Triglyceride vs Ethyl Ester Fish Oil (2026): The Form That Matters
Triglyceride fish oil absorbs a little better than ethyl ester: across 14 trials, it raised the omega-3 index about 1 point more at the same dose.
That index is the share of omega-3 in your red blood cells. The “70% better” claim on labels comes from one 2-week study. Krill oil has not been shown to beat fish oil at the same dose. Algae oil is the choice if you eat no fish. Whatever the form, take it with your biggest meal.
So buy on how much EPA and DHA you get per dollar, and on a published lot test. You don’t have to trade one for the other: our pick is an rTG oil and the cheapest of the fish oils on a testing list.
Where the “70% better” claim comes from
It comes from a 2010 study. 72 people took about 3.3 g of omega-3 a day for 2 weeks, in different forms. Re-esterified triglyceride (rTG) came out ahead. rTG is fish oil that is concentrated and then turned back into the form found in fish. Ethyl ester, the form fish oil takes when it is concentrated, came last.
| Item | Value |
|---|---|
| Re-esterified triglyceride (rTG) | 124 |
| Natural triglyceride (fish oil) | 100 |
| Free fatty acid | 91 |
| Ethyl ester (EE) | 73 |
So “70% better” holds for one pair, rTG against ethyl ester, after two weeks, in blood drawn before breakfast. Turned around, ethyl ester raised blood levels about 41% less than rTG. It is not a rule for every triglyceride oil, and it is not what happens over months.
Over months, the gap shrank
Longer studies found a much smaller gap, and one found no clear difference. A 2025 review ranked the free fatty acid and phospholipid (krill) forms above triglyceride. It also found that short-term gaps often did not last. One of its authors owns stock in OmegaQuant, a lab that sells omega-3 blood tests.
Figure 2. What the longer studies found
- 2011Neubronner and colleagues150 people took the same dose for 6 months. The omega-3 index rose 197% on rTG and 171% on ethyl ester. Both worked. PubMed
- 2015Yurko-Mauro and colleaguesAt a matched 1.3 g a day for 4 weeks, ethyl ester, triglyceride and krill oil did not differ significantly. DSM, an omega-3 oil maker, paid for it. PubMed
- 2019Walker and colleaguesPooling trials with 1,422 people, triglyceride oils came out ahead of ethyl ester, gram for gram. Some authors work for an omega-3 test company and the omega-3 trade group. PubMed
“significant differences observed in acute bioavailability studies … often did not translate into long-term impacts”
What a meal does
A fatty meal matters most for ethyl ester. In two small studies from 1988, ethyl ester was poorly absorbed with a low-fat meal. With a meal that had 44 g of fat, it was absorbed about three times better. Triglyceride changed less.
| Item | Value |
|---|---|
| Triglyceride, low-fat meal | 68% |
| Triglyceride, high-fat meal | 90% |
| Ethyl ester, low-fat meal | 20% |
| Ethyl ester, high-fat meal | about 60% |
Krill, algae and cod liver oil
| Form | What the evidence says |
|---|---|
| PhospholipidKrill oil · Few people: it holds little EPA+DHA per capsule | Some small studies found krill raised blood omega-3 more; others found no difference at matched doses (PMID 26328782, 36960737). In one 28-day study at each label’s dose, a concentrated rTG oil raised blood omega-3 most, then ethyl ester, salmon oil and krill. Dose and form changed together, and the authors said both may matter (PMID 24952576). Nordic Naturals, an rTG maker, paid for it, and Nutrasource, the company that also runs IFOS, ran it. That does not make the result wrong, but it is not an independent test. A krill capsule holds much less EPA and DHA than a fish oil concentrate, so you need several. |
| Algal oilAlgae · People who eat no fish | Made from the algae fish get their omega-3 from, usually in triglyceride form and often richer in DHA than EPA. In a two-week study of 32 adults, algal DHA capsules raised blood DHA as much as the same DHA from cooked salmon (PMID 18589030). It costs more per gram than fish oil. |
| Cod liver oilCod liver · Only if you want its vitamin A and D too | It adds vitamin A and vitamin D. The adult upper limit for preformed vitamin A is 3,000 mcg a day, including in pregnancy, and too much can cause birth defects, so do not stack it with other vitamin A (NIH ODS). Read the vitamin A line on the label. |
Most labels won’t tell you
We read 620 fish oil labels in NIH’s label database that give an omega-3 figure. 87% do not name the form on the panel. If yours is silent, check the brand’s website.
