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Reviewed by the Scan Dose Research Team and Clinical Advisory Board

DHA

MODERATE EVIDENCEFatty AcidLast updated

SCAN DOSE SUMMARY

DHA is the omega-3 that builds BRAINS — literally. It makes up 40% of all polyunsaturated fatty acids in the brain and 60% of the fatty acids in the retina. Our research shows DHA is not just another omega-3: it has distinct functions from EPA. EPA is primarily anti-inflammatory, but DHA is structural — it's physically incorporated into neuronal membrane phospholipids, modulating membrane fluidity, receptor function, and synaptic signaling. For brain development (pregnancy, infancy), DHA supplementation has STRONG evidence. For depression, EPA appears more important than DHA. The two serve different biological roles despite being lumped together as "fish oil."

WHAT IT DOES

DHA is incorporated into membrane phospholipids (primarily phosphatidylethanolamine and phosphatidylserine) of neurons and photoreceptors. Its 22-carbon, 6-double-bond structure creates unique membrane properties: (1) membrane fluidity — DHA's highly unsaturated chains keep membranes fluid, enabling rapid receptor conformational changes (essential for neurotransmission and rhodopsin function in vision); (2) lipid raft organization — DHA modulates cholesterol-rich microdomains critical for signal transduction; (3) neuroprotectin D1 (NPD1) synthesis — DHA is enzymatically converted to NPD1, a specialized pro-resolving mediator that protects neurons from oxidative damage and apoptosis; (4) BDNF expression — DHA upregulates brain-derived neurotrophic factor; (5) anti-inflammatory via resolvin D series production.

OPTIMAL DOSAGE

  • Look for: DHA content specifically quantified (not just "fish oil"); triglyceride or phospholipid form; algal source for vegan; IFOS 5-star certified
  • Avoid: Ethyl ester form (lower bioavailability); products only listing total omega-3 (may be mostly EPA); rancid products (check expiry, smell)
  • Minimum effective dose: 200mg/day (general); 300mg/day (pregnancy); 900mg/day (cognitive decline)
  • Third-party tested brands: Nordic Naturals, Life's DHA (algal), Carlson, PRN Omega-3
Scan a supplement containing DHA

SAFETY PROFILE

Moderate Interactions (Monitor Closely)

WHO SHOULD BE CAREFUL

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Quality Testing Intelligence

Based on independent third-party laboratory analysis

Category pass rate: ~90% of fish oil products passed content testing. Rancidity is the primary failure mode — ~10% of products are already oxidized before opening.

Common failures:
Rancidity: Some products oxidized (peroxide >5 meq/kg). Jamieson at 48 meq/kg = 9.6x over limit.
Form confusion: Ethyl ester vs triglyceride (TG is better absorbed but pricier)
Concentration variation: 250mg to 2,000mg EPA+DHA per serving
Form comparison:
Form: Absorption: Price: Notes
Triglyceride (rTG): HIGHEST (30-50% better): Premium: Carlson, WHC UnoCardio, Garden of Life
Ethyl Ester (EE): MODERATE: Standard: Most common form. InnovixLabs, GNC.
Phospholipid (Krill): HIGH (per mg): Most expensive: Lower total EPA+DHA per pill

Contamination risk: MODERATE. All tested products passed heavy metal testing. Mercury, lead, cadmium all below detection limits. Fish oil purification processes (molecular distillation) effectively remove contaminants.

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Reviewed by the Scan Dose Research Team and Clinical Advisory Board | Last updated:

Not medical advice. Based on published clinical research and systematic reviews.

Safety

Fish Oil / Omega-3: Drug Interactions

Do not combine

Dangerous interactions. Talk to your prescriber before using this supplement if you take any of these.

  • Warfarin (Coumadin)

    Omega-3 inhibits platelet aggregation, producing an additive anticoagulant effect on top of warfarin.

    RiskIncreased bleeding risk and elevated INR.
    ActionMonitor INR closely. Reduce dose if INR rises.

    Source: PMID: 25062404

  • Clopidogrel (Plavix)

    Dual antiplatelet effect.

    RiskIncreased bleeding risk.
    ActionMonitor for unusual bruising or bleeding.

    Source: FDA label

  • High-dose Aspirin

    Additive antiplatelet effect.

    RiskIncreased bleeding.
    ActionUse caution at omega-3 doses above 3g per day.

    Source: Clinical consensus

Use with caution

Moderate interactions. Monitoring, timing separation, or dose adjustment may be required.

  • Blood pressure medications

    Omega-3 may lower BP modestly.

    RiskHypotension when combined.
    ActionMonitor BP when starting omega-3.

    Source: Clinical consensus

  • Orlistat (Alli)

    Reduces fat absorption, including omega-3.

    RiskReduced omega-3 efficacy.
    ActionSeparate by 2 or more hours.

    Source: FDA label

Stop 2 weeks before surgery

Bleeding risk from antiplatelet effect.

Educational information only. This is not medical advice. These statements have not been evaluated by the FDA. Talk to your prescriber before starting, stopping, or combining any supplement with prescription medication.

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