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

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1 Ahn et l. Lipids in Helth nd Disese (2018) 17:162 RESEARCH Absorption rte of krill oil nd fish oil in blood nd brin of rts So Hyun Ahn 1, Su Jin Lim 2, Young Moo Ryu 2, Hye-Ryung Prk 3, Hyung Joo Suh 4 nd Sung Hee Hn 4* Open Access Abstrct Bckground: Krill (Euphusi superb) is smll mrine crustcen with lipid content. The mechnism of Krill oil function is not cler yet nd reserch reports on the bsorption rte of the phospholipids of krill oil in the blood nd brin re very poor. Methods: We studied the effect of orl short-term nd long-term dministrtion of Krill oils (KOs) on biovilbility in the blood nd brin of rts. For short-term testing of fish nd KO biovilbility, rts were divided into four groups: norml, fish oil (FO), Krill oil 1 (KO), nd Krill oil 2 (CKO). The blood nd brin were collected t 2, 4, 8, 12, 24, nd 48 h fter orl dministrtion (1000 mg/rt). Five hundred milligrms of FO, KO, nd CKO were orlly dministered dily for 2 weeks for long-term dministrtion, nd then the brin nd blood were collected. Results: Two types of KOs showed high content of eicospentenoic cid (EPA) nd docoshexenoic cid (DHA) in the PL. The EPA content of CKO nd KO were nd 32.49%, respectively. After short-term KO dministrtion, KO showed higher EPA content thn CKO in the blood fter 2 h. KO showed higher content of DHA thn CKO even fter 2 h. FO incresed until 8 h, but then decresed rpidly until 12 h. Although the totl unsturted ftty cid (UFA) content of KOs ws lower thn the totl UFS content in FO, the remining UFS content in the brin ws higher thn tht in FO over time. Following orl dministrtion of FO, KO, nd CKO for 1 nd 2 weeks, triglycerides (TG) nd PL contents in the blood for KOs were slightly higher thn for FO. EPA nd DHA levels in the brin were slightly higher in KOs following long-term dministrtion, but the difference ws not significnt. Conclusions: Bse on these findings, KOs hve functionl potentil for the brin nd vsculr diseses, nd cn be utilized s multi-functionl mteril composed minly of functionl ingredients. Keywords: Krill oil, Phospholipids, Eicospentenoic cid, Docoshexenoic cid, Biovilbility Bckground Unsturted ftty cids (UFSs) hve been reported to hve beneficil effects on helth [1]. Numerous studies hve reported the helth functions of fish oils (FOs) nd their components such s docoshexenoic cid (DHA) nd eicospentenoic cid (EPA) [1, 2]. Polyunsturted ftty cids (PUFAs) re importnt for mintining helthy cells nd hormone levels. N-6 ftty cids, primrily rchidonic cid, were shown to stimulte inflmmtory processes by stimulting the flux of inflmmtory pro-inflmmtory type-2 prostglndins nd type-4 leukotrienes [3, 4]. The n-3 ftty cids, mostly EPA nd DHA, modify crdiovsculr nd relted diseses, but their mechnisms * Correspondence: sungheeh3@gmil.com 4 BK21Plus, College of Helth Science, Kore University, Seoul 02841, Republic of Kore Full list of uthor informtion is vilble t the end of the rticle remin uncler [5, 6]. Incresed intke of EPA nd DHA my increse EPA nd DHA in the tissues, cellulr lipids, nd circultory lipids [7]. Krill (Euphusi superb) is smll mrine crustcen with lipid content of 12 50%. KOs contin stxnthin, n ntioxidnt molecule, nd high concentrtions of n-3 unsturted ftty cids (n-3 LCPUFA) (30 65%) [8, 9]. Reserches hve shown tht n-3 LCPUFAs in PLS form re more biovilble nd more efficiently bsorbed, prticulrly by brin tissue [10, 11]. Becuse of the lrge mounts of stxnthin nd n-3 LCPUFAs in KOs, these oils hve positive effects on crdiovsculr disese (plsm triglyceride, pltelet ggregtion, nd inflmmtory mrker reduction) [12], insulin resistnce, nd neurocognition [13]. The Author(s) Open Access This rticle is distributed under the terms of the Cretive Commons Attribution 4.0 Interntionl License ( which permits unrestricted use, distribution, nd reproduction in ny medium, provided you give pproprite credit to the originl uthor(s) nd the source, provide link to the Cretive Commons license, nd indicte if chnges were mde. The Cretive Commons Public Domin Dediction wiver ( pplies to the dt mde vilble in this rticle, unless otherwise stted.