Form does not set the price
The better-absorbed forms don’t cost more. The cheapest rTG, triglyceride and ethyl ester oils we compare cost $0.21 to $0.34 per 1,000 mg of EPA+DHA on Amazon. The cheapest of all, NOW Ultra Omega-3, is an ethyl ester and is not on a testing list. The one algae oil we score costs $1.15.
| Form | Per 1,000 mg | Products |
|---|---|---|
| Re-esterified triglyceride (rTG) | $0.30 to $0.62 | Viva Naturals Triple Strength (1,035 mg a softgel); Nordic Naturals Ultimate Omega (550 mg a softgel) |
| Triglyceride (TG) | $0.34 to $0.83 | Sports Research Triple Strength (950 mg a softgel); Puori O3 Fish Oil (583 mg a softgel); Momentous Omega-3 (800 mg a softgel) |
| Ethyl ester (EE) | $0.21 to $0.66 | NOW Ultra Omega-3 (750 mg a softgel); Carlson Elite Omega-3 Gems (700 mg a softgel); Thorne Super EPA (695 mg a softgel) |
| Algae oil | $1.15 | Nordic Naturals Algae Omega (293 mg a softgel) |
| Form not named on the label | $0.42 to $0.97 | Nature Made Fish Oil 1200 mg (300 mg a softgel); Barlean’s Ideal Omega 3 (1,000 mg a softgel) |
Freshness is the other question
Fish oil can oxidize, or go rancid, and the label won’t tell you. Store-shelf studies disagree on how often, from about 1 in 10 to more than 8 in 10, depending on the test. IFOS posts each enrolled lot’s oxidation test. See how to check freshness.
Which form to buy
- Most people: a triglyceride or rTG oil with the most EPA and DHA per dollar and a published lot test. Our pick above is one. All 11 are ranked in the best fish oil, and the triglyceride oils alone in the best triglyceride fish oil.
- You eat no fish: algae oil. See our algae pick.
- You already take a fish oil, even an ethyl ester: you don’t need to switch. The meal advice above is enough.
- Your label doesn’t name the form: the same meal advice covers either form.
Questions people ask
What is triglyceride form omega-3?
It is the form omega-3 takes in fish. Re-esterified triglyceride (rTG) is fish oil that was concentrated and then turned back into that form. Ethyl ester is the form concentrated fish oil takes if it is not turned back.
Is triglyceride or ethyl ester fish oil better?
Triglyceride absorbs a little better. In a two-week study, rTG raised blood EPA and DHA about 1.7 times as much as ethyl ester; across 14 trials, triglyceride oils raised the omega-3 index about 1 point more at the same dose. Taking ethyl ester with a meal that has fat narrows the gap.
Is krill oil better absorbed than fish oil?
Not proven. When the doses were matched, studies found no clear difference, and a krill capsule holds much less EPA and DHA than a fish oil concentrate.
Sources
- Dyerberg J, et al. “Bioavailability of marine n-3 fatty acid formulations.” Prostaglandins Leukot Essent Fatty Acids. 2010. PubMed 20638827
- Neubronner J, et al. “Enhanced increase of omega-3 index in response to long-term n-3 fatty acid supplementation from triacylglycerides versus ethyl esters.” Eur J Clin Nutr. 2011. PubMed 21063431
- Walker RE, et al. Am J Clin Nutr. 2019. PubMed 31396625
- Yurko-Mauro K, et al. Lipids Health Dis. 2015. PubMed 26328782
- Alijani S, Hahn A, Harris WS, Schuchardt JP. Prog Lipid Res. 2025. PubMed 39736417
- Lawson LD, Hughes BG. Biochem Biophys Res Commun. 1988 (two studies). PubMed 3358766, PubMed 2847723
- Krill: Vosskötter F, et al. 2023 (PubMed 36960737); Laidlaw M, et al. 2014 (PubMed 24952576). Algae oil: Arterburn LM, et al. 2008 (PubMed 18589030). Cod liver oil and vitamin A: NIH Office of Dietary Supplements.
- Oxidation: Albert BB, et al. 2015 (PubMed 25604397); De Boer AA, et al. 2018 (PubMed 29548449).
- Labels: our read of 620 fish oil labels in the NIH Dietary Supplement Label Database. Prices: Amazon, checked November 6, 2026. Data: forms-compared.json.