Krill Oil: What You Need to Know
Many people – especially those consuming Western diets – don’t get enough omega-3 fatty acids, including the essential fatty acids DHA and EPA. Omega-3s are important for maintaining a healthy brain and cardiovascular system, reducing inflammation, cutting the risk of a heart attack, lowering the blood pressure, and many other important physiological functions. The good news is that taking a high-quality supplement that’s easily absorbed by the body can boost your omega-3 levels significantly and may improve your health.
Krill oil has moderate levels of DHA and EPA, lower than fish oil as they can’t be concentrated but in a form that is very well absorbed. It also contains the antioxidant powerhouse astaxanthin. Taking a high quality krill oil supplement can be a great way to maintain long term health.
Remember the following when it comes to choosing a krill oil supplement:
- People who get enough omega-3s (specifically DHA and EPA) tend to have better long-term health and get fewer diseases over time, all else being equal.
- Since krill oil is not concentrated, you may need to take more of it to get the same level of DHA and EPA as fish oil.
- Do not refrigerate krill oil as this will cause it to separate and not absorb as well when you take it.
- Choose a high quality krill oil from a reputable manufacturer. Look for the label to give specific amounts of DHA, EPA and astaxanthin. Generally, more is better.
Most people are likely be best served by taking both krill oil and fish oil, alternating:
- A high-quality and pure fish oil with concentrated omega-3s – high DHA and EPA content – in best-absorbed triglyceride form
- A krill oil high in astaxanthin, a powerful antioxidant
People with seafood allergies, vegans, and vegetarians, should consider DHA-containing algal oil supplements instead of fish oil and krill oil.
A Deeper Look at Krill Oil
Antarctic krill, a shrimp-like crustacean, are used to produce krill oil. Although the health benefits of krill oil have not been studied as much as those of fish oil, existing research indicates that many of the benefits are similar due to omega 3 content.
Krill oil is also very special as it naturally contains astaxanthin, which is a powerful antioxidant. Astaxanthin is the red pigment, a carotenoid, that gives some marine organisms their red color. Research studies for its health effects on the body are highly promising.[1, 2] Preliminary results indicate that astaxanthin reduces inflammation, reduces oxidative stress, protects cells, and promotes heart and brain health.[3, 4, 5] There are also very promising studies that indicate that it may also help prevent cancer and generally improve improves immune function.[6, 7, 8] Astaxanthin has also been demonstrated to help with eye health, specifically macular degeneration.[9, 10]
In krill oil, astaxanthin helps to keep omega-3s from breaking down and going rancid, and has been shown to generally reduce oxidative stress and inflammation.
Because krill are easier to harvest than many fish and fish stocks worldwide have been decimated by overfishing, some believe that krill oil is a more sustainable source of omega-3s than fish oil. However, more studies are needed to understand how the omega-3s in krill oil are absorbed and exactly what health benefits they have.
Krill Oil as a Source of Omega-3s (DHA and EPA)
The primary job of omega-3 fatty acids is to regulate levels of various forms of lipids in the brain, heart, and other important parts of the body. Omega-3s have been shown to increase the HDL (“good cholesterol”), decrease triglycerides, and keep blood pressure at normal levels.
Omega 3s come in three types: docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and alpha-linolenic acid (ALA). Marine organisms like fatty fish, krill, and algae contain DHA and EPA, whereas ALA is found in plants and nuts like soybeans, flaxseed, walnuts, and canola oil. EPA is used throughout the body, whereas DHA is mostly found in the eyes and the brain. The human brain is made up of about 60% fat, half of which is DHA. DHA is also found in the retinas, and studies suggest that Omega 3s are important for healthy retina functioning.
Omega 3s help regulate many processes throughout the body and have been shown to help prevent a variety of diseases and conditions, in large part by reducing inflammation. Studies also show that omega-3s reduce triglycerides, lower total cholesterol, slow the development of blood clots, and reduce high blood pressure, all of which are risk factors for heart disease, heart attack, and stroke.[16, 17, 18, 19, 20] Having good levels of omega 3 may help prevent diabetes by lowering triglycerides and raising HDL cholesterol, may help relieve joint pain associated with rheumatoid arthritis and other inflammatory diseases, and may help increases calcium levels and prevent osteoporosis. Studies also suggest that eating foods rich in omega-3s may help prevent or slow the progression of colon, breast, and prostate cancer. In addition, Omega 3s play a role in hormones secretion, muscle activity regulation, cell division, and blood clotting.
