Beneficial effects by intake of Euphausiacea pacifica on high-fat diet-induced obesity

Omega-3 phospholipids and obesity-associated NAFLD: Potential mechanisms and therapeutic perspectives

Prevalence of non-alcoholic fatty liver disease (NAFLD) increases in line with obesity and type 2 diabetes, and there is no approved drug therapy. Polyunsaturated fatty acids of n-3 series (omega-3) are known for their hypolipidaemic and anti-inflammatory effects. Existing clinical trials suggest varying effectiveness of triacylglycerol- or ethyl ester-bound omega-3 in the treatment of NAFLD, without affecting advanced stages such as non-alcoholic steatohepatitis. Preclinical studies suggest that the lipid class used to supplement omega-3 may determine the extent and nature of their effects on metabolism. Phospholipids of marine origin represent an alternative source of omega-3. The aim of this review is to summarise the available evidence on the use of omega-3 phospholipids, primarily in obesity-related NAFLD, and to outline perspectives of their use in the prevention/treatment of NAFLD. A PubMed literature search was conducted in May 2021. In total, 1088 articles were identified, but based on selection criteria, 38 original papers were included in the review. Selected articles describing the potential mechanisms of action of omega-3 phospholipids have also been included. Preclinical evidence clearly indicates that omega-3 phospholipids have strong antisteatotic effects in the liver, which are stronger compared to omega-3 administered as triacylglycerols. Multiple mechanisms are likely involved in the overall antisteatotic effects, involving not only the liver but also adipose tissue and the gut. Robust preclinical evidence for strong antisteatotic effects of omega-3 phospholipids in the liver should be confirmed in clinical trials. Further research is needed on the possible effects of omega-3 phospholipids on advanced NAFLD.

Prospective, randomized, double-blinded, placebo-controlled study on safety and tolerability of the krill powder product in overweight subjects with moderately elevated blood pressure

Background

Krill powder is rich in bioactive ingredients such as eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), phospholipids, protein and astaxanthin. Containing dominantly EPA, it is considered to be effective in lowering lipids, foremost serum triglycerides and LDL cholesterol. Krill-derived protein hydrolysates/peptides may have positive effect on blood pressure and astaxanthin has anti-oxidative and anti-inflammatory properties. Thus, krill powder has a lot of potential in improving lipid and metabolic profile and reinforcing the activity of the antioxidant system. However, randomized clinical trials on krill powder are scarce and systematic data of krill meal on human safety is limited. Some of the earlier studies have reported several, non-serious adverse events, mostly related to gastrointestinal tract, but systematic sufficiently powered study on safety is lacking. The aim of this study was to collect data on safety and tolerability of krill powder in humans and simultaneously gain efficacy data by measuring the risk factors for cardiovascular disease.

Methods

The study was a randomised, double-blinded, placebo-controlled intervention study with 35 overweight subjects with mildly or moderately elevated blood pressure, who took 4 g krill oil powder or 4 g of placebo during an 8-week follow-up period. The study consisted of a pre-screening, screening, day 0 baseline (randomization visit) and three follow-up visits on days 14, 28 and 56. The reported adverse events in the groups were compared as primary endpoint and haematological safety parameters and changes in systolic and diastolic pressure and blood total and lipoprotein lipids were measured as secondary end points.

Results

There were in total 80 reported adverse events during the follow-up; 50 in placebo and 30 in krill powder group. Gastrointestinal symptoms (flatulence, heartburn and diarrhea) were the most commonly reported among those probably related to the test products. No serious adverse events were reported. The mean value of all measured hematology variables remained within the reference values in all study subject and no significant changes were observed in blood pressure or lipid values.

Conclusions

The results seem to indicate that using krill powder as a source for EPA and DHA is safe in therapeutic dose and the risk of adverse events, let alone serious ones, is low.

Trial registration

ClinicalTrials.gov, NCT03112083, retrospectively registered.

Supplementation of krill oil with high phospholipid content increases sum of EPA and DHA in erythrocytes compared with low phospholipid krill oil

Background

Bioavailability of krill oil has been suggested to be higher than fish oil as much of the EPA and DHA in krill oil are bound to phospholipids (PL). Hence, PL content in krill oil might play an important role in incorporation of n-3 PUFA into the RBC, conferring properties that render it effective in reducing cardiovascular disease (CVD) risk. The objective of the present trial was to test the effect of different amounts of PL in krill oil on the bioavailability of EPA and DHA, assessed as the rate of increase of n-3 PUFA in plasma and RBC, in healthy volunteers.

Methods and design

In a semi randomized crossover single blind design study, 20 healthy participants consumed various oils consisting of 1.5 g/day of low PL krill oil (LPL), 3 g/day of high PL krill oil (HPL) or 3 g/day of a placebo, corn oil, for 4 weeks each separated by 8 week washout periods. Both LPL and HPL delivered 600 mg of total n-3 PUFA/day along with 600 and 1200 mg/day of PL, respectively.

