“Contains omega-3” tells you very little. To compare supplements properly, you need to read the individual EPA and DHA amounts, calculate the daily serving—not the amount in one capsule—and identify the chemical form.

PRN De3 is designed around 1,680 mg EPA plus 560 mg DHA in three softgels. This article explains why that 3:1 ratio matters and where the science is still uncertain.

EPA and DHA are related, not identical

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are long-chain marine omega-3 fatty acids. Both can be incorporated into cell membranes and used to form signalling molecules, but their structures and biological roles differ.

Calling EPA “anti-inflammatory” and DHA “structural” is a useful shorthand, but biology is more complicated. Both influence membranes and lipid mediators. The relevant point for shoppers is that a formula dominated by EPA is making a different design choice from a DHA-heavy prenatal product or a 1:1 general wellness oil.

How is the 3:1 ratio calculated?

Divide EPA by DHA: 1,680 ÷ 560 = 3. The ratio is therefore three parts EPA to one part DHA. EPA represents 75% of the combined 2,240 mg, while DHA represents 25%.

Do not divide by the bottle's total fish-oil weight or compare one PRN softgel with another brand's full daily serving. Use the labelled daily dose for both products.

Why might a high-EPA formula matter in dry eye?

Dry eye often involves tear-film instability, ocular-surface stress and inflammatory signalling. Meibomian gland dysfunction can reduce the quality or delivery of the oil layer that slows evaporation. Omega-3 research explores whether shifting the fatty-acid environment can influence those processes over time.

A 2023 systematic review and meta-analysis found that higher omega-3 dose, longer treatment and a greater percentage of EPA were each associated with larger symptom reductions across included randomized trials. This supports examining the ratio rather than buying on “fish oil” alone.

Why not use EPA alone?

DHA remains an important long-chain omega-3 and is abundant in retinal and neural tissue. PRN De3 does not eliminate DHA; it supplies 560 mg daily. The formula emphasizes EPA while preserving a meaningful DHA contribution.

An EPA-only supplement would also no longer match the formula used in the PRN-related dry-eye trials. When evaluating clinical relevance, matching the studied dose and composition matters.

How does PRN De3's ratio compare?

PRN is not simply “the highest EPA number.” Its differentiator is the combined package: 2,240 mg EPA+DHA, a deliberate 3:1 ratio, rTG form, vitamin D3 and formula-specific dry-eye studies. Other U.S. products make different choices—more DHA, GLA, broader micronutrients, or vegan algae oil. See the full U.S. dry-eye supplement comparison.

Does the form matter as much as the ratio?

It can. PRN De3 supplies EPA and DHA in re-esterified triglyceride form. A six-month randomized study found a greater rise in the omega-3 index with rTG than with an equivalent ethyl ester dose. Other pharmacokinetic research shows that meal composition and formulation affect absorption.

This is why a sound comparison asks four questions together: How much EPA? How much DHA? In what ratio? In what form? A low-dose rTG product is not automatically equivalent to a high-dose rTG product, and a high number on an ethyl ester label does not guarantee the same incorporation.

Why does PRN De3 also contain vitamin D3?

The daily dose includes 1,000 IU (25 mcg) vitamin D3. Research has linked low vitamin D status and dry-eye findings, and a randomized trial in vitamin-D-deficient patients found improved tear measures after supplementation. That does not prove that adding D3 improves outcomes in every omega-3 user.

Count vitamin D from all supplements before combining products. People with conditions affecting calcium or vitamin D should ask a clinician first.

How should you use ratio information?

1. Compare the full daily serving.
2. Add EPA and DHA to find the active long-chain omega-3 dose.
3. Calculate EPA ÷ DHA.
4. Identify rTG, TG, ethyl ester or another form.
5. Check added nutrients and allergens.
6. Read the current Supplement Facts panel and manufacturer quality information.
7. Review evidence for the actual formula—not omega-3 in the abstract.

PRN De3 scores well because its specifications are transparent and clinically relevant. The ratio is one reason it is a leading dry-eye omega, but not the only reason.

Frequently asked questions

Is a 3:1 EPA:DHA ratio proven best for dry eye?

No. It is a well-defined, high-EPA design supported by formula-specific studies and a meta-regression signal, but head-to-head ratio trials are insufficient to declare one universal optimum.

Is 2,240 mg the amount per capsule?

No. It is the combined EPA plus DHA in the full three-softgel daily serving.

Should I choose the product with the highest EPA number?

Not automatically. Consider total dose, DHA, form, quality, added ingredients, tolerability, capsule count and professional advice.

Sources

• EyeDropShop U.S.: PRN De3
• Wang and Ko, 2023 meta-analysis
• Neubronner et al., rTG versus ethyl ester
• Vitamin D supplementation randomized trial
• EyeDropShop U.S. omega-3 collection

Educational information only. Consult a healthcare professional before changing supplements, especially if you take blood thinners or other vitamin D products.