Cod liver oil and respiratory infections
What 2 graded rows on cod liver oil agree on for respiratory infections, and where they differ. Counted side by side, never averaged.
Consensus finder Rows from the Cod liver oil page, reviewed Oct 21, 2026 How it decides
What the rows agree on
Each block and row is one graded row from the Cod liver oil page, with its PubMed record.
Your question
Cod liver oil and respiratory infections
2 rows · 34,695 peopleSplit. 1 row found an improvement and 1 found no difference.
- DGrade D× 1
- ∅No effect× 1
- Rows
- 2
- Trials
- 2
- People
- 34,695
Where they differ
From the rowsThe best-graded row, grade D, is a randomized trial of 94 people (2004) and found an improvement. 1 row is graded No effect, our grade for adequately powered trials that found no effect.
The row that found no difference was larger: 34,601 people, against 94 people for the row that found an improvement.
The row that found no difference ran longer (6 months) than the row that found an improvement (5 months).
Only the row that found an improvement names children or teens in its population.
The row that found no difference is newer (2022) than the row that found an improvement (2004).
The rows
1 improved · 1 no difference- DGrade DDoctor visits for upper respiratory infections in young children (with a multivitamin) · Improved
RCT · n 94 · 2004 · Children aged 6 months to 5 years at two inner-city pediatric practices (New York City)
1 teaspoon/day (half for under 1 year) · About 5–6 months (late autumn to spring)
Upper respiratory visits trended down over the season at the supplement practice (within-site trend, P=0.042) and did not change at the control practice; no direct between-group test is reported. Only two practices were randomized, and children also took a multivitamin with selenium.
Row on the Cod liver oil page · PubMed 15562899 (opens PubMed)
- ∅No effectCovid-19 and other acute respiratory infections in winter · No difference
RCT · n 34,601 · 2022 · Adults aged 18–75 in Norway not taking daily vitamin D
5 mL/day · Up to 6 months (median 164 days)
No reduction in positive SARS-CoV-2 tests (RR 1.00), serious covid-19 (RR 1.20, not significant) or other acute respiratory infections (RR 1.04) versus placebo. Only low-grade side effects in either group.
Row on the Cod liver oil page · PubMed 36215222 (opens PubMed)