Natural Factors RxOmega-3
vs
Douglas Laboratories Opti-EPA™ 500
Supplement Comparison

  • The image below shows:
    • Side-by-side charts with label nutrient amounts, per serving
    • Nutrient forms as listed on the label
    • 4 nutrients compared
Bar chart: per-serving label amounts and listed forms for Natural Factors RxOmega-3 vs Douglas Laboratories Opti-EPA™ 500.

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Frequently asked questions

Which active ingredients does Natural Factors RxOmega-3 have?

  • Eicosapentaenoic Acid (EPA) appears as Unspecified
  • Docosahexaenoic Acid (DHA) appears as Unspecified

Which active ingredients does Douglas Laboratories Opti-EPA™ 500 have?

  • Eicosapentaenoic Acid (EPA) appears as Unspecified
  • Docosahexaenoic Acid (DHA) appears as Unspecified

Which categories do Natural Factors RxOmega-3 and Douglas Laboratories Opti-EPA™ 500 belong to?

  • Fish Oil and Omega-3

What health concerns do Natural Factors RxOmega-3 and Douglas Laboratories Opti-EPA™ 500 address?

  • Anti-Inflammatory Support
  • Brain, Focus & Cognitive Function
  • Eye Health
  • General Health
  • Heart & Cardiovascular Health
  • Joint & Bone Health

Which product has a higher amount of EPA + DHA (combined EPA+DHA content - individual amounts of EPA+DHA not specified) per serving?

  • Natural Factors RxOmega-3 has the highest total amount of EPA + DHA (combined EPA+DHA content - individual amounts of EPA+DHA not specified): 1200 mg per serving

How do the serving sizes compare between the two supplements?

  • Serving size:
    • Natural Factors RxOmega-3: 2 softgels
    • Douglas Laboratories Opti-EPA™ 500: 1 softgel

Last updated: February 4, 2026

  • Sources & Methodology: Nutrient data and forms are taken directly from Supplement Facts labels. Reviewed and standardized by the VIOscan Research Team. Learn more on the Methodology page.
  • We show the Recommended Dietary Allowance (RDA) when available. If no RDA exists, we show the Adequate Intake (AI). Tolerable Upper Intake Levels (UL) are used for upper limits. Unless otherwise noted, RDAs shown correspond to healthy adults aged 19–50 years and are sex-specific. Separate values exist for 51–70 years and >70 years, and pregnancy and lactation are excluded. All values come from the Dietary Reference Intakes (DRIs) published by the National Academies of Sciences, Engineering, and Medicine (NASEM), Food and Nutrition Board (FNB).
  • Transparency: We’re funded by our users. We don’t have sponsors or affiliate links, and we don’t sell supplements.
  • Editorial standards: we provide independent, impartial and objective data analysis.
  • This analysis is for educational purposes only. It is not a substitute for medical advice.
  • Questions? Read our Frequently Asked Questions or contact us, we’re here to help.
  • See an error? Report it through our Contact page.
  • Author: VIOscan Research Team