Congenital heart defects (CHDs) are among the most prevalent birth anomalies globally, affecting approximately 8–10 per 1,000 live births and significantly contributing to morbidity and mortality in pediatric populations (1). Endothelial dysfunction is frequently associated with CHDs and characterized by impaired vascular relaxation, enhanced inflammation, and increased oxidative stress, potentially predisposing these children to long-term cardiovascular risks, including early-onset atherosclerosis and hypertension (2,3).

Omega-3 fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have demonstrated protective cardiovascular effects attributed primarily to their anti-inflammatory, antioxidant, and endothelium-protective properties (4,5). Previous studies in adults have reported beneficial outcomes of Omega-3 supplementation on endothelial function parameters, including flow-mediated dilation (FMD), inflammatory markers, and endothelial microparticles (EMPs), indicating improved vascular integrity and reduced cardiovascular risk (6,7). However, evidence regarding the efficacy of Omega-3 fatty acid supplementation in pediatric patients, especially those diagnosed with CHDs, remains sparse and inadequately investigated (8).

Given the existing gap in the literature and considering the potential therapeutic benefits of Omega-3 fatty acids, exploring their impact on pediatric endothelial function is clinically relevant. Thus, this study aimed to assess the efficacy of Omega-3 fatty acid supplementation in improving endothelial function in children with congenital heart defects, hypothesizing that Omega-3 supplementation would result in measurable enhancements in endothelial biomarkers and vascular function parameters.

Study Design and Participants

A randomized controlled trial (RCT) was conducted at a pediatric cardiology outpatient clinic from May to November 2024. After obtaining institutional ethical clearance and informed parental consent, 60 pediatric patients aged 5–15 years with clinically confirmed congenital heart defects (CHDs) were enrolled. Participants diagnosed with acute illness, chronic inflammatory diseases, or those receiving anti-inflammatory medications or other supplements affecting endothelial function were excluded.

Sample Size Calculation

The sample size calculation was based on anticipated differences in endothelial function (flow-mediated dilation, FMD) with Omega-3 supplementation, considering a significance level of 0.05 and a statistical power of 80%. Thus, a sample of 30 participants per group was deemed adequate.

Randomization and Intervention

Participants were randomly assigned in a 1:1 ratio to either the intervention group (n=30) or placebo group (n=30) using computer-generated block randomization. The intervention group received Omega-3 fatty acid supplementation capsules containing a total of 500 mg combined EPA and DHA (250 mg EPA and 250 mg DHA), administered once daily for 12 weeks. The placebo group received identical capsules containing inert vegetable oil, matched for size, shape, color, and taste, administered with the same dosing frequency and duration.

Outcome Measurements

The primary outcome assessed was endothelial function, measured via flow-mediated dilation (FMD) of the brachial artery. FMD was assessed using a high-resolution ultrasound imaging technique (Philips HD11XE Ultrasound Machine) following standardized protocols after a 10-hour fasting period. Brachial artery diameter was measured at baseline and following reactive hyperemia induced by 5-minute forearm cuff occlusion.

Secondary outcome parameters included serum levels of endothelial microparticles (EMPs) and high-sensitivity C-reactive protein (hs-CRP). Venous blood samples (5 ml) were drawn in the morning after fasting and processed immediately. EMP quantification was performed using flow cytometry (Beckman Coulter Navios), while hs-CRP was measured using enzyme-linked immunosorbent assay (ELISA) kits (R&D Systems, Minneapolis, MN, USA).

Follow-up and Compliance Assessment

Participants attended clinic visits at baseline and at the end of the 12-week intervention period. Compliance was evaluated through capsule counts returned by participants during follow-up visits, and adherence was considered adequate if participants consumed at least 80% of the provided capsules.

Statistical Analysis

Data analysis was conducted using SPSS software (version 26, IBM Corp., Armonk, NY, USA). Continuous variables were presented as means ± standard deviation (SD). Paired t-tests were applied for within-group comparisons, and independent t-tests were employed for between-group differences. Statistical significance was set at p < 0.05.

The study initially enrolled 60 pediatric participants with congenital heart defects (CHDs), equally randomized into two groups of 30 participants each. At the end of the intervention period, all participants completed the study, maintaining a 100% retention rate. Baseline demographic characteristics, including age, gender distribution, and body mass index (BMI), demonstrated no statistically significant differences between groups (Table 1).

