Is krill more effective than fish oil for raising the omega-3 index?
Four weeks of daily supplementation with 600 mg of omega-3 polyunsaturated fatty acids (PUFA) as either krill or fish oil was associated with higher omega-3 index in the krill oil group, according to findings published in Lipids in Health and Disease
Krill oil consumption was also found to significantly decrease the ratio of omega-6 to omega-3s, compared with fish oil.
The study was conducted by Dr Peter Jones at the Richardson Centre for Functional Foods and Nutraceuticals, Winnipeg, Canada, and Enzymotec’s K-Real krill oil product. The Israeli company also funded the study.
“These results indicate that bioavailability of krill oil omega-3 PUFA might be more pronounced compared with that of fish oil, likely due to the structural differences between these two marine oils,” wrote the researchers.
According to our knowledge, the current study is the first to compare the effects of krill and fish oils on fatty acid profile in plasma and red blood cells after 4 weeks of consumption, using a randomized crossover design,” added the researchers.
K-Real is described as, “a family of solutions extracted from sustained Antarctic Krill. It is comprised from a mixture of natural phospholipids conjugated to EPA and DHA, astaxanthin and triglycerides with EPA and DHA.”
The new study does not provide any analytical data of the phospholipid or triglyceride content of the krill or fish oil used in the supplements.
The forms
The question of a potential superiority between the forms – fish oil, which has omega-3 in triglyceride form, and krill oil, which delivers omega-3 in phospholipid form – is a relatively recent debate.
The new study joins only a handful of other clinical trials to compare the bioavailability of krill oil to fish oil, with the majority of the science focusing on compared EPA and DHA from natural triglyceride, re-esterified triglyceride, and ethyl ester sources.
A study by Schuchardt et al. (Lipids Health Dis. 2011, 10:145. doi:10.1186/1476-511X-10-145) demonstrated that there was a higher incorporation of EPA, DHA, and total omega-3 fatty acids into plasma phospholipids after ingestion of krill oil, compared with consuming re-esterified triglycerides derived from fish oil and ethyl ester forms, however these differences failed to reach statistical significance. Experts have previously noted that the krill oil used in the Schuchardt et al. paper contained 20-22% free fatty acids, which are highly absorbed.
A comparison study between krill oil with menhaden oil led by Biofortis’ Kevin Maki, PhD, revealed that increases in plasma EPA and DHA were similar with ingestion of both oils (Nutr Res. 2009, Vol. 29, pp. 609-615). However, when expressed per mg of EPA or DHA consumed there was a trend toward a greater increase in plasma EPA and DHA with krill oil.
A third study, by Ulven et al. (Lipids. 2011, Vol. 46, pp. 37-46), found no statistically significant differences in changes in serum lipid levels, or in markers of inflammation and oxidative stress between the groups receiving krill oil (total EPA + DHA of 543 mg per day) or fish oil (total EPA + DHA of 864 mg per day).
‘Step in the right direction’
Commenting on the results of the new study, Dr. Peter Jones, the principal investigator, said: “This study is a step in the right direction to show the benefits of krill oil, and we are very happy with the results.
“The assumption that omega-3 fatty acids are better absorbed when they are bound to phospholipids rather than triglycerides, was suggested as one of the main benefits of krill oil. However, nobody was able to show it so far. This is the first well designed study proving that consumption of krill oil is more efficient than fish oil in elevating the level of omega-3 fatty acids in the red blood cells.”
Study details
Dr Jones and his co-workers recruited 24 healthy volunteers to participate in the three-phase double blinded, randomized, placebo-controlled, crossover trial. The three phases each lasted four weeks each, separated by an eight week ‘washout period’ and included six capsules per supplements of krill (K-Real, Enzymotec) or fish oil (Omevital TG 18/12, Napro Pharma, Norway) or placebo control (corn oil)/
Results showed that both krill and fish oil increased omega-3 levels in plasma and red blood cells, but with greater increases in the krill oil group, compared to placebo.
Both krill and fish oil regimens also reduced the ratio of omega-6 to omega-3s, with greater reductions in the krill oil treatment compared with fish oil.
“Interestingly, krill oil treatment elevated the omega-3 index compared with fish oil treatment (p = 0.0143),” wrote the researchers. “The change in omega-3 index after consumption of krill oil was two-fold higher than fish oil (1.04% and 0.47% following krill and fish oil treatments respectively; p = 0.0043).”
Dr. Ariel Katz, President and CEO of Enzymotec Ltd, welcomed the results as being, “consistent with previous clinical studies on other ingredients developed and manufactured by Enzymotec.
“We will continue to capitalize on consumer trends towards supplementing their diets with premium health and wellness products like our K-Real, krill oil.”
Source: Lipids in Health and Disease
2013, 12:178, doi:10.1186/1476-511X-12-178
“Enhanced increase of omega-3 index in healthy individuals with response to 4-week n-3 fatty acid supplementation from krill oil versus fish oil”
Authors: V.R. Ramprasath, I. Eyal, S. Zchut, P.J.H. Jones
