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Omega-3

Omega-3

Best for

Raise omega-3 levels

Likely strong benefit · 2.5–9120 mg/day for 0–244 weeks · 1 meta-analysis , n=3k

197 papers · 16 claims · 319 outcomes scored · 14 positive

Evidence summary

Evidence summary

Likely strong benefit

Omega-3 delivers a likely strong benefit for raising omega-3 status and building nutrient stores in pregnancy, with meaningful benefits for triglycerides and dry eye.

  • Across 35 studies (n=3,050), omega-3 raised omega-3 status across 103 endpoints.2
  • The evidence base spans 197 papers and 319 outcomes, dominated by positive biomarker and eye-health results.
  • Benefits depend on EPA/DHA dose, baseline status, and product type, especially across non-biomarker outcomes.

Outcomes

What omega-3 actually does, by outcome

Each row is one outcome with effect size, evidence base, the dose that worked in trials, and time to first effect. Magnitude tiers come from native-unit MCID where available, Cohen's d otherwise.

Raise omega-3 levels Likely strong benefit

EPA and DHA build up in blood and cell membranes where they work.

35 meta-analyses n=3.0k 2.5–9120 mg 0–244 wk #1/6
19436468·19709502·21115589·21816071 +31 more
Build nutrient stores in pregnancy Likely strong benefit

Tops up the reserves pregnancy drains fastest.

1 RCT n=238 200–1000 mg — #2/4
26413500
Lose body fat Large effect, needs confirmation

Body fat percentage drops and the mirror shows it before the scale does.

5 RCTs n=136 3–3900 mg 8–26 wk #8/57
25852206·33572368·36079794·37081029 +1 more
Slow macular degeneration progression Likely strong benefit

Slows retinal damage to preserve the central vision you use most.

2 meta-analyses n=— 1000 mg 260 wk #2/5
41482231·31358387
Protect against macular degeneration Large effect, needs confirmation

Builds the protective pigment that shields your central vision from age.

2 meta-analyses n=— 1000 mg 260 wk #1/6
31358387·41482231
Ease dry, gritty eyes Likely benefit

Builds a steadier tear film so your eyes stay comfortable between blinks.

6 meta-analyses n=6.4k 300–3000 mg 8–52 wk #1/3
27442314·31425752·38002640·40557177 +2 more
Improve school results in children Likely benefit

Better reading scores, sharper math, and fewer absences.

2 RCTs n=362 600–800 mg 16 wk
27188814·22970149
Lower triglycerides Proven modest benefit

Reduces the blood fats that rise after meals and drive heart risk.

32 meta-analyses n=116k 0.3–14000 g 3–183 wk #1/90
23817470·23835245·24507770·25852206 +28 more
Protect vision in retinal disease Faint early signal

Keeps sight sharper and retinal signals healthier when disease threatens.

3 meta-analyses n=5.6k 600–3600 mg 208 wk #5/5
29546296·32573764·24805262
Slow cognitive decline in dementia Proven modest benefit

Memory, attention, and orientation hold up longer before fading.

6 meta-analyses n=2.7k 480–3000 mg 17–156 wk #3/23
24077434·26501267·28075381·29083439 +2 more
Improve omega-3 to omega-6 ratio Likely modest benefit

Less raw material for inflammation, more for resolving it.

14 meta-analyses n=1.1k 2.5–9120 mg 3–56 wk #1/6
19436468·21816071·26730723·27565734 +10 more
Boost overall cognitive performance Barely detectable

Broad gains in memory, speed, and mental sharpness at once.

7 meta-analyses n=14k 230–4950 mg 26–260 wk
24507770·26305649·34113957·35373862 +3 more
Strengthen healthy birth weight Proven but unnoticeable

Babies who arrive at the right size face fewer risks at birth.

2 meta-analyses n=8.7k 200–1000 mg — #6/7
26413500·30480773
Strengthen your memory Proven but unnoticeable

Names, conversations, faces, and details stick instead of dissolving.

11 meta-analyses n=1.5k 37–4950 mg 16–156 wk #6/42
25786262·26501267·29083439·31581959 +7 more
Sharpen visual clarity Not enough research

Pick out finer detail, edges, and text more easily.

2 meta-analyses n=5.5k — —
29546296·32573764
Build thinking skills in children Doesn't appear to help

Stronger problem-solving, reasoning, and school performance as children grow.

3 meta-analyses n=5.5k 800 mg —
25803546·27188814·29546296

Forms & standardisation

The best-studied products list the actual milligrams of EPA and DHA, not just the words fish oil23. That detail matters more than the brand name, because two softgels can look the same on the front of the bottle and deliver very different active doses. For eye and blood-fat outcomes, standard fish-oil capsules and purified EPA or EPA plus DHA oils both show up in trials, so the label math matters more than the marketing12.

Risk profile

Adverse events and known drug interactions

Safety events

atrial fibrillation severe
Diarrhea severe
Epistaxis (nosebleed) severe
Severe GI events resulting in treatment discontinuation severe
Dyspnea severe
pain in extremity (grade 3, single case reported) severe
pain severe
hemoglobin_decreased severe

Drug interactions

Cyclophosphamide major decreases effect
Acetaminophen major increases toxicity
Lipid Modifying Agents major increases toxicity
Aspirin moderate increases effect
Warfarin moderate additive
Valproic Acid moderate increases effect
Tazobactam moderate increases concentration
Atorvastatin moderate increases concentration
Antithrombotic Agents moderate increases toxicity
Celecoxib moderate additive

Co-studied with

Supplements that share evidence with omega-3

Omega6Fattyacids Group 8 shared outcomes · d=0.36
Arachidonicacid 4 shared outcomes · d=1.84

Frequently asked

Common questions

How long does omega-3 take to work?

Blood omega-3 levels usually shift over 6 to 12 weeks of daily use. Dry eye studies also judge results over weeks, not days, so this is not a one-and-done supplement123.

Should you take omega-3 with food?

Yes. Taking it with a meal, especially one that includes fat, improves absorption and usually feels easier on your stomach23.

What is the difference between fish oil, EPA, and DHA?

Fish oil is the source, EPA and DHA are the active fats. A good label tells you the milligrams of EPA and DHA separately, because the same capsule weight can deliver very different doses2.

Does omega-3 help memory?

The memory data look small and inconsistent. Some studies see tiny wins, but omega-3 does not stand out as a mental upgrade supplement5.

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Sources

  1. 1. n-3 Fatty Acid Supplementation for the Treatment of Dry Eye Disease (2018) ↑
  2. 2. Omega-3 Fatty Acids Fact Sheet for Health Professionals (2024)
  3. 3. Omega-3 fatty acids and triglyceride lowering, systematic review and meta-analysis
  4. 4. Omega-3 fatty acids and age-related macular degeneration, clinical trials and review
  5. 5. Omega-3 fatty acids and cognitive decline, systematic review and meta-analysis

Generated May 15, 2026

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