Mikko Griinari

Endocannabinoids May Mediate the Ability of (n-3) Fatty Acids to Reduce Ectopic Fat and Inflammatory Mediators in Obese Zucker Rats

Dietary (n-3) long-chain PUFA [(n-3) LCPUFA] ameliorate several metabolic risk factors for cardiovascular diseases, although the mechanisms of these beneficial effects are not fully understood. In this study, we compared the effects of dietary (n-3) LCPUFA, in the form of either fish oil (FO) or krill oil (KO) balanced for eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content, with a control (C) diet containing no EPA and DHA and similar contents of oleic, linoleic, and alpha-linolenic acids, on ectopic fat and inflammation in Zucker rats, a model of obesity and related metabolic dysfunction. Diets were fed for 4 wk. Given the emerging evidence for an association between elevated endocannabinoid concentrations and metabolic syndrome, we also measured tissue endocannabinoid concentrations. In (n-3) LCPUFA-supplemented rats, liver triglycerides and the peritoneal macrophage response to an inflammatory stimulus were significantly lower than in rats fed the control diet, and heart triglycerides were lower, but only in KO-fed rats. These effects were associated with a lower concentration of the endocannabinoids, anandamide and 2-arachidonoylglycerol, in the visceral adipose tissue and of anandamide in the liver and heart, which, in turn, was associated with lower levels of arachidonic acid in membrane phospholipids, but not with higher activity of endocannabinoid-degrading enzymes. Our data suggest that the beneficial effects of a diet enriched with (n-3) LCPUFA are the result of changes in membrane fatty acid composition. The reduction of substrates for inflammatory molecules and endocannabinoids may account for the dampened inflammatory response and the physiological reequilibration of body fat deposition in obese rats.

Krill oil supplementation increases plasma concentrations of eicosapentaenoic and docosahexaenoic acids in overweight and obese men and women.

Antarctic krill, also known as Euphausia superba, is a marine crustacean rich in both eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). We tested the hypothesis that krill oil would increase plasma concentrations of EPA and DHA without adversely affecting indicators of safety, tolerability, or selected metabolic parameters. In this randomized, double-blind parallel arm trial, overweight and obese men and women (N = 76) were randomly assigned to receive double-blind capsules containing 2 g/d of krill oil, menhaden oil, or control (olive) oil for 4 weeks. Results showed that plasma EPA and DHA concentrations increased significantly more (P < .001) in the krill oil (178.4 +/- 38.7 and 90.2 +/- 40.3 micromol/L, respectively) and menhaden oil (131.8 +/- 28.0 and 149.9 +/- 30.4 micromol/L, respectively) groups than in the control group (2.9 +/- 13.8 and -1.1 +/- 32.4 micromol/L, respectively). Systolic blood pressure declined significantly more (P < .05) in the menhaden oil (-2.2 +/- 2.0 mm Hg) group than in the control group (3.3 +/- 1.5 mm Hg), and the response in the krill oil group (-0.8 +/- 1.4 mm Hg) did not differ from the other 2 treatments. Blood urea nitrogen declined in the krill oil group as compared with the menhaden oil group (P < .006). No significant differences for other safety variables were noted, including adverse events. In conclusion, 4 weeks of krill oil supplementation increased plasma EPA and DHA and was well tolerated, with no indication of adverse effects on safety parameters.

Effect of dietary krill oil supplementation on the endocannabinoidome of metabolically relevant tissues from high-fat-fed mice

BackgroundOmega-3 polyunsaturated fatty acids (ω-3-PUFA) are known to ameliorate several metabolic risk factors for cardiovascular disease, and an association between elevated peripheral levels of endogenous ligands of cannabinoid receptors (endocannabinoids) and the metabolic syndrome has been reported. We investigated the dose-dependent effects of dietary ω-3-PUFA supplementation, given as krill oil (KO), on metabolic parameters in high fat diet (HFD)-fed mice and, in parallel, on the levels, in inguinal and epididymal adipose tissue (AT), liver, gastrocnemius muscle, kidneys and heart, of: 1) the endocannabinoids, anandamide and 2-arachidonoylglycerol (2-AG), 2) two anandamide congeners which activate PPARα but not cannabinoid receptors, N-oleoylethanolamine and N-palmitoylethanolamine, and 3) the direct biosynthetic precursors of these compounds.MethodsLipids were identified and quantified using liquid chromatography coupled to atmospheric pressure chemical ionization single quadrupole mass spectrometry (LC-APCI-MS) or high resolution ion trap-time of flight mass spectrometry (LC-IT-ToF-MS).ResultsEight-week HFD increased endocannabinoid levels in all tissues except the liver and epididymal AT, and KO reduced anandamide and/or 2-AG levels in all tissues but not in the liver, usually in a dose-dependent manner. Levels of endocannabinoid precursors were also generally down-regulated, indicating that KO affects levels of endocannabinoids in part by reducing the availability of their biosynthetic precursors. Usually smaller effects were found of KO on OEA and PEA levels.ConclusionsOur data suggest that KO may promote therapeutic benefit by reducing endocannabinoid precursor availability and hence endocannabinoid biosynthesis.

