🔬 Mechanism of action of Omega-3: eicosanoids, resolvins and reduced inflammation
How EPA and DHA work at the molecular level
Omega-3 is a family of polyunsaturated fatty acids, of which the most important are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Their health impact goes far beyond simple "heart fat": they integrate into cell membranes and turn into signaling molecules that regulate inflammation. Let's break the mechanism down step by step.
What are EPA and DHA
EPA (eicosapentaenoic, C20:5) and DHA (docosahexaenoic, C22:6) are long-chain omega-3 fatty acids that the body can synthesize from alpha-linolenic acid (ALA), but very slowly. The main source is fatty fish and seafood. For more on forms and quality — see "Omega-3: TG, EE or rTG".
Eicosanoids from omega-3
From EPA, cells synthesize eicosanoids — signaling molecules, including prostaglandins and leukotrienes. Importantly, eicosanoids from omega-3 differ from those made from omega-6 (arachidonic acid).
| Source | Eicosanoids | Nature |
|---|---|---|
| Omega-6 (arachidonic) | PGE2, LTB4 | More pro-inflammatory |
| Omega-3 (EPA) | PGE3, LTB5 | Less pro-inflammatory |
When EPA "competes" with arachidonic acid for the same enzymes (COX and LOX), less active pro-inflammatory molecules are formed. This is one of the key mechanisms of reducing inflammation. On inflammation and free radicals — see "Oxidative stress and antioxidants".
Resolvins and protectins
The real "highlight" of omega-3 is the ability to form specialized pro-resolving mediators (SPMs): resolvins, protectins and maresins. These molecules actively resolve inflammation and help tissues return to normal.
- Resolvins (from EPA and DHA) — "switch off" the inflammatory response.
- Protectins (from DHA) — protect nervous tissue.
- Maresins — participate in completing inflammation.
These mediators are linked to part of the cardioprotective and neuroprotective effects of omega-3. On the heart — in the omega-3 and infarction meta-analysis, on the brain — in "Omega-3 and the brain".
Cell membranes
DHA especially actively integrates into cell membranes, particularly in the brain and retina. DHA makes membranes more fluid, improving receptor function and signal transmission. Membrane density affects how cells respond to hormones and neurotransmitters.
Why it matters for the body
Chronic "quiet" inflammation underlies many age-related diseases. Omega-3 help shift the balance toward its resolution. However, the balance with omega-6 is important: the typical diet is excessive in omega-6 (vegetable oils), which strengthens the pro-inflammatory background.
How is EPA different from DHA?
EPA is the basis of anti-inflammatory eicosanoids, while DHA is a structural component of brain and retina membranes.
What are eicosanoids?
Signaling molecules (prostaglandins, leukotrienes) formed from fatty acids that regulate inflammation.
What are resolvins?
Pro-resolving mediators from omega-3 that help resolve inflammation and restore tissues.
Why are omega-3 considered anti-inflammatory?
EPA competes with omega-6 for enzymes, producing less inflammatory eicosanoids, plus gives resolvins and protectins.
Why does the brain need DHA?
DHA integrates into neuron membranes, making them fluid and improving signal transmission and receptor function.
Can EPA/DHA be obtained from plants?
From ALA (flax oil) the body synthesizes EPA/DHA weakly. The main source is fish or algae supplements.
What is the omega-6/omega-3 ratio?
The ratio of the two fatty acid families. In a typical diet omega-6 is excessive, strengthening inflammation.
What are SPM mediators?
Specialized pro-resolving mediators (resolvins, protectins, maresins) that actively complete inflammation.
Do omega-3 help with joint pain?
Some studies show a moderate anti-inflammatory effect in arthritis, but it requires regular adequate doses.
What dose of omega-3 is sufficient?
For heart health usually at least 250–500 mg EPA+DHA a day; studies use even higher doses.