When krill was first introduced as a new and exciting source of omega-3s EPA and DHA, we at Igennus Healthcare Nutrition sat back and dismissed its initial positive coverage as a fad. It was yet another source of polyunsaturated fatty acids (PUFAs) whose pitfalls would soon be exposed – not least because of its low dose of EPA and DHA that would not confer significant benefits to users at doses of 100-150mg omega-3 – certainly nothing like high dose fish oil concentrates.
We waited patiently; some coverage highlighted concerns over its sustainability, but no major issues surrounding its low active doses. It’s only a matter of time, surely – before people realise it has been extraordinarily hyped – or so we thought. And then, a couple of years ago, many of our competitors producing omega-3 supplements jumped in, presumably wanting a piece of the growing krill ‘pie’. The final straw came when several ‘thought leaders’ declared themselves on the krill bandwagon. Thus far, we’ve remained quiet on the topic of krill, and kept our [scientific] opinion to ourselves. We recognise that a wide range of people genuinely see krill oil as an equal – if not superior – substitute for fish oil, and we feel it is time to correct this pervasive fallacy.
A few mistruths about krill:
- Heavy marketing of krill oil has focused on the superior bioavailability of the phospholipid form of omega-3 over that of triglyceride omega-3 from fish oil. This appealing concept has been given disproportionate importance while the justifiably important factor of dose has been virtually ignored. Consumers have been misled into believing that taking low doses of EPA and DHA omega-3 from krill oil will provide health benefits comparable to those associated with larger doses of EPA and DHA from fish oil.
- The evidence supporting the need for high doses of omega-3 fatty acids, and in particular EPA, in the treatment of a variety of health conditions [7-10], clearly demonstrates that manufacturer-recommended doses of krill oil capsules (approximately 150 mg) do not provide sufficient levels of EPA and DHA to increase blood plasma levels of omega-3s and have no place in therapeutic, clinical nutrition.
- To achieve the same level of EPA and DHA in red blood cell membranes (an important health biomarker called the omega-3 index) you need approximately 40% more krill oil than fish oil . Since krill oil is already about 3x the price of standard fish oil for the same volume, it is considerably more expensive to achieve higher volumes of krill oil just to achieve the same omega-3 blood profile as produced by fish oil.
Phospholipids in krill are most easily absorbed by the body …but this incredible bioavailability is unproven and irrelevant given the teensy weensy doses!
Krill oil has become popular due to its ‘enhanced’ bioavailability against standard triglyceride forms of omega-3 found in fish oil – a claim made as a result of its omega-3s being in phospholipid form. It is indeed true that phospholipids are the same structure as the fats in our cells and are therefore should be more easily absorbed into the bloodstream and into cells more quickly and efficiently than triglycerides – as yet, however, the human data does not support this claim. The industry, media and even other manufacturers have latched onto this bioavailability message, whilst quietly ignoring the crucial importance of the dosage required to raise blood plasma levels of total omega-3.
The proven health benefits derived from increasing omega-3 intake are related to increasing the omega-3 index: the proportion of total EPA and DHA in our red blood cell membranes. In one study that compared manufacturer-recommended doses of rTG fish oil, ethyl-ester fish oil, TG omega-3 from salmon oil, and phospholipid from krill oil, it was clear that the omega-3 index was increased most effectively by the rTG fish oil (approx. 58% increase), with krill being the least effective (only 11% increase) – behind a standard dose of salmon oil providing triglyceride omega-3 (approx. 17% increase).
Dose for dose, krill oil delivers far less EPA and DHA than standard fish oil. Technologies now exist to concentrate the EPA and DHA from fish oil, meaning much lower volumes of oil can deliver much higher doses of these active ingredients, affordably. Ethyl-esters and re-esterified triglyceride fish oils are concentrated forms of omega-3 designed to deliver high therapeutic doses of just the ‘active’ omega fats – at concentrations of up to 90%.
