Abstract
BackgroundKrill contains two marine omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), mainly bound in phospholipids. Typical products from krill are krill oil and krill meal. Fish oils contain EPA and DHA predominantly bound in triglycerides. The difference in the chemical binding of EPA and DHA has been suggested to affect their bioavailability, but little is known on bioavailability of EPA and DHA in krill meal.This study was undertaken to compare the acute bioavailability of two krill products, krill oil and krill meal, with fish oil in healthy subjects.MethodsA randomized, single-dose, single-blind, cross-over, active-reference trial was conducted in 15 subjects, who ingested krill oil, krill meal and fish oil, each containing approx. 1 700 mg EPA and DHA. Fatty acid compositions of plasma triglycerides and phospholipids were measured repeatedly for 72 hours. The primary efficacy analysis was based on the 72 hour incremental area under the curve (iAUC) of EPA and DHA in plasma phospholipid fatty acids.ResultsA larger iAUC for EPA and DHA in plasma phospholipid fatty acids was detected after krill oil (mean 89.08 ± 33.36% × h) than after krill meal (mean 44.97 ± 18.07% x h, p < 0.001) or after fish oil (mean 59.15 ± 22.22% × h, p=0.003). Mean iAUC’s after krill meal and after fish oil were not different. A large inter-individual variability in response was observed.ConclusionEPA and DHA in krill oil had a higher 72-hour bioavailability than in krill meal or fish oil. Our finding that bioavailabilities of EPA and DHA in krill meal and fish oil were not different argues against the interpretation that phospholipids are better absorbed than triglycerides. Longer-term studies using a parameter reflecting tissue fatty acid composition, like erythrocyte EPA plus DHA are needed.Trial registrationNCT02089165
Highlights
Krill contains two marine omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), mainly bound in phospholipids
Cross-over trial, we provided a single dose of about 1,700 mg EPA and DHA to human volunteers
The content of free fatty acids in the krill oil used in this study, was low (2.6% of EPA and DHA as free fatty acids), supporting the view that the phospholipids, and not the free fatty acids, in krill oil are responsible for the higher bioavailability we found. This view, is challenged by our finding that the iAUCPL after krill meal was non-significantly smaller than after fish oil, but was identical, if corrected for the dose given. While this finding was not reflected in the iAUCTG, 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
Summary
Krill contains two marine omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), mainly bound in phospholipids. In Western countries, like Germany or the United States, mean levels of the marine omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid are below the range defined as optimal [1]. In large parts, this is due to a decline in uptake of EPA and DHA [1], and due to the fact that, under Western dietary conditions, only a very low percentage (if any) of alpha-linolenic acid. As discussed in more detail elsewhere, bioavailability of EPA and DHA depends on a host of factors, like composition of food ingested with EPA and DHA (if any), other matrix effects, and others [5,6]
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