How much omega-3 should I take per day?

Most health organizations recommend 250-500mg of combined EPA and DHA per day for healthy adults. The American Heart Association recommends 1,000mg of combined EPA and DHA daily for people with coronary heart disease. Higher doses up to 2,000-3,000mg may be used for triglyceride reduction under medical supervision.

Is fish oil the same as omega-3?

Not exactly. Fish oil is one source of omega-3 fatty acids, but omega-3s also come from krill oil, algal oil, flaxseed, chia seeds, and walnuts. The key difference is that fish oil and krill oil provide EPA and DHA directly, while plant sources provide ALA, which your body must convert to EPA and DHA at a very low rate (typically under 10%).

Can fish oil supplements cause side effects?

Common side effects include fishy burps, mild nausea, and loose stools. Taking fish oil with a meal usually reduces these. In high doses (above 3,000mg of EPA and DHA per day), fish oil may increase bleeding risk and has been associated with a higher incidence of atrial fibrillation in some clinical trials.

Should I take fish oil if I eat fish regularly?

If you eat two or more servings of fatty fish per week (salmon, mackerel, sardines, herring), you may already be getting enough EPA and DHA from diet alone. A supplement is most useful for people who rarely eat fish. If you are unsure, an omega-3 index blood test can measure your levels.

Omega-3 Fish Oil Supplements: EPA, DHA, and What to Know

Published: March 16, 2026•Updated: March 16, 2026

Omega-3 fatty acids are some of the most studied nutrients in the world. Fish oil supplements are the most popular way to get them, but not all products are created equal. The type of omega-3, the source, the dose, and even the form of the capsule all affect what you actually absorb. Here is what you should know before buying one.

What Are Omega-3 Fatty Acids?

Omega-3s are a family of polyunsaturated fatty acids that your body cannot make on its own. The three main types are ALA (alpha-linolenic acid), EPA (eicosapentaenoic acid), and DHA (docosahexaenoic acid).

ALA comes from plant foods like flaxseed and walnuts. EPA and DHA come primarily from fatty fish and marine sources. Your body can convert ALA to EPA and DHA, but the conversion rate is very low, typically under 10%. That is why most research on omega-3 benefits focuses on EPA and DHA specifically.

EPA vs. DHA: What Each One Does

EPA and DHA serve different roles in the body, though they often work together:

• EPA (eicosapentaenoic acid): Plays a key role in supporting the body's normal inflammatory response. Most studied for cardiovascular and mood support. The prescription omega-3 drug Vascepa uses pure EPA.
• DHA (docosahexaenoic acid): A major structural component of the brain and retina. Important during pregnancy and early development. Also supports cardiovascular health.

Most supplements provide both EPA and DHA. Some products are weighted toward one or the other depending on the intended use.

Sources of Omega-3 Supplements

Fish Oil

The most common and affordable source. Typically derived from anchovies, sardines, or mackerel. Provides both EPA and DHA. Available in triglyceride or ethyl ester forms.

Krill Oil

Sourced from small Antarctic crustaceans. Contains EPA and DHA bound to phospholipids, which some research suggests may improve absorption. Also contains the antioxidant astaxanthin. Typically more expensive per mg of omega-3.

Algal Oil

Derived from microalgae, making it the only vegan source of preformed DHA and EPA. Algae are where fish get their omega-3s in the first place. A good option for people who do not eat fish or have fish allergies.

Cod Liver Oil

Provides EPA and DHA along with vitamins A and D. The added vitamins can be a benefit or a concern depending on your overall intake. Lower in total omega-3 per serving than concentrated fish oil.

How Much Do You Need?

Recommended intakes vary by organization and health status:

Daily intake recommendations for EPA + DHA

General health (most organizations): 250-500mg of combined EPA and DHA per day
American Heart Association (heart disease): 1,000mg of combined EPA and DHA per day
Triglyceride reduction: 2,000-3,000mg per day under medical supervision
FDA upper safety limit: Up to 5,000mg per day of EPA and DHA from supplements is generally considered safe

Pay attention to the EPA and DHA content per serving, not the total fish oil amount. A 1,000mg fish oil capsule may contain only 300mg of combined EPA and DHA.

What the Research Shows

Omega-3 supplementation has been studied extensively. Here is where the evidence is strongest:

• Triglycerides: Well-established. Omega-3s can lower blood triglyceride levels by 15-30% at therapeutic doses, according to the NIH Office of Dietary Supplements.
• Heart health: A 2019 meta-analysis found that omega-3 supplementation reduced the risk of heart attack and coronary heart disease death. Benefits were more consistent in people with existing heart disease or low fish intake.
• Joint comfort: Multiple studies suggest EPA and DHA may support joint comfort by helping regulate the body's inflammatory response, particularly in people with rheumatoid arthritis.
• Brain and mood: DHA is a major structural fat in the brain. Some research links higher omega-3 intake with better cognitive function in older adults, though results from supplementation trials are mixed.

Important: High-dose omega-3 supplementation (above 3,000mg EPA+DHA per day) has been associated with increased risk of atrial fibrillation in some clinical trials. Talk to your doctor before taking high doses.

What to Look For in an Omega-3 Supplement

EPA + DHA Per Serving

Check the supplement facts for actual EPA and DHA content, not just total fish oil. Look for at least 500mg of combined EPA and DHA per serving.

Triglyceride Form

Fish oil in triglyceride (TG) form is better absorbed than ethyl ester (EE) form. Many budget products use ethyl esters. Check the label or contact the manufacturer if it is not listed.

Third-Party Testing

Fish oil can contain mercury, PCBs, and other contaminants. Look for products tested by IFOS (International Fish Oil Standards), NSF, or USP for purity and potency.

Freshness

Omega-3s are prone to oxidation. Quality products list a "best by" date and keep peroxide values low. If your fish oil smells or tastes strongly rancid, do not use it.

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