Omega-3s: A Practical Guide to EPA, DHA and Sources

Omega-3 fatty acids are among the most researched nutrients in the world, and fish oil remains one of Australia's most purchased supplements. Yet the shelf can be baffling: fish oil, krill oil, algal oil, "triple strength", concentrates, triglyceride versus ethyl ester forms. This guide walks through what actually matters when comparing omega-3 products.

What omega-3s are — and why EPA and DHA are the headline

Omega-3s are a family of polyunsaturated fats the body cannot make from scratch. The three you will see on labels are:

• ALA (alpha-linolenic acid) — the plant form, found in flaxseed, chia and walnuts.
• EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) — the long-chain marine forms found in oily fish and marine algae.

The body can convert a small amount of ALA into EPA and DHA, but research consistently shows this conversion is inefficient. That is why supplement discussion focuses on EPA and DHA directly. DHA is a major structural fat in the brain and retina; EPA and DHA together are involved in normal cell membrane function throughout the body.

What the research broadly says

Omega-3 research is vast and, honestly, mixed. Large reviews and long-running population studies have generally associated regular oily fish consumption with markers of cardiovascular wellbeing, and health authorities in many countries encourage eating oily fish regularly. Trials of supplements have produced more variable results, and scientists continue to debate dose, formulation and who benefits most. The fairest summary is: food-first advice (two to three serves of oily fish per week) is well established, and supplementation is commonly used by people who eat little or no fish — ideally with guidance from their practitioner.

Fish oil

Standard fish oil is the workhorse of the category: widely available, well studied and economical. Key things to check on the label:

• EPA and DHA per capsule, not just "1000 mg fish oil". A standard 1000 mg capsule typically provides around 300 mg combined EPA/DHA; concentrated products may provide double or triple that.
• Form. Concentrates come as ethyl esters or re-esterified triglycerides. Some absorption studies favour the triglyceride form, particularly when taken without food, though both deliver omega-3s.
• Freshness and purity. Reputable Australian-listed products are tested for oxidation and contaminants such as heavy metals. A strongly fishy or rancid smell from a capsule is a reasonable cue to replace the bottle. Storing capsules away from heat and light helps.

Krill oil

Krill oil comes from small Antarctic crustaceans. Its points of difference:

• Its omega-3s are partly bound to phospholipids, and some studies have explored whether this improves absorption; findings are interesting but not conclusive.
• It naturally contains astaxanthin, an antioxidant pigment that also gives krill oil its red colour and helps protect the oil from oxidation.
• Typical capsules are smaller but contain less total EPA/DHA than concentrated fish oil, so compare the actual milligrams per dose — and the price per milligram of EPA/DHA, which is often higher for krill.

People with shellfish allergies should avoid krill oil and speak with their practitioner about alternatives.

Algal oil — the plant-based option

Algal oil is grown from marine microalgae — the original source from which fish obtain their omega-3s. It is the established option for vegetarians and vegans, and for anyone who prefers to avoid fish products. Points to note:

• Algal oils are typically rich in DHA, with newer products also including meaningful EPA. Check the split on the label.
• Because it is produced in controlled cultivation, algal oil avoids concerns about ocean contaminants and fishery sustainability.
• It is usually the most expensive per milligram of omega-3, though prices have come down as production has scaled.

Practical buying and usage tips

• Compare combined EPA + DHA per daily dose across products — it is the only fair comparison between fish, krill and algal oils.
• Take with meals containing some fat, which supports absorption and reduces fishy aftertaste.
• Check the AUST L number and expiry date, and store the bottle in a cool, dark place (some products prefer refrigeration after opening).
• Talk to your practitioner first if you take blood-thinning medication, are preparing for surgery, or are pregnant — omega-3 dosing in these situations warrants individual advice.

You can compare EPA/DHA content and source types across our heart and energy range, where marine oils sit alongside other nutrients commonly chosen for cardiovascular wellbeing routines.

The bottom line

EPA and DHA are the numbers that matter, oily fish remains the gold-standard source, and fish, krill and algal oils are simply three vehicles for the same nutrients — differing in concentration, form, price and dietary suitability. Read the label, compare per-dose amounts, and let your practitioner help you decide whether supplementation makes sense for you.