The evidence for fish oil supplementation for children with asthma

Fish oil, rich in omega-3 fatty acids like EPA and DHA, is gaining recognition for its potential to help manage asthma, especially in children. These healthy fats, found primarily in fish and seafood, have impressive anti-inflammatory properties, making them an excellent option for asthma treatment.

When considering fish oil for children, it’s essential to understand the different types of omega-3 fatty acids: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA is found in plant oils like flaxseed, soybean, and canola, while EPA and DHA are mainly found in fish and seafood. Since the body can only convert a small amount of ALA into EPA and DHA, obtaining these fatty acids directly from dietary sources or supplements is necessary. Omega-3s are vital for cell membrane structure, particularly in the brain, retina, and sperm cells, and support functions in the heart, blood vessels, lungs, immune system, and endocrine system.

Overall, omega-3s are essential for health, benefiting everything from brain function to heart health. Studies suggest that fish oil supplements can improve asthma symptoms in children with minimal side effects.

In this article, we’ll explore how fish oil can benefit children with asthma. We’ll review the latest research, discuss the safety of fish oil, and provide useful tips for parents and healthcare providers on incorporating fish oil into asthma management for kids.

Should Children Take Fish Oil? Safety, Benefits, and Dosage Guidelines

Considerations and Safety

Fish oil supplements are generally safe for children, but there are some considerations to keep in mind. For years the evidence suggested that high doses of fish oil, particularly very high doses (>7 grams per day), may increase bleeding times and the risk of hemorrhagic complications.² However, one notable large, randomized controlled trial actually reported less perioperative and postoperative bleeding in patients supplemented with high levels of preoperative fish oil (8-10 grams for 2-5 days before surgery). The study concluded that “fish oil supplementation did not increase perioperative bleeding and reduced the number of blood transfusions. Higher achieved n-3-PUFA [omega-3-polyunsaturated fatty acid] levels were associated with lower risk of bleeding.” This provides compelling evidence for the safety of fish oil supplements, even around the time of surgery. Nonetheless, fish oil supplementation should be used cautiously in patients taking blood-thinning medications.³ The American Heart Association noted in 2019 that up to 4 grams per day is likely safe for adults, and this guideline can be cautiously considered when thinking about dosing for children.^4,5 

Despite these considerations, numerous studies demonstrate that fish oil supplementation in children is both beneficial and safe. Research on fish oil for asthma in children found no adverse events and indicated improvements in peak flow and reduced use of asthma medication.⁶ A meta-analysis on fish oil’s effect on insulin sensitivity in children showed beneficial outcomes without significant adverse events.⁷ In children with intestinal failure-associated liver disease, fish oil lipid emulsions significantly reduced liver injury and the need for liver transplantation compared to soybean oil emulsions, again with no major safety concerns.^8,9

Furthermore, fish oil supplements enriched with DHA have been linked to better cognitive and behavioral functioning in children, suggesting both efficacy and safety.¹⁰ Studies on Omega-3, fish oil, and Vitamin D3 supplements for depression in children and adolescents revealed positive effects on depression symptoms without significant adverse events.¹¹ For extremely preterm children, switching from soy-based lipid emulsions to a soy-medium chain triglycerides-olive-fish oil-containing lipid emulsion was associated with improved neurodevelopmental outcomes and no significant adverse effects.¹²

Overall, fish oil supplementation appears to be a safe and beneficial option for children, with studies consistently reporting minimal adverse events and various health benefits across different conditions.

Although specific recommendations for EPA and DHA intake haven’t been established, the average daily recommended amount of ALA varies by age and sex, starting from 0.5 grams for infants to 1.6 grams for teen boys and adult men (see table below).¹³ Ensuring children receive appropriate amounts of omega-3s through a balanced diet or supplements can support their overall health and development.

Given the research on fish oil supplementation in children at much higher dosages—such as studies administering 1 gram per kilogram per day for children with liver disease, and those showing benefits with doses up to 2 grams per day—I am more generous with my dosing strategy. I have found efficacy and tolerability at higher doses than the NIH recommendations. Ensuring children receive appropriate amounts of omega-3s through a balanced diet or supplements can support their overall health and development.

