Where this article links to a product, that link may be an affiliate link and this site may earn a commission at no extra cost to you. See our Affiliate Disclosure.
An omega-3 bottle that says 1,000 mg on the front very often contains about 300 mg of the thing people are buying it for. Both numbers are printed on the pack. Only one of them is on the front.
This is the most consistent label misreading in the category, and it is not a trick — it is simply that the large number describes the oil and the small number describes the omega-3s inside the oil.
Here is how to read the panel properly, what the different product types are, and which figures are comparable between bottles.
Total oil versus EPA and DHA
Fish oil is a mixture. The omega-3 fatty acids EPA and DHA are components of it, not the whole of it.
The National Institutes of Health’s Office of Dietary Supplements gives the standard illustration: a typical fish oil supplement provides about 1,000 mg of fish oil, containing 180 mg of EPA and 120 mg of DHA. That is 300 mg of combined EPA and DHA in a 1,000 mg capsule — roughly thirty per cent.
Concentrated products exist where that proportion is far higher. The only way to know which you are holding is to find the EPA and DHA lines on the Supplement Facts panel and add them together.
The comparison figure is combined EPA + DHA per capsule. Not milligrams of fish oil, not capsules per bottle, not the front of the pack. Once you have that number for two products, you can compare their prices honestly — and the concentrated product is frequently the cheaper one per milligram of omega-3, despite the higher shelf price.
The four product types
Fish oil. The default. EPA and DHA in the proportions above unless the product states it is concentrated.
Krill oil. Carries its omega-3s largely as phospholipids rather than triglycerides, which has been suggested to give higher bioavailability. Krill capsules typically contain considerably less EPA and DHA per capsule than fish oil capsules, so the per-capsule arithmetic matters even more here.
Cod liver oil. Provides EPA and DHA plus vitamins A and D. That is a genuine reason to read this particular panel closely rather than treat it as interchangeable with fish oil: the vitamin A content is a real consideration if you also take a multivitamin, and vitamin A is one of the nutrients where more is not better. See our guide to vitamins and minerals for how those reference figures work.
Algal oil. The plant-based route, made from algae rather than fish. NIH notes these usually provide around 100 to 300 mg of DHA, with some also containing EPA. This is the option for anyone avoiding fish products, and the EPA content is the thing to check rather than assume.
Triglyceride or ethyl ester — the line in the small print
Concentrating fish oil involves chemistry, and the omega-3s can end up in different chemical forms. Labels that mention this will say natural triglyceride, re-esterified triglyceride, free fatty acid, or ethyl ester.
NIH’s summary is measured and worth quoting rather than inflating: omega-3s as re-esterified triglycerides, natural triglycerides and free fatty acids have somewhat higher bioavailability than ethyl esters — and all forms meaningfully raise blood levels.
“Somewhat higher” is the accurate phrase, and it is a good deal less dramatic than the marketing built on it. Treat the form as a tiebreaker between two otherwise comparable products, not as the main decision.
ALA is not a substitute, and the label will not tell you
Flaxseed, chia and walnut products are sold as omega-3 sources, and they are — but of a different omega-3. ALA is the plant form.
The body can convert ALA into EPA and then into DHA. NIH states the conversion is very limited, with reported rates of less than 15 per cent.
So a flaxseed oil capsule and a fish oil capsule are not two routes to the same place, and a product front that says “omega-3” without distinguishing them is telling you less than it appears to. If EPA and DHA are what you are after and you avoid fish, algal oil is the direct route; flax is not.
The reference numbers that actually exist
This is a category where the official picture is thinner than the marketing implies, and it is worth knowing.
An Adequate Intake exists for ALA: 1.6 g a day for adult men and 1.1 g a day for adult women. For EPA and DHA specifically, the Institute of Medicine did not set a requirement for the general non-pregnant population.
Which means a percentage figure on an omega-3 panel is often calculated against the ALA reference, or is absent entirely with a “Daily Value not established” footnote. That is not a defect in the product; it reflects what reference figures exist.
Safety, and the interaction to take seriously
No Tolerable Upper Intake Level has been set for EPA and DHA. The Institute of Medicine did caution that high doses of DHA and EPA — around 900 mg a day or more — might reduce immune function. Regulatory bodies have concluded that dietary supplements providing no more than 5 g a day of EPA and DHA are safe, and bleeding risk is a recognised consideration at higher doses.
The specific interaction to raise with a doctor or pharmacist: fish oil might prolong clotting times, and NIH flags this particularly in combination with warfarin. Anyone taking an anticoagulant should have that conversation before starting, not after.
That also applies before planned surgery, and it is worth mentioning an omega-3 supplement to a surgeon or anaesthetist the way you would mention any other medication.
Storage, and the one sensory check worth doing
Oils are among the supplement formats where the storage line on the pack is doing real work rather than covering a legal base. Follow what the label specifies, and note the expiry date against how long the bottle will take you to finish.
A strongly rancid smell on opening a capsule is a reasonable prompt to stop using that bottle and contact the retailer with the batch number, which is one of the practical reasons to keep the packaging rather than decant.
The buying checklist
- Find EPA and DHA on the panel and add them. That sum is your comparison number.
- Check the serving size — is that sum per capsule, or per two?
- Work out cost per 1,000 mg of combined EPA and DHA across the bottles you are comparing.
- If it is cod liver oil, read the vitamin A and D lines as well.
- If the product is plant-based, confirm whether it supplies EPA and DHA or only ALA.
- Check the chemical form if it is stated — a tiebreaker, not a decider.
- Check any anticoagulant medication with your pharmacist first.
The general principles behind all of this — serving sizes, percentages, proprietary blends — are set out in our guide to reading a supplement label.
Sources
- National Institutes of Health, Office of Dietary Supplements, Omega-3 Fatty Acids — Fact Sheet for Health Professionals.
- U.S. Food and Drug Administration, Dietary Supplement Labeling Guide: Chapter IV, Nutrition Labeling.
This article is a guide to reading product labels and is general information only. It is not medical advice, it makes no claim that omega-3 supplementation benefits any condition, and it does not diagnose, treat, or cure any condition. Speak with a qualified healthcare professional before starting any supplement, particularly if you take prescription medication.