What is the difference between triglyceride and ethyl ester omega-3?

In natural fish oil, EPA and DHA are attached to a glycerol backbone as triglycerides — the same molecular form found in whole fish. To concentrate EPA/DHA, manufacturers use ethanol transesterification, replacing the glycerol with ethanol to create ethyl esters. This form is cheaper to produce but absorbs approximately 27% less efficiently. Re-esterified triglyceride (rTG) products reconvert the ethyl esters back to a triglyceride structure, recovering the absorption advantage at a higher cost.

Is krill oil better than fish oil?

Krill oil and fish oil have different strengths. Krill oil carries omega-3s as phospholipids, which may preferentially cross the blood-brain barrier and are absorbed without requiring bile acids. Krill oil also contains choline and astaxanthin. However, krill oil provides significantly less EPA and DHA per capsule than concentrated fish oil products. For achieving higher omega-3 blood levels, a high-quality rTG fish oil typically offers better gram-for-gram efficiency.

Should omega-3 supplements be taken with food?

Yes. Omega-3 absorption is significantly higher when taken with a fat-containing meal. A meal with dietary fat stimulates bile acid release, which is required for effective absorption of triglyceride-form omega-3s. A 2017 pharmacokinetic study of omega-3-carboxylic acids (PMID 28344197) found that EPA and DHA concentrations were meaningfully lower when omega-3s were taken in a fasted state compared to after a meal — an effect particularly pronounced with ethyl ester forms.

Moderate Evidence

Best Omega-3 Form: Which One Actually Works?

Fish oil supplements differ substantially in how they deliver EPA and DHA to the body. The molecular form — natural triglyceride, ethyl ester, or re-esterified triglyceride — determines how efficiently the omega-3 fatty acids are absorbed. Most budget fish oils use the ethyl ester form for cost reasons, but this form consistently underperforms triglyceride-based products in absorption studies.

Updated 2026 · Reviewed by Dr. Brennan Commerford, D.C.

All Forms Ranked by Evidence

1
100/ 100· Top TierBest by EvidenceFF Preferred
Omega-3 EPA/DHA (AvailOm® High EPA) 2:1
Form: AvailOm® High EPA
2
95/ 100· Top Tier
Omega-3 EPA/DHA (triglyceride)
Form: triglyceride
3
70/ 100· Solid
Omega-3 EPA/DHA (ethyl ester)
Form: ethyl ester
—
Verification pending
ALA (Alpha-Linolenic Acid) Flax
Form: Standard
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pending
Algal DHA
Form: Standard
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pending
Algal DHA (Non-esterified)
Form: Non-esterified
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pending
Algal Oil
Form: Oil
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pendingFF Preferred
Availom High DHA
Form: AvailOm®
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pending
DHA (from Algae) 80mg
Form: Microalgae
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pending
Docosahexaenoic Acid Ethyl Ester
Form: Standard
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pending
EPA+DHA
Form: Free Fatty Acids
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pending
Fish Oil
Form: Oil
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pending
Krill Oil
Form: Oil
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pending
Krill Oil (Phospholipid-Bound EPA/DHA)
Form: Phospholipid-Bound EPA/DHA
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pending
Omega 3 Fatty Acids
Form: Standard
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pending
Omega-3
Form: Base
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pending
Omega-3 DHA Microalgae Oil
Form: Microalgae Oil
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pending
Omega-3 EPA/DHA (FFA Lysine Complex)
Form: FFA Lysine Complex
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pending
Omega-3 Fatty Acid Ethyl Ester
Form: Ethyl Esters
Evidence for this form is under review — no score is shown until it is verified.
—
Verification pending
Triglyceride, Ethyl-Ester & Phospholipids Omega-3 Forms
Form: Standard
Evidence for this form is under review — no score is shown until it is verified.

Plant-based omega-3s

These forms are not scored on this ranking. Plant sources provide ALA, which the body converts to EPA and DHA at low rates.

Editorial note

The rTG form achieves approximately 124% relative bioavailability compared to natural fish oil (the 100% reference), outperforming ethyl ester concentrates (~73%) in head-to-head absorption studies. The triglyceride backbone mirrors the natural structure of EPA and DHA in food.

All Forms Compared

Re-esterified Triglyceride (rTG)

Best For

Cardiovascular support, anti-inflammatory support

EPA/DHA re-attached to a glycerol backbone — mirrors the natural food form.

Natural Triglyceride (NTG)

Best For

Moderate-concentration fish oil, food-first approach

The form found in whole fish. Lower EPA/DHA concentration per gram than concentrates.

Krill Oil (Phospholipid Form)

Best For

Brain support, smaller daily dose

Contains choline alongside omega-3s. Lower absolute EPA/DHA per capsule than fish oil concentrates.

Ethyl Ester (EE)

Best For

N/A — most budget fish oil concentrates

Requires pancreatic esterase to cleave the ethyl group before absorption. Absorption is further reduced when taken in a fasted state.

Frequently Asked Questions

What is the difference between triglyceride and ethyl ester omega-3?: In natural fish oil, EPA and DHA are attached to a glycerol backbone as triglycerides — the same molecular form found in whole fish. To concentrate EPA/DHA, manufacturers use ethanol transesterification, replacing the glycerol with ethanol to create ethyl esters. This form is cheaper to produce but absorbs approximately 27% less efficiently. Re-esterified triglyceride (rTG) products reconvert the ethyl esters back to a triglyceride structure, recovering the absorption advantage at a higher cost.
Is krill oil better than fish oil?: Krill oil and fish oil have different strengths. Krill oil carries omega-3s as phospholipids, which may preferentially cross the blood-brain barrier and are absorbed without requiring bile acids. Krill oil also contains choline and astaxanthin. However, krill oil provides significantly less EPA and DHA per capsule than concentrated fish oil products. For achieving higher omega-3 blood levels, a high-quality rTG fish oil typically offers better gram-for-gram efficiency.
Should omega-3 supplements be taken with food?: Yes. Omega-3 absorption is significantly higher when taken with a fat-containing meal. A meal with dietary fat stimulates bile acid release, which is required for effective absorption of triglyceride-form omega-3s. A 2017 pharmacokinetic study of omega-3-carboxylic acids (PMID 28344197) found that EPA and DHA concentrations were meaningfully lower when omega-3s were taken in a fasted state compared to after a meal — an effect particularly pronounced with ethyl ester forms.

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Deep dive: Re-esterified Triglyceride (rTG) research

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Emerging-evidence note

The brain-delivery finding cited above comes from a small preliminary trial conducted specifically in adults at elevated genetic risk for Alzheimer's disease (APOE4 carriers); it does not apply to the general population. That same trial found no difference in cognitive scores between groups, so this is a delivery/mechanism finding only — more research is needed. Talk to your physician before use.

FormulaForge formulates and sells supplements containing the ingredients discussed on this page. Our formulary recommendations are based on peer-reviewed bioavailability research. All cited studies are independently verifiable.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.