Absorption rate of krill oil and fish oil in blood and brain of rats

Abstract Background Krill (Euphausia superba) is a small marine crustacean with a lipid content. The mechanism of Krill oil function is not clear yet and research reports on the absorption rate of the phospholipids of krill oil in the blood and brain are very poor. Methods We studied the effect of oral short-term and long-term administration of Krill oils (KOs) on bioavailability in the blood and brain of rats. For short-term testing of fish and KO bioavailability, rats were divided into four groups: normal, fish oil (FO), Krill oil 1 (KO), and Krill oil 2 (CKO). The blood and brain were collected at 2, 4, 8, 12, 24, and 48 h after oral administration (1000 mg/rat). Five hundred milligrams of FO, KO, and CKO were orally administered daily for 2 weeks for long-term administration, and then the brain and blood were collected. Results Two types of KOs showed high content of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the PL. The EPA content of CKO and KO were 41.13 and 32.49%, respectively. After short-term KO administration, KO showed a higher EPA content than CKO in the blood after 2 h. KO showed higher content of DHA than CKO even after 2 h. FO increased until 8 h, but then decreased rapidly until 12 h. Although the total unsaturated fatty acid (UFA) content of KOs was lower than the total UFS content in FO, the remaining UFS content in the brain was higher than that in FO over time. Following oral administration of FO, KO, and CKO for 1 and 2 weeks, triglycerides (TG) and PL contents in the blood for KOs were slightly higher than for FO. EPA and DHA levels in the brain were slightly higher in KOs following long-term administration, but the difference was not significant. Conclusions Base on these findings, KOs have functional potential for the brain and vascular diseases, and can be utilized as a multi-functional material composed mainly of functional ingredients.