Omega-3 Fatty Acids: What Does the Evidence Show?

As a functional medicine nurse practitioner, I don't recommend supplements because they're trending. I look at your diet, health history, medications, and goals to determine whether an omega-3 supplement, and which type and dose, makes sense for you.

Omega-3s are essential fats your body can't make on its own. There are three main types:

• EPA: found in fatty fish and marine oils; well studied for heart health and mood
• DHA: also from fish and algae; a key structural fat in the brain and eyes
• ALA: from flaxseed, chia, walnuts, and canola oil; converts to EPA/DHA only in small amounts, so it's not an equivalent substitute

Food first. The best sources are salmon, sardines, herring, mackerel, trout, and anchovies. If you don't eat fish, algae-based supplements provide DHA (and sometimes EPA).

Heart health. Omega-3s can lower triglycerides and modestly reduce blood pressure. Prescription-strength EPA is used for patients with high triglycerides and cardiovascular risk, but that's different from over-the-counter fish oil and requires medical supervision. For most healthy adults, eating fish 1 to 2 times a week remains the standard recommendation.

Inflammation. This is one of the better-supported benefits. EPA and DHA are converted into specialized molecules (resolvins, protectins, and maresins) that actively help the body resolve inflammation rather than just suppress it. In rheumatoid arthritis specifically, meta-analyses show consistent reductions in joint pain, morning stiffness, and NSAID use after 3 to 4 months of supplementation. Evidence for vague "chronic inflammation" in otherwise healthy people is weaker, and omega-3s aren't a substitute for treating the underlying cause of inflammatory symptoms.

Mood. Several reviews suggest omega-3s (especially higher-EPA formulas) may modestly help as an add-on to standard depression treatment, not a replacement for therapy or medication.

Pregnancy. Adequate DHA supports fetal brain and eye development. Many prenatals include it, though amounts vary, worth discussing with your OB.

• Memory/cognition: no consistent evidence that supplementation prevents cognitive decline in healthy adults
• Sleep: limited, inconsistent data; CBT-I remains first-line for chronic insomnia
• Dry eye: larger trials show mixed-to-minimal benefit
• Osteoarthritis: much less convincing than for rheumatoid arthritis

Generally well tolerated. Common side effects: fishy aftertaste, mild stomach upset, burping, loose stools. Higher doses may raise bleeding risk, especially if you're on blood thinners, so talk to your provider first. Because supplements aren't as tightly regulated as medications, look for third-party tested products.

Not everyone needs to. A supplement may make sense if you:

• Rarely eat fatty fish
• Have elevated triglycerides (under medical guidance)
• Are pregnant and need more DHA
• Have another evidence-backed reason, identified with your provider

If you already eat fatty fish regularly, you may not need to add anything.