A nutritional-toxicological assessment of Antarctic krill oil versus fish oil dietary supplements

Hepatic and intestinal insights into the molecular mechanisms of dietary Antarctic krill-induced body color differentiation in Plectropomus leopardus

Antarctic krill (Euphausia superba), which is rich in astaxanthin, has been widely utilized as a dietary supplement in fish aquaculture. Our study was to feed juvenile leopard coral grouper (Plectropomus leopardus) a diet containing 50 % Antarctic krill, revealing significant body color differentiation between a reddened group (BKR) and a non-reddened group (BKB), followed by comparative analysis with the control group (BCon) without krill supplementation. Histological analysis and carotenoid content in the liver and intestine were differentially regulated in color-differentiated individuals. Transcriptomic profiling revealed differentially expressed genes (DEGs) among color-differentiated individuals, with up-regulated DEGs in BKR being linked to carotenoid uptake, metabolism, and transport. Key DEGs (acss2l, insig1, fabp7, and bco1) were validated through qRT-PCR and FISH. Additionally, WGCNA identified potential gene regulatory networks in the liver and intestine that were responsive to the body coloration. This study elucidates the molecular mechanisms by which Antarctic krill influences carotenoid-based body coloration, offering new insights into the application of Antarctic krill in aquaculture.

Detection and Quantification of Adulteration in Krill Oil with Raman and Infrared Spectroscopic Methods

Raman and infrared spectroscopy, used as individual and low-level fused datasets, were evaluated to identify and quantify the presence of adulterants (palm oil, PO; ω-3 concentrates in ethyl ester, O3C and fish oil, FO) in krill oil. These datasets were qualitatively analysed with principal component analysis (PCA) and classified as adulterated or unadulterated using support vector machines (SVM). Using partial least squares regression (PLSR), it was possible to identify and quantify the adulterant present in the KO mixture. Raman spectroscopy performed better (r² = 0.98; RMSEP = 2.3%) than IR spectroscopy (r² = 0.91; RMSEP = 4.2%) for quantification of O3C in KO. A data fusion approach further improved the analysis with model performance for quantification of PO (r² = 0.98; RMSEP = 2.7%) and FO (r² = 0.76; RMSEP = 9.1%). This study demonstrates the potential use of Raman and IR spectroscopy to quantify adulterants present in KO.

New Pyrroline Isolated from Antarctic Krill-Derived Actinomycetes Nocardiopsis sp. LX-1 Combining with Molecular Networking

Antarctic krill (Euphausia superba) of the Euphausiidae family comprise one of the largest biomasses in the world and play a key role in the Antarctic marine ecosystem. However, the study of E. superba-derived microbes and their secondary metabolites has been limited. Chemical investigation of the secondary metabolites of the actinomycetes Nocardiopsis sp. LX-1 (in the family of Nocardiopsaceae), isolated from E. superba, combined with molecular networking, led to the identification of 16 compounds a-p (purple nodes in the molecular network) and the isolation of one new pyrroline, nocarpyrroline A (1), along with 11 known compounds 2-12. The structure of the new compound 1 was elucidated by extensive spectroscopic investigation. Compound 2 exhibited broad-spectrum antibacterial activities against A. hydrophila, D. chrysanthemi, C. terrigena, X. citri pv. malvacearum and antifungal activity against C. albicans in a conventional broth dilution assay. The positive control was ciprofloxacin with the MIC values of <0.024 µM, 0.39 µM, 0.39 µM, 0.39 µM, and 0.20 µM, respectively. Compound 1 and compounds 7, 10, and 11 displayed antifungal activities against F. fujikuroi and D. citri, respectively, in modified agar diffusion test. Prochloraz was used as positive control and showed the inhibition zone radius of 17 mm and 15 mm against F. fujikuroi and D. citri, respectively. All the annotated compounds a-p by molecular networking were first discovered from the genus Nocardiopsis. Nocarpyrroline A (1) features an unprecedented 4,5-dihydro-pyrrole-2-carbonitrile substructure, and it is the first pyrroline isolated from the genus Nocardiopsis. This study further demonstrated the guiding significance of molecular networking in the research of microbial secondary metabolites.