Results

Changes in plasma EPA, DPA, DHA, total n-3 PUFA, n-6:n-3 ratio and EPA + DHA concentrations between LPL and HPL krill oil supplementations were observed to be similar. Intake of both forms of krill oils increased the RBC level of EPA (p < 0.001) along with reduced n-6 PUFA (LPL: p < 0.001: HPL: p = 0.007) compared to control. HPL consumption increased (p < 0.001) RBC concentrations of EPA, DPA, total and n-3 PUFA compared with LPL. Furthermore, although LPL did not alter RBC n-6:n-3 ratio or the sum of EPA and DHA compared to control, HPL intake decreased (p < 0.001) n-6:n-3 ratio relative to control with elevated (p < 0.001) sum of EPA and DHA compared to control as well as to LPL krill oil consumption. HPL krill oil intake elevated (p < 0.005) plasma total and LDL cholesterol concentrations compared to control, while LPL krill oil did not alter total and LDL cholesterol, relative to control.

Conclusions

The results indicate that krill oil with higher PL levels could lead to enhanced bioavailability of n-3 PUFA compared to krill oil with lower PL levels.

Trial registration

Clinicaltrials.gov# NCT01323036.

Hydroxyeicosapentaenoic acids from the Pacific krill show high ligand activities for PPARs

PPARs regulate the expression of genes for energy metabolism in a ligand-dependent manner. PPARs can influence fatty acid oxidation, the level of circulating triglycerides, glucose uptake and insulin sensitivity. Here, we demonstrate that 5-hydroxyeicosapentaenoic acid (HEPE), 8-HEPE, 9-HEPE, 12-HEPE and 18-HEPE (hydroxylation products of EPA) obtained from methanol extracts of Pacific krill (Euphausia pacifica) can act as PPAR ligands. Two of these products, 8-HEPE and 9-HEPE, enhanced the transcription levels of GAL4-PPARs to a significantly greater extent than 5-HEPE, 12-HEPE, 18-HEPE, EPA, and EPA ethyl-ester. 8-HEPE also activated significantly higher transcription of GAL4-PPARα, GAL4-PPARγ, and GAL4-PPARδ than EPA at concentrations greater than 4, 64, and 64 μM, respectively. We also demonstrated that 8-HEPE increased the expression levels of genes regulated by PPARs in FaO, 3T3-F442A, and C2C12 cells. Furthermore, 8-HEPE enhanced adipogenesis and glucose uptake. By contrast, at the same concentrations, EPA showed weak or little effect, indicating that 8-HEPE was the more potent inducer of physiological effects.

Enhanced increase of omega-3 index in healthy individuals with response to 4-week n-3 fatty acid supplementation from krill oil versus fish oil

BACKGROUND

Due to structural differences, bioavailability of krill oil, a phospholipid based oil, could be higher than fish oil, a triglyceride-based oil, conferring properties that render it more effective than fish oil in increasing omega-3 index and thereby, reducing cardiovascular disease (CVD) risk.

OBJECTIVE

The objective was to assess the effects of krill oil compared with fish oil or a placebo control on plasma and red blood cell (RBC) fatty acid profile in healthy volunteers.

PARTICIPANTS AND METHODS

Twenty four healthy volunteers were recruited for a double blinded, randomized, placebo-controlled, crossover trial. The study consisted of three treatment phases including krill or fish oil each providing 600 mg of n-3 polyunsaturated fatty acids (PUFA) or placebo control, corn oil in capsule form. Each treatment lasted 4 wk and was separated by 8 wk washout phases.

RESULTS

Krill oil consumption increased plasma (p = 0.0043) and RBC (p = 0.0011) n-3 PUFA concentrations, including EPA and DHA, and reduced n-6:n-3 PUFA ratios (plasma: p = 0.0043, RBC: p = 0.0143) compared with fish oil consumption. Sum of EPA and DHA concentrations in RBC, the omega-3 index, was increased following krill oil supplementation compared with fish oil (p = 0.0143) and control (p < 0.0001). Serum triglycerides and HDL cholesterol concentrations did not change with any of the treatments. However, total and LDL cholesterol concentrations were increased following krill (TC: p = 0.0067, LDL: p = 0.0143) and fish oil supplementation (TC: p = 0.0028, LDL: p = 0.0143) compared with control.

CONCLUSIONS

Consumption of krill oil was well tolerated with no adverse events. Results indicate that krill oil could be more effective than fish oil in increasing n-3 PUFA, reducing n-6:n-3 PUFA ratio, and improving the omega-3 index.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01323036.