Krill Oil vs. Fish Oil

Krill oil has been getting considerable hype lately as a newer, better alternative to fish oil. The argument follows one off a couple different lines. First, krill are lower on the food chain and farmed from Antarctica, so better for the environment and less likely to have mercury contamination. Second, krill contains the antioxidant astaxanthin, which may have helpful properties. And in a related point, this new supplement has been touted as an especially useful treatment for PMS. Unfortunately, krill-derived oil is not best thing since sliced bread. This article will separate the facts from the hype around krill oil. Bottom line: krill is fine but fish is cheaper. And at least as good.

First, what are krill?
Krill are a marine crustacean, just like shrimp. Krill occurs in all the oceans of the world, but the largest populations by far are in the Southern Ocean, around Antarctica. Krill tend to swarm together as a defense mechanism. Populations can cram up to 60,000 individuals into a single cubic meter of water.

Is Eating Krill Oil Better for the Environment?
No. While krill populations regenerate rapidly, melting ice in the antarctic has krill populations in decline. Furthermore, krill hold a critical position in the food chain. Krill feed on algae and turn those nutrients into a form edible by much larger animals like whales. Declines in krill population therefore have disproportionate impact on ecosystmes. Fortunately, most krill is farmed around Antarctica and the prohibitive cost of operations in that area make major expansion unlikely.

Is eating Krill advantageous because of lower mercury?
Yes and no. First, fish oil from large reputable vendors is typically certified mercury-free. These supplements are usually purified by a steam-distillation process ("molecular distillation") that removes trace metals. The bottom line is that fish oil capsules are much safer than eating fish. Even so, krill are likely to be much lower in mercury than fish.

Is eating krill better because of the antioxidants?
Again, yes and no. Krill-derived oil contains the antioxidants astaxanthin and the related stucture, vitamin A. These compounds are not present at the same levels in fish oil, so this is a real benefit of krill-based oil. But, if you are taking fish oil supplements, you probably are also taking a multivitamin, so this is partly moot. Also, I recommend you take vitamin E with any omega-3 supplement, whether from fish, krill, or flax. I recommend this addition because there is some potential for the poly unsaturated fatty acids to act as pro-oxidants without extra antioxidant support. Take home lesson: you should take vitamin E with krill or fish oil, so there is little benefit to krill here. astaxanthin, astaxanthin structure, krill oil antioxidant

Will krill oil help with PMS?
Maybe. Studies are out there on this, and while the data is a little weak, it suggests that the antioxidants rather than the omega-3 oils are responsible for the effects (1). Krill-derived oil can work, but fish oil, a multivitamin taken together with vitamin E will probably have similar effects. Also, I recommend avoiding flax oil around the PMS-time. Flax oil contains lignans, which are converted to phytoestogens in the colon. No need for more hormones running around at that time of the month.

Flaxseed oil, like krill oil, is often billed as a fish oil alternative

What's the verdict?
Take fish oil. It's much cheaper, it's no worse for the environment, it's just as safe, and you should be taking additional antioxidants like vitamin E anyway. Krill oil has beneficial properties, but they don't add up to a good reason to switch.

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1. Sampalis, F, Bunea, R, Pelland, MF, et al. "Evaluation of the effects of Neptune Krill Oil(TM) on the management of premenstrual syndrome and dysmennorhea" Alt Med Rev. 8 (2003) 171-179.