Omega-3 (fish oil, krill oil, algal oil) and heart
What 5 graded rows on omega-3 (fish oil, krill oil, algal oil) agree on for heart, and where they differ. Counted side by side, never averaged.
Consensus finder Rows from the Omega-3 (fish oil, krill oil, algal oil) page, reviewed Oct 21, 2026 How it decides
What the rows agree on
Each block and row is one graded row from the Omega-3 (fish oil, krill oil, algal oil) page, with its PubMed record.
Your question
Omega-3 (fish oil, krill oil, algal oil) and heart
5 rows · 247,661 peopleMostly no difference: 4 of 5 rows, and most of the people. 1 found a worse outcome.
- AGrade A× 1
- CGrade C× 1
- DGrade D× 1
- ∅No effect× 2
- Rows
- 5
- Trials
- 5
- At least: a review without a trial count
- People
- 247,661
- Pooled reviews may count some twice
Where they differ
From the rowsThe best-graded row, grade A, is a meta-analysis of 81,210 people (2021) and found a worse outcome. 2 rows are graded No effect, our grade for adequately powered trials that found no effect.
The row that found a worse outcome was larger: 81,210 people, against a median of 12,969 people for the 4 rows that found no difference.
Only the 4 rows that found no difference name women and men in their population.
The row that found a worse outcome is newer (2021) than the 4 rows that found no difference (2008 to 2020).
The best grade is A among the row that found a worse outcome, and C among the rows that found no difference.
The rows
4 no difference · 1 worse- CGrade CBlood EPA+DHA: krill oil vs fish oil at matched amounts · No difference
RCT · n 66 · 2015 · Healthy adults, 22 per arm
1.3 g/day EPA+DHA (about 816 mg EPA + 522 mg DHA) in every arm · 4 weeks
No significant difference in plasma EPA+DHA at week 4 (p = 0.052) or red-cell EPA+DHA; bioavailability differed by less than 24% between products.
Row on the Omega-3 (fish oil, krill oil, algal oil) page · PubMed 26328782 (opens PubMed)
- DGrade DBlood DHA: algal oil capsules vs cooked salmon · No difference
RCT · n 32 · 2008 · Healthy men and women aged 20–65
600 mg/day DHA · 2 weeks
DHA rose about 80% in plasma phospholipids and about 25% in red cells in both groups; the two sources were bioequivalent.
Row on the Omega-3 (fish oil, krill oil, algal oil) page · PubMed 18589030 (opens PubMed)
- ∅No effectHeart and blood-vessel events, pooled trials (all doses) · No difference
Meta-analysis · n 140,482 · 2020 · 86 RCTs (162,796 participants) of adults at varying cardiovascular risk; cardiovascular-event analysis in 43 RCTs
0.5 to more than 5 g/day (19 trials gave at least 3 g/day) · 12 to 88 months
Little or no effect on cardiovascular events (RR 0.96), all-cause mortality (RR 0.97) or stroke (high/moderate certainty). Possible slight reduction in coronary heart disease events and mortality (low/moderate certainty). Triglycerides fell by about 15%, dose-dependently (high certainty).
Row on the Omega-3 (fish oil, krill oil, algal oil) page · PubMed 32114706 (opens PubMed)
- ∅No effectHeart and blood-vessel events at 1 g/day (VITAL) · No difference
RCT · n 25,871 · 2019 · US men 50+ and women 55+ at usual risk (VITAL)
1 g/day marine n-3 fatty acids · Median 5.3 years
Major cardiovascular events HR 0.92 (95% CI 0.80–1.06) and invasive cancer HR 1.03; neither significant. Secondary: total myocardial infarction HR 0.72 (0.59–0.90). No excess bleeding.
Row on the Omega-3 (fish oil, krill oil, algal oil) page · PubMed 30415637 (opens PubMed)
- AGrade AIrregular heart rhythm risk · Worse
Meta-analysis · n 81,210 · 2021 · 7 cardiovascular-outcome RCTs (≥500 participants, ≥1 year), mean age 65
≤1 g/day in trials with 72.6% of participants; >1 g/day in the rest · Weighted mean 4.9 years
Omega-3 was associated with more atrial fibrillation (HR 1.25). Risk was higher in trials using >1 g/day (HR 1.49) than ≤1 g/day (HR 1.12); each extra 1 g/day raised the HR by about 11%.
Row on the Omega-3 (fish oil, krill oil, algal oil) page · PubMed 34612056 (opens PubMed)