Dietary Krill Oil Supplementation Reduces Hepatic Steatosis, Glycemia, and Hypercholesterolemia in High-Fat-Fed Mice

Krill oil (KO) is rich in n-3 fatty acids that are present in phospholipids rather than in triglycerides. In the present study, we investigated the effects of dietary KO on cardiometabolic risk factors in male C57BL/6 mice fed a high-fat diet. Mice (n = 6-10 per group) were fed for 8 weeks either: (1) a nonpurified chow diet (N); (2) a high-fat semipurified diet containing 21 wt % buttermilk + 0.15 wt % cholesterol (HF); (3) HF supplemented with 1.25 wt % KO (HFKO1.25); (4) HF with 2.5 wt % KO (HFKO2.5); or (5) HF with 5 wt % KO (HFKO5.0). Dietary KO supplementation caused a significant reduction in liver wt (i.e., hepatomegaly) and total liver fat (i.e., hepatic steatosis), due to a dose-dependent reduction in hepatic triglyceride (mean +/- SEM: 35 +/- 6, 47 +/- 4, and 51 +/- 5% for HFKO1.25, -2.5, and -5.0 vs HF, respectively, P < 0.001) and cholesterol (55 +/- 5, 66 +/- 3, and 71 +/- 3%, P < 0.001). Serum cholesterol levels were reduced by 20 +/- 3, 29 +/- 4, and 29 +/- 5%, and blood glucose was reduced by 36 +/- 5, 34 +/- 6, and 42 +/- 6%, respectively. Serum adiponectin was increased in KO-fed animals (HF vs HFKO5.0: 5.0 +/- 0.2 vs 7.5 +/- 0.6 microg/mL, P < 0.01). These results demonstrate that dietary KO is effective in improving metabolic parameters in mice fed a high-fat diet, suggesting that KO may be of therapeutic value in patients with the metabolic syndrome and/or nonalcoholic fatty liver disease.

Supplementation of diet with krill oil protects against experimental rheumatoid arthritis

BackgroundAlthough the efficacy of standard fish oil has been the subject of research in arthritis, the effect of krill oil in this disease has yet to be investigated. The objective of the present study was to evaluate a standardised preparation of krill oil and fish oil in an animal model for arthritis.MethodsCollagen-induced arthritis susceptible DBA/1 mice were provided ad libitum access to a control diet or diets supplemented with either krill oil or fish oil throughout the study. There were 14 mice in each of the 3 treatment groups. The level of EPA + DHA was 0.44 g/100 g in the krill oil diet and 0.47 g/100 g in the fish oil diet. Severity of arthritis was determined using a clinical scoring system. Arthritis joints were analysed by histopathology and graded. Serum samples were obtained at the end of the study and the levels of IL-1α, IL-1β, IL-7, IL-10, IL-12p70, IL-13, IL-15, IL-17 and TGF-β were determined by a Luminex™ assay system.ResultsConsumption of krill oil and supplemented diet significantly reduced the arthritis scores and hind paw swelling when compared to a control diet not supplemented with EPA and DHA. However, the arthritis score during the late phase of the study was only significantly reduced after krill oil administration. Furthermore, mice fed the krill oil diet demonstrated lower infiltration of inflammatory cells into the joint and synovial layer hyperplasia, when compared to control. Inclusion of fish oil and krill oil in the diets led to a significant reduction in hyperplasia and total histology score. Krill oil did not modulate the levels of serum cytokines whereas consumption of fish oil increased the levels of IL-1α and IL-13.ConclusionsThe study suggests that krill oil may be a useful intervention strategy against the clinical and histopathological signs of inflammatory arthritis.

Krill oil significantly decreases 2-arachidonoylglycerol plasma levels in obese subjects

We have previously shown that krill oil (KO), more efficiently than fish oil, was able to downregulate the endocannabinoid system in different tissues of obese zucker rats.We therefore aimed at investigating whether an intake of 2 g/d of either KO or menhaden oil (MO), which provides 309 mg/d of EPA/DHA 2:1 and 390 mg/d of EPA/DHA 1:1 respectively, or olive oil (OO) for four weeks, is able to modify plasma endocannabinoids in overweight and obese subjects.The results confirmed data in the literature describing increased levels of endocannabinoids in overweight and obese with respect to normo-weight subjects. KO, but not MO or OO, was able to significantly decrease 2-arachidonoylglycerol (2-AG), although only in obese subjects. In addition, the decrease of 2-AG was correlated to the plasma n-6/n-3 phospholipid long chain polyunsaturated fatty acid (LCPUFA) ratio. These data show for the first time in humans that relatively low doses of LCPUFA n-3 as KO can significantly decrease plasma 2-AG levels in obese subjects in relation to decrease of plasma phospholipid n-6/n-3 LCPUFA ratio. This effect is not linked to changes of metabolic syndrome parameters but is most likely due to a decrease of 2-AG biosynthesis caused by the replacement of 2-AG ultimate precursor, arachidonic acid, with n-3 PUFAs, as previously described in obese Zucker rats.

Dietary krill oil significantly reduces hepatic steatosis, glycaemia and hypercholesterolaemia in high-fat-fed mice

Dietary krill oil (KO), rich in n-3 fatty acids associated with phospholipid, is extracted from Antarctic krill (Euphausia superba). Taken as a dietary supplement, it is believed to have important anti-inflammatory and cardioprotective properties.. In order to investigate the effects of KO on lipid and glucose metabolism, the present study was carried out in mice fed a high-fat diet supplemented with different doses of KO. Male C57BL/6 mice were fed a high-fat (HF) diet (w/w; 21% butterfat, 0.15% cholesterol) supplemented with 0, 1.25, 2.5 or 5% (w/w) dietary KO. Animals (six to ten per group) were killed after 8 weeks. Livers were analysed for lipid content and serum samples for lipids, glucose and adiponectin. Dietary KO supplementation caused a significant reduction in liver weight (i.e. hepatomegaly) and total liver fat (i.e. hepatic steatosis) as a result of a dose-dependent reduction in hepatic TAG ( 35 (SE 6) %, 47 (SE 4) % and 51 (SE 5) % with KO supplementation of 1.25, 2.5 and 5.0% respectively; P<0.001) and cholesterol (55 (SE 5) %, 66 (SE 3) % and 71 (SE 3) % with KO supplementation of 1.25, 2.5 and 5.0% respectively; P<0.001).