Omega-3

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)

The evidence picture is much less top-heavy under the current grading system. Blood pressure is the strongest supported health effect, while triglycerides, cardiovascular events, pregnancy-related uses, depression, and cognition mostly land in mixed territory, and dry eye now looks negative rather than clearly helpful. Form and dose still matter, but the broad "works for everything" reputation overstates what the current grading supports.

What the research says

Each row is a different health effect. A means the support looks strongest, B likely helpful, C mixed or modest, and — not enough human evidence yet.

B · Likely helpful
B
Blood pressure
Pooled effect null — 8 of 15 reviews report no effect. Subgroup signals exist for hypertensives at ≥2 g/day, but pooled BP literature does not support benefit.
44 papers · 28 research reviews
C · Mixed or limited evidence
C
Triglycerides & lipid profile
39 of 44 reviews positive. Long-chain omega-3 reduces triglycerides ~15% dose-dependently; effect largest at ≥2 g/day EPA+DHA in hypertriglyceridemia.
83 papers · 44 research reviews
C
Cardiovascular events & mortality
34 of 37 reviews positive-leaning. EPA-dominant preparations (Vascepa, JELIS) drive most benefit signal; balanced fish oil literature is more null.
70 papers · 52 research reviews
C
Pregnancy maternal outcomes
19 of 23 reviews positive. A Cochrane review of nearly 20,000 pregnancies shows omega-3 reduces both preterm birth and especially early preterm birth.
50 papers · 32 research reviews
C
Depression & mood disorders
Pooled effect mixed but consistently positive in subgroup analysis — effect strongest in moderate-to-severe depression and EPA-major formulations (≥60% EPA).
47 papers · 30 research reviews
C
ADHD & pediatric cognition
Mostly mixed reviews. Modest effect on attention and hyperactivity scores in pediatric populations; effect inconsistent across trials and formulations.
30 papers · 15 research reviews
C
Pregnancy infant & child development
Mostly mixed reviews on infant cognitive and visual development. Some signal for early visual processing; cognitive outcomes at age 2–7 inconsistent.
39 papers · 23 research reviews
C
Dry eye disease
Small evidence base — 4 reviews. Improves tear breakup time and dry-eye symptoms in moderate cases; benefit unclear at low doses.
19 papers · 4 research reviews
C
Rheumatoid arthritis & joint inflammation
Genuine disagreement in reviews. Some reductions in tender/swollen joint counts and NSAID use, but pooled effects are inconsistent across populations.
19 papers · 5 research reviews
C
Cognitive decline & dementia prevention
Pooled trials in healthy older adults at dementia risk show no slowing of cognitive decline. Treatment trials in MCI/AD also null.
31 papers · 15 research reviews

Quick facts

Dose, form and timing based on trials in the database.

Typical dose
1–4 g/day combined EPA+DHA. Triglyceride reduction trials cluster at 2–4 g/day; most general-health trials use 1 g/day. Doses are reported as combined EPA+DHA, not total fish oil mass
Best taken
With a meal containing fat to improve absorption. Divided doses (twice daily) are common at higher doses to reduce stomach upset
Form
EPA-dominant or balanced EPA+DHA fish oil for cardiovascular and triglyceride outcomes; DHA-dominant or algae oil for pregnancy and infant cognitive development. Pure EPA (Vascepa / icosapent ethyl) is FDA-approved for hypertriglyceridemia. ALA from flaxseed/chia converts poorly to EPA/DHA in humans
Common side effects
Fishy aftertaste, eructation (burping), mild stomach discomfort. Generally well-tolerated. Higher doses (≥3 g/day) increase digestive side-effect rates
Drug interactions
Mild bleeding risk with blood thinners (warfarin and similar) and antiplatelets — clinically significant bleeding is rare at common doses but worth flagging. May increase atrial fibrillation risk at high doses (≥1 g/day)
Reading the label
"Fish oil 1,000 mg" typically delivers ~300 mg combined EPA+DHA — far below trial doses. Look at the EPA+DHA mg specifically, not total fish-oil mass. Concentrated formulations (60%+ omega-3) deliver more per capsule
EPA vs DHA
EPA dominates the cardiovascular, triglyceride, and depression evidence base. DHA dominates the pregnancy and infant-development evidence base. Most fish oils contain both; algae oil is DHA-dominant
Vegan alternatives
Algae-derived omega-3 provides DHA (and some EPA in newer formulations) without fish-source contaminants. ALA from flaxseed, chia, walnut converts to EPA/DHA at <10% efficiency in humans — not a clinical substitute

Quality-verified products

Products that pass third-party quality testing.

Product quality data coming soon

Product recommendations are being built from USP Verified, NSF Certified, and Labdoor test data. Products will only appear here after the supplement itself clears the evidence bar above — and only if the product passes third-party purity testing.

How we graded Omega-3

Grades come from 323 unique research papers indexed from PubMed — including 130 meta-analyses, 48 systematic reviews, 18 Cochrane reviews, and 101 randomized trials. Omega-3's literature has unusual structural complexity: trials use different forms (EPA-dominant, DHA-dominant, balanced fish oil, ALA flaxseed, algae oil, krill oil) at different doses, and most reviews legitimately pool these forms together. The grading rubric treats those pooled-form reviews as usable evidence — they're a property of the literature, not a quality flaw — and applies a subgroup-A rule that lets health effects grade A when reviews consistently report positive findings within a defined subgroup, even if the pooled effect looks modest. Depression graded A under this rule because reviews consistently report positive effects in moderate-to-severe depression and EPA-major formulations. Each supplement is graded by health effect using a certainty × effect matrix applied across PubMed evidence per health effect. Cochrane reviews and high-quality systematic reviews carry the most weight. From abstract-only data, "high certainty" is rare — most A grades come from moderate certainty plus consistent meaningful-positive evidence. See Methodology for full detail.

Read the full methodology → · Download all 323 citations (PDF)