Application of Liquid Chromatography Coupled to Mass Spectrometry in Quality Assessment of Dietary Supplements-A Case Study of Tryptophan Supplements: Release Assay, Targeted and Untargeted Studies

Dietary supplements are widely consumed in the EU and the USA. Based on their similarity to pharmaceuticals, consumers mistakenly believe that dietary supplements have also been approved for safety and efficacy. However, in the absence of mandatory testing, data on supplement quality is scarce. Thus, we applied liquid chromatography coupled with tandem mass spectrometry to analyse the quality of dietary supplements containing tryptophan (Trp). We examined 22 supplements in tablets or capsules, produced in the USA, Great Britain, Germany, France, Czech Republic, and Poland. Trp release, crucial for bioavailability and efficiency, was assessed. Additionally, we performed a qualitative analysis of the main ingredient and screened for contaminants. Among the contaminants, we detected Trp's metabolites, condensation products of Trp and carbonyl compounds, Trp degradation products, degradation products of kynurenine, and other contaminants such as glucosamine and melatonin. The main ingredient content was in the range of 55-100% in capsules and 69-87% in tablets. Surprisingly, almost no Trp release was noted from some supplements. Our study confirms the need to advance research on supplements. We believe that the high-quality analysis of supplements based on reliable analytical techniques will be an important contribution to the discussion on the regulatory framework of these products.

Vitamin D status and supplementation in Antarctica: a systematic review and meta- analysis

Living at high latitudes is associated with vitamin D (VD) deficiency. An ideal setting to study this is the Antarctic continent, which has temporary inhabitants, but the magnitude of the effect of living in Antarctica and the effects of VD supplementation on this population remain unclear. We performed a systematic review and meta-analysis to assess the effect of temporary residence in Antarctica and impact of VD supplementation on VD status of this population. Random‐effects meta‐analyses were performed to assess serum 25-hydroxyvitamin D (25(OH)D) concentration changes after Antarctic residence (13 studies, 294 subjects) and after VD supplementation (5 studies, 213 subjects). Serum 25(OH)D mean difference after temporary residence in Antarctica was -15.0 nmol/L (95%CI: -25.9, -4.2; I²=92%). Subgroup meta-analyses of studies evaluating Antarctic summer and winter stays showed 25(OH)D only decreases when overwintering (winter 25(OH)D change -17.0 nmol/L [95%CI: -24.1, -9.8; I²=83%] vs. summer 25(OH)D change 1.3 nmol/L [95%CI: -14.6, 17.1; I²=86%]). The meta-analysis of VD supplementation studies in Antarctica showed a mean 25(OH)D increase after supplementation of 10.8 nmol/L (95%CI: 3.3, 18.3; I²=88%). In conclusion, VD status significantly worsens after inhabiting Antarctica, particularly when over-wintering. VD supplementation can prevent worsening of VD status and should be considered in this population. 

Monochloropropanediol esters and glycidyl esters in dietary supplements based on fish oils

Dietary supplements based on fish oils might be contaminated with thermal processing contaminants, which are generated during the fish oil deodorisation. In the study, 30 samples of dietary supplements were analysed in terms of the occurrence of 3-monochloropropane-1,2-diol esters (3-MCPDE), 2-monochloropropane-1,3-diol esters (2-MCPDE) and glycidyl esters (GE). The results showed that the highest levels of 3-MCPDE (mean: 1461 µg kg^-1) as well as 2-MCPDE (mean: 357 µg kg^-1) were observed in the products containing shark liver oil. In the case of GE, they were mainly detected in the supplements including shark liver and cod liver oils. Although the results indicated that the consumption of the investigated supplements constituted no more than 1% of tolerable daily intake (TDI), the occurrence of MCPDE and GE in fish oil dietary supplements with a special attention to the origin of ester precursors should be thoroughly investigated in further studies.

