The best fish oil for you depends on why you’re taking it, but for most people, a supplement in triglyceride form with a combined EPA and DHA dose of at least 500 mg per day is a solid starting point. Beyond that baseline, the right choice comes down to your health goals, how much you’re willing to spend, and whether you can tolerate swallowing large capsules. Here’s how to sort through the options.
EPA vs. DHA: Which One Matters More
Fish oil contains two key omega-3 fatty acids, EPA and DHA, and they do different things in your body. DHA concentrates in your brain and eyes, playing a structural role in cell membranes throughout the nervous system. EPA is more involved in managing inflammation and has shown the strongest evidence for cardiovascular benefits. A purified EPA formulation is the only omega-3 that has demonstrated clear results for people with heart disease who already take statins and have elevated triglycerides.
For mood support, EPA appears to be the more important of the two. Harvard Health reports that the most effective omega-3 preparations for depression contain at least 60% EPA relative to DHA, with most successful clinical trials using doses between 1 and 2 grams per day of combined omega-3s. If you’re taking fish oil primarily for general health, a balanced EPA/DHA supplement works fine. If you have a specific goal, lean toward whichever fatty acid the evidence supports for that condition.
Triglyceride Form vs. Ethyl Ester Form
This is one of the biggest quality differences most people overlook. Fish oil supplements come in two main forms: triglyceride (sometimes labeled “rTG” for re-esterified triglyceride) and ethyl ester (often labeled “EE”). The difference in absorption is dramatic.
In controlled studies, EPA from the triglyceride form was absorbed at 68% and DHA at 57%, compared to just 20% and 21% respectively from ethyl esters when taken without food. Even when subjects ate a high-fat meal alongside the ethyl ester form, absorption only climbed to around 60% for both fatty acids. That’s still lower than the triglyceride form taken on an empty stomach. When triglyceride-form fish oil was paired with a fatty meal, EPA absorption jumped to 90%.
A separate study found that the overall bioavailability of ethyl ester EPA and DHA was only 40 to 48% compared to the triglyceride form, with peak blood levels about 50% lower. In practical terms, a cheaper ethyl ester supplement might look like a bargain on the label, but you could be absorbing less than half the omega-3s listed. Triglyceride-form supplements cost more, but you get substantially more of what you’re paying for. Check the label or the manufacturer’s website for the form. If it doesn’t say, it’s almost certainly ethyl ester.
How Much to Take
There’s no single recommended dose for healthy adults. The American Heart Association doesn’t recommend omega-3 supplements for people without a high cardiovascular risk, but it does suggest about 1 gram per day of combined EPA and DHA for people with existing coronary heart disease. For managing high triglycerides specifically, the AHA supports 4 grams per day of prescription-grade omega-3s, which is a clinical dose that requires medical oversight.
Most general-purpose fish oil capsules contain around 300 mg of combined EPA and DHA per 1,000 mg capsule, meaning the rest is other fats. A “1,000 mg fish oil” label can be misleading if you don’t flip it over and check the EPA and DHA lines in the supplement facts. You may need two or three standard capsules to reach a meaningful dose. Concentrated formulas pack 600 to 900 mg of EPA and DHA into a single softgel, which is more convenient and often a better value per milligram of actual omega-3.
What to Look for on the Label
When comparing products, focus on these specifics:
- Combined EPA + DHA per serving, not total fish oil. This is the number that matters.
- Form (triglyceride vs. ethyl ester). Triglyceride or rTG is better absorbed.
- Third-party testing. Look for seals from organizations like IFOS (International Fish Oil Standards), NSF, or USP, which verify purity, potency, and freshness.
- TOTOX value. This measures total oxidation. A TOTOX value above 20 indicates rancid oil. Reputable brands publish this number or make it available on request. If your fish oil tastes strongly fishy or gives you foul-smelling burps, oxidation is a likely culprit.
Store your fish oil in a cool, dark place or in the refrigerator. Heat, light, and air all accelerate oxidation. If you buy in bulk, freezing capsules extends shelf life and can also reduce fishy aftertaste.
Algae Oil as an Alternative
If you’re vegetarian, vegan, or simply concerned about ocean sustainability, algae oil is a legitimate option. Fish get their omega-3s from eating microalgae in the first place, so algae-derived supplements cut out the middleman. A 2024 study published in the International Journal of Molecular Sciences found that the bioavailability of DHA and EPA from microalgal oil was statistically equivalent to fish oil, with a geometric mean ratio of 112% for combined DHA and EPA.
The main compositional difference is the ratio: most algae oils are higher in DHA than EPA (roughly a 3:1 ratio), while fish oil typically leans toward EPA (about a 3:2 ratio). If you need a high-EPA supplement for mood support, finding an algae-based option with the right ratio takes more effort, though products are increasingly available. For general brain health, the naturally high DHA content in algae oil is actually an advantage.
Sustainability Certifications
Overfishing is a real concern with omega-3 supplements, particularly those sourced from small forage fish like anchovies, sardines, and menhaden. Two certifications help identify responsibly sourced products. The Marine Stewardship Council (MSC) certification requires that fisheries maintain healthy target populations, avoid depleting ecosystems, and minimize bycatch of non-target species. Friend of the Sea (FOS) is a similar program with its own set of environmental standards. Either seal on a bottle indicates independent verification that the fish weren’t harvested in a way that damages marine ecosystems.
Blood Thinners and Fish Oil
Omega-3 fatty acids can affect how your blood clots. They reduce platelet aggregation and may lower levels of certain clotting factors. For most people, this effect is mild and even beneficial. But if you take blood-thinning medications like warfarin, it can become a problem. In one documented case, a patient who doubled her fish oil intake from 1,000 to 2,000 mg per day saw her INR (a measure of blood clotting time) jump from 2.8 to 4.3 within a month, with no other changes to her diet or medications. That’s a clinically significant shift that increases bleeding risk.
If you’re on anticoagulants or antiplatelet drugs, or you’re scheduled for surgery, your prescribing physician needs to know about your fish oil use. This applies to high-dose omega-3s especially, but even standard doses can add to the effect of medications that already thin your blood.
Picking the Right Supplement
For general health, a triglyceride-form fish oil providing 500 to 1,000 mg of combined EPA and DHA daily covers most bases. Take it with a meal that contains some fat to maximize absorption. For mood support, look for a product with at least 60% EPA and aim for 1 to 2 grams of total omega-3s. For heart health, follow whatever dose your cardiologist recommends based on your lipid profile.
Price per milligram of EPA + DHA is a better comparison metric than price per capsule. A 90-count bottle of concentrated triglyceride-form fish oil at $30 will often deliver more usable omega-3s than a 200-count bottle of standard ethyl ester capsules at $15. Do the math on the supplement facts panel, not the front label.