Omega-3: EPA, DHA, foods and cellular functions
Omega-3 fatty acids are part of our diet and cellular structure. Understanding ALA, EPA and DHA helps organise intake and compare products accurately.
What are omega-3s?
They are a family of polyunsaturated fatty acids. ALA is an essential fatty acid that must come from the diet. The body converts some ALA into EPA and DHA, but conversion is relatively limited. [1]
Their role in the body
Fatty acids are incorporated into cell membranes, which surround cells and help organise communication with their environment. DHA occurs at particularly high concentrations in the brain and retina. [2]
EPA and DHA also participate in the formation of molecules involved in normal signalling processes. Dietary patterns influence tissue fatty acid composition over time. [1]
Food sources
- ALA: flaxseed, chia seeds, walnuts and some plant oils.
- EPA and DHA: oily fish such as sardines, salmon, mackerel and herring.
- Alternative sources: microalgal oils used in some DHA or EPA-and-DHA supplements.
Amounts vary by species, portion and source. Fish-based meals and plant foods such as nuts and seeds can both contribute to a varied diet.
Fish oil and microalgal oil
Fish oil can supply EPA and DHA, while microalgal products offer a source suitable for plant-based diets. Check which fatty acids and quantities are stated on the label. Cod liver oil is a different category and can also provide vitamins A and D; account for these if using other supplements containing the same vitamins. [1]
Reading the label
Look at EPA and DHA per daily serving, not only the total oil amount. For example, 1,000mg fish oil might contain 180mg EPA and 120mg DHA: 300mg of these two omega-3s. This is an illustration of label reading, not a recommended dose.
- Serving: how many capsules provide the stated amounts?
- Source: fish, microalgae or another ingredient?
- Composition: EPA, DHA and any added vitamins.
- Quality information: origin, batch, date and storage directions.
Practical considerations
Follow the pack instructions and discuss intake when there is a specific treatment goal. High doses need medical guidance, particularly with a history of heart rhythm disorders. Tell your healthcare professional about anticoagulant or antiplatelet medicines. [3]
Check ingredients in the case of fish allergy, and store oils according to the label to protect them from heat and oxidation.
Scientific sources
- NIH Office of Dietary Supplements — Omega‑3 Fatty Acids: Health Professional
- NIH Office of Dietary Supplements — Omega‑3 Fatty Acids: Consumer
- NCCIH — Omega‑3 Supplements
Informational article. Supplement choices should reflect your diet, needs and health history. For diagnosed deficiency, chronic illness, medication use, pregnancy or breastfeeding, consult a healthcare professional.