Effects of Drying Methods on the Content, Structural Isomers, and Composition of Astaxanthin in Antarctic Krill

Antarctic krill (Euphausia superba) is one of the important bioresources in Antarctic waters, containing many bioactives (e.g., astaxanthin), which have a highly potential value for commercial exploitation. In this study, the effects of processing methods on the content, structural isomers, and composition of astaxanthins (free astaxanthin and astaxanthin esters) were studied. Three drying methods, comprising freeze-drying, microwave drying, and hot-air drying, were used. Free astaxanthin (Ast), astaxanthin monoesters (AM), and astaxanthin diesters (AD) in boiled krill (control) and dried krill were extracted and analyzed using high-resolution mass spectrometry with ultraviolet detection. After the three processes, total astaxanthin loss ranged from 8.6 to 64.9%, and the AM and AD contents ranged from 78.3 to 16.6 and 168.7 to 90.5 μg/g, respectively. Compared to other kinds of astaxanthin esters, astaxanthin esters, which linked to eicosapentaenoic acid and docosahexaenoic acid, as well as the Ast, were more easily degraded, and AM was more susceptible to degradation than AD. All-E-astaxanthin easily transformed to the 13Z-astaxanthin than to the 9Z-astaxanthin during the drying process, but the proportions of optical isomers changed due to drying by no more than 5%. The results suggested that freeze-drying, low-power microwave drying (≤1 kW), and low-temperature hot-air drying (≤60 °C) are optimal drying methods for ensuring the quality of krill products.

Reduced metabolites of nitroaromatics are distributed in the environment via the food chain

Increased industrial processes have introduced emerging toxic pollutants into the environment. Phytoremediation is considered to be a very useful, economical and ecofriendly way of controlling these pollutants, however, certain pollutants can potentially travel through the food chain and accumulate at hazardous levels. Four isomers of dinitrotoluenes (DNT) were investigated and observed their potential toxicity towards A. thaliana. Two different aphid species (generalist and specialist) were allowed to feed on plants treated with DNTs and toxicity to aphids determined. Reduced metabolites of DNT (in both plant and aphids) were recovered and quantified through GC-MS analyses. 2,6-DNT was observed to be the toxic of the DNTs tested. Complete metabolism of DNTs to their reduced products was never achieved for higher concentrations. Regioselectivity was observed in the case of 2,4-DNT, with 4A2NT as the dominant isomer. Feeding aphids showed a similar toxicity pattern for DNT isomers as host plants. Metabolites were recovered from the body of aphids, demonstrating the potential transport of metabolites through the food chain. Plants show varied toxicity responses towards the DNT isomers. Aphids fed on A. thaliana plants treated with DNTs were shown to have ANTs present, which reflects the propagation of DNT metabolites through the food chain.

Signals from the south; humpback whales carry messages of Antarctic sea-ice ecosystem variability

Southern hemisphere humpback whales (Megaptera novaeangliae) rely on summer prey abundance of Antarctic krill (Euphausia superba) to fuel one of the longest-known mammalian migrations on the planet. It is hypothesized that this species, already adapted to endure metabolic extremes, will be one of the first Antarctic consumers to show measurable physiological change in response to fluctuating prey availability in a changing climate; and as such, a powerful sentinel candidate for the Antarctic sea-ice ecosystem. Here, we targeted the sentinel parameters of humpback whale adiposity and diet, using novel, as well as established, chemical and biochemical markers, and assembled a time trend spanning 8 years. We show the synchronous, inter-annual oscillation of two measures of humpback whale adiposity with Southern Ocean environmental variables and climate indices. Furthermore, bulk stable isotope signatures provide clear indication of dietary compensation strategies, or a lower trophic level isotopic change, following years indicated as leaner years for the whales. The observed synchronicity of humpback whale adiposity and dietary markers, with climate patterns in the Southern Ocean, lends strength to the role of humpback whales as powerful Antarctic sea-ice ecosystem sentinels. The work carries significant potential to reform current ecosystem surveillance in the Antarctic region.