2 Ahn et l. Lipids in Helth nd Disese (2018) 17:162 Pge 2 of 8 KOs re bundnt in n-3 ftty cids, phospholipids, nd vrious ntioxidnts tht re generlly different from those in FOs [14, 15]. Ftty cids in FO minly include triglycerides, while in KOs, 30 65% of ftty cids re present s phospholipids, the min component of the cell membrne [16]. Binding between phospholipids nd n-3 ftty cids gretly promotes the pssge of molecules through the intestinl wll, incresing bsorption rtes nd ultimtely improving n-3: n-6 ftty cid rtios [17, 18]. These KOs not only confer vrious functions, but lso hve high biovilbility, so smll mounts of KOs still exhibit positive functions. The demnd for functionl mterils or functionl foods for treting vrious geritric diseses tht occur with ging is currently incresing. Prticulrly, it is urgent to serch for nd develop functionl mterils for senile dementi such s Alzheimer s disese. Studies of phosphtidylserine hving n-3 PUFAs reveled improvement in cerebellum nd cerebrl cortex function in the elderly [19, 20]. However, studies of the biovilbility of KOs re limited, prticulrly the biovilbility of KOs in the blood nd brin. We investigted the effects of orl short-term nd long-term dministrtion of KOs on biovilbility in the blood nd brin of rts. The results of this study suggest tht Kos re effective functionl mterils in the brin. Methods Animls nd oils Mle Sprgue-Dwley rts ( g, 6 weeks old) were purchsed from Orient Bio (Seoul, Kore) nd grown in individul cges. Experimentl nimls were kept t temperture of 21 ± 1 C nd reltive humidity of 50 55%. Wter nd feed were provided d libitum during the dpttion period of 1 week. All experiments were pproved by the Ethics Committee for Use of Experimentl Animls t Kyonggi University ( ). FO nd KOs were prepred by Aph B&H Co. Ltd. (Chungcheongbuk-do, Kore). FO contined DHA ( mg/g), EPA ( mg/g), nd n-3 ( mg/ g). KOs contined DHA (76.24 mg/g), EPA ( mg/ g), phospholipid ( mg/g), phosphtidylcholine in phospholipid ( mg/g of phospholipid), nd stxnthin (0.19 mg/g). All chemicls were regent-grde. Short-term nd long-term dministrtion For short-term evlution of fish nd KO biovilbility, rts were divided into 4 groups (6 rts/group): norml, FO (FO), KO 1 (KO), nd KO 2 (CKO). KO1 is product mde by enzyme extrction nd CKO is product mde by solvent extrction. After 24 h strvtion, sline, FO, nd KOs were orlly dministered (1000 mg/rt). The blood nd brin were collected fter 2, 4, 8, 12, 24, 48 h of orl dministrtion. The groups for the long-term tests were divided in the sme mnner s for the short-term test. Sline, FO, KO, nd CKO (500 mg) were orlly dministered every dy to ech rt for 2 weeks. After 2 weeks, rts scrificed, nd blood nd brins were collected. Triglyceride nd phospholipid of oils Triglyceride (TG) nd phospholipid nlysis (PL) ws conducted by thin-lyer chromtogrphy (TLC) [21]. To detect TG nd PL, 30 mg of smple dissolved in chloroform ws plced on TLC silic gel plte (Merck KGA, Drmstdt, Germny) nd 100 μl of smples were loded. The development solvent contined chloroform, methnol, cetic cid, wter (75: 40: 8: 3). After loding, the TLC plte ws dried, nd then 0.2% 2,7-dichlorofluorescein regent (in 