Let's start at the beginning. What is krill oil? Krill are small crustaceans that are found in deep ocean waters. They look a bit like tiny shrimp. Krill are rich source of omega-3 fatty acids, especially EPA and DHA. They are near the bottom of the food chain. In fact, they are where many of the ocean fish actually get their omega-3 fatty acids. Because they're near the bottom of the food chain, they are less contaminated with PCBs and mercury than the predators at the top of the food chain. At this point you're probably thinking that they're sounding pretty good. But, we need to dig a bit deeper.
First we need to look at the oils themselves. In most fish oil supplements the omega-3 fatty acids are found primarily as triglycerides. In the high purity, high potency pharmaceutical grade fish oil supplements the omega-3 fatty acids are found primarily as ethyl esters. In krill oil the omega-3 fatty acids are found as a mixture of triglycerides and phospholipids. So what is the difference?
The krill oil manufacturers would have you believe that omega-3 phospholipids are more rapidly absorbed than omega-3 triglycerides and are directly incorporated into cell membranes. As a biochemist I find that last statement highly misleading. In fact, triglycerides and phospholipids in the foods that we eat are broken down to their component parts and reassembled several times before they actually make it into cell membranes. So
omega-3 phospholipids may be more rapidly absorbed, but they are not directly incorporated into cell membranes.
Notice that I said "may be more rapidly absorbed". I didn't say "are more rapidly absorbed". Those words were chosen carefully, because the science isn't clear.
Some of the companies who sell krill oil claim that they have clinical studies showing that krill oil is substantially better absorbed than fish oil. But those studies are unpublished and, therefore, unreliable. If you look at the three published studies comparing krill oil and fish oil absorption, the data are much less compelling.
For example, one study (Lipids Health Dis., 2011, 10:145. Doi:10.1186/1476-511X-10-145) reported a higher uptake of omega-3 fatty acids into the bloodstream from krill oil than from fish oil in either the triglyceride or ethyl ester form. However, those differences were not statistically significant. A second study (Nutr. Res., 2009, 29: 609-615) found no difference in the uptake of omega-3 fatty acids into the bloodstream between krill oil in menhaden oil. And a third study Lipids, 2011, 46: 37-46) found no difference in the uptake of omega-3 fatty acids into the bloodstream or in markers of inflammation and oxidative stress between subjects taking krill oil or fish oil. So if krill oil has any advantage in terms of uptake and utilization of omega-3 fatty acids, it's pretty marginal.
Another claim of the krill oil manufacturers is that krill oil is less contaminated than fish oil. While that may be true for some of the fish oil products on the market, it's definitely not true of the high purity pharmaceutical grade fish oil supplements.
And finally, what about the claim that krill oil is more sustainable? There is no question that sustainability of our fish supply is an important issue. But, what krill oil proponents forget is that small fish eat the krill; bigger fish eat the smaller fish and so on. Depleting the bottom of the food chain on which ocean fish rely will eventually affect their sustainability just as much as overfishing.
And, on the negative side, krill oil is generally more expensive and has lower concentrations of omega-3 fatty acids than fish oil. So, is it worth the added cost? I'll let you be the judge.
So what's the bottom line for you?
1) The so-called advantages of Krill oil appear to be greatly over hyped.
- Based on the scientific studies published to date any advantage in uptake and utilization of omega-3 fatty acids from krill oil is minimal at best.
- The purity argument is a red herring (If you'll pardon the pun). Differences in purity are more likely to depend on the purification methods and quality control standards of the manufacturer than on the source of the oil.
- The sustainability argument is another red herring. In the long run it doesn't matter whether you deplete the bottom of the food chain or the top of the food chain.
2) Finally, my advice to you whether you use krill oil or fish oil is to be sure to choose a company that manufactures a high purity pharmaceutical grade oil, has rigorous quality control standards, and has published clinical studies showing that their supplement is well utilized.
To Your Health!
Dr. Stephen G Chaney
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.