Fish oil is one of the most popular dietary supplements in the world, after multivitamins and multimineral supplements[*]. Distilled mostly from fatty fish like salmon, sardines, mackerel, and anchovies, fish oil comes with a host of health benefits from reducing inflammation to boosting brain and heart health.
Fish oil supplements are known for their omega-3 fatty acid content, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In fact, until recently, fish and fish oil were the most popular ways of getting your daily dose of omega-3 fats.
However, krill oil, a new omega-3 supplement, is gaining popularity as a fish oil alternative.
Krill oil is also high in EPA and DHA, and studies suggest that it may offer additional benefits compared to conventional fish oil supplements.
In this article, you’ll learn the differences between krill oil and fish oil supplements. You’ll also learn the health benefits and risks of each and how to decide which one is right for you.
Krill oil is a marine oil derived from krill, a small, reddish-pink, shrimp-like crustacean about two inches long.
While there are at least 85 known species of krill, most krill oil is harvested from Euphausia superba (Antarctic krill), found in the Antarctic ocean.
In Norwegian, “krill” means “whale food,” but they’re much more than that. Krill are an integral part of marine ecosystems. They feed on microscopic phytoplankton and, in turn, support marine life including birds, fish, squid, and whales.
Krill oil is an excellent source of the omega-3 fatty acids EPA and DHA, with the total fat content of live krill ranging from about 12-50% depending on the season[*].
And while fish oil is yellow or gold in appearance, an antioxidant called astaxanthin gives krill oil a reddish hue.
Along with the omega-3 fatty acids EPA and DHA, krill oil also contains the fatty acids:
- Arachidonic acid
- Behenic acid
- Lignoceric acid
- Ln-9 neuronic acid
- Linoleic acid
- Ln-9 oleic acid
- Stearic acid
- Pentadecanoic acid
- Palmitic acid
- Myristic acid[*]
So, how is the fatty acid makeup of krill oil different from fish oil? Let’s find out.
Fish oil is a marine oil produced from the tissues of oily fish.
They contain EPA and DHA, which are precursors to eicosanoids (hormone-like signaling compounds) used by your body.
Most fatty fish used to produce fish oil do not produce omega-3 fatty acids, but instead, accumulate omega-3s as a result of consuming microalgae or smaller fish rich in omega-3 fatty acids.
The fillets and belly cavities of oily fish contain up to 15.5% fat content[*].
Omega-3 fatty acids found in fish oil and krill oil are essential because your body cannot make them on its own, so you must consume them from dietary sources.
The ratio of omega-6 fatty acids to omega-3 fatty acids in your body can have a significant influence on your health and risk of disease. It is likely that humans evolved on a diet with an equal amount of omega-6 and omega-3 fatty acids, but in modern Western diets, the ratio is approximately fifteen to one[*].
A review that examined the effects of different omega fatty acid ratios in humans found that an omega-6 to omega-3 index of 4:1 decreases the risk of dying of all causes by 70%[*].
A ratio of approximately 2:1 can prevent colorectal cancer from proliferating, reduce your risk of breast cancer, and decrease symptoms of arthritis and asthma[*].
A high omega-6 to omega-3 ratio is also associated with obesity[*].
Fish oil or other omega-3 sources are vital throughout the lifespan. Here are a few ways your body benefits from omega-3 supplementation:
#1: Brain Health and Development
According to epidemiological studies, mothers low in DHA are more likely to have children with poor neural development and cognitive disorders[*].
In older adults, omega-3 fatty acids can increase synaptic plasticity and enhance neurogenesis (the creation of new neurons), which is associated with better cognitive function and less loss of white and gray brain tissue during aging[*].
The brain health benefits of fish oil come from increasing your levels of EPA and DHA. DHA is essential for brain development and cognitive function, and eicosapentaenoic acid (EPA) regulates mood and behavior[*].
Taking fish oil or other omega-3 supplements can reduce inflammation in your brain and improve the health of your central nervous system[*].
#2: Heart Disease
Heart disease is the deadliest disease in developed countries, but taking omega-3 supplements like fish oil can reduce your risk of cardiovascular issues[*].
Eating too many omega-6 fatty acids and insufficient amounts of omega-3 fatty acids leads to chronic inflammation.
Chronic inflammation is linked to joint pain, heart problems, Alzheimer’s, dementia, and other health problems, but omega-3 fatty acid supplements like fish oil can lower inflammation in your body.
#4: Lean Muscle Mass
Getting enough omega-3 fatty acids in your diet can also increase your lean muscle mass by increasing muscle protein synthesis and reducing muscle protein breakdown[*].
- Reduce inflammation
- Improve your cholesterol levels
- Decrease the risk of your red blood platelets forming dangerous clots
But there are some differences when it comes to your source of omega-3s. Here are just a few ways krill oil may win out over fish oil:
#1: Krill Oil Contains Additional Nutrients
In addition to omega-3s, krill oil also offers vitamin A, vitamin E, vitamin B12, and folate[*].
And because krill eat marine lichen, krill oil also contains astaxanthin, an antioxidant with neuroprotective properties that reduces damage to your brain and central nervous system from oxidative stress[*][*].