Table 1: Baseline characteristics of study participants

After 12 weeks of supplementation, the Omega-3 group demonstrated significant improvement in endothelial function compared to baseline and to the placebo group, as measured by flow-mediated dilation (FMD) of the brachial artery (Table 2). Specifically, the Omega-3 group showed a notable increase in mean FMD percentage from baseline (6.2 ± 1.5%) to post-intervention (10.8 ± 1.7%; p < 0.001). Conversely, the placebo group showed no significant change from baseline (6.4 ± 1.3%) to post-intervention (6.6 ± 1.4%; p = 0.54).

Table 2: Changes in endothelial function parameters after 12 weeks of intervention

*Significant within-group change compared to baseline (p < 0.001).

Additionally, the intervention group demonstrated a significant reduction in circulating endothelial microparticles (EMPs) and serum hs-CRP levels post-intervention, compared to baseline and placebo (Table 2). EMP levels decreased significantly from 1250 ± 230 particles/µL at baseline to 810 ± 150 particles/µL (p < 0.001). Similarly, hs-CRP reduced from 3.5 ± 0.8 mg/L at baseline to 1.8 ± 0.5 mg/L post-intervention (p < 0.001). No significant changes were observed in these parameters within the placebo group throughout the intervention period.

These data suggest a beneficial impact of Omega-3 supplementation on endothelial function parameters among pediatric CHD patients (Table 2).

This randomized controlled trial evaluated the efficacy of Omega-3 fatty acid supplementation in improving endothelial function among pediatric patients with congenital heart defects (CHDs). The primary findings indicate that daily supplementation with Omega-3 fatty acids significantly enhanced flow-mediated dilation (FMD), decreased endothelial microparticles (EMPs), and reduced inflammatory markers such as hs-CRP compared to placebo, suggesting improved endothelial function and vascular health in this vulnerable pediatric population.

Endothelial dysfunction, characterized by impaired vasodilation and heightened inflammatory and oxidative processes, is common among children with CHDs and predisposes them to adverse cardiovascular outcomes later in life (1,2). Our findings align with previous adult studies indicating that Omega-3 fatty acids can ameliorate endothelial dysfunction via anti-inflammatory, antioxidant, and vasoprotective mechanisms (3,4). Similar results were reported by Yagi et al. (5), who demonstrated that Omega-3 supplementation significantly improved FMD in adult patients with coronary artery disease.

In the current study, supplementation with Omega-3 fatty acids notably increased FMD by approximately 74%, highlighting its potential role in enhancing endothelium-dependent vasodilation in pediatric CHD patients. This is consistent with studies reporting the efficacy of Omega-3 fatty acids in augmenting endothelial nitric oxide production and subsequent vasorelaxation (6,7). This improvement may translate into reduced future cardiovascular risks among CHD patients, given the crucial role of endothelial function as an early predictor of cardiovascular health (8).

Furthermore, the significant reduction in EMP levels following supplementation provides supportive evidence of improved endothelial integrity and decreased endothelial injury. EMPs are recognized biomarkers reflecting endothelial damage and inflammation, and their reduction correlates with reduced cardiovascular risk (9,10). Del Turco et al. (11) similarly reported decreased EMP concentrations after Omega-3 supplementation in adults, emphasizing its protective role in endothelial maintenance.

The observed reduction in hs-CRP in our study suggests an anti-inflammatory effect of Omega-3 fatty acids, corroborating findings from previous investigations in adults and adolescents with cardiovascular risks (12,13). Omega-3 fatty acids are known to modulate inflammatory pathways by attenuating pro-inflammatory cytokine production, thereby reducing systemic inflammation and vascular stress (14).

Despite promising results, our study has some limitations. Firstly, the relatively short duration of 12 weeks may limit understanding of the long-term cardiovascular benefits of Omega-3 supplementation. Secondly, the sample size, although statistically adequate, could limit generalizability, highlighting the need for larger-scale pediatric studies. Lastly, dietary intake variations among participants were not rigorously controlled, which might have impacted baseline Omega-3 status and influenced response variability (15).