Common Side Effects and Tips for Mitigation

Common side effects of fish oil supplementation include an unpleasant taste, bad breath, heartburn, nausea, diarrhea, headache, and upset stomach. Many of these side effects can be mitigated by taking fish oil with meals. A practical approach is to use a small medicine cup, espresso cup, or shot glass to pre-measure the liquid fish oil and place it by the child’s plate at mealtime. Encourage the child to take the fish oil supplement halfway through their meal.

Keeping fish oil supplements cold can improve the taste, and many children are willing to consume them, even straight from a spoon without complaint. Fish oil supplements should never smell rancid or overly “fishy.” Any foul-smelling fish oil should be discarded immediately.

Evidence

Fish Oil Supplementation and Asthma in Children & Adults

Asthma is a chronic inflammatory condition of the airways that affects millions worldwide, including both children and adults. The management of asthma typically involves inhaled corticosteroids and other pharmacological interventions. However, dietary supplements, such as fish oil rich in omega-3 polyunsaturated fatty acids (n-3 PUFA), have been investigated for their potential anti-inflammatory effects and their role in managing asthma. 

How does fish oil work for asthma?

Morin et al. (2013) investigated the impact of a marine lipid fraction (MAG-EPA) on lung inflammation using an allergic model of asthma in animals. The study included detailed measurements of inflammatory markers and lung function. The results demonstrated that the use of MAG-EPA significantly reduced lung inflammation and improved lung function markers, supporting the potential anti-inflammatory effects of specific fish oil formulations in asthma.¹

Evidence from Key Studies in Pediatric Populations

1. Yang et al. (2013) conducted a systematic review and meta-analysis that included various observational studies and randomized controlled trials examining the association between fish oil intake and asthma risk in different populations, including children and adults. The meta-analysis found a modest protective effect of fish oil intake on asthma risk, particularly in populations with higher baseline levels of omega-3 fatty acids. However, the overall evidence was limited by heterogeneity among the included studies, suggesting the need for further research to establish more definitive conclusions.²⁰
2. Lang et al. (2019) performed a multicenter randomized controlled trial involving 98 overweight/obese adolescents and young adults (aged 12-25 years) with uncontrolled asthma. Participants were randomized to receive either 4 g/day of n-3 PUFA or a soy oil placebo for 24 weeks. The primary outcome was the Asthma Control Questionnaire (ACQ) score, with secondary outcomes including blood leukocyte n-3 PUFA levels, urinary leukotriene-E4, spirometry results, and asthma-related events. The study found that while n-3 PUFA supplementation increased the n-3 to n-6 PUFA ratio in granulocytes and monocytes, it did not significantly improve ACQ scores, spirometry results, or reduce asthma exacerbations. However, a significant reduction in asthma-related phone contacts was observed, suggesting some benefit in reducing healthcare utilization.²¹
3. Zhang et al: A 2023 study published in Pediatric Allergy Immunology evaluated the association between dietary n-3 polyunsaturated fatty acids (PUFAs) intake and asthma in 8543 children and adolescents from the National Health and Nutrition Examination Survey (NHANES) data between 2013 and 2020. Using multivariate logistic regression and other statistical analyses, the study found that higher n-3 PUFA intake was associated with lower odds of asthma. Specifically, compared to the lowest intake group, the adjusted odds ratios for asthma were significantly lower in the second and third highest intake groups. The study identified an L-shaped relationship between n-3 PUFA intake and asthma, with a critical turning point at approximately 59.0 mg/kg/day, indicating that beyond this threshold, increased intake of n-3 PUFAs was associated with further reduced asthma risk.²²