Persistent Organic Pollutants in the East Antarctic Atmosphere: Inter-Annual Observations from 2010 to 2015 Using High-Flow-Through Passive Sampling

In the first multiyear sampling effort for POPs in the eastern Antarctic atmosphere, 32 PCBs and 38 organochlorine pesticides were targeted in air collected with a high-flow-through passive sampler. Agricultural chemicals were found to dominate atmospheric profiles, in particular HCB and endosulfan-I, with average concentrations of 12 600 and 550 fg/m³, respectively. HCB showed higher concentrations in the austral summer, indicative of local, temperature-dependent volatilisation, while endosulfan-I appeared to show fresh, late-austral-summer input followed by temporally decreasing levels throughout the year. The current-use herbicide, trifluralin, and the legacy pesticides mirex and toxaphene, were detected in Antarctic air for the first time. Trifluralin was observed at low but increasing levels over the five-year period. Its detection in the Antarctic atmosphere provides evidence of its persistence and long-range environmental transport capability. While a time frame of five years exceeds the duration of most Antarctic air monitoring efforts, it is projected that continuous monitoring at the decadal scale is required to detect an annual 10% change in atmospheric concentrations of key analytes. This finding emphasizes the importance of continuous, long-term monitoring efforts in polar regions, that serve a special role as sentinel environments of hemispheric chemical usage trends.

Lipid-modifying effects of krill oil in humans: systematic review and meta-analysis of randomized controlled trials

Context

Some experimental and clinical trials have shown that krill oil, extracted from small red crustaceans, might be an effective lipid-modifying agent, but the evidence is not conclusive.

Objective

The effect of krill oil supplements on plasma lipid concentrations was assessed through a systematic review of the literature and a meta-analysis of available randomized controlled trials.

Data sources

PubMed and Scopus were searched up to March 25, 2016, to identify RCTs investigating the effect of krill oil supplements on plasma lipids.

Study selection

Randomized controlled trials that investigated the impact of at least 2 weeks of supplementation with krill oil on plasma/serum concentrations of at least one of the main lipid parameters (ie, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, or triglycerides) and that reported sufficient information on plasma/serum lipid levels at baseline and at the end of study in both krill oil and control groups were eligible for inclusion.

Data extraction

Two reviewers independently extracted the following data: first author's name, year of publication, study location, study design, number of participants in the krill oil and control groups, dosage of krill oil, type of control allocation, treatment duration, demographic characteristics of study participants, and baseline and follow-up plasma concentrations of lipids. Effect size was expressed as the weighted mean difference (WMD) and 95% confidence interval (95%CI).

Results

Meta-analysis of data from 7 eligible trials (14 treatment arms) with 662 participants showed a significant reduction in plasma concentrations of low-density lipoprotein cholesterol (WMD, -15.52 mg/dL; 95%CI, -28.43 to -2.61; P = 0.018) and triglycerides (WMD, -14.03 mg/dL; 95%CI, -21.38 to -6.67; P < 0.001) following supplementation with krill oil. A significant elevation in plasma concentrations of high-density lipoprotein cholesterol was also observed (WMD, 6.65 mg/dL; 95%CI, 2.30 to 10.99; P = 0.003), while a reduction in plasma concentrations of total cholesterol did not reach statistical significance (WMD, -7.50 mg/dL; 95%CI, -17.94 to 2.93; P = 0.159).

Conclusion

Krill oil supplementation can reduce low-density lipoprotein cholesterol and triglycerides. Additional clinical studies with more participants are needed to assess the impact of krill oil supplementation on other indices of cardiometabolic risk and on the risk of cardiovascular outcomes.

Krill Oil-In-Water Emulsion Protects against Lipopolysaccharide-Induced Proinflammatory Activation of Macrophages In Vitro

Background: Parenteral nutrition is often a mandatory therapeutic strategy for cases of septicemia. Likewise, therapeutic application of anti-oxidants, anti-inflammatory therapy, and endotoxin lowering, by removal or inactivation, might be beneficial to ameliorate the systemic inflammatory response during the acute phases of critical illness. Concerning anti-inflammatory properties in this setting, omega-3 fatty acids of marine origin have been frequently described. This study investigated the anti-inflammatory and LPS-inactivating properties of krill oil (KO)-in-water emulsion in human macrophages in vitro. Materials and Methods: Differentiated THP-1 macrophages were activated using specific ultrapure-LPS that binds only on the toll-like receptor 4 (TLR4) in order to determine the inhibitory properties of the KO emulsion on the LPS-binding capacity, and the subsequent release of TNF-α. Results: KO emulsion inhibited the macrophage binding of LPS to the TLR4 by 50% (at 12.5 µg/mL) and 75% (at 25 µg/mL), whereas, at 50 µg/mL, completely abolished the LPS binding. Moreover, KO (12.5 µg/mL, 25 µg/mL, or 50 µg/mL) also inhibited (30%, 40%, or 75%, respectively) the TNF-α release after activation with 0.01 µg/mL LPS in comparison with LPS treatment alone. Conclusion: KO emulsion influences the LPS-induced pro-inflammatory activation of macrophages, possibly due to inactivation of the LPS binding capacity.

