Fish oil supplies concentrated omega-3s (EPA and DHA) used for heart, brain, and metabolic health. Modern processing and third-party testing reduce contaminant risks. Evidence strongly supports triglyceride lowering and selective cardiovascular benefit with prescription preparations; routine supplement use should prioritize dietary sources and clinician guidance for high-dose therapy. Choose supplements with clear EPA/DHA labeling, purity testing, and sustainable sourcing.
Why people take fish oil
Fish oil supplements remain popular because they provide concentrated omega-3 fatty acids - primarily EPA and DHA - which support heart and brain health and play roles in inflammation and immune function. Many people use supplements when they don't eat enough oily fish like sardines, mackerel, or salmon.Where fish oil comes from and how it's processed
Manufacturers typically extract oil from small pelagic fish (anchovies, sardines, menhaden) or as a by-product of fish meal production. The crude oil goes through refining steps to remove free fatty acids, odors, and contaminants. Common further processing includes molecular distillation and concentration into ethyl ester or re-esterified triglyceride forms.Molecular distillation and other purification methods reduce contaminants such as mercury and PCBs, and most reputable manufacturers subject final products to third-party testing by organizations like USP, NSF, or IFOS to confirm purity and label accuracy.
Evidence and uses
Clinical evidence is strongest for specific uses: omega-3s reliably lower triglyceride levels, and prescription EPA-only formulations have shown cardiovascular event reduction in selected high-risk patients. For general heart-disease prevention, the evidence is more mixed, and major health organizations emphasize getting omega-3s from food first and using supplements when necessary.DHA is important during pregnancy for fetal brain development, so many prenatal guidelines encourage seafood intake or a prenatal supplement with DHA when intake is low. High-dose therapy (generally grams per day) is used under medical supervision for severe hypertriglyceridemia. 1
Safety and dosing
Typical over-the-counter supplements provide 250-1,000 mg combined EPA+DHA per serving, but label potency varies widely. For specific medical conditions, clinicians may recommend higher prescription doses; do not exceed recommended amounts without medical advice.Side effects are usually mild (fishy aftertaste, GI upset). At high doses, omega-3s can affect bleeding risk and may interact with blood thinners. People who are pregnant, nursing, on anticoagulants, or preparing for surgery should consult a clinician.
Choosing a product
Look for:- Clear EPA+DHA amounts on the label.
- Third-party testing seals (USP, NSF, IFOS) or readily available batch results.
- Source and sustainability information (small pelagic species or certified fisheries).
- Alternatives such as algal oil if you prefer a vegetarian source of DHA (and in some products, EPA). 2
Bottom line
Fish oil supplements are a convenient way to increase EPA and DHA if your diet lacks oily fish. Benefits and appropriate doses depend on individual health goals. Choose tested products, check EPA/DHA content, and consult your healthcare provider for medical or high-dose use.- Confirm current wording and recommendations from the American Heart Association and other major health bodies on omega-3 supplements versus dietary intake.
- Verify which algal oil products commonly provide EPA in addition to DHA and cite prevalence.
- Confirm standard therapeutic dosing guidance (e.g., grams/day) for prescription omega-3 products and identify current prescription formulations and indications.