95% methnol) ws spryed onto the TLC plte. TG nd PL were identified using UV detector. Bnds corresponding to TG nd PL were scrped off nd methylted with 14% BF 3 in methnol. The resulting ftty cid methyl ester ws nlyzed by gs chromtogrphy [22]. TG in plsm Blood from the portl vein ws collected in heprinized microcentrifuge tube (contining 20 μl of 1000 IU heprin/ml of blood). Plsm seprted by centrifugtion ws nlyzed using the FUJI DRI CHEM 3500 (Tokyo, Jpn). Lipid extrction of plsm nd brin Lipid extrction for ftty cid nlysis ws performed s described by Folch with some modifictions [23]. Lipid in 1 ml of plsm nd brin were extrcted in 4 ml of chloroform: methnol = 2:1 mixture. Ten microgrms of heptdecnoic cid were dded s n internl stndrd. The superntnt ws removed by nitrogen purging. After cid hydrolysis using 8.3 M HCl, methyltion ws crried out nd the hexne lyer ws nlyzed by gs chromtogrphy. Gs chromtogrphy nlysis A gs chromtogrph (Vrin 3800; Vrin Inc., Wlnut Creek, CA, USA) fitted with Supelcowx 10 fused-silic cpillry column (30 m length, 0.25 mm id., 0.25 μm film thickness; Supelco, Bellefonte, PA, USA) nd flme ioniztion detector were used [24]. Initilly, the column ws mintined t 180 C for 1 min nd then incresed to 230 C t rte of 1.5 C/min. The temperture ws then held t 230 C for 10 min. Helium ws used s crrier gs t flow rte of 1 ml/min nd split rtio of 50:1. The injector nd detector tempertures were 240 C nd 250 C, respectively. Ftty cid methyl esters were verified ginst the retention times of known stndrds.

3 Ahn et l. Lipids in Helth nd Disese (2018) 17:162 Results TG nd PLs in KOs To investigte the biovilbility of KOs, we nlyzed TG nd PLs in KOs by TLC (Fig. 1). Perill oil nd FO were used s stndrd smples. In ddition, the ftty cid compositions of TG nd PLs were nlyzed (Tbles 1 nd 2). Becuse KOs hve high PL content, they were compred with perill nd FOs. PL ws not detected in FO nd perill oil, but ws detected in both types of KOs. TG ws detected in ll oils, but ws most bundnt in FO (Fig. 1). These results revel the differences between FO nd KOs. Tbles 1 nd 2 show the results of ftty cid nlysis fter oil ws eluted by scrping TG nd PL spots seprted from FO nd KOs. For the ftty cid composition of TG in fish nd KOs, myristic cid (14:0) nd plmitic cid (16:0), which re niml ftty were, showed significntly higher in KOs thn FO (Tble 1). In ddition, UFSs such s oleic cid (18:1, n-9), vccenic cid (18:1, n-7), linoleic cid (18:2, n-6), gmm linoleic cid (18:3, n-3), steridonic cid (18:4, n-3), nd gdoleic cid (20:1, n-9) were significntly higher in KOs thn FO. In contrst, the content of EPA nd DHA in FO ws more thn 2-fold higher. Mysteric cid nd plmitic cid were nd 23.47% in KOs, respectively, which re similr to the vlues reported by Gigliotti et l. [25]. In contrst, plmitoleic cid nd oleic cid were lower in our KOs thn the contents described previously. This my be becuse of differences in the tretment with oil [25]. Tble 2 shows the ftty cid composition in PL in FO nd KOs. FO contined no PL, but the ftty cid composition in the PL of KOs ws found. Prticulrly, two KOs showed high contents of EPA nd DHA in PL. The EPA content of CKO ws 41.13% nd