Lipase Treatment of Dietary Krill Oil, but Not Fish Oil, Enables Enrichment of Brain Eicosapentaenoic Acid and Docosahexaenoic Acid

Abstract

Scope: Currently available omega-3 fatty acid supplements do not enrich the docosahexaenoic acid (DHA) of the adult brain because they are absorbed as triacylglycerol, whereas the transporter at the blood brain barrier requires lysophosphatidylcholine (LPC)-DHA. The hypothesis that treatment of krill oil (KO), which contains DHA/eicosapentaenoic acid (EPA) at the SN2 position of phosphatidylcholine, with SN1-specific lipase will generate LPC-DHA/EPA and which can be absorbed intact and transported into the brain, is tested.

Methods: KO and fish oil (FO) are treated with Mucor meihei lipase, incorporated into AIN 93G diet, and fed to 2-month-old mice for 30 days. Fatty acid composition is analyzed by gas chromatography/mass spectroscopy. Brain derived neurotrophic factor (BDNF) is measured by ELISA.

Results: Lipase-treated (LT) KO increases brain DHA and EPA, respectively, 5-and 70-fold better than untreated (UT) KO. FO, whether lipase-treated or not, has no effect on brain DHA/EPA. LTKO is also more efficient in enriching liver DHA/EPA, but less efficient than UTKO and FO in enriching adipose tissue and heart. Brain BDNF is significantly increased by LTKO, but only marginally by other preparations.

Conclusions: Pretreatment of dietary KO with lipase enables it to efficiently increase brain DHA/EPA because of the generation of LPC-DHA/EPA.

Keywords: blood-brain barrier; fish oil; krill oil; omega 3 fatty acids.