Krill oil and fish oil both contain DHA and EPA omega-3s. When making the choice, consider factors like the concentration of omega-3s.

You’ve probably heard that it’s important to get omega-3 fatty acids (omega-3s) in your diet. Their benefits have been highly publicized: They decrease cholesterol, promote heart health, support brain health, and decrease inflammation in the body.

Your body can’t make omega-3s on its own, so including them in your diet is essential. Both fish oil and krill oil are great sources of these essential fatty acids. Fish oil comes from oily fish such as salmon, sardines, and albacore tuna. Krill oil comes from krill, small cold-water crustaceans that resemble shrimp.

Fish oil and krill oil both contain two types of omega-3s: DHA and EPA. Although fish oil has a higher concentration of DHA and EPA than krill oil, the DHA and EPA in krill oil is thought to have more antioxidants and be more absorbable by the body.

Fish oil has been mainstream for decades so it’s better studied than krill oil. Still, krill oil is making a name for itself as an effective, if not superior, source of omega-3s. Keep reading to learn more.

According to the Mayo Clinic, people in the United States have lower levels of DHA and EPA in their bodies than people in Japan and other nations with lower heart disease rates. Following are a few of the other possible pros of taking fish or krill oil:

Fish oil

Some research has shown omega-3s in fish oil may:

Even so, much of the research on omega-3s isn’t conclusive. For example, a 2013 study that involved over 1,400 people found omega-3s didn’t reduce heart attacks or death in people with heart disease or heart disease risk factors. More research is needed to prove fish oil improves most conditions.

Krill oil

According to the Cleveland Clinic, animal studies have shown krill oil improves DHA absorption and DHA delivery to the brain. This means less krill oil is needed than fish oil for health benefits.

But according to a 2014 commentary, a trial that concluded krill oil is superior to fish oil was misleading due to its use of an atypical fish oil.


Although krill oil is thought to have similar effects as fish oil in the body, it hasn’t been well-studied in humans. The Cleveland Clinic recommends getting omega-3s from foods or supplementing your diet with fish oil instead of krill oil until more human studies on krill oil are completed.

Both fish oil and krill oil supplements are generally considered safe when used in recommended doses. You may be able to minimize potential side effects, such as stomach upset, by taking supplements with a meal.

You shouldn’t use fish oil or krill oil if you have a fish or shellfish allergy. Fish oil or krill oil may also increase your bleeding risk, lower blood pressure, or impact blood sugar levels.

Talk to your doctor before using if you:

Fish oil

Eating one to two meals of fatty fish weekly is also considered safe, despite concerns about the high mercury levels, PCBs, and other contaminants in fish.

Fish lowest in mercury are:

  • salmon
  • pollack
  • canned light tuna
  • catfish

Fish highest in mercury are:

  • tilefish
  • shark
  • king mackerel
  • swordfish

Quality fish oil supplements don’t contain mercury, but they may still cause minor side effects. This includes:

Krill oil

Because krill are at the bottom end of the ocean’s food chain, they don’t have time to accumulate high levels of mercury or other contaminants.

Krill oil supplements may cause gastrointestinal upset. However, they typically don’t cause belching.

Seafood’s surge in popularity over the last couple decades has put a strain on some fish species and the environment. According to the Monterey Bay Aquarium Seafood Watch, “90 percent of the world’s fisheries are fully exploited, over-exploited, or have collapsed.”

Sustainable fishing and sustainable aquaculture (fish farming) is the practice of harvesting and processing seafood so it doesn’t deplete an ocean species, alter its ecosystem, or negatively impact the environment.

To support sustainable fishing efforts — and make sure you’re getting the highest quality product possible — make sure the fish oil and krill oil you use is obtained using sustainable methods. Look for products certified sustainable by the Marine Stewardship Council (MSC) or the International Fish Oil Standards Program (IFOS).

You should also keep in mind the freshest and highest quality fish oils don’t taste fishy or have a strong, fishy odor.

Fish oil and krill oil are available in capsule, chewable, and liquid forms. A standard dose of fish oil or krill oil for adults is 1 to 3 grams daily. However, it’s best to consult your doctor for the dose that’s right for you. They may advise you to use more or less.

When it comes to omega-3s, more in your diet isn’t better. Taking too much doesn’t offer better results, but it does increase your risk of serious side effects.

Technically, you can cook with liquid fish oil or krill oil, but it’s not common. If you want to experiment, try adding a teaspoon in your morning smoothie or a homemade vinaigrette.

Your body needs omega-3s to function, but studies are mixed on the best way to get them and how much you need. Eating sustainable seafood twice a week should help you get enough, but it’s no guarantee. It can be difficult to know exactly how much omega-3 is present in the fish you eat.

As an alternative or in addition to eating fatty fish, you can enjoy flax or chia seeds as they have a high omega-3 content.

Both fish oil and krill oil are reliable sources of omega-3s. Krill oil appears to have a health edge over fish oil because it may be more bioavailable, but it’s also more expensive and not well-studied. On the other hand, studies are mixed on some of the health benefits of fish oil.

Unless you’re pregnant, or until research on both types of omega-3s is definitive, whether to use fish oil or krill oil comes down to personal preference.