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Krill Oil vs. Fish Oil: Which Is The Better Supplement?

In recent years there has been much hoopla surrounding krill oil supplementation, and many proponents suggest that it is superior to supplementation of fish oil. There is a lot to like about krill oil including: it is less susceptible to oxidation and contamination, it contains omega-3 fatty acids (in phospholipid form), and it also contains a super-antioxidant called “astaxanthin.” Although krill appears to be the new flashy omega-3 supplement on the block, it is important to avoid assuming that all of the marketed krill oil benefits are supported by science.

Fish oil is the older supplement on the block that’s been around awhile.  It has been scientifically supported for the treatment of various conditions such as high triglycerides and heart disease. As humans evolved, we weren’t supplementing krill, rather we were eating fish. The fish oil provides higher amounts of omega-3 fatty acids (DHA and EPA) and therefore may actually be the better supplement if you are serious about optimizing your mental health.

Krill Oil vs. Fish Oil

It is important to realize that both krill oil and fish oil supplements are thought to provide health benefits. Both provide us with rich sources of omega-3 fatty acids which are considered “essential” for both physical and mental health. On a standard American diet, most people consume between 10x and 30x the amount of omega-6 fatty acids than they do omega-3’s.

This can lead to an array of health problems including: cardiovascular disease, cognitive deficits, and mood disorders. Most nutritionists suggest that we should be consuming roughly an equal amount of omega-3 and omega-6 fatty acids, not an overwhelmingly lopsided amount of omega-6’s. As a means to obtain sufficient omega-3’s, people can consume fish regularly or take various forms of fish oil (or krill oil).

Krill Oil

Krill are tiny crustacean creatures (Euphausia superba) that are commonly harvested in the Antarctic ocean primarily as a means to feed fish. In recent years, supplement companies have began harvesting them in large quantities to extract their “oil” to market as a healthy dietary supplement. Krill oil contains omega-3 fatty acids bound in a phospholipid structure, meaning they are easily absorbed by humans. They also contain a potent natural antioxidant called “astaxanthin” which gives the oil its “reddish” color.

Fish Oil

Fish oil is extracted from the tissue of oily fish such as salmon and mackerel. Much of the fish oil is obtained via fish farming operations that harvest fish for the purpose of creating supplements. Marine and freshwater fish tend to vary in their quantities of omega-3 fatty acids. The fish do not naturally produce omega-3 fatty acids, but generally accumulate them by eating algae and other smaller fish that contain them. The omega-3 fatty acids from fish oil are attached to triglycerides.

Advantages of Krill Oil

There are several speculative advantages that krill oil may have over fish oil. While none of these advantages have been scientifically proven, they have been hypothesized.

  • Absorption: In fish oil, omega-3 fatty acids are expressed in the format of triglycerides. In krill oil, they are linked by a structure consisting of double-chain phospholipids. Since the fats within human cell walls are already in the format of phospholipids, it is speculated that krill oil may have greater bioavailability than fish oil. In other words, the body may process krill oil more efficiently than fish oil.
  • Antioxidant (Astaxanthin): Fish oil isn’t touted for having potent antioxidant effects, it is mostly known for its omega-3 content. Krill oil on the other hand, is known for containing “astaxanthin,” a very potent antioxidant. Astaxanthin has been speculated to improve cardiovascular health, immune function, prevent neurodegenerative diseases, and decrease inflammation. Other research has even hinted at the possibility of its ability to slow aging via reduction of oxidative stress.
  • Environmental sustainability: Krill makes up the largest biomass on earth (170 million to 740 million tons), weighing more than any population. Since there are more krill than other creatures, the harvesting of krill is likely more environmentally stable than harvesting fish to create fish oil. There currently is no major threat to the over-harvesting of krill and the population of krill should be easily sustained.
  • Phospholipids: The omega-3 fatty acids in krill are linked with phospholipids. This means that they are more likely to provide greater bioavailability and are probably better absorbed by humans compared to fish oils. Phospholipids can help improve functionality of membranes and may even elicit antioxidant effects that protect against free radicals.
  • Toxicity: Many people claim that krill oil is significantly less likely to contain toxins such as: mercury, PCBs, and various toxic metals in comparison to fish oil. It is relatively clear that krill oil is likely to contain less toxins than fish oil. That said, a 2014 study comparing profiles of fish oils and Antarctic krill oils found that the krill oils contained “intermediate” levels of POP contaminants compared to other products.

Source: http://www.ncbi.nlm.nih.gov/pubmed/25170991
Source: http://www.ncbi.nlm.nih.gov/pubmed/21042875

Disadvantages of Krill Oil

There are a couple of disadvantages associated with krill oil when compared to fish oil.