EPA content of KO ws 32.49%. The EPA content of CKO ws significntly higher thn tht of Pge 3 of 8 Tble 1 Ftty cid composition in triglyceride (TG) of fish oil nd kill oils TG (Are %) FO1) KO2) 14: ± 4) 0.00b CKO3) ± ± ± ± 0.04b 0.10 ± 0.00c 5.73 ± 0.04b 7.61 ± 0.05 c 1.13 ± ± 0.01b ± ± 0.01b 16:0 c 0.09 ± :1 18: ± :1(n-9) 0.25 ± 0.00c 18:1(n-7) b 0.09 ± ± ± :2(n-6) 0.15 ± 0.00b 2.33 ± ± :3(n-3) b 0.06 ± ± ± 0.00c 18:4(n-3) 0.07 ± 0.00c 1.04 ± ± 0.04b 20:1(n-9) 0.11 ± ± ± 0.00b 20: ± ± 0.03b 0.00 ± 0.00c c 20:4(n-6) 3.01 ± ± ± 0.00b 20:5(EPA) ± ± 0.07b ± 0.13b b 22:5(DPA) 2.82 ± ± ± 0.02b 22:6(DHA) ± ± 0.02c ± 0.07b Totl ) FO: Fish oil, 2)KO: Krill oil 1, 3)CKO: Krill oil 2, 4) ± Men stndrd devition, One-wy nlysis of vrince with Duncn s multiple comprison test with men vlues KO. However, the content of DHA ws 19.76% for KO nd 15.81% for CKO, indicting tht the content in KO ws significntly higher. Composition of SFA, monounsturted ftty cid (MUFA), nd PUFA We lso investigted the composition of sturted ftty cid (SFA), MUFA, nd PUFA in TG nd PL of the oils (Tble 3). SFA nd MUFA in TG of FO were significntly lower thn in KO nd CKO. In contrst, PUFA in Fig. 1 Seprtion of triglyceride (TG) nd phospholipid (PL) in fish oil nd krill oils using thin-lyer chromtogrphy. Perill oil (PO) ws s control nd smple oils were fish oil (FO), krill oil 1 (KO), nd krill oil 2 (CKO)

4 Ahn et l. Lipids in Helth nd Disese (2018) 17:162 Pge 4 of 8 Tble 2 Ftty cid composition in phospholipid (PL) of fish oil nd krill oils PL (Are %) FO 1) KO 2) CKO 3) 14:0 Not detected 2.22 ± 4) 0.04 b 3.46 ± : ± ± : ± 0.03 b 1.49 ± : ± ± 0.01 b 18:1(n-9) 5.39 ± ± 0.01 b 18:1(n-7) 5.43 ± ± 0.03 b 18:2(n-6) 1.52 ± 0.02 b 1.72 ± :3(n-3) 1.42 ± ± 0.00 b 18:4(n-3) 0.50 ± ± 0.02 b 20:1(n-9) 0.00 ± ± : ± ± :4(n-6) 0.26 ± 0.01 b 0.40 ± :5(EPA) ± 0.46 b ± :5(DPA) 0.91 ± ± 0.02 b 22:6(DHA) ± ± 0.05 b Totl ) FO: Fish oil, 2) KO: Krill oil 1, 3) CKO: Krill oil 2, 4) ± Men stndrd devition, One-wy nlysis of vrince with Duncn s multiple comprison test with men vlues TG of FO ws the highest t 99.22%. Ftty cids in PL of FO ws not detected, but ftty cids in PL of KO nd CKO ws detected. KO showed higher MUFA content thn CKO, nd CKO showed higher PUFA content. Effect of KOs short-term dministrtion on ftty cid composition in blood Figure 2 shows the contents of EPA, DHA, TG, nd PL in the blood fter 2, 4, 8, 12, nd 24 h of orl dministrtion of KO, FO, nd CKO. Regrdless of the oil type, EPA nd DHA tended to increse until 2 h fter orl dministrtion. KO showed higher EPA content thn CKO fter 2 h. Prticulrly, KO showed higher contents of DHA thn CKO even fter 2 h. FO generlly incresed until 8 h, but decresed rpidly until 12 h. The mount of TG in the blood ws highest in CKO until 4 h, but there ws no significnt difference from KO. After 2 h of orl dministrtion of CKO nd KO, the TG vlue decresed. For CKO, the mount of TG in the blood ws higher thn tht in the other groups t 24 nd 48 h. The TG bsorption rte of FO ws not high but ws mintined t similr level nd then decresed. Effect of KOs short-term dministrtion on ftty cid composition in the brin The results of nlysis of brin EPA nd DHA fter 2, 4, 8, 12, 24, nd 48 h re shown in Fig. 3. EPA nd DHA contents grdully incresed over time, wheres FO Fig. 2 Chnges of eicospentenoic cid (EPA), docoshexenoic cid (DHA), TG (triglycerides), nd phospholipid in plsm fter short-term dministrtion of fish oil (FO), krill oil 1 (KO), nd krill oil 2 (CKO)