Evidence from Key Studies in Adult Only Populations

4. Double-blind Placebo-Controlled Study: A 1993 double-blind, placebo-controlled study examined the effects of taking 18 capsules daily of Max-EPA (3.2 g/day eicosapentaenoic acid) on seasonal hay fever and asthma in 37 adult pollen-sensitive asthmatic subjects over two pollen seasons. Of the 25 subjects who completed the study, both the fish oil and placebo groups showed significant increases in bronchial reactivity during the pollen season, but there were no significant differences between the groups in peak expiratory flow, symptom variability, or medication usage. The study concluded that dietary fish oil supplementation does not prevent seasonal hay fever and asthma in adults.²³
5. Laerum et al. (2007) conducted a large population-based study, the Respiratory Health in Northern Europe (RHINE), involving 16,187 adults aged 23–54 years who answered a postal questionnaire about their fish and cod oil intake in both childhood and adulthood. Multiple logistic and Cox regression analyses were used to examine the relationships between fish intake and asthma, adjusting for confounders such as gender, smoking, BMI, household size, parental education, and family history of asthma. The results indicated that adults who consumed fish less than weekly had more asthma symptoms, and those who never ate fish in childhood had an increased risk of developing asthma and an earlier onset of the disease. Interestingly, the study found a U-shaped association with cod oil intake, where both non-users and daily users had a higher risk of asthma, suggesting a threshold effect for the protective benefits of fish intake.²⁴
6. Hardy et al. (2016) A systematic review by Hardy et al. evaluated multiple studies on fish oil supplementation and asthma exacerbations, focusing on different formulations and EPA ratios. The review included both animal models and human studies, assessing surrogate markers like inflammatory cytokines, pulmonary function, and airway inflammation. The results were mixed, with some studies showing significant anti-inflammatory effects and improvement in asthma markers with specific EPA
   ratios, while others did not show significant benefits. The variability in results highlighted the need for more standardized research to confirm the efficacy of fish oil supplementation in asthma management.²⁵

The research on fish oil supplementation in asthma management is promising, especially in pediatric populations, though some studies have mixed results. Given its favorable safety profile, I feel confident incorporating fish oil into a comprehensive asthma management plan. This approach can provide anti-inflammatory benefits that complement traditional pharmacological or other naturopathic treatments.

As clinicians, we should consider each patient’s health profile and potential interactions with medications when recommending fish oil. Encouraging patients to obtain omega-3 fatty acids from both dietary sources and supplements can optimize outcomes. Despite the need for further standardized research, the current evidence supports the thoughtful integration of fish oil into asthma care, enhancing overall management and potentially improving patient health.

Fish Oil Supplementation During Pregnancy

The role of prenatal nutrition in shaping long-term health outcomes for children has become a hot topic in recent years. One particularly intriguing area is how fish oil supplementation during pregnancy might influence the risk of asthma and other allergic conditions in children. Below, I’ve synthesized key studies from the past 10 years on PubMed to provide valuable insights for pediatric and family medicine clinicians on the benefits and potential risks of maternal fish oil supplementation.