Krill oil, however, only delivers around 18% total EPA and DHA combined. As a result, the volume of krill oil required, and therefore the number of capsules needed, to deliver scientifically established therapeutic doses of EPA+DHA, would have to be substantially more than if taking fish oil. Manufacturers presumably realise that not many people could afford to take 10+ capsules of krill daily, so recommended doses tend to be less than 1 gram of oil, providing 150-200 mg of omega-3s EPA and DHA. At this low dose, consumers will not see positive increases in their omega-3 index.
But krill contains astaxanthin! …at 1/10th of the dose of an astaxanthin supplement
Krill oil is also hailed for its natural content of the powerful antioxidant astaxanthin – again, not in meaningful quantities. Antioxidants offer significant protection against oxidative stress and inflammation and thus the content of astaxanthin present in krill that protects the free fatty acids from oxidation may be partly responsible for health benefits observed in krill studies. Astaxanthin is a very beneficial nutrient and suggested doses are upwards of 6mg; to put this into perspective, krill oil capsules tend to contain only around one tenth of this amount – approximately 500mcg!
An alternative to fish oil… that’s 5x more expensive for the same result!
Scientists are now beginning to understand that even to simply restore optimum health – identified by biomarkers such as the omega-3 index and the AA to EPA ratio – the average person would need at least 1g of total EPA and DHA, not just 1g of fish oil daily. To get this dose from pure krill oil you would need to take a minimum of 10 capsules daily and up to 20g of oil per day. So, depending on the brand you choose, this could cost anything from £2.30 – £5.00 or more per day. To achieve this from concentrated fish oils delivering 90% active ingredient per volume of oil, you would need a maximum of 1.1g of oil from as little as 2 capsules, which can be achieved comparatively cheaply at £1.00 per day.
As an example, we have compared our Pharmepa RESTORE concentrated EPA fish oil with a leading brand of krill oil. Krill oil would likely confer the same benefits as concentrated EPA & DHA fish oil if you consumed more than 5 times the advised volume, but its concentration of active omega-3 EPA and DHA is so low that it would cost you up to 5 times more than the concentrated fish oil. To achieve the benefits of increased omega-3 blood levels from krill oil would cost in excess of £150.00 each month, in comparison with less than £30.00 a month for the same result with concentrated fish oil.
(Concentrated EPA fish oil)
Leading krill brand
(Low EPA and DHA)
Leading krill brand
(Low EPA and DHA)
|Dose||2 capsules||2 capsules||10 capsules (5x dose recommended on packaging)|
|Active EPA /DHA||1000 mg||104 mg||520 mg|
|Form of omega-3||Re-esterified triglyceride||Phospholipid||Phospholipid|
|Suitable application||Therapeutic – clinical nutrition||Wellbeing support||Therapeutic – clinical nutrition|
|Impact on omega-3 index||Yes – significant||NO – insignificant||Yes – significant|
An alternative to fish oil… with little scientific backing
Since krill is still relatively new to the market, scientific studies determining its health benefits for humans are thus far very limited when compared to the abundance of strong research into omega-3s from fish oil. The science behind the claims made for krill, and whether or not it stands up as a superior source of omega-3s, cannot currently justify support for the use of krill in place of fish oil for anything beyond general health promotion. Even if you are simply supplementing with krill oil to support general wellbeing, a standard fish oil would be perfectly adequate, for 1/3 of the price of krill oil.
In the few studies comparing krill oil to fish oil, the researchers were only able to conclude that krill oil is as good as fish oil – not better. Whilst the studies do suggest EPA and DHA from krill oil may be slightly better absorbed, the methods used by the researchers are often not of high scientific quality, with some studies coming under heavy criticism. In addition, in order for the researchers to give the participants the same EPA and DHA dose, the krill oil had to be ‘topped up’ with fish oil or considerably larger volumes of krill oil had to be ingested.
Studies considering like for like doses of fish and krill oil on cardiovascular and metabolic risk factors such as triglyceride levels (TG), cholesterol and markers of both inflammation and oxidative stress, have failed to show any difference between groups given krill or fish oil. Systolic blood pressure response, however, has been shown to be significantly reduced by taking fish oil but not krill oil when compared directly. Thus, any potential benefit of greater omega-3 absorption from krill oil does not seem to translate into additional cardiovascular health benefits.
