Study on Krill Powder Suggests: There is More to Seafood Than Fat - Can Krill Give You What Fish Oil Can't? Plus: Krill Protein's EAA Content More Than an Able Match to Whey

If you listened to the SuppVersity Science News Round Up on Super Human Radio, yesterday, you may remember that the color of food can tell you something about it's antioxidant activity... well, guess what: It's the lipid-soluble pigment and potent antioxidant astaxanthin that gives krill its "healthy" orange-red color.
In a way this post could be regarded as a follow-up on yesterday's news about the profound weight-loss effects of high dose EPA (and to a lesser degree) DHA supplementation. After all, parts of the supplement industry have been working hard on establishing krill oil as a more efficient alternative for regular fish oil (see "Neptune Krill Oil, the New or Better Fish Oil?"). And in a way, the Rossmeisel study, I had in the news back in June 2012, would support this claim, since one of the proven benefits of krill oil actually is that it contains way more of the phospholipid variety of the long-chain omega-3 fatty acids that is more readily incorporated into the cells than the triglyceride variety from cheaper fish oils (see "Only Phospholipid Based DHA+EPA Reduces Fat Cell Growth & Elevated Insulin Levels Despite Obesogenic Diet").

Moreover, the results of a 2011 study by Burri et al. (Burri. 2011), which showed that other than fish oil, krill oil with an equimolar amount of EPA and DHA in it actally decreased the expression of those hepatic genes for gluconeogenesis and glycolysis which could be responsible for the problematic increase in glucose levels Poudyal et al. observed in response to high dose omega-3 supplementation (yesterday's news). Now, these observations certainly raise the question:

Can we ward off the negatives and maximize the benefits by using krill instead of fish?

You can't eat krill? Fraser Lewry's recipe for krill fried rice looks very real (and delicous) to me
The results of a very recent study from Norway appear to hold the answer to this question. Moreover, the fact that the researchers did use krill powder instead of the krill equivalent to fish oil, which was by the way regarded mostly as an unwanted waste product that was left over, when McDonald's & Iglu picked up the fish fillets for their Fish Macs and Captain Iglu (R) Fischstäbchen, actually sparks another intriguing question: Wouldn't it be more prudent to eat the whole fish, or in this case whole krill (powdered or not), anyway?

Now, while we will come back to the question of "eating whole krill" later, let's initially take a closer look a the experiment Bjorndal et al. conducted. The scientists two groups of particularly inflammation prone transgenic male mice of a C57BL/6 strain which constitutively expresses high TNFα (tumor necrosis factor-alpha aka cachexin, or cachectin) levels iso-caloric "high fat" diets. Half of the animals were randomized to the notorious high carbohydrate + high fat diet you usually see in studies like these, the other had parts of the protein and fats replaced with the protein and fat from krill powder (see figure 1 for more details).

Figure 1: The composition of the experimental diets (Bjørndal. 2012).
From the "if it fits your macros" perspective, this may look like a minor, negligible change. Over the course of the six weeks the experiment lasted, it did however make a huge difference, as far as the rodents' ability to handle the lipid and energy overload was concerned. And those differences were, as the researchers had already expected, particularly pronounced in the liver:
"The liver of mice fed the krill powder diet displayed increased β-oxidation, reduced lipogenesis, and reduced cholesterol- and glucose metabolism compared to high-fat fed mice, resulting in improved plasma and hepatic lipid levels." (Bjørndal. 2012)
In short, the provision of the krill based lipid + protein mixture affected the lipid metabolism, the expression of genes involved in glucose metabolism and the fatty acid composition in plasma and liver of the animals, while keeping the mitochondrial respiratory electron transport chain in liver intact.
Figure 2: Graphical illustration of statistically significant changes in hepatic gene expression (colors indicate involvement in glucose, cholesterol or fatty acid metabolism; center) and corresponding downstream effects on plasma lipids (small graphs on the right; created based on data from Bjørndal. 2012)
However, even though we see beneficial effects on lipid metabolism, the absence of beneficial effects on blood glucose despite the presence of the previously observed (Burri. 2011) and with the study at hand now confirmed beneficial effects on the expression of respective genes in the liver makes it quite clear that krill oil, just like fish oil cannot make up for the sheer energy overload of the typical western diet (see yesterday's news).

How come this sh*t doesn't work?

And what about the protein in krill powder? Since we don't have a direct comparison to a krill oil only supplement it is difficult to tell, whether the protein content of the powder used in the study at hand did actually make a difference, also because we do have evidence from previous studies (e.g. Burri. 2011) that krill oil alone elicited similar beneficial effects on the hepatic gene expression. Nevertheless,the favorable amino acid profile of krill protein concentrates (see figure above; data based on Gigliotti. 2008 and Sindayikengera. 2006), alone would suggest that the powder has way more to offer than just the oil.
With the increased energy expenditure from fat in response to both krill and fish oil, comes a lower reliance on glucose as a fuel source. Therefore, more of the sugary glue that makes an excellent fuel, but a very bad lubricant, will remain floating around in the blood, so that the unquestionably impressive >50% reduction of hepatic glyocogen breakdown and the corresponding -45% reduction in gluconeogenesis (see figure 2, green hexagons) are probably just enough to compensate the decreased glucose oxidation, so that the overall amount of glucose that's floating around freely in the blood of the krill oil / or powder supplemented animals will remain the same (with fish oil, and in the absence of these epigenetic changes, it will even go up!).

Bottom Line: While krill powder appears to have the edge over plain fish oil, it's use is yet likewise no panacea for all the ailments of the metabolic syndrome. 

The impressive amino acid composition of the protein fraction in krill powder (see information box on the right), as well as Yamada et al.'s 2011 observation that an obviously fat-free, since water soluble krill extract directly antagonizes triglyceride accumulation (=increase in fat content) in adipocytes by suppressing PPARγ and C/EBPα expression (Yamada . 2011), still speak in favor of my initial hypothesis that there is more healthy stuff in krill (and fish) than EPA, DHA & the rest of the omega-3 fatty acid megillah, so to say.

  • Bjørndal B, Vik R, Brattelid T, Vigerust NF, Burri L, Bohov P, Nygård O, Skorve J, Berge RK. Krill powder increases liver lipid catabolism and reduces glucose mobilization in tumor necrosis factor-alpha transgenic mice fed a high-fat diet. Metabolism. 2012 Oct;61(10):1461-72.
  • Burri L, Berge K, Wibrand K, Berge RK, Barger JL. Differential effects of krill oil and fish oil on the hepatic transcriptome in mice. Front Genet. 2011;2:45. Epub 2011 Jul 12.
  • Gigliotti JC, Jaczynski J, Tou JC.  Determination of the nutritional value, protein quality and safety of krillprotein concentrate isolated using an isoelectric solubilization/precipitation technique Food Chemistry, Volume 111, Issue 1, 1 November 2008, Pages 209–214.
  • Sindayikengera S, Xia WS. Nutritional evaluation of caseins and whey proteins and their hydrolysates from Protamex. J Zhejiang Univ Sci B. 2006 Feb;7(2):90-8. 
  • Yamada H, Ueda T, Yano A. Water-soluble extract of Pacific Krill prevents triglyceride accumulation in adipocytes by suppressing PPARγ and C/EBPα expression. PLoS One. 2011;6(7):e21952.