🐟 Omega-3: triglycerides (TG), ethyl ester (EE) or rTG — what to choose
We break down the benefits, norms, food sources and forms of fish oil
Omega-3 is a family of polyunsaturated fatty acids, the key ones being EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). They are not synthesized in sufficient quantities in the body and must come from food or supplements. Omega-3 is called "essential fats" for a reason: they participate in the work of the heart, brain, eyes and immune system.
The abbreviations EE, TG and rTG appear on supplement labels — they describe how exactly EPA and DHA are "attached" to a carrier molecule. Absorption depends on this. Let's break down everything: history, benefits, how much to take, where to get it from food and which form to choose.
History of the discovery of omega-3
Interest in omega-3 began with observations of the Eskimos of Greenland in the 1970s. Danish scientists Hans Olaf Bang and Jørn Dyerberg noticed that the Inuit, who ate fatty fish, very rarely suffered from cardiovascular disease, despite a fatty diet. This is how the famous "Eskimo hypothesis" was born.
1930s — first descriptions
Scientists found that fish fat contains special polyunsaturated acids that are absent in most vegetable oils. They were named omega-3 by the position of the double bond.
1970s — expedition to Greenland
Bang and Dyerberg confirmed: the Inuit have a low level of cardiovascular disease and a characteristic fatty blood profile thanks to large amounts of EPA and DHA from fish.
1982 — discovery of eicosanoids
Sune Bergström, Bengt Samuelsson and John Vane received the Nobel Prize in Physiology or Medicine for the discovery of prostaglandins — substances produced from omega-3 that regulate inflammation.
1990s and beyond
Large-scale studies (GISSI-Prevenzione, DART, etc.) confirmed the benefits of omega-3 for the heart. Today omega-3 is one of the most studied dietary supplements.
What omega-3s are good for humans
Omega-3s are important for many systems. Here are the main areas of their benefit:
Lowering triglycerides
EPA and DHA lower blood triglycerides, support vessel elasticity and normal blood pressure. This is one of the main reasons to take omega-3.
DHA for memory
DHA is the main structural fat of the brain. It is important for memory, concentration and protection against age-related cognitive decline.
Retina
DHA is part of the retina. Its sufficiency is important for vision, especially with age and with computer vision syndrome.
Anti-inflammatory effect
Omega-3s participate in the synthesis of anti-inflammatory substances (resolvins), helping to control chronic systemic inflammation.
Response modulation
They support the balance of the immune response, helping the body fight inflammation without excessive "overload".
Child development
DHA is important for the development of the fetal brain and vision. Omega-3 sufficiency matters during pregnancy and lactation.
Where omega-3 is found: foods with numbers
The best source of EPA and DHA is fatty fish. Vegetable oils contain another type of omega-3 — alpha-linolenic acid (ALA), from which the body can produce EPA/DHA, but very inefficiently (less than 5–10%). Therefore the main bet is on fish.
| Food | EPA+DHA (g/100 g) | Comment |
|---|---|---|
| Mackerel | ~2.5–4.0 | Very rich source |
| Herring | ~2.0–2.7 | Excellent source |
| Salmon | ~1.5–2.5 | Wild is higher, farmed is lower |
| Sardines | ~1.0–1.5 | Good source |
| Tuna | ~0.3–1.0 | Depends on the species |
| Anchovies | ~1.5–2.0 | Good source |
| Trout | ~1.0 | Medium source |
| Flaxseed oil | ALA ~57 (not EPA/DHA) | Plant-based, weak conversion |
| Walnuts | ALA ~2.5 | Plant ALA |
| Eggs (enriched) | ~0.15–0.3 | Chickens on omega-3 feed |
Omega-3 norms per day and month
There is no official "daily norm" of EPA+DHA, but there are recommendations from scientific societies. WHO and many cardiology societies advise getting EPA+DHA from food or supplements. For prevention, 250–500 mg/day of EPA+DHA is usually recommended, and for correcting triglycerides — up to 1000–2000 mg/day.
| Goal | EPA+DHA dose/day |
|---|---|
| General prevention | 250–500 mg |
| Heart support | ~1000 mg |
| High triglycerides (therapeutic) | 2000–4000 mg (prescription) |
Monthly norm
When taking ~1 g/day of EPA+DHA, about 30 g of pure omega-3 goes per month. If a capsule contains 300 mg of EPA+DHA, then you need 3 capsules per day, and about 90 capsules per month (a jar of 90 capsules ≈ 1 month). Always count by the milligrams of EPA+DHA, not by the capsule weight.
Three forms of omega-3: TG, EE, rTG
In nature, omega-3 in fish are in the form of triglycerides (TG) — three fatty acids per glycerol molecule. Concentrates are made in two ways: they are converted into ethyl ester (EE) or then returned back into triglycerides, obtaining rTG.
| Form | Structure | Product type | EPA+DHA concentration |
|---|---|---|---|
| TG | Natural triglycerides | Whole fish oil | ~18–30% |
| EE | Ethyl ester | Concentrate, cheap | ~50–70% |
| rTG | Re-esterified triglycerides | Premium concentrate | ~60–90% |
TG and rTG
Natural structure, rapid breakdown, higher rise of omega-3 in plasma.
EE
Requires an additional enzymatic step, absorption is lower, especially on an empty stomach. Partly fixed by taking with fatty food.
Which form to choose
If your budget allows — choose rTG: better absorption with high concentration. A good middle option is quality TG. Cheap EE makes sense only if taken with fatty food and in a sufficient dose. With any choice, look at the milligrams of EPA+DHA and independent purity tests (IFOS, GOED).
What is rTG in omega-3?
rTG is re-esterified triglycerides: concentrated omega-3 returned to the natural triglyceride structure. It is considered the gold standard in absorption and concentration.
How is EE different from TG?
EE is ethyl ester (concentrate, cheaper, absorbed worse). TG is natural triglycerides (absorbed better, but less concentrated).
Which omega-3 form is absorbed best?
TG and rTG are absorbed better than EE. Studies show a higher blood level of EPA/DHA with triglyceride forms (Dyerberg et al., 2010).
Which foods have the most omega-3?
Mackerel (~2.5–4 g/100 g), herring (~2–2.7), salmon (~1.5–2.5), sardines (~1–1.5), anchovies (~1.5–2). Vegetable oils contain ALA, from which EPA/DHA is almost not synthesized.
How much omega-3 do I need per day?
For prevention 250–500 mg of EPA+DHA/day, for heart support ~1000 mg. Therapeutic doses up to 4 g/day — only as prescribed by a doctor.
What does "1000 mg omega-3" on the jar mean?
Often this is the mass of all the fat in the capsule, not the amount of EPA+DHA. Look at the actual milligrams of EPA+DHA — they can be 180–900 mg per capsule.
Can I take omega-3 on an empty stomach?
Better with food containing fat: this improves absorption, especially for the EE form. TG/rTG forms are more "tolerant" to taking on an empty stomach.
How to check the quality of fish oil?
Look for purity certificates (IFOS, GOED), check oxidation indicators (TOTOX < 26) and purification from mercury and PCBs. Fresh oil should not have a sharp rancid smell.
Will omega-3 from vegetable oils help?
Flaxseed and nut oils contain ALA, from which the body produces EPA/DHA weakly (less than 5–10%). Vegans are better off with microalgae supplements with ready DHA.
Does the form affect "fish burp" smell?
Yes, rTG and TG forms with higher bioavailability are less likely to cause "fish burp". Enteric-coated capsules and taking with food also help.