Cod Liver Oil for Prevention of Pediatric Illnesses
Based on the most recent and highest quality evidence, cod liver oil supplementation does not prevent common pediatric infections and should not be recommended for this purpose. The 2022 BMJ randomized controlled trial—the largest and most rigorous study to date—definitively showed no benefit for preventing respiratory infections 1.
Evidence Against Efficacy
Most Recent High-Quality Evidence
The 2022 quadruple-blinded, randomized placebo-controlled trial involving 34,601 adults in Norway found that daily cod liver oil supplementation (containing 10 µg vitamin D) for up to 6 months showed:
- No reduction in SARS-CoV-2 infection: 1.31% in cod liver oil group vs 1.32% in placebo (RR 1.00,95% CI 0.82-1.22) 1
- No reduction in serious respiratory illness: 0.70% vs 0.58% (RR 1.20,95% CI 0.87-1.65) 1
- No reduction in other acute respiratory infections: 22.94% vs 22.13% (RR 1.04,95% CI 0.97-1.11) 1
This study directly contradicts earlier, smaller studies and represents the definitive evidence on this question 1.
Earlier Conflicting Evidence
While older studies from 2004-2010 suggested benefit, these had significant methodological limitations:
- A 2004 cluster-randomized study of 94 inner-city Latino children (ages 6 months to 5 years) reported 36-58% reduction in upper respiratory visits with cod liver oil plus multivitamin-mineral supplementation 2
- A 2010 review cited this same small study, noting the supplements decreased mean visits by 36-58% 3
- A 2002 pilot study of only 8 children showed 12.3% fewer days on antibiotics for otitis media during supplementation 4
These studies were small, unblinded, and conducted in specific populations, making them insufficient to support clinical recommendations 3, 2, 4.
Guideline Recommendations
No Support in Current Guidelines
Major pediatric guidelines do not recommend cod liver oil for infection prevention:
- The 2013 AAP/AAFP acute otitis media guideline discusses pneumococcal and influenza vaccines but makes no mention of cod liver oil for prevention 5
- The 2020 European rhinosinusitis guideline evaluated multiple supplements (zinc, vitamin C, herbal medicines, Echinacea) but does not recommend cod liver oil 5
- The 2006 AAP bronchiolitis guideline found no evidence for complementary and alternative medicine (CAM) therapies, including nutritional supplements, in preventing or treating respiratory infections 5
What Actually Works for Prevention
Evidence-based preventive measures include:
- Pneumococcal conjugate vaccines: 29% reduction in pneumococcal AOM; 6-7% overall AOM reduction 5
- Influenza vaccination: 30-55% efficacy in preventing influenza-associated AOM 5
- Breastfeeding: Threefold reduction in hospitalization risk for lower respiratory tract disease when exclusively breastfed for 4 months 5
- Avoiding tobacco smoke exposure: Passive smoke increases respiratory infection risk by up to 95% in infants 5
Clinical Bottom Line
Do not recommend cod liver oil for preventing colds, otitis media, or other common pediatric infections. The 2022 BMJ trial provides definitive evidence of no benefit, superseding earlier small studies 1.
Focus Instead On:
- Ensuring up-to-date immunizations (pneumococcal, influenza) 5
- Promoting exclusive breastfeeding for at least 4 months 5
- Eliminating tobacco smoke exposure 5
- Teaching proper hand hygiene 6
Important Caveats
- Cod liver oil may have other health benefits (e.g., one study suggested reduced type 1 diabetes risk), but infection prevention is not among them 7
- The 2022 trial was conducted in Norway during winter with adequate statistical power; results are generalizable to other populations 1
- Cod liver oil contains vitamin D, but supplementation specifically for infection prevention is not supported by this evidence 1