5 Ahn et l. Lipids in Helth nd Disese (2018) 17:162 Pge 5 of 8 Tble 3 Composition rtio of sturted ftty cid (SFA), monounsturted ftty cid (MUFA), nd polyunsturted ftty cid (PUFA) in fish oil nd krill oils Are % SFA MUFA PUFA TG 1) FO 0.24 ± 0.00 c 0.55 ± 0.03 c ± 0.13 KO ± ± ± 0.21 c CKO ± 0.15 b ± ± 0.28 b PL 2) FO Not detected KO ± ± ± 2.32 b CKO ± ± 0.06 b ± ) TG: triglyceride, 2) PL: phospholipids, SFA: 14:0, 16:0, 18:0; MUFA: 16:1, 18:1(n- 9), 18:1(n-7); PUFA: 18:2(n-6), 18:3(n-3), 18:4(n-3), 20:4(n-6), 20:5, 22:5, 22:6. Vlues re presented s the men ± S.E (n = 4). One-wy nlysis of vrince with Duncn s multiple comprison test with men vlues showed the highest level t 2 h nd decresed slowly fter orl dministrtion of KO nd CKO. Regrdless of the type of oil, MUFA nd PUFA incresed over time (Tble 4). Notbly, lthough the totl UFS content of the KOs ws lower thn the totl UFS content of the FO, the remining UFS content ws higher thn tht of the FO over time. Studies of the reltive orl biovilbility of n-3 supplements hve shown controversil results, nd severl studies reported tht phospholipid form (krill) is better bsorbed thn ethyl ester or TG type FO [16, 26]. Effect of KOs long-term dministrtion on ftty cid composition in blood nd brin Chnges in EPA nd DHA contents during 2 weeks of orl dministrtion of oils re shown in Fig. 4. The contents of EPA nd DHA in the blood of FO, KO, nd CKO were highest in CKO (15.71 nd μg/mg) t 1 week. FO showed higher EPA contents (11.86 μg/mg) thn KO nd CKO fter 2 weeks. There ws no significnt difference in DHA content between FO, KO, nd CKO fter orl dministrtion for 2 weeks. The chnges in TG nd PL contents in the blood fter orl Tble 4 Composition of SFA, MUFA, nd PUFA in brin fter orl dministrtion of fish oil nd krill oils mg/g brin SFA MUFA PUFA ± ± ± FO ± ± ± KO ± ± ± 5.38 CKO ± ± ± FO ± ± ± 7.97 KO ± ± ± 7.23 CKO ± ± ± FO ± ± ± 7.10 KO ± ± ± 9.62 CKO ± ± ± FO ± ± ± 5.07 KO ± ± ± 3.91 CKO ± ± ± FO ± ± ± 7.05 KO ± ± ± 4.47 CKO ± ± ± FO ± ± ± KO ± ± ± 6.39 CKO ± ± ± 7.70 SFA: 14:0, 16:0, 18:0; MUFA: 16:1, 18:1(n-9), 18:1(n-7); PUFA: 18:2(n-6), 18:3(n-3), 18:4(n-3), 20:4(n-6), 20:5, 22:5, 22:6. Vlues re presented s the men ± S.E (n = 4). One-wy nlysis of vrince with Duncn s multiple comprison test with men vlues dministrtion of FO, KO, nd CKO for 1 nd 2 weeks showed tht KOs were slightly higher thn FO, but the difference ws not significnt. These tendencies were similr in the brin (Fig. 5). CKO decresed grdully s the period of dministrtion incresed, wheres the content of FO nd KO ws initilly low, but the bsorption rte ws higher following continuous consumption. However, there were no significnt differences between groups. The mount of EPA nd DHA in the brin ws Fig. 3 Chnges in eicospentenoic cid (EPA) nd docoshexenoic cid (DHA) in brin lipid fter short-term dministrtion of fish oil (FO), krill oil 1 (KO), nd krill oil 2 (CKO)

