When omega-3 and the immune system are discussed, it is often said that omega-3 "strengthens" the immune system. In the scientific literature, EPA and DHA are instead usually attributed a modulating role: the mechanisms studied are those through which these fatty acids may be involved in regulating excessive inflammatory processes and in their resolution. That is a different approach from so-called immune stimulants. Important to note first: there is no EFSA-authorised health claim for omega-3 and the immune system — the associations described here are the subject of research and are not established effects. This page summarises which mechanisms are described in studies and how the body of evidence should be interpreted.
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Test & prices →Immune stimulation vs. immunomodulation: an important distinction
Popular food supplements are frequently marketed with promises to "strengthen" or "boost" the immune system. For many health conditions, however, a strong immune response is not the goal — quite the contrary: in autoimmune diseases (such as rheumatism, Hashimoto's thyroiditis, Crohn's disease, multiple sclerosis), allergic conditions or chronic inflammatory states, the problem is an excessive or misdirected immune reaction, not one that is too weak.
What does immunomodulation mean?
The term immunomodulation broadly describes an influence on the immune system in both directions — in the sense of a balance. In investigations of EPA and DHA, several points of action are described: a possible influence on the production of pro-inflammatory cytokines, on the differentiation of regulatory T cells, and on the formation of pro-resolving mediators involved in the resolution of inflammation. These mechanisms are drawn largely from laboratory and model studies and are not to be understood as an established health effect in humans.
Modulation, not stimulation
In research, EPA and DHA are not attributed an increase in immune activity in the sense of a "booster", but a modulating role. The conceptual distinction between stimulation and modulation matters mainly for understanding the mechanisms described. Whether, and to what extent, a health benefit can be derived from this is not conclusively established scientifically; there is no authorised EFSA health claim for omega-3 and the immune system.
The immune system: a brief overview
To understand the effect of omega-3, a brief overview of relevant immune cells and signalling pathways is helpful:
Innate immune system
The innate immune system reacts rapidly but non-specifically to pathogens and tissue damage. Neutrophils, macrophages and natural killer (NK) cells are the main actors. Macrophages play a special role: they can differentiate into both pro-inflammatory (M1 macrophages, producing TNF-alpha, IL-1, IL-6) and anti-inflammatory (M2 macrophages, producing IL-10, TGF-beta) phenotypes. Experimental studies describe that EPA and DHA may shift this polarisation towards the M2 phenotype.
Adaptive immune system
The adaptive immune system responds more slowly but with high specificity. T helper cells (CD4+) coordinate the immune response: Th1 cells stimulate cellular immunity, Th2 cells humoral immunity (antibodies), Th17 cells are involved in autoimmune processes. Regulatory T cells (Tregs) dampen excessive reactions. Studies investigate whether EPA and DHA shift the Th1/Th2/Th17/Treg balance towards less pro-inflammatory activity — a mechanism discussed in research in connection with inflammatory processes.
Cytokines: immune system messengers
Cytokines are signalling proteins through which immune cells communicate. Pro-inflammatory cytokines (TNF-alpha, IL-1, IL-6, IL-17) promote inflammatory reactions; anti-inflammatory cytokines (IL-10, TGF-beta) dampen them. The literature describes that EPA and DHA may influence the cytokine balance at several levels — both via the arachidonic acid cascade and through the formation of specialised pro-resolving mediators.
Scientific evidence: what does research on omega-3 and immune function show?
Research on omega-3 and immune function is multifaceted: from cell culture studies to animal studies and clinical intervention trials. Two particularly relevant works:
Calder PC: Immunomodulation by omega-3 — mechanisms in detail
Philip Calder's widely cited mechanistic review summarises how EPA and DHA act on the immune system: (1) through incorporation into immune cell membranes and modification of membrane fluidity and receptor expression, (2) through influence on the transcription factor NF-kappaB and thus gene expression of pro-inflammatory mediators, (3) through formation of specialised pro-resolving lipid mediators (resolvins, protectins, maresins) and (4) through PPAR-gamma activation. Calder emphasises: the effect of omega-3 on the immune system is complex and bidirectional — depending on context and dose.
