The market for Omega-3 supplements is huge — and confusing. Between cheap capsules from the chemist and premium oils from direct sales companies, there are worlds of difference in quality, bioavailability and purity. But how do you really recognise good Omega-3? Here are the 9 most important criteria you should know before buying.
TL;DR — The key points in brief
- The TOTOX value measures the freshness of the oil — ideally below 10; the GOED limit is a maximum of 26.
- Triglyceride form (TG/rTG) is absorbed up to 30% better than cheaper ethyl ester products.
- What matters is not the total amount of fish oil, but the actual EPA+DHA content per daily dose (minimum: 250 mg).
- IFOS 5-star certification is the gold standard for independently verified purity and freshness.
- Always calculate the price per gram of EPA+DHA — not per capsule or millilitre.
1. TOTOX value: The most important freshness indicator
The TOTOX value (Total Oxidation Value) measures how fresh — or how rancid — an Omega-3 oil is. It is calculated from:
TOTOX = 2 × Peroxide Value (PV) + Anisidine Value (AV)
The peroxide value measures early oxidation products, the anisidine value later ones. Why does this matter? Polyunsaturated fatty acids such as EPA and DHA oxidise extremely quickly. A rancid oil can act counter-productively in the body and promote free radicals — the opposite of what you want.
| Rating | TOTOX Value | Meaning |
|---|---|---|
| Excellent | < 5 | Exceptionally fresh |
| Very good | 5 – 10 | High quality, recommended |
| Acceptable | 10 – 26 | GOED/IFOS limit max. 26 |
| Poor | > 26 | Rancid, not recommended |
Practical tip
A good Omega-3 oil smells neutral or slightly of the sea — never fishy or rancid. If your oil smells unpleasant, it is likely oxidised.
2. Triglyceride form vs. ethyl ester
This is one of the most important and most underestimated quality differences. Omega-3 comes in various molecular forms:
| Property | Natural Triglyceride (TG) | Re-esterified TG (rTG) | Ethyl Ester (EE) |
|---|---|---|---|
| Bioavailability | 100% (reference) | ~124-134% | ~73-76% |
| Origin | Directly from fish | Reconstituted | Synthetically modified |
| EPA+DHA concentration | Lower (~30%) | Very high (>60%) | Very high |
| Gastric tolerance | Very good | Good | Worse |
| Price | Moderate | Higher | Cheaper |
Conclusion: Natural triglyceride form offers the best combination of bioavailability and tolerability. Ethyl esters are cheaper but are absorbed up to 30% less efficiently. You therefore need more of them for the same effect.
3. EPA/DHA content per daily dose
It is not the amount of "fish oil" that counts, but the actual content of EPA and DHA. Many cheap products contain only 300 mg EPA+DHA per capsule with 1,000 mg fish oil — the rest are other, less valuable fatty acids.
Recommended daily doses according to EFSA:
| Goal | EPA + DHA per day | EFSA Health Claim |
|---|---|---|
| Basic supply | 250 mg | Normal heart function |
| Brain & eyes | 250 mg DHA | Normal brain function, vision |
| Pregnancy | 250 mg + 200 mg DHA | Brain/eye development of foetus |
| Reducing triglycerides | 2,000 mg | Normal triglyceride levels |
| Blood pressure | 3,000 mg | Normal blood pressure |
Comparison tip
Always compare Omega-3 products based on the cost per gram of EPA+DHA — not per capsule or per millilitre. Only then can you recognise the true value.
4. Purity: Heavy metals, PCBs, dioxins
Fish are at the top of the food chain and can accumulate contaminants. High-quality fish oil supplements must comply with strict limits for:
- Heavy metals: Mercury, lead, arsenic, cadmium
- PCBs: Polychlorinated biphenyls (persistent organic pollutants)
- Dioxins and furans: EU Regulation 1259/2011 sets clear limits
A good Omega-3 oil is well below the legal limits. Small fish such as sardines and anchovies naturally contain fewer contaminants than large predatory fish such as tuna.
5. Certifications: IFOS and GOED
Not every certification is worth the same:
- IFOS (International Fish Oil Standards): The gold standard. Independent third-party certification with a 5-star system. Tests purity, potency and freshness. Very few products achieve 5 stars.
- GOED (Global Organization for EPA and DHA): Sets industry standards and minimum requirements. More of a trade association — membership alone is not direct proof of quality.
6. Sustainability
Fish oil production has an ecological footprint. Look out for:
- MSC (Marine Stewardship Council): Globally recognised, strict ecosystem and stock criteria
- Friend of the Sea (FOS): International NGO certification, also recognised
- Traceable origin: Can the origin of the fish be traced without gaps?
7. Bioavailability and absorption
The best composition is of no use if your body cannot absorb the fatty acids. Important factors:
- Molecular form: TG > rTG > EE (see point 2)
- Take with fat: Omega-3 is fat-soluble — absorption increases significantly when taken with a fatty meal
- Antioxidant protection: Olive oil polyphenols or vitamin E protect the oil from oxidation in the body
8. Taste and tolerability
A product is useless if you don't take it regularly. Quality indicators:
- No fishy burping (a sign of good quality and freshness)
- Pleasant taste (lemon, orange or neutral)
- Liquid oil vs. capsules — preference is individual
9. Value for money
Expensive does not automatically mean better. Always calculate like this:
Cost per gram EPA+DHA = Price per bottle / (EPA+DHA per daily dose × days per bottle)
Factors that justify a higher price:
- IFOS certification (independently verified)
- Triglyceride form (higher bioavailability)
- Very low TOTOX value (< 5)
- MSC certification
Factors that do not justify a higher price:
- MLM/network marketing distribution (commission structure in the price)
- Elaborate marketing without substance
- Compulsory subscription with a long minimum term
Our product comparisons
We have compared the most popular Omega-3 oils against these criteria:
Eqology vs. Zinzino → · Eqology vs. Norsan →* Some links are affiliate links. The price does not change for you.
Checklist: What your Omega-3 oil should offer
| Criterion | Minimum | Ideal |
|---|---|---|
| TOTOX value | < 26 | < 10, preferably < 5 |
| EPA+DHA per day | 250 mg | 1,000-2,000 mg |
| Molecular form | — | Triglyceride (TG/rTG) |
| Purity | EU limits | IFOS 5-star |
| Sustainability | — | MSC or FOS |
| Antioxidant protection | Vitamin E | Olive oil polyphenols |
Medical disclaimer
This article is for general information purposes only and does not replace medical advice. All health claims are based on EFSA-approved health claims. If you have any doubts about dosage, please consult your doctor.
Frequently Asked Questions
Are Omega-3 capsules or liquid oil better?
Liquid oil is generally cheaper per gram of EPA+DHA and offers higher bioavailability, as it does not need to pass through a gelatine capsule. Capsules are more convenient for travelling.
Why is the TOTOX value so important?
Oxidised (rancid) fish oil can generate free radicals in the body — the opposite of the desired antioxidant effect. A low TOTOX value indicates that the oil is fresh and effective.
Can I overdose on Omega-3?
The EFSA considers daily doses of up to 5,000 mg EPA+DHA to be safe. Therapeutic doses above 3,000 mg should be discussed with a doctor, especially when taking blood-thinning medications.
Further comparison articles on specific products — Eqology, Zinzino and Norsan in direct comparison — can be found in the comparisons overview. All background information on TOTOX values, heavy metals and certifications is provided in the quality overview.