Omega-3

fatomega-3 fatty acid

Best in the morningTake with food

What is it

Omega-3 fatty acids are a family of essential polyunsaturated fats important for cardiovascular health, brain development, and reducing inflammation. The three most relevant forms are EPA and DHA (from marine sources) and ALA (from plants).

How it works

Omega-3 fatty acids are incorporated into cell membranes throughout the body, where they influence membrane fluidity, receptor function, and signaling. EPA and DHA are precursors to specialized pro-resolving mediators (resolvins and protectins) that actively turn off inflammation, and they shift the balance away from inflammatory omega-6-derived signals. DHA is particularly concentrated in the brain and retina, where it supports neural function and visual development. EPA is more associated with cardiovascular and inflammatory effects. ALA from flax, chia, and walnuts can be converted to EPA and a small amount of DHA, but conversion is inefficient — typically less than 10 percent of ALA becomes EPA in adults, and less than 1 percent becomes DHA.

Evidence for 7 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

High triglycerides

Grade A

Strong evidence

EPA+DHA at 2 to 4 g/day reduces triglycerides by 20 to 50 percent. Prescription omega-3 products are FDA-approved for severe hypertriglyceridemia.

Fetal brain and visual development

Grade A

Strong evidence

DHA is concentrated in fetal brain and retina. Maternal intake during pregnancy supports infant neurodevelopment and visual acuity.

Cardiovascular event prevention

Grade B

Good evidence

REDUCE-IT trial showed prescription icosapent ethyl (4 g/day pure EPA) reduced cardiovascular events in high-risk people on statins. Over-the-counter fish oil trials have been more mixed.

Rheumatoid arthritis symptoms

Grade B

Good evidence

3 g/day or more of EPA+DHA reduces joint stiffness and tenderness modestly. Supplements complement standard care.

Depression (adjunct)

Grade C

Moderate evidence

Some trials suggest EPA-predominant formulas may help as antidepressant add-ons, particularly in major depression. Evidence is mixed.

Dry eye syndrome

Grade C

Moderate evidence

Mixed evidence. The large DREAM trial did not show benefit; some smaller trials and earlier reviews suggest modest improvement.

Cognitive decline prevention

Grade D

Mixed evidence

Trials of omega-3 supplementation in cognitively healthy adults have not consistently shown benefit for preventing dementia.

5 commercial forms

Fish oil (triglyceride form)

natural form, well absorbed with food

The form found in fish. Generally well absorbed when taken with a fat-containing meal. Most over-the-counter fish oil is in this form.

Fish oil (ethyl ester)

concentrated, requires food for good absorption

A processed form that allows higher EPA+DHA concentration per capsule. Absorbs less well on an empty stomach than the triglyceride form.

Re-esterified triglycerides (rTG)

concentrated triglyceride form, well absorbed

Ethyl esters converted back to triglyceride form. High EPA+DHA content with good absorption.

Krill oil (phospholipid form)

phospholipid-bound, may absorb better at lower doses

EPA+DHA bound to phospholipids. Some studies suggest better absorption at lower doses, though comparisons at matched doses are less clear. More expensive.

Algal oil

plant-source DHA (and some EPA)

DHA extracted from algae. The original source of DHA in fish. Suitable for vegans and vegetarians.

Dosage

There is no formal RDA for EPA and DHA in the U.S., but most health organizations suggest at least 250 to 500 mg of combined EPA+DHA per day for general health, with higher doses (1,000 mg or more) for cardiovascular benefit and 2,000 to 4,000 mg under medical supervision for elevated triglycerides. The AI for ALA is 1.6 g/day for men and 1.1 g/day for women. The FDA considers up to 3 g/day of combined EPA+DHA generally safe.

When and how to take it

Omega-3s are fat-soluble and absorb best when taken with a meal containing fat — even a small amount substantially improves absorption. Many people take fish oil in the morning to avoid sleep-time burping; others take it with the evening meal. Splitting larger doses (above 1 g of combined EPA+DHA) into two daily doses can reduce fishy aftertaste and improve absorption. Freezing fish oil capsules can reduce burping for sensitive people. Enteric-coated capsules dissolve in the intestine rather than the stomach, also reducing this side effect.

Food sources

Food	Amount	%DV
Salmon (Atlantic, farmed), 3 oz cooked	1.24 g EPA+DHA	—
Sardines (canned in oil), 3 oz	0.74 g EPA+DHA	—
Mackerel (Atlantic), 3 oz cooked	1.02 g EPA+DHA	—
Anchovies (canned), 3 oz	1.2 g EPA+DHA	—
Trout (rainbow, cooked), 3 oz	0.84 g EPA+DHA	—
Tuna (light, canned in water), 3 oz	0.17 g EPA+DHA	—
Flaxseed (ground), 1 Tbsp	1.6 g ALA	—
Chia seeds, 1 oz	5 g ALA	—
Walnuts, 1 oz	2.5 g ALA	—

Safety

Omega-3s are well tolerated. Common side effects include fishy aftertaste, burping, and mild digestive upset. High doses (above 3 g/day) can prolong bleeding time slightly, particularly with anticoagulants. Quality varies — choose supplements that have been tested for mercury, PCBs, and oxidation. Rancid fish oil tastes and smells bad and provides little benefit.

Who should be cautious

People on anticoagulants or scheduled for surgery should discuss high-dose use with their doctor. Pregnant and breastfeeding women benefit from DHA for fetal brain development — most prenatal vitamins include some. People with seafood allergies should choose algal oil. People with atrial fibrillation should know that very high doses (above 4 g/day) have been associated with increased AFib risk in some trials.

Interactions

High-dose omega-3s may increase bleeding risk with anticoagulants (warfarin, DOACs) and antiplatelet drugs (aspirin, clopidogrel), though the clinical significance is modest at typical doses. May lower blood pressure slightly, which can interact with antihypertensives. Prescription omega-3 products (icosapent ethyl, omega-3-acid ethyl esters) have specific drug indications.

Frequently asked questions

How much omega-3 should I take per day?⌄

At least 250 to 500 mg of combined EPA+DHA for general health, 1,000+ mg for cardiovascular support, and 2,000 to 4,000 mg under medical supervision for high triglycerides.

Is plant-based ALA enough?⌄

ALA is essential and offers some health benefit on its own, but conversion to EPA and DHA is inefficient. Vegans and vegetarians may benefit from algal-source DHA.

How do I avoid fish oil burps?⌄

Take with a meal containing fat, freeze the capsules, choose enteric-coated formulas, or split the dose. Rancid fish oil burps the worst — check the smell.

Is krill oil better than fish oil?⌄

Some studies suggest better absorption per dose, but at matched EPA+DHA doses, evidence for clinical superiority is limited. Krill oil also provides astaxanthin, an antioxidant.

Can fish oil thin my blood?⌄

At very high doses (above 3 g/day) it can modestly extend bleeding time. Clinical significance at typical doses is small, but discuss with your doctor if you take anticoagulants or have surgery scheduled.

Track Omega-3 with Pilora

Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.

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Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you're pregnant, breastfeeding, on medications, or managing a chronic condition.