Evidence from Key Studies

1. Fish Oil and Asthma Risk Reduction A 2016 study published in The New England Journal of Medicine investigated the impact of fish oil supplementation on the risk of persistent wheeze and asthma in offspring. The study included 736 pregnant women who received either 2.4 g of n-3 long-chain polyunsaturated fatty acids (LCPUFA) or a placebo from 24 weeks gestation until birth. The findings revealed a 30.7% relative reduction in the risk of persistent wheeze or asthma in the fish oil group compared to the control group, with particularly strong effects in children of mothers with low baseline levels of EPA and DHA. This study highlights the potential of prenatal fish oil supplementation to significantly reduce respiratory morbidity in early childhood.¹⁴
2. Long-term Prophylactic Potential A 2017 study conducted a follow-up of a randomized controlled trial involving 533 Danish pregnant women. The results, gathered over 24 years, showed that offspring of mothers who took fish oil had a significantly reduced risk of being prescribed asthma medication and receiving an asthma discharge diagnosis compared to the olive oil group. No significant differences were found in lung function or allergic sensitization. This long-term study underscores the importance of the intrauterine environment in the development of pediatric and adult asthma, suggesting that maternal fish oil supplementation may offer lasting protective benefits.¹⁵
3. Metabolic Mechanisms The metabolic mechanisms behind the asthma-protective effects of fish oil were explored in a 2019 study published in EBioMedicine. Utilizing metabolomic profiling of plasma samples from 577 children at 6 months of age, the study identified distinct metabolic profiles associated with maternal fish oil supplementation. These profiles included lower levels of n-6 LCPUFA-related metabolites and altered levels in tryptophan, tyrosine, and glutamic acid pathways. The study concluded that these metabolic changes were significantly associated with a reduced risk of asthma by age 5, explaining 24% of the observed protective effect. This research provides a deeper understanding of how prenatal nutrition influences the child’s metabolic pathways and subsequent asthma risk.¹⁶
4. Impact on Atopic and Non-Atopic Asthma A 2023 study examined the effects of fish oil supplementation on atopic and non-atopic asthma and infections. The double-blind, randomized controlled trial involved 736 pregnant women and followed 695 children up to age 6. Results indicated a 73% reduction in the risk of non-atopic asthma and a 16% decrease in infections in the fish oil group. The study found no significant effect on atopic asthma overall but noted a reduction in risk for children of mothers with low baseline n-3 LCPUFA levels and FADS risk genotypes. These findings suggest that prenatal fish oil supplementation can significantly protect against non-atopic asthma and various infections, though its effect on atopic asthma may depend on genetic and nutritional factors.¹⁷
5. Risk of Croup Another 2023 study, a secondary analysis of a 2 × 2 factorial designed randomized controlled trial, investigated the effects of prenatal n-3 LCPUFA and high-dose vitamin D supplementation on croup risk. The trial included 736 pregnant women, with results showing a significant reduction in the risk of croup in the n-3 LCPUFA group and the high-dose vitamin D group compared to controls. These findings highlight the potential of these supplements as preventive strategies against respiratory disorders in early childhood.¹⁸
6. Metabolic Health Considerations While the benefits of fish oil supplementation for respiratory health are evident, potential adverse effects on metabolic health were highlighted in a 2024 study published in The American Journal of Clinical Nutrition. This follow-up study of 736 pregnant women found that children in the n-3 LCPUFA group had a higher mean BMI and increased risk of being overweight at age 10 compared to the control group. Although increases in lean mass, fat mass, and fat percentage were observed, these were not statistically significant. The study also noted a tendency towards a higher metabolic syndrome score in the n-3 LCPUFA group. These findings underscore the need for careful consideration of the long-term metabolic implications of prenatal fish oil supplementation.¹⁹

I feel optimistic regarding the above research that suggests maternal fish oil supplementation can help protect against childhood asthma and certain infections and offer substantial benefits for pediatric respiratory health. However, the potential for increased BMI and higher metabolic syndrome scores in children requires careful consideration. As I aim to do with all patients, I will have discussions with pregnant patients about the benefits and risks of fish oil supplementation, especially if there is a family history of obesity and metabolic syndrome, and support the family in making informed decisions. I encourage my fellow clinicians to take a similar approach, ensuring recommendations are tailored to each patient’s unique health profile and risk factors.

Discussion & Conclusion

So, is fish oil the key to better asthma management in children? The answer is that while it is not the ultimate solution, it does hold significant promise as part of a comprehensive care plan. The evidence on fish oil supplementation for asthma management is mixed, with some studies showing benefits while others do not. This variability can be attributed to differences in study design, population characteristics, dosage, duration of supplementation, and the specific formulations of fish oil used, particularly the EPA ratios. Understanding these nuances is crucial for pediatric and family medicine practitioners.

Despite the mixed evidence, fish oil supplementation shows potential as an adjunctive therapy in asthma management due to its anti-inflammatory properties and overall safety profile. In my clinical experience, fish oil supplementation is particularly beneficial in young children, whose immune systems may be more adaptable. Given the safety of this dietary supplement, it is a promising option worth considering as part of a broader asthma management strategy.

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References

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