  • Reduced omega-3 content: The primary reason most people take fish and krill oil supplements is to elevate their levels of omega-3 fatty acids. Although krill oil may be more efficiently absorbed, the levels of omega-3 fatty acids that it contains (per serving) are significantly less than levels obtained via fish oil. Despite the potential of krill’s superior absorption, the omega-3 PUFA content is minimal compared to fish oil. One popular krill oil brand contains only 150 mg EPA and 90 mg DHA per serving, compared to fish oil which generally contains over 5X the omega-3’s per serving.
  • Poorly researched: A bulk of the studies demonstrating krill oil’s efficacy as a supplement are problematic. Most are not long-term studies and comparisons being made to fish oil are often scientifically skewed. There may be significant publication bias in these studies and ulterior motives for certain “scientific” results. Krill oil warrants significant future scientific investigation before it should be touted as an effective supplement in humans, let alone a superior one to fish oil.

Advantages of Fish Oil

When compared to krill oil, there are several notable advantages associated with fish oil.  To better understand why fish oil is scientifically regarded as a healthy supplement, read the article “Fish Oil Benefits.”

  • High omega-3 content: The amount of omega-3 fatty acid content within fish oil is significantly greater than that derived from krill oil. Even the best krill oil supplements don’t generally contain more than 300 mg of combined DHA and EPA (omega-3s) per serving. Even the lowest grade fish oils tend to contain over double that, many of the quality ones contain 4-5X the amount of omega-3s. The primary reason most people take krill or fish oil is to increase their dietary omega-3 fatty acids. In regards to omega-3 content, fish oil is the clear winner.
  • Scientifically supported: There is a lot of science behind using fish oil as a supplement. There are numerous studies solely dedicated to testing fish oil for depression, triglyceride levels, and cardiovascular disease. While there is clearly still a need for more research, many suggested uses for fish oil are supported by science; krill oil doesn’t have much scientific support.

Source: http://www.nlm.nih.gov/medlineplus/druginfo/natural/993.html

Disadvantages of Fish Oil

There are a few speculative disadvantages associated with fish oil when compared to krill oil. Although these generally do not apply to high-quality brands of fish oil, they are considered a problem for your average consumer who doesn’t do much research.  By finding a high quality fish oil supplement, you can avoid all forms of contamination.

  • Contamination: Many have speculated that fish oil is highly susceptible to contamination as a result of mercury and PCB contents. Contamination is thought to be a bigger issue with fish oil than it is with krill oil. That said, ConsumerLab testing has found no tested fish oil supplement to contain mercury, and most only have trace levels of PCBs. They suggest that eating fish is much more likely to be contaminated than fish oil.
  • Oxidation: This occurs when omega-3 fatty acids are exposed to sources of heat, light, or oxygen. Oxidation is common in fish oils, while uncommon among krill oils due to protection from the “antioxidant” astaxanthin. The oxidation tends to be most common among liquid fish oils that aren’t properly stored (at cool temperatures and out of the sun).
  • Poorer absorption: The omega-3 fatty acid is in triglyceride format and therefore isn’t regarded as being as efficiently absorbed as krill oil. Although the comparative “poorer absorption” may be likely, no evidence has proven this suggestion. If the omega-3s were in phospholipid format, they would likely be more efficiently used by our body.
  • Rancidity: Another concern is that fish oil supplements are often subject to spoilage and quickly become rancid. The rancidity tends to result in a gross, “fishy” smell and is sometimes difficult to detect. If the fish oil that you’re consuming is rancid, it is likely causing all harm and no benefit.

Why it’s difficult to compare Krill Oil vs. Fish Oil…

It’s been very tough to compare the bioavailability of krill oil to that of fish oil due to various characteristics of krill oil. Krill oil contains less active omega-3 fatty acids (DHA and EPA) and also contains astaxanthin. The krill oil tends to contain phospholipids, triglycerides, and non-esterified fatty acids, while fish oil contains triglycerides.

No study has been conducted in which the doses of the therapeutic omega-3’s DHA and EPA have been matched from krill and fish oil. If such a study were to be conducted, it would need to be both randomized, controlled, and would need to measure blood-levels of both DHA and EPA. Those in support of krill oil tend to believe that it offers greater bioavailability compared to fish oil.

The argument in support of krill has stemmed from the statistic that a lower dose of krill oil resulted in similar blood levels of DHA and EPA to fish oil. In these comparisons though, the degree to which the doses differed were insignificant to point that many researchers disagree with the claim that krill oil provides greater bioavailability.