The brain also benefits from DHA in a many ways. In particular, DHA can help fight depression and maintain, or even improve, cognitive functioning.[12, 16, 22] The synapses between neurons contain DHA, indicating that having a sufficient amount of this type of omega-3 is crucial for neurotransmission.[15, 16, 23] As a result, research indicates that abnormally low levels could be a contributor to Alzheimer’s disease and other forms of dementia.[14, 15, 24, 25] Omega-3s help the body produce energy by undergoing β-oxidation, which splits carbon atoms and releases CO2. This in turn helps produce adenosine triphosphate (ATP), an organic chemical involved with many cellular processes. Read more about the benefits of Omega-3s here.
Omega-3 deficiency is common
Most Americans currently don’t get enough omega-3s in their diet, mainly because consumption of fatty fish – which is high in omega 3s – has declined significantly over the past century. Many of the fish we do eat are farmed, and farmed fish contain a lot less DHA and EPA than wild fish because of what they are fed.
Symptoms of a clinical omega 3 deficiency can include fatigue, memory difficulties, dry skin, heart conditions, circulation problems, abrupt changes in mood, and even depression. Insufficiency of DHA and EPA may be asymptomatic but still have far-reaching negative effects on the body and brain, especially in the longer term.
Most people won’t have access to enough wild-caught, uncontaminated, fatty fish to get optimal DHA and EPA levels from food. Many choose to take supplements containing fish oil, krill oil, and algal oil. Fish oil should be in triglyceride form for best absorption, sourced from small wild fish, and be processed by a high-quality producer. Krill oil is already in the highly-absorbable phospholipid form and contains astaxanthin, which is excellent for health in its own right.[1, 2, 26] Krill oil is less concentrated, however, and contains less omega-3 fatty acids. Algal oil is a great option for those with seafood allergies or determined to avoid animal-sources while still getting the omega-3s that are necessary for long term health.
Krill oil is not concentrated like fish oil, and as a result provides less DHA and EPA per pill or serving. However, the EPA and DHA molecules in krill oil might be more easily absorbed by the body than those of fish oil. That’s because EPA and DHA in krill oil are bonded to phospholipids, and those in fish oil are bonded to triglycerides.[11, 13, 18] Phospholipids are more absorbable because they dissolve in water, whereas those in fish oil don’t. That means in order to get the most benefit from fish oil, it must be consumed with fatty foods; no such limitation applies to krill oil.[21, 23, 27]
Absorption of Omega-3s in Krill Oil vs. Fish Oil
Although krill oil has less EPA and DHA than fish oil does, there is some evidence that krill oil is more easily absorbed by the body. This is because between 30 and 65 percent of the EPA and DHA molecules in krill oil are bonded to phospholipids, whereas those in fish oil are bonded to triglycerides. Phospholipids are both hydrophobic and hydrophilic, while triglycerides are only hydrophobic. In other words, the fatty acids in krill oil dissolve in water, but those in fish oil do not. As a result, scientists have hypothesized that the EPA and DHA molecules in krill oil are more bioavailable than those in fish oil, if fish oil is not consumed with fatty foods.[29, 30, 31] However, the research on this is mixed; while some studies have found that the omega-3s in krill oil are more bioavailable than those in fish oil, other studies have not.
For example, one double-blinded trial compared bioavailability of fish oil (both triglyceride and ethyl ester forms) and krill oil. It found that krill oil produced the greatest concentrations of EPA and DHA in blood plasma, followed by fish oil in the triglyceride and ethyl ester forms in that order. However, the study only used 12 participants, and the authors said larger studies over longer periods were needed to confirm the bioavailability findings. They also said the krill oil used in the study contained free EPA and DHA, whereas the fish oil did not, which might have affected the results and should be investigated further. Another review of numerous studies found that krill oil might be more bioavailable than fish oil, but that it was difficult to reach a firm conclusion because of variations in study durations, amounts of DHA and EPA used, and study subjects. The authors also said that more studies are needed, particularly with human subjects.
Other studies have found no significant differences in bioavailability between fish and krill oil. The authors of one study found that when doses and concentrations of EPA and DHA were matched, plasma and red blood cell levels of omega-3s as a result of taking either fish or krill oil supplements were substantially the same. Bioavailability thus was deemed to be comparable. Another study also found the two sources to be comparable in omega-3 bioavailability even if the dose of EPA and DHA in krill oil is only about two-thirds of the dose in fish oil.
Krill Oil Differentiator from Fish Oil: Astaxanthin
One thing that is clear is that Krill oil also naturally contains astaxanthin, which is a powerful antioxidant that helps keep omega-3s from going rancid and has been shown to reduce inflammation. Astaxanthin is a xanthophyll carotenoid that renders oxidants and other free radicals harmless by donating or receiving electrons without becoming an oxidant itself. Because of the way it is configured, astaxanthin can intercept reactive molecules that otherwise would damage a cell.
