after 6 months of treatment and 6 months of stopping treatment

Table 9. Serum matrix metalloproteinase-9 (MMP-9) level in the studied groups

MMP (ng/ml)	Omega-3 group (n = 56)	Placebo group (n = 60)	tp
At beginning
Min–Max	56.0–65.0	50.0–71.0	0.08
Mean ± SD	60.70 ± 3.76	59.33 ± 6.28
After 6 months of treatment
Min–Max	26.0–40.0	45.0–67.0	> 0.001*
Mean ± SD	33.67 ± 3.35	57.33 ± 6.28
After 6 months of stopping treatment
Min–Max	29.0–43.0	40.0–71.0	>0.001*
Mean ± SD	36.77 ± 3.31	56.33 ± 6.28
Fp1	> 0.001*	1.000
p2	> 0.001*	0.07
p3	> 0.001*	0.07
p4	> 0.001*	0.08

n number, Min minimum, Max maximum, SD standard deviation, t independent t test, pp value for comparing the studied groups

*Statistically significant at p ≤ 0.05; F: F test (ANOVA) with repeated measures (the significance between periods was assessed using post hoc test (Bonferroni); p₁: p value for comparing the three studied periods; p₂: p value for comparing baseline and after 6 months of treatment; p₃: p value for comparing baseline and after 6 months of stopping treatment; p₄: p value for comparing after 6 months of treatment and 6 months of stopping treatment

Table 10. Serum interleukin-17 (Il-17) level in the studied groups

IL17 (pg/ml)	Omega-3 group (n = 56)	Placebo group (n = 60)	tp
At beginning
Min–Max	1.50–2.0	1.50–2.10	0.362
Mean ± SD	1.77 ± 0.18	1.86 ± 0.17
After 6 months of treatment
Min–Max	0.70–1.20	1.40–1.90	> 0.001*
Mean ± SD	0.91 ± 0.17	1.80 ± 0.24
After 6 months of stopping treatment
Min–Max	1.0–1.50	1.40–2.00	> 0.001*
Mean ± SD	1.20 ± 0.17	1.78 ± 0.24
Fp1	< 0.001*	0.495
p2	< 0.001*	0.09
p3	< 0.001*	0.07
p4	< 0.001*	0.08

n number, Min minimum, Max maximum, SD standard deviation, t Independent t test, pp value for comparing the studied groups

*Statistically significant at p ≤ 0.05; F: F test (ANOVA) with repeated measures (the significance between periods was assessed using Post Hoc Test (Bonferroni); p₁: p value for comparing the three studied periods; p₂: p value for comparing baseline and after 6 months of treatment; p₃: p value for comparing baseline and after 6 months of stopping treatment; p₄: p value for comparing after 6 months of treatment and 6 months of stopping treatment

Eighteen patients (32.1%) reported adverse effects from omega-3 PUFA supplementation. The most common side effects were an unpleasant taste and fishy burping (26.8%), followed by gastrointestinal symptoms, including heartburn, nausea, and diarrhea (5.4%). No cases of bleeding, bad breath, or foul-smelling sweat were observed.

Discussion

The present work investigated the effects of omega-3 PUFA supplementation in asthmatic children and adolescents. Over 6 months, the participants in the supplement group received 1200 mg of omega-3 PUFAs daily with a meal alongside their regular asthma medications. Currently, no universally accepted standard exists for the recommended daily intake of omega-3 PUFAs in asthmatic children. Variations in research populations, intervention types, and sources have contributed to conflicting results across different studies [31, 32–33].

Our findings showed significant improvements in asthma severity, control, and pulmonary function after 6 months of omega-3 supplementation, with these benefits persisting, albeit to a lesser degree, for 6 months after discontinuation. In the omega-3 group, the proportion of children and adolescents with moderate and severe asthma decreased from 76.7 to 26.7%, compared to a lesser reduction in the placebo group (73.3% to 53.3%). Six months after stopping the supplement, these percentages were 37.5% and 46.6% in the omega-3 and placebo groups, respectively. Additionally, the percentage of children with well-controlled asthma in the omega-3 group increased significantly, from 0% to approximately 82%, after 6 months of supplementation, compared to the placebo group, which increased from 3.33 to 43.3%. Although the percentage of well-controlled children dropped to 66% after 6 months of supplement discontinuation, it remained significantly higher than both the baseline and the control group (46.6%).