Concerns with the Study on Australian and New Zealand Fish Oil Products by Nichols et al. (Nutrients 2016, 8, 703)

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Australian and New Zealand Fish Oil Products in 2016 Meet Label Omega-3 Claims and Are Not Oxidized

We provide new fish oil product results to assist industry in Australia and New Zealand and, ultimately, consumers in understanding the high product quality assurance protocols in place, together with the high product quality that has been determined by both industry and independent laboratories. Fish oil capsule products common to Australia and New Zealand were purchased in May 2016 in Richmond, Victoria, Australia. Products were from two groups; five standard fish oil products and five fish oil concentrates. Noting Therapeutic Goods Administration (TGA) requirement for use of standard methods, for all analyses undertaken a laboratory was selected that met the TGA criteria, including with accreditation. Total n-3 content exceeded the label-claimed content for all 10 products, with supplements containing on average 124% of the claimed content (range 115%–136%); eicosapentaenoic acid and docosahexaenoic acid (EPA + DHA) content averaged 109% of the label claim (range 99%–119%). All 10 products (100%) similarly met the international recommended peroxide value (PV) level. Anisidine value (pAV) met the international recommended level for eight of the 10 products, with two products known to contain flavorings that interfere with the pAV test. When accredited laboratories and standard protocols are used, Australian and New Zealand fish oil products have been shown to clearly meet their label claims for EPA + DHA content, and are not oxidized.

Reaching Nutritional Adequacy Does Not Necessarily Increase Exposure to Food Contaminants: Evidence from a Whole-Diet Modeling Approach

BACKGROUND

Dietary guidelines are designed to help meet nutritional requirements, but they do not explicitly or quantitatively account for food contaminant exposures.

OBJECTIVE

In this study, we aimed to test whether dietary changes needed to achieve nutritional adequacy were compatible with acceptable exposure to food contaminants.

METHODS

Data from the French national dietary survey were linked with food contaminant data from the French Total Diet Study to estimate the mean intake of 204 representative food items and mean exposure to 27 contaminants, including pesticides, heavy metals, mycotoxins, nondioxin-like polychlorinated biphenyls (NDL-PCBs) and dioxin-like compounds. For each sex, 2 modeled diets that departed the least from the observed diet were designed: 1) a diet respecting only nutritional recommendations (NUT model), and 2) a diet that met nutritional recommendations without exceeding Toxicological Reference Values (TRVs) and observed contaminant exposures (NUTOX model). Food, nutrient, and contaminant contents in observed diets and NUT and NUTOX diets were compared with the use of paired t tests.

RESULTS

Mean observed diets did not meet all nutritional recommendations, but no contaminant was over 48% of its TRV. Achieving all the nutrient recommendations through the NUT model mainly required increases in fruit, vegetable, and fish intake and decreases in meat, cheese, and animal fat intake. These changes were associated with significantly increased dietary exposure to some contaminants, but without exceeding 57% of TRVs. The highest increases were found for NDL-PCBs (from 26% to 57% of TRV for women). Reaching nutritional adequacy without exceeding observed contaminant exposure (NUTOX model) was possible but required further departure from observed food quantities.

CONCLUSIONS

Based on a broad range of nutrients and contaminants, this first assessment of compatibility between nutritional adequacy and toxicological exposure showed that reaching nutritional adequacy might increase exposure to food contaminants, but within tolerable levels. However, there are some food combinations that can meet nutritional recommendations without exceeding observed exposures.

