Krill Oil vs. Fish Oil: The Best Way to Get Your Omega-3s

June 29, 2023

The Great Debate: Krill Oil vs. Fish Oil

By now you’ve likely heard about the many health benefits of omega-3 fatty acids, a type of dietary fat called polyunsaturated fatty acids that occur primarily in marine sources. Indeed, getting enough omega-3s has been linked with a reduced risk of heart disease, cancer, depression, and anxiety; it’s been shown to fight inflammation and decrease age-related cognitive decline; it also contributes to improved joint, bone, and eye health.

It’s not just for these reasons that omega-3s are considered “essential.” Our bodies really need them: They’re an integral part of our cell membranes, and they play a key role in cell function. Also, we can’t produce omega-3s on our own, meaning we have to get them from outside sources like salmon (2,260 mg per 3.5 ounces), oysters (370 mg per 6 oysters), flax seeds (2,350 mg per tablespoon of whole seeds), and soybeans (670 mg per half cup). And yet more than 90% of Americans consume less than the recommended 1,100 mg for women and 1,600 mg for men per day from our diet.

So, it makes sense to make up for what you’re missing by taking a daily omega-3 supplement. Most Americans who do are getting it in the form of fish oil (fish like mackerel, salmon, and herring are top food sources of omega-3s). And while there’s nothing wrong with fish oil, a growing body of research suggests there’s a smarter source: Krill oil. Here’s what you need to know about krill oil, and what the science shows about its health-enhancing potential.

What is Krill Oil?

It comes from krill, shrimp-like crustaceans that live in every ocean around the world, though their highest concentrations are in the Antarctic ocean. Krill are small — only about 2 inches long — but the pinkish-red, transparent creatures play a huge role in the ecosystem as a primary food source for fish, seals, penguins, and whales.

Antarctic krill in the water column of the Southern Ocean off the coast of the Antarctic Peninsula

Like fish oil, krill oil has two key types of omega-3 fatty acids: Eicosapentaenoic acid or EPA, and docosahexaenoic acid or DHA. They do various and different things: EPA helps produce eicosanoids, signaling molecules that help manage inflammation and immune response, for instance; DHA is a component of cell membranes, and it facilitates messaging between nerves and is essential to brain development and function. DHA and EPA also work together in your body, and you need both.

Krill themselves use their reserves of fatty acids to help them survive when times get tough. In fact, they can live up to 200 days without food by shrinking and tapping into their body’s biomaterial as an energy source.

The 6 Big Advantages of Krill Oil over Fish Oil

1. Omega-3s in Krill Oil are Easier to Absorb.

Though both fish oil and krill oil contain EPA and DHA, the molecular structure of their fatty acids is different in a way that matters. In krill, the omega-3s are in the form of phospholipids, molecules made up of glycerol, two fatty acids, and the mineral phosphorus. In fish oil, the omega-3s are in the form of triglycerides, compounds made up of glycerol and three fatty acids.

That slight difference in molecular makeup appears to give krill oil the advantage in terms of omega-3 bioavailability: The phospholipid form of omega-3 fatty acids in krill was shown to help facilitate the incorporation of omega-3s into tissues faster and more effectively than the triglyceride form in fish, according to findings in the International Journal of Molecular Sciences and elsewhere. In other words, the omega-3s in krill are easier for the body to absorb, suggesting that because of that efficiency, you can take about 37% less krill oil than fish oil to get the same amount of benefit.

2. The Phospholipids in Krill Oil Offer Critical Benefits Fish Oil Can’t Provide.

Humans need sufficient levels of phospholipids to ensure optimal cell function, cell growth, and the generation of new cells. In fact, phospholipids have been shown to help boost brain health and have protective effects against heart disease and liver disease, poor immune function, stress, depression, and more.

But as we age, our cells’ phospholipid levels naturally decrease. And because modern-day diets contain only about a third of the phospholipids they used to 100 years ago, it’s tough to replenish stores through food alone. Supplementing with krill oil — which has omega-3s in phospholipid form — can help fill in those nutritional gaps; fish oil won’t.

3. Krill Oil Has Brain-Boosting Choline; Fish Oil Does Not.

Keeping things on a molecular level for another moment, the structure of phospholipids in krill oil brings one more benefit to the table. Phospholipid molecules have what’s called a “head group,” a phosphate group that can be modified with a simple organic molecule. In the case of krill oil, the molecule is choline, an essential vitamin-like nutrient.

Choline is probably best known for its vital role in brain development in utero and early childhood, but it’s also essential for a healthy heart, liver, brain, and more at every age. Our bodies convert choline to acetylcholine, a neurotransmitter that’s important for learning, breathing, memory, sleep, and metabolism.

