Abbreviations on omega-3 packaging

A fish-oil capsule contains several things at once: fat in which omega-3 fatty acids are dissolved, the fatty acids themselves in different proportions, and additives that protect the whole thing from rancidity. The manufacturer can put the mass of any of these on the front — and each will be formally true.

That is why, in the comparison, we use only two values: milligrams of EPA and milligrams of DHA in one capsule. The rest goes into the product description as information, but does not enter the calculation. If the manufacturer does not state these two numbers, we say so plainly instead of calculating them from percentages.

The terms one by one

EPAeicosapentaenoic acid

One of the two long-chain omega-3 fatty acids on which our whole comparison is based. It is always stated on the label in milligrams, usually in a table together with DHA. Check whether the table refers to one capsule or to a serving of two or three — this is the most common place where half the value is lost.

DHAdocosahexaenoic acid

The other fatty acid we calculate. The EPA-to-DHA ratio sometimes differs twofold between products, and it determines which oil costs less for a particular target. A product that is cheap for a 300/200 mg target can be the most expensive for 2000/500 mg, because one value cannot be reached without inflating the other.

ALAalpha-linolenic acid

A plant omega-3 fatty acid from flaxseed, rapeseed or chia oil. Formally, it is an omega-3 fatty acid, so it counts toward the total stated on the package — although it is neither EPA nor DHA. The statement “1000 mg omega-3” on a flaxseed-oil product therefore describes something entirely different from the same statement on a fish-oil concentrate.

DPAdocosapentaenoic acid

The third omega-3 fatty acid found in fish oil, stated rarely and in small amounts. We do not include it in the comparison, but when the manufacturer declares it, it remains in the product description.

TGtriglycerides

The natural form of fat in which fatty acids occur in fish. The manufacturer declares it on the label and we transcribe that declaration. We do not decide which form is better — it is a dispute in which each side has studies supporting its claim.

rTGre-esterified triglycerides

A form created when concentrated oil is joined back into triglycerides. rTG products are usually more expensive than EE products with the same EPA and DHA content, as shown in our comparison.

EEethyl esters

An intermediate form created during fish-oil concentration. It is cheaper to produce, so it is common in products with a high fatty-acid content at a low price. Many manufacturers do not state the form at all — then we leave this field blank instead of guessing.

KrillAntarctic krill oil

A source of EPA and DHA bound to phospholipids rather than fat. The fatty-acid content in a capsule is usually several times lower than in a fish-oil concentrate, and the price is higher, so comparing package prices is misleading. The calculation per milligram of EPA and DHA shows this immediately.

Algae oilplant source

Microalgae oil — the only plant source of ready-made DHA and, in some products, EPA as well. These are the same algae eaten by fish, so the source is simply one step earlier in the chain.

TOTOXoxidation indicator

A measure of how rancid the oil is: the anisidine value plus twice the peroxide value, i.e. TOTOX = AV + 2 × PV. The GOED monograph permits TOTOX up to 26, with a peroxide value up to 5 meq/kg and an anisidine value up to 20. Few manufacturers state this value, usually those who have something to show. No number does not mean the oil is bad — only that it is unknown, and that is exactly how we mark it.

Cod liver oiloil from cod liver

A separate product, not a synonym for fish oil. The oil comes from the liver, not fish flesh, so alongside EPA and DHA it also provides vitamins A and D — the label must state them in the table together with the percentage of NRV. Cod liver oil is not concentrated, so it contains several times less EPA and DHA per gram of oil than a concentrate.

IFOSfish-oil certification programme

An independent programme for testing purity, freshness and compliance of composition with the declaration, run by the Nutrasource laboratory. The results for individual batches are publicly available, which distinguishes it from certificates that cannot be verified.

GOEDomega-3 producers' organisation

An industry association that publishes a monograph with requirements for omega-3 oils. Manufacturers refer to it in product descriptions. It is an industry standard, not an official authorisation.

Other groups of terms

Vitamin D Magnesium, zinc, iron Vitamin C B vitamins Collagen Creatine Probiotics Label and calculations

How the numbers from a label turn into the cost of a day is shown in the omega-3 calculator — for now this is the only finished category. The rules by which we build the ranking are described in the How we rank section.