Superior bioavailability? Study backs krill oil over fish oil … but not because of phospholipids
Writing in the journal Lipids in Health and Disease, the research team report the findings of a study that compared the acute bioavailability of two krill products - krill oil and krill meal - with fish oil in a small group of healthy subjects.
Led by Anton Köhler at the University of Munich, but sponsored by Olympic Seafood AS who produce the Rimfrost brand of Krill Oil, the study and in partnership with researchers at the University of Eastern Finland, the randomised crossover trial found that eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) had a higher bioavailability in krill oil than krill meal or fish oil.
“Profiles of EPA and DHA were measured in fatty acids of plasma phospholipids and triglycerides,” explained the team. “We found a larger incremental area under the curve for EPA and DHA in plasma phospholipid fatty acids (primary endpoint) after krill oil, as compared to the other two sources of EPA and DHA."
However, Köhler and colleagues also noted that since the krill meal had also been found to have a lower bioavailability, previous suggestions that krill may have better availability due to its content of phospholipids versus triglycerides might be incorrect.
Indeed, they said that while the low content of free fatty acids in the krill oil support the view that phospholipids, and not free fatty acids, in krill oil are responsible for the higher bioavailability, this view is challenged by the fact that bioavailability for krill meal was identical to that of fish oil once corrected for differences in dose.
“It argues against the interpretation that the differences in bioavailability we found are due to differences in the chemical form of phospholipids vs. triglycerides, as the fat in krill oil and krill meal is identical,” explained Köhler and colleagues. “Rather, differences in the food matrix seem to be responsible.”
“However, based on our data, we cannot provide a mechanistic explanation, why EPA + DHA had a better bioavailability in krill oil than in fish oil.”
The team performed the randomised, single-dose, single-blind, cross-over trial in 15 participants who were given krill oil, krill meal and fish oil; each containing approximately 1,700 mg of EPA and DHA combined.
In each condition, the fatty acid compositions of plasma triglycerides and phospholipids were measured repeatedly for 72 hours – with primary outcome measures from the study based on 72 hour incremental area under the curve (iAUC) of EPA and DHA in plasma phospholipid fatty acids.
Köhler and colleageus reported a larger iAUC for EPA and DHA in plasma phospholipid fatty acids after krill oil (mean 89.08) than after krill meal (mean 44.97) or after fish oil (mean 59.15). They noted that while there was a statistically significant difference between krill oil and both krill meal and fish oil, there was no statistically significant difference between krill meal and fish oil.
“Bioavailability of EPA plus DHA was not different between krill meal and fish oil, which argues against the interpretation that phospholipids are better absorbed than triglycerides,” noted the team, who added that further trials using parameters that also reflect tissue EPA plus DHA are now needed.
“These intriguing results will be followed up in new clinical trials which are targeting longer-term parameter of omega- 3 fatty acid bioavailability,” said Dr Inge Bruheim of Olympic Seafood, who also worked on the study.
Source: Lipids in Health and Disease
Published online ahead of print, doi: 10.1186/s12944-015-0015-4
“Clinical study shows that bioavailability of EPA/DHA from krill oil is superior to fish oil”
Authors: Anton Köhler, et al