The rise and rise of krill in the omega-3 supplement world comes down to the story of greater bioavailability, thanks to krill’s phospholipid content, which helps deliver the all-important DHA and EPA more effectively than fish oil.
Marketing stories assert that krill is between 2.5 and 20 times more bioavailable than fish oil. Because of that, less krill is needed, so the krill pills are half the size of fish oil’s horse pills (as it were).
But a published study released this week, conducted by DSM—suppliers of the leading fish oil, Meg-3, and the leading algae source, Life’sDHA (but, notably, not of krill)—concluded that they’re all the same.
The randomized, double-blind study monitored 66 healthy adults over a four-week period and compared fish oil triglyceride (TG), fish oil ethyl ester (EE) and phospholipid (PL) forms with the same dose and concentrations of EPA and DHA. Triglycerides is the form found naturally in fish; ethyl esters are more popular (largely because of price) but have been shown to be about 15 percent less bioavailable than triglycerides. Phospholipids are the type found in krill, although the phospholipid content of krill has been shown to vary widely—study authors noted a variance of between 19 percent and 81 percent phospholipids depending on the formulation.
At a daily intake of 1.3 grams, and, notably, given with a high-fat meal, researchers found no statistically significant difference in total plasma and red blood cell EPA plus DHA levels across the board.
However, looking closely at the study, it did in fact find the triglyceride form was 19 percent higher than the ethyl ester form (108 to 90.9). In addition, the krill oil product was characterized as having 44 percent of the EPA + DHA in phospholipids, 40 percent in triglycerides and 10 percent in diglycerides, meaning it was really 50 percent glyceride since both the tri- and di- are handled identically in the gut.
“So what people mean when they say ‘krill oil’ can vary a lot,” Bill Harris, Ph.D., president/CEO of OmegaQuant, an analytical services firm, and author of nearly 200 published studies on omega-3s, told NewHope360. “It’s not too surprising that krill oil behaved a lot like triglycerides in this study since half of the krill oil was triglycerides.”
DSM lauded the study as showing that if you’ve seen one EPA/DHA, you’ve seen ’em all.
“It has previously been suggested that krill oil has greater bioavailability than fish or algal oil, but the studies referenced to make such claims had critical design flaws,” said Karin Yurko-Mauro, Ph.D., director of clinical research, Nutritional Lipids, for DSM. “This new study was designed to objectively determine if there are significant differences in the bioavailability of different forms of omega-3s dose for dose, in order to provide more evidence and give a clear message to consumers.”
Krill oil supplier Aker BioMarine took issue with the study design and conclusions. These were based on a lack of baseline levels of EPA/DHA and not properly noting the time it takes to reach a steady state of these omega-3s in the system.
"EPA, with an estimated elimination half-life of approximately 80 hours, can be expected to be largely at steady state after four weeks," the company said in a statement. "This is not the case for DHA, which has a much slower elimination with a half-life of at several hundred hours. Thus, DHA are expected to continue to rise for several months after the four-week point decided as the end point in this study."
Nevertheless, this study deigns to upend the apple cart to some degree, which had placed PL atop the podium, TG second, EE third.
“From the consensus literature to date, the TG form tends to provide a 15 percent better bioavailability than the EE form,” Bruce Holub, Ph.D., University Professor Emeritus at the Department of Human Health & Nutritional Sciences at the University of Guelph, Ontario, told NewHope360. “However, one should note that the cost efficiency to the consumer for a concentrate of EPA/DHA in the EE form is often better than the TG form since the small advantage—say, 15 percent—in bioavailability for the TG form is offset by the EE concentrate often being more than 15 percent less costly per mg of EPA/DHA than the concentrate in TG form. There is a processing cost in converting an EE concentrate to a TG concentrate.”
Future studies, Holub said, should compare EPA/DHA in purified TG vs. EE vs. PL vs. free fatty acid forms in well-controlled clinical trials (chronic, not acute), on low versus higher fat dietary intakes. This study came close, though they did not also include a free fatty acid form, and notably did not compare the fat intake in diets, which could have a significantly confounding effect because a high-fat diet presumably could boost absorption of all of the above, as seen here.
“I think at the end of the day [this study] is substantially right,” said Harris. “When given with some fat in the food, there isn’t a major difference in bioavailability of these products.”
The trick, of course, is that most consumers tend to take their supplements with the lowest-fat meal of the day—breakfast.
For those who eat fats with breakfast (a spoonful of peanut butter will do), or who take their supplements with dinner, it may all come down to which supplement has the highest content of EPA and DHA for the best price.