While we can produce a small amount of choline in the liver, it’s not enough to meet our needs, so we must get some from diet — the recommended daily intake for men is 550 mg/day; for women, 425 mg/day. But as it turns out, most of us fall short: 90% of the American population has an inadequate intake of choline, according to the National Health and Nutrition Examination Survey.

Unfortunately, a deficiency in choline can lead to serious health concerns, including fatty liver, muscle damage, and atherosclerosis (the buildup of cholesterol plaque in artery walls). Supplementing with krill oil is one easy way to help you hit your choline levels, along with reaching for natural food sources like beef liver, eggs, and soybeans.

4. Krill Oil Has More Potent Antioxidant Power than Fish Oil.

Though omega-3 fatty acids do have some antioxidant actions — they help reduce inflammation and counter cell-damaging free radicals — they’re not technically antioxidants. Krill oil, however, does contain a naturally-occurring antioxidant called astaxanthin, adding to its toolbox of beneficial compounds; fish oil does not.

Comparing dissolvability of phospholipids in krill oil to fish oil

Astaxanthin is responsible for the dark red color of krill oil, and it helps keep the omega-3 fatty acids in the oil stable. In our cells, astaxanthin has been shown to offer protection against free radicals and help normalize oxidative stress — the process by which free radicals are formed — in people with higher levels of oxidative stress such as smokers. The result: Less inflammation throughout the body, and especially the vascular system.

Astaxanthin has been linked with a number of health benefits including improved heart, liver, joint, eye, and prostate health, faster recovery from exercise, and pain reduction. Thanks to astaxanthin, krill oil has 48 times the antioxidant power of fish oil.

5. Krill Oil Has Fewer Fishy Side Effects than Fish Oil.

Fish oil capsules and fish tail in brown jar

One of the top complaints about fish oil supplements is their tendency to cause a fishy aftertaste and “fish burps.” The cause of this unpleasant side effect goes back to the structure of the omega-3s in fish oil: Because they’re triglycerides and don’t absorb well in the body, fish oil omega-3s tend to sit on the surface of your stomach contents, which can result in reflux and that gross aftertaste.

Recall that krill oil’s omega-3s, on the other hand, are phospholipids, which means they disperse more easily in the fluids in your stomach and don’t have the same reflux reaction. As a result, you (and anyone near you) don’t have to deal with your supplements revisiting you.

6. Krill Have Naturally Lower Mercury Levels Than Fish.

Mercury levels in the atmosphere have gone up exponentially in recent decades, thanks to increases in mercury emissions from things like the burning of fossil fuels and gold mining. That mercury eventually falls into our water systems, where it starts to make its way up the food chain: Microscopic algae and other tiny sea creatures eat it, which are subsequently ingested by small fish and other marine life, which are then gobbled up by larger fish, and so on.

Top view of white table with antarctic krill and Raw fresh whole tuna fish over dark wet metal background.

That’s why, generally speaking, the bigger the fish, the higher the mercury levels. Krill — which finds itself near the bottom of the food chain — accumulates much less mercury than the tunas of the world.

Now, mercury in fish oil supplements isn’t really a concern. Experts have learned how to process mercury out successfully. But regularly eating popular fish like tuna, salmon, tilapia, and pollock does introduce more mercury to your system, plus it increases demand for the fish. This in turn contributes to overfishing, habitat destruction, irresponsible catch methods that hurt other species like sea turtles and dolphins, and more. So if you’re looking for a more sustainable way to get your omega-3s, supplementing with krill oil is a more planet-friendly bet.

Given the recent wealth of research on krill oil’s functionality and benefits, it makes sense to make the switch from fish oil if you want to get the most out of your omega-3 supplement. While you might pay a little more for krill oil, the health perks more than make up for the slightly higher cost. And if you’re not already taking omega-3s, now’s a great time to start so you can start reaping all of the body and mind benefits these healthy fats have to offer.


Amazing Krill Facts

» A female krill can lay up to 10,000 eggs at one time.

» Krill are one of the largest single-species biomass on earth.

» Krill swim in huge swarms up to 3.7 miles long, with a density of up to 1 million individuals per cubic meter.

» Krill swarms are so dense, they can be seen from outer space.

» The estimated weight of all krill is far more than the total weight of all humans: 725 metric tons vs. 250 million metric tons, respectively.

» Krill can live up to 200 days without food by slowing their metabolism.

» When under threat, krill can spontaneously molt, which leaves behind a confusing empty shell.

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