Kavyani et al.: 32 meta-analyses — reduction of inflammatory markers as an immunological signal
The umbrella meta-analysis by Kavyani et al. (2022), which pooled 32 prior meta-analyses, documents the clinical measurability of immunomodulation: significant reduction in CRP (ES = −0.40; P < 0.001), TNF-alpha (ES = −0.23; P = 0.002) and IL-6 (ES = −0.22; P = 0.010). These markers are at the same time immune mediators: TNF-alpha and IL-6 are cytokines that play a role in immune signalling. The authors interpret the observed reduction as an indication of immunomodulatory effects; an established health effect cannot be derived from this alone.
Resolvins and protectins: the body's own resolution programme
One of the most fascinating discoveries of modern immunology is the identification of specialised pro-resolving lipid mediators (SPMs) — a family of lipid molecules formed directly from EPA and DHA. The most important representatives are resolvins (from EPA: E-series; from DHA: D-series), protectins (also neuroprotectins, from DHA) and maresins (also from DHA).
What do resolvins do?
In research, resolvins are described not as classic anti-inflammatories but as coordinators of the resolution of inflammation. The functions below are drawn largely from laboratory and animal models:
- Promoting neutrophil apoptosis: Exhausted neutrophils are guided towards controlled apoptosis, rather than disintegrating necrotically (which would generate new inflammatory stimuli).
- Stimulating macrophage phagocytosis: Macrophages are activated to absorb apoptotic neutrophils and cellular debris (efferocytosis) — this actively terminates the inflammatory stimulus.
- Regulating cytokine production: Resolvins inhibit the release of pro-inflammatory cytokines (TNF-alpha, IL-1, IL-6) and promote the release of anti-inflammatory mediators (IL-10).
- Restoring tissue homeostasis: They signal to the tissue to return to its normal state after inflammation resolves.
Protectins (neuroprotectins)
Protectins are formed primarily from DHA. They protect tissues from excessive inflammatory damage, inhibit neutrophil migration into tissues and have neuroprotective properties. In the context of immunomodulation, they are particularly relevant for the brain (where DHA is found in high concentration) and for regulating inflammatory processes in the nervous system.
SPMs: why this goes beyond "anti-inflammatory"
Classical anti-inflammatories such as NSAIDs or corticosteroids passively suppress inflammatory processes. For the SPMs formed from EPA and DHA (resolvins, protectins, maresins), research instead discusses an active triggering of cellular resolution programmes. This mechanistic difference is the reason omega-3 is usually classified in the literature as immunomodulatory rather than immunosuppressive — robust clinical evidence for a resulting health benefit is largely lacking.
Omega-3 in research on autoimmune diseases
Autoimmune diseases, in which the immune system turns against the body's own structures, are the subject of numerous dietary and supplement studies — including on omega-3. The following sections summarise the state of research. They do not constitute a treatment recommendation: omega-3 is a food supplement and not a medicine; diagnosis and therapy belong in the hands of a doctor.
Rheumatoid arthritis (RA)
In RA, the immune system releases pro-inflammatory cytokines (TNF-alpha, IL-1, IL-6, IL-17). Part of the research on omega-3 has recorded changes in inflammatory markers in this context. An assessment of this body of evidence can be found on the page Omega-3 for rheumatism and arthritis.
Systemic lupus erythematosus (SLE)
For SLE there are a few smaller clinical studies and epidemiological data that have recorded inflammatory markers and activity scores (e.g. SLEDAI). The data base is limited and larger randomised studies are lacking; reliable conclusions cannot be drawn from it.
Crohn's disease and ulcerative colitis
Omega-3 has been investigated in several studies in inflammatory bowel disease (IBD). A Cochrane review pooling several studies reports inconsistent results — for Crohn's disease no consistent finding on remission maintenance, and for ulcerative colitis mixed signals on individual parameters. Research here is not concluded.
Multiple sclerosis (MS)
DHA is found in high concentration in myelin sheaths and nerve cell membranes. Epidemiological data describe, in some populations, a statistical association between fish consumption and MS frequency; such observational data do not allow a cause-and-effect statement. Clinical intervention studies are small and heterogeneous, and robust meta-analyses are lacking.
