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Randomized Controlled Trial
. 2011 Aug 22;10:145.
doi: 10.1186/1476-511X-10-145.

Incorporation of EPA and DHA Into Plasma Phospholipids in Response to Different omega-3 Fatty Acid Formulations--A Comparative Bioavailability Study of Fish Oil vs. Krill Oil

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Randomized Controlled Trial

Incorporation of EPA and DHA Into Plasma Phospholipids in Response to Different omega-3 Fatty Acid Formulations--A Comparative Bioavailability Study of Fish Oil vs. Krill Oil

Jan Philipp Schuchardt et al. Lipids Health Dis. .
Free PMC article


Background: Bioavailability of omega-3 fatty acids (FA) depends on their chemical form. Superior bioavailability has been suggested for phospholipid (PL) bound omega-3 FA in krill oil, but identical doses of different chemical forms have not been compared.

Methods: In a double-blinded crossover trial, we compared the uptake of three EPA+DHA formulations derived from fish oil (re-esterified triacylglycerides [rTAG], ethyl-esters [EE]) and krill oil (mainly PL). Changes of the FA compositions in plasma PL were used as a proxy for bioavailability. Twelve healthy young men (mean age 31 y) were randomized to 1680 mg EPA+DHA given either as rTAG, EE or krill oil. FA levels in plasma PL were analyzed pre-dose and 2, 4, 6, 8, 24, 48, and 72 h after capsule ingestion. Additionally, the proportion of free EPA and DHA in the applied supplements was analyzed.

Results: The highest incorporation of EPA+DHA into plasma PL was provoked by krill oil (mean AUC0-72 h: 80.03 ± 34.71%*h), followed by fish oil rTAG (mean AUC0-72 h: 59.78 ± 36.75%*h) and EE (mean AUC0-72 h: 47.53 ± 38.42%*h). Due to high standard deviation values, there were no significant differences for DHA and the sum of EPA+DHA levels between the three treatments. However, a trend (p = 0.057) was observed for the differences in EPA bioavailability. Statistical pair-wise group comparison's revealed a trend (p = 0.086) between rTAG and krill oil. FA analysis of the supplements showed that the krill oil sample contained 22% of the total EPA amount as free EPA and 21% of the total DHA amount as free DHA, while the two fish oil samples did not contain any free FA.

Conclusion: Further studies with a larger sample size carried out over a longer period are needed to substantiate our findings and to determine differences in EPA+DHA bioavailability between three common chemical forms of LC n-3 FA (rTAG, EE and krill oil). The unexpected high content of free EPA and DHA in krill oil, which might have a significant influence on the availability of EPA+DHA from krill oil, should be investigated in more depth and taken into consideration in future trials.


Figure 1
Figure 1
Increase of n-3 FA concentrations in plasma PL after the ingestion of supplements. Healthy young males received n-3 FA as fish oil rTAG (solid line), EE (dash line), or krill oil (dash dot line) supplements in a crossover manner. Results show change of EPA, DHA, EPA+DHA, and total n-3 FA levels in plasma PL (% of total FAs, mean ± standard deviation) from baseline concentrations over 72 h.

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