As a result, although research on astaxanthin is limited, some studies have linked it to several health benefits. For example, one review of numerous randomized controlled trials found that astaxanthin:
(1) lowered stress from oxidation in people who were overweight or obese, as well in as people who smoked;
(2) prevented DNA from being damaged by oxidation, lowered inflammation markers like c-reactive protein, and increased immunity during the skin test for tuberculosis;
(3) lowered triglycerides and raised HDL-cholesterol; and
(4) improved blood and cognition; improved vision; and improved fertility in men. The researchers concluded that astaxanthin might slow the functional declines associated with aging.
Other research has found additional potential benefits of astaxanthin. For example, one study concluded that it helped slow the proliferation of breast and skin cancer cells. Additional studies have shown that astaxanthin might improve skin health and help prevent heart disease.[37, 38] However, the evidence for some of these benefits, although highly promising, is scarce research-wise. Some of the studies were conducted using animals rather than humans and more research is needed.
Potential Pollutants and Environmental Impact of Krill Oil
Many krill oil manufacturers claim that krill oil is less likely than fish oil to be contaminated with mercury and other pollutants because krill live deeper in the oceans than many fish and are lower on the food chain. However, at least one study found that krill can contain persistent organic pollutants that can be dangerous to human health, including higher levels of some toxins — such as chlorobenzenes — than in the fish oils tested. In addition, it is possible for other toxins to be introduced when krill oil is processed. For this reason, always choose a reputable high quality manufacturer and brand when choosing your krill oil.
On a more global level, the production of krill oil is thought to be more sustainable than the production of fish oil. Krill are easier to harvest than many fish species. Furthermore, obtaining omega-3 directly from fish is becoming more expensive and potentially more detrimental to the environment, as commercial fishing has led to the decline of certain fish populations. An alternative source of omega-3 such as krill oil may be a plausible and sustainable option. However, krill oil is still a relatively new focus for health research. Further studies are needed to fully understand how the omega-3 in krill oil is absorbed by the body, as well as its potential health benefits.
Considerations for Krill Oil Supplements and Contraindications
According to the National Heart Association, one should try to eat fatty fish at least twice a week, which provides approximately 400-500 mg per week of EPA and DHA.[14, 25] Americans consume only 10 to 20 mg of EPA and DHA daily, or about 70-140 mg weekly, the Mayo Clinic estimates. Existing human research trials indicate that the health benefits of DHA and EPA generally increase proportionally with amount consumed, with the upper limit at 2,000 mg per day.
Thus, it is safe to consume up to 2,0000 mg of DHA + EPA daily from a high-quality, well-absorbed fish, krill, or algal oil. According to the Food and Drug Administration, no one should consume more than 3000 mg of omega-3 fatty acids in one day from food and supplements combined, and no more than 2000 mg of that amount should come from supplements.
Taking too much omega-3 can cause a variety of side effects, including burping, a bloated stomach, diarrhea, and gas. The same problems can be caused by specific ingredients in a given supplement, so a smaller dose or different supplement may be the solution if this occurs to you. Talk to your doctor if the side effects don’t go away or if more serious side effects like bleeding or changes in blood pressure or blood sugar occur.
Medications that affect blood pressure, blood sugar, or cholesterol, or increase the risk of bleeding, can interact with omega-3 supplements in undesirable ways. Be careful about taking nonsteroidal anti-inflammatory drugs while taking an omega-3 supplement. Individuals taking these medications should always consult with a doctor before beginning omega-3 supplementation to discuss proper dosage.
Choosing a High Quality Krill Oil
Omega-3 fatty acids, especially DHA and EPA, are vital for long-term well being. The current best bet to get maximum health benefits is to take fish oil and krill oil at alternating times. This way you get the best of both worlds — high omega-3 content from the concentrated fish oil and high antioxidant action from the astaxanthin in krill.
Supplements are not effectively regulated and it can be hard to tease out quality brands from those that use the wrong form or cut corners. We took a scientific approach to evaluating supplement options and here present our top choices after rigorous analysis and application of our methodology. When choosing a krill oil supplement, you should be concerned about the source, the processing it’s been through, the reputation of the manufacturer, and appropriate dosage of labeled active ingredients.
When choosing a krill oil supplement, always select a high-quality brand in order to avoid sources of krill oil that have been contaminated by persistent organic pollutants or other toxins. Manufacturers should always certify that their products are free from mercury, lead, and cadmium, and do third party independent testing to prove it. Although krill oil is more expensive than fish oil, it generally contains smaller doses of omega-3 fatty acids because the DHA and EPA are not concentrated in this form. However, the body absorbs omega-3s in krill oil very efficiently and the astaxanthin contained within is very promising as a health-promoting substance. Krill oil is a great addition to almost everyone’s supplement regimen for this reason.
Exact amounts of DHA, EPA, and astaxanthin contained per serving of krill oil should be listed on the label. The brand should undergo third-party independent testing and review by consumer-watchdog agencies. Here are our recommended choices. Read about our selection methodology here.