Some studies that suggest krill’s superiority in terms of bioavailability actually used significantly different amounts of omega-3 fatty acids in attempt to skew results. Currently there is not sufficient evidence to support the claim that krill oil has greater bioavailability than fish oil. Further human trials must be conducted to determine the bioavailability of each.

  • Source: http://www.ncbi.nlm.nih.gov/pubmed/25156381

Krill oil research may contain skewed data

It is important to discuss the fact that a bulk of krill oil studies contain skewed comparisons of krill oil to fish oil. Additionally many of these studies may be subject to significant publication bias in order to sell more krill oil supplements. Research comparing krill oil and fish oil tends to seemingly always find krill oil as being a superior supplement for the treatment of various conditions.

However, a closer examination of these studies often reveals blatant flaws. A study from 2013 by Ramprasath et al. published in “Lipids” compared krill and fish oil in a trial of 24 healthy volunteers. Their results suggested that krill oil may be superior to fish oil in increasing omega-3 fatty acid content. What wasn’t obvious to your average reader was the fact that the fish oil used in the comparison wasn’t even a typical fish oil.

The fish oil utilized contained 32% linoleic acid, which isn’t anywhere near an accurate representation of a commercial fish oil supplement. There have been other comparative studies conducted in which there may be quality concerns regarding the fish oil. Much of the fish oil used in comparison to krill contained substandard amounts of omega-3 fatty acid content.

In the future it will be important to publish comparative data from unbiased sources using quality krill oil and fish oil supplements. Currently a majority of the research seems to be motivated by supplement companies.

  • Source: http://www.ncbi.nlm.nih.gov/pubmed/24383554
  • Source: http://www.ncbi.nlm.nih.gov/pubmed/24304605

Which is better? Krill Oil vs. Fish Oil.

Fish oil is clearly the superior supplement to fish oil based on the omega-3 fatty acid content per serving (as well as cost). Assuming your goal is to improve various aspects of mental health such as cognitive function and mood, you’d be much better off taking a fish oil supplement than krill oil. Fish oils provide significantly more omega-3 fatty acids (DHA and EPA) per serving in comparison to krill oil.

Although fish oil often prompts consumer concerns of oxidation and rancidity, these can be mitigated by purchasing fish oil from a high quality IFOS-certified supplier. Many people wrongfully assume that Antarctic krill oil is always free of toxins, yet some research shows that krill can contain trace toxins, which could damage your health.

Combining krill oil and fish oil

There’s certainly nothing wrong with taking both krill and fish oil simultaneously, in fact many people do. There are even products (e.g. Purity Products) that infuse krill and fish oil together so that you get the best of both worlds. The fish oil supplements will contain the omega-3 fatty acids (what you want for your brain), and if you take krill along with it, you’ll get the added benefit of astaxanthin, a much-hyped super-antioxidant.

Although some people may want to test combined supplementation of krill and fish oil, the combined effect isn’t well researched in humans. A study conducted on mice attempted to investigate the vague health benefits of omega-3 fatty acids. The mice were given Lovaza (pharmaceutical-grade fish oil) 4.40 g/kg diet and krill oil 1.17 g oil/kg diet.

When the effects of the krill and fish oil were examined together, it was found that the combination shortened the lifespan of mice by 6.6% in comparison to the control group. Researchers concluded that when taken together, the consumption of omega-3 fatty acid-rich fish and krill oils are unlikely to increase lifespan or health of healthy individuals.

  • Source: http://www.ncbi.nlm.nih.gov/pubmed/24816553

Why you should take fish oil over krill oil…

So many people want the newest, flashiest supplement, even if it hasn’t been well-researched (i.e. krill oil). There is certainly a lot to like about krill oil, and many potential benefits. In the future, it may end up being proven as a superior supplement to fish oil, but at present, significantly more comparative studies need to be conducted before it can be recommended as being safer and more effective than fish oil.

Although you may be tempted to hop on the krill oil bandwagon with all of the brilliant marketing, proceed with a healthy degree of skepticism. If you are really concerned about your mental health or brain development and are looking to supplement omega-3 fatty acids, it’s common sense to find a high quality fish oil rather than krill oil. Not only will you be using a supplement that has proven itself, you’ll be getting significantly greater quantities of omega-3s per serving and for your money.

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{ 2 comments… add one }
  • EricTan February 9, 2016, 4:05 am

    I am suffering from high cholesterol and have been taking Omega 3 fish oil (salmon) for more than 20 years. Indeed it has increased my HDL cholesterol above average and protected my heart… otherwise I wouldn’t have the opportunity to send this comment.

    • Dagan Haddad June 27, 2016, 10:08 pm

      I’m w/EricTan – I had a heat attack in 2011 – I take krill oil in place of cholesterol meds, as no matter which version… they killed my muscles.

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