Future studies should consider longer intervention periods, larger diverse cohorts, and precise dietary monitoring to validate the efficacy and durability of Omega-3 supplementation effects. Additionally, investigations into the specific molecular mechanisms behind Omega-3-induced improvements in endothelial function within pediatric CHD populations are warranted.

Omega-3 fatty acid supplementation significantly improved endothelial function parameters, including FMD, EMPs, and hs-CRP levels, in pediatric patients with congenital heart defects. These findings suggest potential clinical utility of Omega-3 supplementation as an adjunctive therapy to enhance endothelial health and reduce future cardiovascular risks in this population.

1. Baumann C, Rakowski U, Buchhorn R. Omega-3 fatty acid supplementation improves heart rate variability in obese children. Int J Pediatr. 2018;2018:8789604.
2. Umetani K, Singer DH, McCraty R, Atkinson M. Twenty-four hour time domain heart rate variability and heart rate: relations to age and gender over nine decades. J Am Coll Cardiol. 1998 Mar;31(3):593–601.
3. Buchhorn R, Baumann C, Willaschek C. Alleviation of arrhythmia burden in children with frequent idiopathic premature ventricular contractions by omega-3-fatty acid supplementation. Int J Cardiol. 2019 Sep;291:52–6.
4. Buchhorn R, Conzelmann A, Willaschek C, Störk D, Taurines R, Renner TJ. Heart rate variability and methylphenidate in children with ADHD. Atten Defic Hyperact Disord. 2012 Jun;4(2):85–91.
5. Lakusić N, Mahović D, Babić T, Sporis D. [Changes in autonomic control of heart rate after ischemic cerebral stroke]. Acta Med Croatica. 2003;57(4):269–73. Croatian.
6. Silvetti MS, Drago F, Ragonese P. Heart rate variability in healthy children and adolescents is partially related to age and gender. Int J Cardiol. 2001 Dec;81(2–3):169–74.
7. Ponikowski P, Anker SD, Chua TP, Szelemej R, Piepoli M, Adamopoulos S, et al. Depressed heart rate variability as an independent predictor of death in chronic congestive heart failure secondary to ischemic or idiopathic dilated cardiomyopathy. Am J Cardiol. 1997 Jun;79(12):1645–50.
8. Pinto AM, Sanders TA, Kendall AC, Nicolaou A, Gray R, Al-Khatib H, et al. A comparison of heart rate variability, n-3 PUFA status and lipid mediator profile in age- and BMI-matched middle-aged vegans and omnivores. Br J Nutr. 2017 Mar;117(5):669–85.
9. Hoffmann J, Grimm W, Menz V, Maisch B. Cardiac autonomic tone and its relation to nonsustained ventricular tachyarrhythmias in idiopathic dilated cardiomyopathy. Clin Cardiol. 2000 Feb;23(2):103–8.
10. Akyürek O, Diker E, Güldal M, Oral D. Predictive value of heart rate variability for the recurrence of chronic atrial fibrillation after electrical cardioversion. Clin Cardiol. 2003 Apr;26(4):196–200.
11. Cardoso CR, Moraes RA, Leite NC, Salles GF. Relationships between reduced heart rate variability and pre-clinical cardiovascular disease in patients with type 2 diabetes. Diabetes Res Clin Pract. 2014 Oct;106(1):110–7.
12. Van Voorhees EE, Dennis PA, Watkins LL, Patel TA, Calhoun PS, Dennis MF, et al. Ambulatory heart rate variability monitoring: Comparisons between the Empatica E4 wristband and Holter electrocardiogram. Psychosom Med. 2022 Feb–Mar;84(2):210–4.
13. Zulfiqar U, Jurivich DA, Gao W, Singer DH. Relation of high heart rate variability to healthy longevity. Am J Cardiol. 2010 Apr;105(8):1181–5.
14. Nalbant A, Vatan MB, Varım P, Varım C, Kaya T, Tamer A. Does vitamin D deficiency effect heart rate variability in low cardiovascular risk population? Open Access Maced J Med Sci. 2017 Mar;5(2):197–200.
15. Mustafa G, Kursat FM, Ahmet T, Alparslan GF, Omer G, Sertoglu E, et al. The relationship between erythrocyte membrane fatty acid levels and cardiac autonomic function in obese children. Rev Port Cardiol. 2017 Jul–Aug;36(7–8):499–508.