These results aligned with studies by Barua et al. (2023), who reported improvements in asthma control and respiratory function after 3 months of omega-3 supplementation [34], as well as with Sultan et al. (2019) and Papamichael et al. (2019), who recorded that omega-3 PUFAs supplementation decreased airway inflammation and alleviated asthma manifestations [11, 14]. Similarly, Lorensia et al. (2018) observed significant improvements in lung function and asthma control following omega-3 supplementation in adolescents and adults [28]. Other studies, including Farjadian et al. (2016), reported improvements in spirometry and asthma symptoms with omega-3 treatment [31].

However, these findings contrasted with Lang et al. (2019), who found no improvement in asthma outcomes with omega-3 PUFA supplementation [15], and Brigham et al. (2019), who found no significant link between omega-3 intake and asthma severity [35]. Brannan et al. (2015) also reported that high doses of omega-3 did not affect sputum eosinophil percentages or asthma symptom control [36]. These discrepancies highlight the variability in omega-3’s effects, potentially due to differences in study populations, dosages, and study durations.

Interestingly, the placebo group in the present study also showed significant improvements in asthma severity, control, and pulmonary function compared to baseline. This improvement may be attributed to better adherence to asthma medications during regular follow-ups, as structured monitoring and repeated clinical visits likely enhanced medication compliance and self-management, thereby improving outcomes even without active supplementation [37, 38].

Oxidative imbalance is considered a crucial factor in the pathogenesis of asthma [39], with lipid peroxidation resulting in the generation of harmful products like malondialdehyde (MDA) [40]. Glutathione reductase (GR) helps combat oxidative stress by reducing oxidized glutathione to its active form. However, glutathione deficiency, common in conditions like asthma, exacerbates oxidative stress and inflammation [41]. Moreover, MMP-9 contributes to airway remodeling in asthma by degrading type IV collagen [42], while allergen inhalation in chronic severe asthma enhances IL-17 expression in the airways, resulting in a neutrophilic influx and further airway remodeling [43].

Recently, Barua et al. (2023) demonstrated that omega-3 PUFAs can displace arachidonic acid from cell membranes, competing for enzymes and lowering the production of inflammatory mediators, thereby improving lung function and reducing asthma severity [34]. In addition, fish oil supplementation has proven beneficial in certain asthma types due to its anti-inflammatory properties [44]. Conversely, insufficient omega-3 intake can result in heightened inflammation, potentially exacerbating asthma symptoms [45].

In the current study, 6 months of omega-3 supplementation significantly increased glutathione reductase and decreased MDA, MMP-9, and IL-17. These improvements persisted, though diminished, for 6 months after discontinuation, remaining significantly better than baseline and placebo group values.

These findings were consistent with prior research, including that of Oliver et al. (2021), which reported that omega-3 supplementation enhanced antioxidant capacity by increasing glutathione precursors [46]. Similarly, Yang et al. (2019) and Sadeghi et al. (2019) observed that polyunsaturated fatty acids supplementation reduced oxidative stress and lipid peroxidation biomarkers by boosting antioxidant enzymes including glutathione reductase and glutathione peroxidase [47, 48]. Additionally, our results aligned with Heshmati et al.’s (2019) and Fazelian et al.’s (2021) studies, which discovered that omega-3 fatty acids improve antioxidant defenses by increasing glutathione reductase and peroxidase activity while reducing MDA levels, which positively impacts various diseases [49, 50]. Abhari et al. (2019) also found that omega-3 reduced inflammatory markers and MDA in ulcerative colitis patients while boosting antioxidant levels [51].

Our findings supported previous research indicating that PUFAs play protective roles in conditions with increased metalloproteinase (MMP) activity [52, 53], demonstrating their potential to suppress MMP-2 and MMP-9 activity [49] and reduce MMP-9 levels [54]. Furthermore, our study confirmed previous research showing that omega-3 supplementation significantly reduces IL-17A levels, suggesting that omega-3 may help reduce inflammation by lowering IL-17 levels [11, 31, 55].

The sustained post-supplementation improvements noted in the current study are likely due to the prolonged biological activity of omega-3 PUFAs, driven by their membrane incorporation and subsequent molecular adaptations [56, 57]. Following their integration into phospholipid bilayers of immune and airway cells, EPA and DHA form stable reservoirs that continue to modulate membrane structure, signaling, and receptor function after discontinuation. Omega-3 PUFAs also compete with arachidonic acid, reducing pro-inflammatory eicosanoids and promoting an anti-inflammatory state [58]. Additionally, they shift macrophages and T cells toward pro-resolving phenotypes and act as precursors of specialized pro-resolving mediators (SPMs), such as resolvins and protectins, which actively resolve inflammation and have prolonged effects [57, 59]. Their influence on gene expression, through the activation of nuclear receptors (e.g., PPAR-γ) and inhibition of transcription factors such as NF-κB, further support the long-lasting anti-inflammatory effects [56].

