Fish Oil vs Krill Oil vs Algae Omega-3: What's the Difference?

For most people, fish oil is the best choice: it gives you the most EPA and DHA for your money, and it has the most research behind it. Krill oil is an option if you want small capsules and don't mind paying more for less omega-3. Algae oil is the pick if you're vegan, vegetarian or allergic to fish, since it's the original source of the omega-3s fish contain.

All three provide the two long-chain omega-3s that matter most, EPA and DHA. The differences come down to how much you get per capsule, the form they're in, cost, allergies and diet.

Quick Comparison

Figures from the NIH Office of Dietary Supplements and product labels. Amounts vary a lot between products, so always check the label.

First: EPA and DHA Are What Count

There are three main omega-3s:

• ALA, from plants like flaxseed, chia and walnuts.
• EPA and DHA, from fish, krill and algae.

Your body can turn a little ALA into EPA and DHA, but not much, which is why supplements focus on EPA and DHA directly. The NIH notes that EPA and DHA are actually made by microalgae, and fish get them by eating algae, or eating things that eat algae.

When you compare products, ignore the big number on the front ("1,000 mg fish oil") and look for the EPA and DHA amounts on the Supplement Facts panel. A typical standard fish oil capsule has 1,000 mg of fish oil but only about 300 mg of EPA and DHA combined. Our guide on how to read a supplement label shows where to look.

Fish Oil: The Default Choice

Fish oil is the most common, cheapest and best-studied omega-3 supplement. Most large trials of omega-3s used fish oil.

Pros:

• The most EPA and DHA for your money.
• Concentrated versions pack 600–1,000 mg or more of EPA and DHA into a capsule.
• The largest body of research.

Cons:

• "Fishy burps" for some people. Taking it with a meal, or choosing an enteric-coated or lemon-flavored version, usually helps.
• Quality varies. Look for third-party testing for freshness and contaminants like mercury.

About forms: fish oil comes as natural triglycerides, ethyl esters (a concentrated form) or re-esterified triglycerides. The NIH notes triglyceride forms are absorbed somewhat better than ethyl esters, but all forms raise blood EPA and DHA levels. Taking ethyl esters with a meal that has some fat helps.

Nordic Naturals Ultimate Omega is a concentrated triglyceride fish oil with 650 mg EPA and 450 mg DHA per two soft gels, and a lemon flavor that helps with aftertaste:

For more options, see our ranking of the best fish oil supplements.

Krill Oil: Smaller Capsules, Less Omega-3

Krill oil comes from Antarctic krill, small shrimp-like crustaceans. Its omega-3s are mostly attached to phospholipids, and it naturally contains astaxanthin, a red antioxidant pigment.

The absorption question: krill oil is often marketed as "better absorbed" than fish oil. The NIH says some studies suggest its phospholipid form has somewhat higher bioavailability, and others don't. Even if it is absorbed a bit better, a typical krill capsule has far less EPA and DHA than a fish oil capsule, so you usually need more capsules, or end up with a lower dose.

Pros:

• Small capsules that are easy to swallow.
• Many people get fewer fishy burps.
• Contains astaxanthin and choline.

Cons:

• Much less EPA and DHA per capsule.
• The most expensive per gram of EPA and DHA.
• Not safe if you're allergic to shellfish.

Kori Krill Oil 1200 mg provides about 250 mg of EPA and DHA per soft gel, plus phospholipids and astaxanthin:

Algae Oil: The Vegan Option

Algae oil comes from microalgae grown in tanks, the same organisms that put omega-3s into the ocean food chain in the first place. It's the only source of EPA and DHA that's suitable for vegans.

Pros:

• Vegan and vegetarian friendly.
• Safe for people with fish or shellfish allergies.
• Grown in controlled conditions, so there's less concern about ocean contaminants.
• The NIH cites a small study finding DHA from algal oil was absorbed as well as DHA from cooked salmon.

Cons:

• Many products are mostly DHA with little EPA. Check the label if you want both.
• Usually costs more than fish oil.
• Less research than fish oil, especially for EPA.

Nordic Naturals Algae Omega is a vegan algae oil with about 715 mg of omega-3s per two soft gels, including both EPA and DHA:

Which One Should You Choose?

How Much Omega-3 Do You Need?

There's no official daily target for EPA and DHA in the US. Many health organizations suggest about 250–500 mg of EPA and DHA a day for healthy adults, which is roughly what two servings of oily fish a week provide. Higher doses are sometimes used for specific health goals, but those are best discussed with your doctor.

A few safety notes from the NIH:

• The FDA considers up to 5 g a day of EPA and DHA from supplements safe when used as directed.
• High doses can affect bleeding. If you take blood thinners or have surgery coming up, talk to your doctor first.
• Omega-3s can interact with some medications, so check with your doctor or pharmacist if you take any regularly.

FAQ

Is krill oil better than fish oil?

Not for most people. Krill oil's omega-3s may be absorbed slightly better, but studies disagree, and a krill capsule contains much less EPA and DHA than a fish oil capsule. Fish oil gives you more omega-3 for your money.

Is algae omega-3 as good as fish oil?

For DHA, it appears to be: a small study found DHA from algal oil was absorbed as well as DHA from salmon. Many algae products have less EPA than fish oil, so check the label if EPA matters to you.

Can I get enough omega-3 from flaxseed or chia?

Probably not enough EPA and DHA. Flax and chia provide ALA, and your body converts only a small amount of ALA into EPA and DHA. If you don't eat fish, an algae oil supplement is the more reliable option.

Why does fish oil give me fishy burps?

Burps happen when some of the oil comes back up before it's digested. Taking it with a meal, freezing the capsules, or choosing an enteric-coated or lemon-flavored product usually helps.

Should I take omega-3 if I already eat fish?

If you eat oily fish like salmon, sardines or mackerel twice a week, you may not need a supplement. If you rarely eat fish, a supplement is an easy way to fill the gap.

The Bottom Line

All three provide EPA and DHA. Fish oil is the best value and the best studied, so it's the right choice for most people. Krill oil suits people who want small capsules and don't mind paying more for less omega-3. Algae oil is the best option for vegans, vegetarians and anyone with a fish allergy. Whichever you choose, compare products by their EPA and DHA content, not the total oil on the front of the bottle.