Physical and oxidation stability of self-emulsifying krill oil-in-water emulsions

Krill oil is a unique source of omega-3 fatty acids since it is a mixture of phospholipids and triacylglycerols. Due to the presence of phospholipids, it can form oil-in-water emulsions without additional food additives. In this work, the physical stability of krill oil-in-water emulsions was determined at various pH values (3-7) and NaCl concentrations (50-1000 mM). The initial particle size ranged from 150 to 165 nm. The emulsions were the most stable at pH ≥ 5.0 and salt concentrations below 100 mM. Lipid oxidation was accelerated by iron and inhibited by Trolox and α-tocopherol. Trolox was a more effective antioxidant than α-tocopherol. α-Tocopherol had a better inhibitory effect when it was added after homogenization than when added to the lipid prior to homogenization. These results indicate that krill oil emulsions could represent a self-emulsifying, oxidatively stable source of omega-3 fatty acids that may be used in functional foods.

Comparison of bioavailability of krill oil versus fish oil and health effect

Background

The aim of this review is to summarize the effects of krill oil (KO) or fish oil (FO) on eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) incorporation in plasma phospholipids or membrane of red blood cells (RBCs) as shown in human and animal studies. Furthermore, we discuss the findings in relation to the possible different health effects, focusing on lipids, inflammatory markers, cardiovascular disease risk, and biological functions of these two sources of long-chain n-3 polyunsaturated fatty acids (PUFAs).

Methods

A literature search was conducted in PubMed in January 2015. In total, 113 articles were identified, but based on selection criteria, 14 original papers were included in the review.

Results

Studies on bioavailability of EPA and DHA from KO and FO in humans and animals are limited and the interpretation is difficult, as different amounts of EPA and DHA have been used, duration of intervention differs, and different study groups have been included. Two human studies – one postprandial study and one intervention study – used the same amount of EPA and DHA from KO or FO, and they both showed that the bioavailability of EPA and DHA from KO seems to be higher than that from FO. Limited effects of KO and FO on lipids and inflammatory markers in human and animal studies were reported. Gene expression data from animal studies showed that FO upregulated the cholesterol synthesis pathway, which was the opposite of the effect mediated by KO. KO also regulated far more metabolic pathways than FO, which may indicate different biological effects of KO and FO.

Conclusion

There seems to be a difference in bioavailability of EPA and DHA after intake of KO and FO, but more studies are needed before a firm conclusion can be made. It is also necessary to document the beneficial health effects of KO with more human studies and to elucidate if these effects differ from those after regular fish and FO intake.

Recent advances in omega-3: Health Benefits, Sources, Products and Bioavailability

The joint symposium of The Omega-3 Centre and the Australasian Section American Oil Chemists Society; Recent Advances in Omega-3: Health Benefits, Sources, Products and Bioavailability, was held November 7, 2013 in Newcastle, NSW, Australia. Over 115 attendees received new information on a range of health benefits, aquaculture as a sustainable source of supply, and current and potential new and novel sources of these essential omega-3 long-chain (LC, ≥ C20) polyunsaturated fatty acid nutrients (also termed LC omega-3). The theme of "Food versus Fuel" was an inspired way to present a vast array of emerging and ground breaking Omega-3 research that has application across many disciplines. Eleven papers submitted following from the Omega-3 Symposium are published in this Special Issue volume, with topics covered including: an update on the use of the Omega-3 Index (O3I), the effects of dosage and concurrent intake of vitamins/minerals on omega-3 incorporation into red blood cells, the possible use of the O3I as a measure of risk for adiposity, the need for and progress with new land plant sources of docosahexaenoic acid (DHA, 22:6ω3), the current status of farmed Australian and New Zealand fish, and also supplements, in terms of their LC omega-3 and persistent organic pollutants (POP) content, progress with cheap carbon sources in the culture of DHA-producing single cell organisms, a detailed examination of the lipids of the New Zealand Greenshell mussel, and a pilot investigation of the purification of New Zealand hoki liver oil by short path distillation. The selection of papers in this Special Issue collectively highlights a range of forward looking and also new and including positive scientific outcomes occurring in the omega-3 field.