Regarding the side effects, approximately 32% of participants in the omega-3 group reported mild issues, primarily fishy burping (26.8%) and discomfort in the digestive tract, including heartburn, nausea, and diarrhea (5.4%). No participants experienced more severe side effects like bad breath, foul-smelling sweat, or bleeding. These findings were consistent with previous studies. For example, Reisman et al. (2006), in a systematic review of eight adult and two pediatric trials, reported that gastrointestinal symptoms were the most commonly observed adverse effects of omega-3 supplementation, including nausea, vomiting, and fishy-tasting eructation [60]. Janczyk et al. (2015) similarly found mild abdominal discomfort as the only adverse event in the omega-3 group [61]. Yan et al. (2018) also reported that omega-3 PUFA supplementation was generally well tolerated, with only minor gastrointestinal complaints [62]. While Gidding et al. (2014) noted the occurrence of frequent nosebleeds, these were self-limiting and did not necessitate discontinuation of supplementation [63].

Overall, the adverse effects observed in our study were mild, transient, and did not require any intervention or withdrawal from treatment, supporting the safety profile of omega-3 PUFA use in children and adolescents with asthma.

Finally, it is worth noting that the attrition rate was somewhat higher in the omega-3 group (12.5%) compared to the placebo group (6.25%). Although this raises a potential concern regarding attrition bias, the final number of participants in both groups remained above the required sample size, making it unlikely to have significantly affected the validity of the study outcomes. The differential attrition may have been influenced by factors such as capsule palatability or a perceived lack of immediate benefit, both of which are known to impact adherence in intervention studies.

Limitations

The current study had some limitations, including a relatively small sample size and the absence of data on omega-3 PUFA levels in erythrocyte membranes and participants’ nutritional intake. Percentile-based interpretations of pulmonary function tests were not applied. Some attrition and noncompliance occurred, particularly in the omega-3 group; although this was anticipated and accounted for in the sample size calculation, it remains a consideration. Moreover, MDA analysis was limited to approximately half of the participants due to assay kit shortages attributed to import-related issues. Another limitation is that, although omega-3 and placebo capsules were visually identical and nearly odorless, a formal sensory validation to confirm their similarity in taste and smell was not conducted.

Conclusion

Omega-3 PUFA supplementation, when used alongside standard treatments, can enhance asthma control and reduce exacerbations in asthmatic children and adolescents. More studies are needed to identify the ideal dosages and treatment duration and to investigate the potential benefits of antioxidant-rich foods in bronchial asthma management in these age groups.

Acknowledgements

Sincere gratitude is extended to Dr. Nehal Saber El-Taiby, a Clinical Pharmacist at Tanta University, for her valuable assistance with placebo preparation.

Authors’ contributions

AMA, AAE, and DE conceptualized the study and formulated the research plan. EA and DE were responsible for data collection, while GS performed the laboratory tests. DE interpreted the data and drafted the initial manuscript, with contributions from EA, AMA, and AAE. All authors reviewed and assented to the manuscript's last version.

Funding

Not applicable.

Data availability

Upon reasonable request, the corresponding author can supply the data related to the current study.

Declarations

Ethics approval and consent to participate

This study’s approach complied with the Helsinki Declaration guidelines and subsequent amendments. The Committee of Research Ethics at the Faculty of Medicine, Tanta University, Egypt, approved the study (approval code: 34546/3/21). Additionally, the research was retrospectively listed in the Pan African Clinical Trial Registry (Registration ID: PACTR2024125552874300. Parents or authorized caregivers of all study participants provided informed written consent.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

Abbreviations

C-ACT

Childhood Asthma Control Test

FEV1

Forced expiratory volume during the first second

FVC

Forced vital capacity

GINA

Global Initiative for Asthma

GR

Glutathione reductase

IL-17

Interleukin-17

MDA

Malondialdehyde

MMP-9

Matrix metalloproteinase-9

NF-κB

Nuclear factor kappa-light-chain-enhancer of activated B cells

PFTs

Pulmonary function tests

PPAR-γ

Peroxisome proliferator-activated receptor gamma

PUFA

Polyunsaturated fatty acid

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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