Omega-3 fatty acids are a family of polyunsaturated fats considered essential because the human body cannot produce them and must obtain them through diet. These fats are integrated into cell membranes throughout the body, influencing their function and communication. Chronic inflammation is a prolonged, low-grade immune response that can damage tissues over time. This persistent, underlying inflammation is a factor in the development of many chronic health conditions, and omega-3s play a specialized role in helping the body manage and resolve this detrimental process.
Key Types of Omega-3s and Their Function
The three primary omega-3 fatty acids are alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). ALA is found primarily in plant sources and is the precursor molecule. While the body can convert ALA into the longer-chain forms, EPA and DHA, this process is generally inefficient.
EPA and DHA are long-chain fatty acids often referred to as marine omega-3s because they are abundant in fatty fish. They are incorporated into cell membranes, affecting fluidity and signaling. DHA is highly concentrated in the brain and retina, supporting cognitive and visual development.
EPA and DHA are also the starting materials for producing specialized signaling molecules known as eicosanoids. Most anti-inflammatory and cardiovascular benefits are attributed to the direct intake of EPA and DHA.
The Anti-Inflammatory Mechanism
Omega-3 fatty acids counteract inflammation through a two-part mechanism involving competition and active resolution. Inflammation begins when the body uses omega-6 fatty acids, specifically arachidonic acid (AA), to produce pro-inflammatory signaling molecules. EPA and DHA compete with AA for the same enzymes that process fatty acids into eicosanoids.
A higher concentration of EPA and DHA effectively shifts the balance away from highly inflammatory molecules toward less potent ones. Their presence in cell membranes results in the formation of lipid mediators that are less inflammatory than those derived from omega-6 fats.
The second part of the mechanism involves the synthesis of specialized pro-resolving mediators (SPMs). These compounds, which include resolvins, protectins, and maresins, are biosynthesized directly from EPA and DHA. Resolvins are produced from both EPA and DHA, while protectins and maresins are derived from DHA.
SPMs actively stop the inflammatory process and promote the return to tissue homeostasis. They signal immune cells, such as neutrophils and macrophages, to stop their attack and clear away cellular debris. This ensures inflammation is actively resolved, preventing the transition to chronic inflammation.
Dietary and Supplemental Sources
The most straightforward way to obtain the beneficial long-chain EPA and DHA is by consuming cold-water fatty fish. The U.S. Department of Agriculture recommends consuming at least two servings of fish per week. Rich sources include:
- Salmon
- Mackerel
- Herring
- Sardines
- Trout
For individuals who do not eat fish, plant-based sources provide ALA, which is found in flaxseeds, chia seeds, walnuts, and plant oils like canola and soybean oil. Since the conversion of ALA to EPA and DHA is inefficient, those seeking higher levels of the long-chain forms may consider supplements.
Omega-3 supplements come in several forms. Fish oil is the most common, providing a mixture of EPA and DHA. Krill oil delivers omega-3s in a phospholipid form, which may enhance absorption. Algal oil offers a vegetarian and vegan source of DHA and sometimes EPA, as algae are the original producers of these fatty acids.
When selecting a supplement, it is important to look beyond the total oil content and check the label for the specific amounts of EPA and DHA. High-quality supplements will often state that they have been purified to remove potential contaminants like mercury and polychlorinated biphenyls (PCBs).
Establishing Effective Dosage
For general health maintenance, most major health organizations recommend a combined daily intake of 250–500 milligrams (mg) of EPA and DHA for healthy adults. However, managing chronic inflammation often requires a significantly higher intake to achieve a therapeutic effect.
Studies focusing on anti-inflammatory benefits, such as those for rheumatoid arthritis, have often used dosages in the range of 1,000 mg to 4,000 mg (1 to 4 grams) of combined EPA and DHA per day. Some research has shown that doses exceeding 2.6 grams daily can effectively lower inflammatory markers in the body.
The United States Food and Drug Administration (FDA) has stated that consuming up to 5,000 mg (5 grams) of combined EPA and DHA daily is generally considered safe for adults. Very high doses can potentially increase the risk of bleeding, especially in people taking blood-thinning medications.
Because individual needs vary based on diet, health status, and other medications, consult a physician or registered dietitian before beginning a high-dose omega-3 regimen. A healthcare professional can help determine a specific, safe, and effective dosage tailored to your health goals.