Unlike fish oil, krill oil provides antioxidants and phospholipids, which enhance its stability and bioavailability and provide distinct health benefits. Whereas the EPA and DHA found in fish oil are in the form of re-esterified triglycerides, the omega-3s in krill oil occur in a phospholipid-bound form as well as free (unbound) form[*].
#2: Krill Oil May Have Fewer Contaminants
Since krill are smaller and lower in the food chain than most fish, they contain less mercury and other contaminants[*]. Also, make sure to choose a krill oil that goes through a rigorous testing process.
#3: Krill Oil Absorbs Better
Compared to fish oil, an equivalent dosage of EPA and DHA from krill oil absorbs better in your body. A double-blind crossover trial comparing krill oil and fish oil found that krill oil increased circulating omega-3 fatty acids by approximately 33% more than fish oil[*].
A separate study concluded that the participants achieved equivalent omega-3 fatty acid levels with a krill oil dose that was about 40% lower than the fish oil dose. That suggests that the EPA and DHA in krill oil absorb more efficiently[*].
A similar study of women who were given fish oil and krill oil found that it only took 71% of the amount of krill oil compared to fish oil to achieve equal blood levels of omega-3 fatty acids[*].
#4: Krill Oil For Brain and Heart Health
A trial comparing the effects of krill oil and fish oil on cardiovascular health found that in addition to improving various markers of heart health, krill oil reduced fasting glucose, which also contributes to a reduced risk of heart disease[*].
In addition to enhancing the bioavailability of the omega-3 fatty acids EPA and DHA, the phospholipids in krill oil also offer brain and cellular health benefits thanks to their anti-inflammatory and antioxidant properties[*][*][*][*].
The authors of a study comparing the results of krill oil versus fish oil in mice concluded that krill oil is more beneficial for lowering inflammation and improving insulin sensitivity[*].
While fish oil increases the activity of cholesterol synthesis pathways, krill oil reduces the activity of these pathways, meaning that krill oil may be a better choice if you wish to lower your cholesterol[*].
A genomic analysis study found that fish oil altered the expression of four genes, whereas krill oil changed the expression of thirteen genes, including genes involved in the metabolism of glucose, cholesterol, and lipids[*].
Krill oil supplementation can increase your body’s antioxidant capacity and improve your ratio of fatty acids to inflammatory markers[*]
Risks of Krill Oil
Adverse effects from krill oil are rare, but may include:
- Fishy taste
- Sweat that smells like fish
- Gas or heartburn
- Upset stomach
Omega-3 supplements like krill oil and fish oil can also cause blood thinning. If you’re on blood-thinning medications or use non-steroidal anti-inflammatory drugs (NSAIDs), talk to your doctor before using krill oil.
If you have an allergy to seafood, shellfish, or crustaceans, speak to your doctor before using krill oil.
Unlike fisheries that harvest large fatty fish, krill fisheries do not contribute to overfishing, but some forms of krill harvesting can be harmful to the ecosystem.
Most companies that use sustainable harvesting practices will say so on their website. If not, contact the manufacturer to make sure they’re using environmentally-friendly techniques.
Risks of Fish Oil
Similar to krill oil, the adverse effects of fish oil include unpleasant aftertaste, stomach problems, and headaches.
Fish oil can also cause blood thinning. If you’re on blood-thinning medications or non-steroidal anti-inflammatory drugs (NSAIDs), talk to your doctor before supplementing
If you have an allergy to seafood, shellfish, or crustaceans, talk to your doctor before using fish oil.
Some fish oil supplements may be contaminated with mercury and other toxins, depending on the species of fish from which they are derived.
Larger fish that are high in omega-3 fatty acids also accumulate toxic substances like mercury, dioxins, polychlorinated biphenyls, and chlordane through a process called biomagnification. Because of biomagnification, the FDA and EPA in the United States advise some people to limit their intake of large fish[*].
Because fish oil does not contain phospholipids or astaxanthin, it’s more likely to be rancid than krill oil supplements, which can create toxic byproducts and increase inflammation in your body[*][*].
One analysis of fish oil supplements found that 44-73% of them had gone rancid[*].
Fishing of large fish for their omega-3 content may also contribute to overharvesting. When it comes to environmental sustainability, fish oil is not the best choice for an omega-3 supplement.
Additionally, fish farming — the primary source of fish oil supplements–adversely affects the environment by polluting oceans with large amounts of fish feed and waste.
Both krill oil and fish oil are excellent sources of omega-3 fatty acids, and their health benefits are backed up with extensive, high-quality research.
However, compared to fish oil, krill oil offers a few more benefits, like additional phospholipids, antioxidants, and other nutrients.
The phospholipids and astaxanthin found in krill oil also enhance its shelf life, reduce rancidity, and allow your body to absorb krill oil more easily than fish oil.
Sustainably-sourced krill oil is also a better choice for the environment because, unlike fish oil, krill harvesting does not contribute to overfishing or pollution from fish farming.
Still curious about the benefits of krill oil? Read this.