Omega-3, immune cells and cellular mechanisms
The following overview summarises mechanisms described in laboratory, animal and cell studies. They reflect the state of research investigated and are not to be understood as an established health effect in humans.
| Immune cell / Structure | Effect of EPA/DHA | Mechanism |
|---|---|---|
| Macrophages (M1) | Fewer pro-inflammatory cytokines (TNF-alpha, IL-6) | Membrane composition, NF-kappaB inhibition |
| Macrophages (M2) | Promotes anti-inflammatory polarisation | PPAR-gamma activation |
| Neutrophils | Reduced migration into tissue | Resolvins inhibit chemotaxis |
| Exhausted neutrophils | Orderly apoptosis rather than necrosis | Resolvin E1 promotes apoptosis |
| Regulatory T cells (Tregs) | Promotes differentiation | Cytokine network modulation |
| Th17 cells | Reduction in autoimmune stimulation | IL-17 signalling pathway modulation |
| Dendritic cells | Modified antigen presentation | Membrane fluidity, lipid rafts |
| B cells (antibodies) | Modulation of antibody production | Cytokine network effects |
EPA vs. DHA: who acts where in the immune system?
EPA and DHA have different profiles in immunomodulation:
EPA: more potent in cytokine reduction and eicosanoid modulation
EPA is the direct competitor of arachidonic acid in eicosanoid synthesis. From EPA, prostaglandins of series 3 and leukotrienes of series 5 are formed — both considerably less pro-inflammatory than arachidonic acid products (series 2 and 4 respectively). EPA is also the primary source of E-series resolvins. For cytokine reduction (TNF-alpha, IL-6), EPA-predominant formulations show more consistent effects.
DHA: membrane incorporation, neuroprotectin, structural immune action
DHA is preferentially incorporated into immune cell membranes and modifies their physical properties — fluidity, lipid raft formation (microdomains serving as platforms for receptor signalling). DHA is the source of protectins and D-series resolvins, as well as maresins. In the brain, DHA is found in especially high concentration — hence DHA has particular importance for neuroinflammatory processes.
Omega-3 and infection defence: what do we know?
A frequently asked question is whether a modulating effect of omega-3 could impair infection defence if inflammatory reactions are dampened.
In the available research literature, the effect studied is related predominantly to excessive and chronic inflammatory processes, not to the primary recognition and fighting of pathogens. Individual studies have recorded effects on immune cell functions such as NK cells or on vaccine response, with inconsistent results. Reliable, generalisable statements cannot be derived from this.
Omega-3 has also been discussed scientifically in the context of respiratory infections, among other things with regard to the role of pro-resolving mediators in the resolution of strongly inflammatory reactions. However, robust causal conclusions are not possible from the available observational data; they do not demonstrate a disease-related benefit.
Omega-3 and vaccination
Several studies have investigated whether omega-3 influences vaccine response. The evidence is inconsistent: some studies report altered antibody titres after influenza vaccination, others find no difference. A general statement cannot be derived from this. Questions around a specific vaccination are best clarified with your doctor.
The omega-6/omega-3 ratio and immune health
The effect of omega-3 on the immune system cannot be considered in isolation — it is closely linked to the ratio of omega-6 to omega-3 in the diet. In a Western diet, this ratio is typically 15:1 to 20:1 (omega-6 to omega-3). This means arachidonic acid dominates in immune cell membranes — and with it, the pro-inflammatory eicosanoids derived from it.
An increase in omega-3 intake improves the ratio in favour of EPA and DHA. The goal is not to eliminate omega-6 entirely — linoleic acid and arachidonic acid are essential fatty acids with important functions. The aim is to restore an immune cell membrane composition that allows both acute defence responses and orderly resolution of inflammation.
More information on the omega-6 to omega-3 ratio can be found on the page Omega-3 vs omega-6: the right ratio.
In which groups has omega-3 been studied in the immune context?
