Fish oil has long been praised for its many benefits. These most notably include improving cardiovascular health by lowering triglycerides and blood pressure, and easing the pain and inflammation associated with joint pain and arthritis. In adddition, a lot of work has been carried out on the effects of the biologically active omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on areas as diverse as cognitive and mood enhancement, brain and nerve health, influence on hormone levels, and influence on weight loss.
Krill oil is a marine oil which is rich in DHA and EPA. While the similar ingredient profiles would suggest similar functions for fish and krill oils, there are some notable differences between the two products. The biggest of these is structural – while the fatty acids in fish oil are present in ester form, they are present as phospholipids, or as free fatty acids in krill. Many people believe that this heightens the bioavailability of the active ingredients in krill oil, and this is a popular topic of research.
Bioavailability and use both play roles in determining the optimal dosage of these supplements.
Fish Oil vs Krill Oil Dosage
The dosage of both fish and krill oils is based upon the recommended daily intake (RDI) for the active ingredients of fish oil, EPA and DHA. This recommendation does not take into account properties of krill oil that have yet to be verified by the sort of rigorous research that fish oil has been subject to.
The Australian and New Zealand National Health and Medical Research Council has set a minimum RDI of 90-160mg omega-3 per day for the maintenence of overall health and normal body functioning, and recommends that no more that 3g of DHA and EPA be consumed per day (3). The American Heart Foundation recommends as little as 1g of fish oil-based EPA and DHA per day to improve cardiovascular health, and various sources recommend up to 6g for the effective treatment of joint problems and inflammation. These numbers include any omega-3 fatty acids that are taken in through the diet, in food like oily fish, eggs or nuts.
The fact that these recommendations based upon the active ingredients and not on an absolute volume takes into account the fact that these values vary between brands and batches of product, which can be highly significant. Purity can become an issue for people who are taking larger doses.
One of the big reaasons people choose krill oil is the perception that lower doses are needed to attain the same effect. This is true to some extent. One experiment showed that 80% of the fatty acids in krill oil passed through to the bloodstream, whereas the figure for fish oil was only 50% (1). Another, similar study gave participants equal volumes of fish and krill oil and saw identical metabolic effects. This research also brought to light the fact that krill oil, in general, contains a lower percentage of omega-3, negating benefits of the better absorption (2). This type of research is still in its very early stages, and it will be interesting to see if the benefits of krill oil can be better understood and leveraged in future.
In addition, because omega-3 and omega-6 fatty acids compete for processing within the body, it is believed that the ratio can be just as important as the amount. The ratios stated as optimal vary widely, between 1:1 and 1:10 parts omega-3:omega-6. These amounts can be difficult to obtain through a normal western diet, which is estimated to contain, on average, a 1:15-1:30 ratio of omega-3:omega-6 fatty acids. In very general terms, the products of omega-6 fatty acids are pro-inflammatory and effects of omega-3 fight inflammation, and many people bellieve optimising this ratio is the most effective way to control inflammatory conditions.
Fish Oil vs Krill Oil Side Effects
Both of these omega-3 rich marine oils are very safe, and serious side effects are very rare. The major issues are digestive, or concern the smell of fish oil, which has the tendency to cause indigestion, particularly reflux and "fish burps". Krill oil has the unfortunate tendency to produce similar side effects. The severity of these side effects are largely tied to the volume of oil consumed. People are, in general, more likely to consume greater amounts of fish oil, which has spurred a move toward krill oil, despite the similar efficacy of both oils. The good news is that many manufacturers have "odourless" versions of these oils, which can be used if the smell or taste present a persistent problem.
Buying Fish Oil vs Krill Oil - Price
Value for money is a major concern for most people, and the large price difference between fish and krill oil is worth mentioning. Fish oil is largely a by-product of the fishing industry - the vast majority is produced from otherwise unusable material. In addition, the oil concentration can top 80% in much of the product that is used in the production of oil, and fish are high in antioxidant minerals and fat-soluble vitamins, like vitamin A, selenium and iodine. These factors can enhance the pre-processing stability of fish oil (4).
Krill is one of this planet's largest untapped natural resources, and the huge recent upswing in demand for krill is not putting a dent in our oceans' seemingly limitless supply of this small crustacean (4). However, the processing required to make krill oil is very different. Krill is harvested with the major purpose of producing oil, which means that the raw material is more expensive than the cheap byproduct from which fish oil is extracted. In addition, krill on average contains 5% oil, so despite the presence of natural antioxidants, this means that krill must be kept cold or live stored, or processed immediately at sea to prevent the oxidation of the volatile product (5). This is a big reason why krill oil is significantly more expensive than fish oil. Manufacturers of krill oil often stipulate a lower dosage, possibly in part to offset the higher price. As we covered above, there is little research to back this up. The small amount of independent study that has been carried out indicates that equal doses of each supplement are necessary to deliver the same amount of active ingredients.
Although they are similar, it is important to remember that fish oil and krill oil are two different supplements. Krill oil is a very new player on the market, and there is a lot of research that remains to be done into the mechanism of action, along with exciting potential benefits which have already started to attract a lot of interest.
(1) Schuchardt JP, Schneider I, Meyer H, Neubroner 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 Health Dis. 2011 Aug 22;10:145.
(2)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 Jan;46(1):37-46.
(3) Nutrient Reference Values for Australia and New Zealand. Australian Government National Health and Medical Research Council and Ministry of Health Manatu Hauora. http://www.nrv.gov.au/nutrients/fats-total-fat-fatty-acids. Accessed 30th April 2014.
(4) Kwantes JM, Grundmann O. A Brief Review of Krill Oil History, Research, and the Commercial Market. Journal of Dietary Supplements, Early Online:1–13, 2014.
(5) Fish Oil. https://www.consumerlab.com/ - accessed 20/11/2013