In brief
Fats you must get from food. ALA comes from plant foods, and EPA and DHA come mainly from fish and other seafood. They are part of the structure of cell membranes.
- DHA levels are especially high in the retina, brain and sperm cells.
- Eating fish and other seafood as part of a balanced diet promotes heart health, but many large trials of omega-3 supplements for heart disease found no benefit.
- High doses of omega-3s may cause bleeding problems when taken with warfarin or other blood thinners.
How it works
EPA and DHA come mainly from cold-water fatty fish such as salmon, mackerel, tuna, herring and sardines. ALA comes from plant foods such as flaxseed, chia seeds and walnuts. The body converts some ALA into EPA and then DHA, but only in very small amounts.
Omega-3s compete with omega-6 fats to make signalling molecules called eicosanoids, tipping the balance towards less inflammatory activity. Fish oil and other omega-3 supplements lower triglyceride levels.
Food sources
- Salmon
- Mackerel
- Tuna
- Herring
- Sardines
- Flaxseed
- Chia seeds
- Walnuts
From the AskBioMap food guide:
Connections
3 connections on the map. Select a topic to read its page.
Omega-3 fats is needed for
DHA levels are especially high in the brain and retina.
Sources: NIH Office of Dietary Supplements, Omega-3 fatty acids fact sheet for consumers; NIH Office of Dietary Supplements, Omega-3 fatty acids: fact sheet for health professionals
Omega-3 fats has been studied for
- Coronary heart disease Supported
Eating fish and seafood promotes heart health, but many large trials of omega-3 supplements found no benefit.
Source: NIH Office of Dietary Supplements, Omega-3 fatty acids: fact sheet for health professionals
Omega-3 fats helps control
EPA and DHA compete with omega-6 fats to make eicosanoids, tipping the balance towards less inflammatory activity.
Source: NIH Office of Dietary Supplements, Omega-3 fatty acids: fact sheet for health professionals
Medicines and supplements
General education only. Never start, stop or change a medicine without your prescriber.
Sources
- Omega-3 fatty acids fact sheet for consumers
- Omega-3 fatty acids: fact sheet for health professionals
Each connection above names its own source. See every source AskBioMap uses.
Summarised from the NIH Office of Dietary Supplements. Sources read on 13 October 2026. General education only, not medical advice. Spotted a mistake? Please tell us through the HuBu-Intel contact page.