The following overview shows which population groups omega-3 has been researched in, in connection with inflammatory and immune parameters, and how reliable the respective body of evidence is. The details describe the state of research and do not constitute a recommendation or a promise of benefit for individual groups.
| Population group | Aspect studied | State of evidence |
|---|---|---|
| People with RA or autoimmune diseases | Change in cytokine and inflammatory markers | Several meta-analyses available |
| People with elevated inflammatory markers | CRP, IL-6, TNF-alpha | Umbrella meta-analysis available |
| Older adults (inflammaging) | Chronic low-grade inflammation | Limited |
| Athletes | Training-related inflammation and recovery markers | Individual RCTs, inconsistent |
| People with metabolic syndrome | Inflammatory markers with visceral adipose tissue | Several studies available |
| Pregnant women | Child's immune development and allergy-related endpoints | Limited to inconsistent |
Practical assessment
In the scientific literature, omega-3 is described predominantly as immunomodulatory and not as immunostimulating or immunosuppressive. What is mainly studied is its possible involvement in the orderly resolution of inflammatory processes. Whether a health benefit arises from this for individual population groups is not conclusively established scientifically.
Omega-3 is a food supplement and replaces neither medical treatment nor medication. There is no EFSA-authorised health claim for omega-3 and the immune system. The body of evidence is most extensive for effects on inflammatory markers; for specific diseases the available data are limited and larger studies are needed.
More on the inflammatory mechanisms of EPA and DHA described in studies can be found on the page Omega-3 and inflammation: the evidence. Research in the area of joints is assessed on the page Omega-3 for rheumatism and arthritis.
Frequently asked questions
What does research describe about the role of omega-3 in the immune system?
In the scientific literature, EPA and DHA are usually described as immunomodulatory rather than immunosuppressive. The mechanisms studied mainly concern the regulation of excessive, chronic inflammatory processes. There is no EFSA-authorised health claim for omega-3 and the immune system; the associations described are the subject of ongoing research and are not established health effects.
What do studies on omega-3 in relation to autoimmune diseases investigate?
Some studies have investigated omega-3 in the context of autoimmune diseases. Statements about benefit or safety are a matter for medical assessment in each individual case; this page makes no health promises in this regard. Anyone with a diagnosed condition, or taking medication such as immunomodulators or biologics, should always discuss supplementation with a doctor beforehand.
What are resolvins and which foods contain them?
Resolvins are not nutrients found directly in foods — the body synthesises them from EPA and DHA. This means you do not consume resolvins, but EPA and DHA as precursors, from which the body produces resolvins (and protectins, maresins). Sources of EPA and DHA are oily fish (salmon, mackerel, herring, sardines), algae oil (vegan alternative) and concentrated fish oil supplements.
What is known about omega-3 and vaccination?
The evidence on omega-3 and vaccine response is inconsistent: some studies report altered antibody titres after influenza vaccination, others find no difference. No reliable conclusion can be drawn from this. For individual questions around a vaccination, medical advice is the right point of contact.
What EPA+DHA amounts were used in studies on inflammatory markers?
In studies that recorded inflammatory markers such as CRP, IL-6 or TNF-alpha, amounts of 1–3 g EPA+DHA per day were mostly used; some studies used higher amounts. These figures describe study designs and are not an intake recommendation. For product selection, the EPA+DHA content is decisive, not the number of capsules. Higher amounts should be medically supervised.
Note for patients on immunosuppression
Patients taking immunosuppressants (e.g. after organ transplant) should discuss omega-3 supplementation at higher doses with their transplant physician. Although no direct interactions have been documented, caution is advisable with any change in supplementation. At low to moderate doses (up to 2 g EPA+DHA/day), the risk is very low according to current knowledge.
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Medical disclaimer
This article is for general information purposes only and does not replace medical advice. There is no EFSA-authorised health claim for omega-3 and the immune system. Authorised immune claims exist only for certain other nutrients (e.g. vitamin C, vitamin D, zinc), not for omega-3. The associations described on this page reflect the state of scientific studies and are not established effects. Omega-3 supplements are food supplements and are not a substitute for a balanced diet or medical treatment. In the event of existing conditions, especially autoimmune diseases, or use of immunomodulators, always seek medical advice.