6 Ahn et l. Lipids in Helth nd Disese (2018) 17:162 Pge 6 of 8 Fig. 4 Chnges in eicospentenoic cid (EPA), docoshexenoic cid (DHA), TG (triglycerides), nd phospholipid in plsm fter long-term dministrtion of fish oil (FO), krill oil 1 (KO), nd krill oil 2 (CKO) slightly higher in KOs thn in the long-term dministrtion period, but there ws no significnt difference. The results re lso shown in Tble 5. Discussion Our results of TG nd PLs in oils re similr to those reported in other studies; becuse PL nd TG require different digestive enzymes, the biovilbility nd tissue ttchment of n-3 PUFA my differ. In turn, this cn led to other physiologicl nd helth effects [27]. Thus, EPA nd DHA esterified with PLA in KOs my gretly impct humn helth. However, it is unusul to preferentilly esterify EPA nd DHA with PL [28]. The composition of sturted ftty cid (SFA), MUFA, nd PUFA in TG nd PL of the oils (Tble 3) were investigted. Ftty cids were not detected in PL of FO but ftty cids were detected in PL of KO nd CKO. KO showed higher MUFA content thn CKO, nd CKO showed higher PUFA content. These results indicte tht the biovilbility of UFA, which is reltively high in TG of FO, nd UFA, nd re bundnt in PL of KOs. In result of short-term dministrtion on blood ftty cid composition, the bsorption Fig. 5 Chnges in eicospentenoic cid (EPA) nd docoshexenoic cid (DHA) in brin lipid fter long-term dministrtion of fish oil (FO), krill oil 1 (KO), nd krill oil 2 (CKO)

7 Ahn et l. Lipids in Helth nd Disese (2018) 17:162 Pge 7 of 8 Tble 5 Composition of SFA, MUFA, nd PUFA in the brin fter long-term dministrtion of fish oil nd krill oils SFA MUFA PUFA 1 week (μg/g brin) FO ± ± ± 3.66 KO ± ± ± 1.34 CKO ± ± ± weeks (μg/g brin) FO ± ± ± 1.88 KO ± ± ± 3.48 CKO ± ± ± 1.19 SFA: 14:0, 16:0, 18:0; MUFA: 16:1, 18:1(n-9), 18:1(n-7); PUFA: 18:2(n-6), 18:3(n-3), 18:4(n-3), 20:4(n-6), 20:5, 22:5, 22:6. Vlues re presented s the men ± S.E (n = 4). One-wy nlysis of vrince with Duncn s multiple comprison test with men vlues rte of PL in the blood ws highest in CKO. FO showed similr tendency to KO but hd the lowest vlue. The bsorption rte of n-3 ftty cids is ffected by the chemicl form nd n excellent bsorption rte for PL-bound n-3 ftty cids in KOs hs been suggested [15, 16, 26, 29]. Considering tht PL ws not detected in the FO smple, our results re resonble. EPA nd DHA contents grdully incresed over time, wheres FO showed the highest level t 2 h nd decresed slowly fter orl dministrtion of KO nd CKO in brin. Regrdless of the type of oil, MUFA nd PUFA incresed over time (Tble 4). DHA is prticulrly concentrted in the brin, nervous tissue, nd retin nd is essentil for norml neurologicl function. Deficiency of DHA is ssocited with mny neurologicl disorders DHA bsorption is greter when it is delivered by liposomes thn by oil. This ws demonstrted by n increse in the DHA rtio in both lymphtic tricylglycerol nd PL delivered by liposomes compred to by the FO diet [17]. KO is complex combintion of multiple ctive ingredients with synergistic bio- ctivities. The brin exclusively consumes DHA in the form of lysophosphtidylcholine (LPC). Recent studies showed tht in the blood brin brrier (Mfsd2), the crrier trnsports LPC-DHA, but not DHA. Therefore, it is necessry to increse the level of LPC-DHA in the plsm to efficiently concentrte DHA in the brin [30, 31]. The exct mechnism of KOs is not cler. However, the unique biomoleculr profile of KOs hs demonstrtes the possibility of erosion of n-3 (EPA/DHA) ftty cids in PLs nd distinguishes KOs from FO. Also, the contents of EPA nd DHA in the blood of FO, KO, nd CKO were highest in CKO t 1 week. FO showed higher EPA contents thn KO nd CKO fter 2 weeks. There ws no significnt difference in DHA content between FO, KO, nd CKO fter orl dministrtion for 2 weeks. The chnges in TG nd PL contents in the blood fter orl dministrtion of FO, KO, nd CKO for 1 nd 2 weeks showed tht KOs were slightly higher thn FO, but the difference ws not significnt. These tendencies were similr in the brin. FO is better source for n-3 PUFA thn KO. However, the biovilbility of n-3 PUFAs from krill oil (minly PL) is s, or possibly more, efficient s n-3 PUFA from fish oil (TG). This supports the results of study with krill oil nd menhden oil in humns [32]. In ddition, the potentil function of KO suggests tht biovilbility to certin phospholipid-rich regions, such s the brin in the body, my be higher thn FO. Conclusion By evluting the bsorption rte of KOs following short-term nd long-term dministrtion, the contents of EPA nd DHA remining in the blood nd brin fter KOs ingestion were higher thn those following ingestion of FO. This my be becuse of the chemicl structure of the unique lipid component (phospholipid) in KOs. Therefore, KOs hve functionl potentil for the brin nd vsculr diseses, nd cn be utilized s multi-functionl mteril composed minly of functionl ingredients. Abbrevitions DHA: Docoshexenoic cid; EPA: Eicospentenoic cid; FO: Fish oil; KOs: Krill oils; PL: Phospholipid nlysis; PUFAs: Polyunsturted ftty cids; TG: Triglyceride; TLC: Thin-lyer chromtogrphy; UFSs: Unsturted ftty cids Funding This work ws supported by grnts from Aph B&H Co. Ltd. (Chungcheongbuk-do, Kore). Avilbility of dt nd mterils The dt tht support the findings of this study re vilble upon request to the corresponding uthor. Authors contributions SHH plnned the reserch nd interpreted the results. HJS nd SHH collected the test dt, elucidted the results, nd drfted the mnuscript. HJS nd SHH eqully contributed to this work. SHA, SJL, YMR, nd HRP lso collected the test dt nd drfted the mnuscript. Ethics pprovl nd consent to prticipte Experiments were pproved by the Ethics Committee for Use of Experimentl Animls t Kyonggi University ( ). Consent for publiction Not pplicble. Competing interests The uthors declre tht they hve no competing interests. Publisher s Note Springer Nture remins neutrl with regrd to jurisdictionl clims in published mps nd institutionl ffilitions. Author detils 1 Deprtment of Food nd Nutrition, Kore University, Seoul 07249, Republic of Kore. 2 Alph B&H, Seoul 06705, Republic of Kore. 3 Deprtment of Food Science nd Biotechnology, Kyonggi University, Suwon 16227, Republic of Kore. 4 BK21Plus, College of Helth Science, Kore University, Seoul 02841, Republic of Kore.

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