Krill doesn’t produce fishy burps… but you may experience loose stools and flatulence!
Digestive side effects are sometimes experienced with high-dose fish oil consumption and the absence of ‘fishy burps’ is an attractive prospect for many people – but krill is certainly not without its gastrointestinal side effects. One study – 4 weeks of supplementation with krill oil – resulted in 20% of subjects reporting gas or bloating, compared with no individuals within the fish oil group reporting similar symptoms. In addition, 36% of the krill oil group reported flatulence and 20% reported diarrhoea or loose stools compared with only 8% of the fish oil group reporting any of these issues. Although this study did not address reflux or ‘fishy burps’ associated with taking omega-3 oils, it seems the use of krill oil may be more likely to result in a number of more unpleasant gastrointestinal disturbances compared to the same dose of fish oil.
- Schuchardt JP, Schneider I, Meyer H, Neubronner J, von Schacky C, Hahn A: Incorporation of EPA and DHA into plasma phospholipids in response to different omega-3 fatty acid formulations–a comparative bioavailability study of fish oil vs. krill oil. Lipids in health and disease 2011, 10:145.
- Ulven SM, Kirkhus B, Lamglait A, Basu S, Elind E, Haider T, Berge K, Vik H, Pedersen JI: Metabolic effects of krill oil are essentially similar to those of fish oil but at lower dose of EPA and DHA, in healthy volunteers. Lipids 2011, 46:37-46.
- Maki KC, Reeves MS, Farmer M, Griinari M, Berge K, Vik H, Hubacher R, Rains TM: Krill oil supplementation increases plasma concentrations of eicosapentaenoic and docosahexaenoic acids in overweight and obese men and women. Nutrition research 2009, 29:609-615.
- Kidd P: Astaxanthin, cell membrane nutrient with diverse clinical benefits and anti-aging potential. Alternative medicine review : a journal of clinical therapeutic 2011, 16:355-364.
- Deutsch L: Evaluation of the effect of Neptune Krill Oil on chronic inflammation and arthritic symptoms. Journal of the American College of Nutrition 2007, 26:39-48.
- Grimstad T, Bjorndal B, Cacabelos D, Aasprong OG, Janssen EA, Omdal R, Svardal A, Hausken T, Bohov P, Portero-Otin M, et al: Dietary supplementation of krill oil attenuates inflammation and oxidative stress in experimental ulcerative colitis in rats. Scandinavian journal of gastroenterology 2012, 47:49-58.
- Sublette ME, Ellis SP, Geant AL, Mann JJ: Meta-analysis of the effects of eicosapentaenoic acid (EPA) in clinical trials in depression. The Journal of clinical psychiatry 2011, 72:1577-1584.
- Ballantyne CM, Braeckman RA, Soni PN: Icosapent ethyl for the treatment of hypertriglyceridemia. Expert opinion on pharmacotherapy 2013, 14:1409-1416.
- Bloch MH, Qawasmi A: Omega-3 fatty acid supplementation for the treatment of children with attention-deficit/hyperactivity disorder symptomatology: systematic review and meta-analysis. Journal of the American Academy of Child and Adolescent Psychiatry 2011, 50:991-1000.
- Martins JG: EPA but not DHA appears to be responsible for the efficacy of omega-3 long chain polyunsaturated fatty acid supplementation in depression: evidence from a meta-analysis of randomized controlled trials. Journal of the American College of Nutrition 2009, 28:525-542.
- Ghasemifard, S., G.M. Turchini, and A.J. Sinclair, Omega-3 long chain fatty acid “bioavailability”: A review of evidence and methodological considerations. Prog Lipid Res, 2014. 56C: p. 92-108.
Laidlaw, M. Cockerline, C., Rowe, W., A randomized clinical trial to determine the efficacy of manufacturers’ recommended doses of omega-3 fatty acids from different sources in facilitating cardiovascular disease risk reduction. Lipids in Health and Disease 2014, 13:99.