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Omega-3 Dosing: Bioavailability-Adjusted EPA + DHA Across Formulations

The omega-3 calculator picks dose, formulation, and AF cap from your goal and meal context. The unique signal is the absorbed mg after bioavailability adjustment — re-esterified TG with food delivers about 85% of the label dose; ethyl ester on a low-fat meal drops to roughly 30%. The same number on the bottle can be 2–3x apart in physiological exposure.

The decision tree

Three branches in order: goal drives the dose range, AF history caps the upper bound, formulation × meal context computes the absorbed mg.

1. Daily EPA + DHA range (by goal):

  • General health: 1000–2000 mg/day
  • Cardiovascular prevention: 1000–2000 mg/day (Cochrane PMID 32114706, 86 RCTs / 162,796 participants)
  • Triglyceride reduction: 2000–4000 mg/day (REDUCE-IT PMID 30415628 used 4 g/day icosapent ethyl, 25% relative-risk reduction in CV events)
  • Rheumatoid arthritis: 2700–3000 mg/day, EPA-rich (Gkiouras 2024 MA, PMID 35900212; 23 RCTs)
  • Pregnancy: 300–600 mg DHA/day (Cochrane PMID 30480773; preterm birth RR 0.89, early preterm RR 0.58)

2. AF cap (REDUCE-IT signal):

REDUCE-IT reported AF/flutter hazard ratio 1.5 at 4 g/day icosapent ethyl, with 3.1% on treatment vs 2.1% on placebo. The calculator caps the dose at 2000 mg/day for users with prior AF history regardless of goal — this is the trial's clearest contraindication signal. For users without AF history, doses at or above 4 g/day surface a non-blocking warning. Real-world AF rates are 1/3 to 1/5 of trial rates, but the signal is real.

3. Bioavailability multiplier:

The calculator's wedge over a generic dose chart is the absorbed-mg adjustment:

  • Re-esterified TG (rTG): about 85% absorption with a fatty meal
  • Natural TG: about 65% absorption
  • Ethyl ester (EE) with a fatty meal: about 65% absorption
  • Ethyl ester on a low-fat meal: drops to roughly 30%
  • Krill oil (phospholipid): about 75% absorption, self-emulsifying
  • Algal oil: about 65% absorption

Many "negative" omega-3 trials used EE without controlling fat intake. The trial used the dose; patients did not absorb it. The same product can deliver 2–3x different physiological exposure depending on meal context.

What the calculator does NOT cover

  • Prescription icosapent ethyl (Vascepa) at 4 g/day for established CVD + TG >=150 — clinician-prescribed; covered in the dosing range but the prescription path requires statin pre-treatment per REDUCE-IT eligibility.
  • PISCES-style 4 g EPA+DHA in hemodialysis patients (PMID 41201837, NEJM 2026) — clinician-supervised; CV event hazard ratio 0.57 in CKD populations is a major finding but out of scope for self-serve dosing.
  • Cancer prevention — Cochrane and large RCTs show no consistent benefit; the calculator does not include this indication.
  • ADHD adjunctive at 500–1000 mg/day — small effect size (d about 0.2), consider clinician guidance; not surfaced as a goal here.
  • Triple antithrombotic therapy — relative contraindication; surface to cardiology before adding fish oil.

Where the math stops being safe to extrapolate

The Cochrane 2020 review (PMID 32114706) is the most extensive systematic assessment of omega-3 cardiovascular effects. Key findings: little or no effect on all-cause mortality (high-certainty), cardiovascular mortality (moderate-certainty), or stroke (moderate-certainty). The benefit is narrower than the supplement industry implies: triglyceride reduction is real and dose-dependent (high-certainty); coronary heart disease mortality and events are slightly reduced (low-certainty). The calculator only dispenses doses for indications with non-trivial effect sizes; it does not pretend to extend lifespan in healthy adults.

The bioavailability adjustment is itself an estimate. Published ranges for each formulation span 50–95% (rTG), 40–80% (TG), 20–70% (EE), and the exact number depends on the specific product, capsule technology, and individual gut absorption. The calculator uses midrange values — treat the absorbed mg as a reasonable expectation, not a guarantee. The Omega-3 Index blood test is the only way to verify you actually reached therapeutic exposure.

The RA evidence in particular is more modest than older meta-analyses suggested. Gkiouras 2024 (PMID 35900212, 23 RCTs) found small effects on pain (SMD -0.16), tender joints (-0.20), and swollen joints (-0.10), and the certainty of evidence was rated mostly low to very low. The calculator includes the indication because the signal is consistent and the safety profile is favourable, but the language emphasizes that supplementation does not replace DMARDs.