Lipid Class Specific Quantitative Analysis of n-3 Polyunsaturated Fatty Acids in Food Supplements

Enzymatic Preparation, In-Depth Molecular Analysis, and In Vitro Digestion Simulation of Palmitoleic Acid (ω-7)-Enriched Fish Oil Triacylglycerols

In this study, an enzymatic reaction was developed for synthesizing pure triacylglycerols (TAG) with a high content of palmitoleic acid (POA) using fish byproduct oil. The characteristics of synthesized structural TAGs rich in POA (POA-TAG) were analyzed in detail through ultrahigh-performance liquid chromatography Q Exactive orbitrap mass spectrometry. Optimal conditions were thoroughly investigated and determined for reaction systems, including the use of Lipozyme TL IM and Novozym 435, 15 wt % lipase loading, substrate mass ratio of 1:3, and water content of 2.5 and 0.5 wt %, respectively, resulting in yields of 67.50 and 67.45% for POA-TAG, respectively. Multivariate statistical analysis revealed that TAG 16:1/16:1/20:4, TAG 16:1/16:1/16:1, TAG 16:1/16:1/18:1, and TAG 16:0/16:1/18:1 were the main variables in Lipozyme TL IM and Novozym 435 enzyme-catalyzed products under different water content conditions. Finally, the fate of POA-TAG across the gastrointestinal tract was simulated using an in vitro digestion model. The results showed that the maximum release of free fatty acids and apparent rate constants were 71.44% and 0.0347 s-1, respectively, for POA-TAG lipids, and the physical and structural characteristics during digestion depended on their microenvironments. These findings provide a theoretical basis for studying the rational design of POA-structural lipids and exploring the nutritional and functional benefits of POA products.

Quantitative analysis of fatty acids and vitamin E and total lipid profiling of dietary supplements from the German market

Certain polyunsaturated fatty acids with n-3 double bonds are essential nutrients for the human body and are part of the bilayer of cell membranes or precursors of tissue hormones. The most abundant dietary n-3 fatty acids in human nutrition are α-linolenic, eicosapentaenoic, and docosahexaenoic acid and can be taken up through dietary sources such as vegetable oils or fish or, alternatively, dietary supplements with high levels of n-3 fatty acids. In previous studies, considerable variation of lipid patterns and quantities of n-3 fatty acids were observed. In this study, 33 dietary supplements from the German market, based on fish-, krill-, microalgae, and plant oil, have been analyzed. Lipid profiling (LC–MS) revealed triacylglycerols as the dominant lipid species in most samples. However, krill oil was rich in phospholipids and samples containing fatty acid concentrates featured abundant fatty acid ethyl esters and diacylglycerols. Furthermore, total lipid profiles showed considerable variance depending on the lipid sources (e.g., fish or plant oil), which was also apparent in fatty acid analysis. The contents of n-3 fatty acids ranged between 150 and 570 mg/g capsule content (GC–MS) and vitamin E (α-tocopherol and tocopheryl acetate) were found in quantities ranging from 1.2 to 86.1 mg/g capsule content (HPLC–UV/Vis). While our analyses indicated a good agreement between labeled and present quantities of total n-3 fatty acids and vitamin E for the majority of samples, significant differences in agreement between individual fatty acids were observed, as well as frequent mismatches between declared and present vitamin E derivatives.

The Effect of Dietary Phospholipids on the Ultrastructure and Function of Intestinal Epithelial Cells

Dietary composition substantially determines human health and affects complex diseases, including obesity, inflammation and cancer. Thus, food supplements have been widely used to accommodate dietary composition to the needs of individuals. Among the promising supplements are dietary phospholipids (PLs) that are commonly found as natural food ingredients and as emulsifier additives. The aim of the present study was to evaluate the effect of major PLs found as food supplements on the morphology of intestinal epithelial cells upon short-term and long-term high-dose feeding in mice. In the present report, the effect of short-term and long-term high dietary PL content was studied in terms of intestinal health and leaky gut syndrome in male mice. We used transmission electron microscopy to evaluate endothelial morphology at the ultrastructural level. We found mitochondrial damage and lipid droplet accumulation in the intracristal space, which rendered mitochondria more sensitive to respiratory uncoupling as shown by a mitochondrial respiration assessment in the intestinal crypts. However, this mitochondrial damage was insufficient to induce intestinal permeability. We propose that high-dose PL treatment impairs mitochondrial morphology and acts through extensive membrane utilization via the mitochondria. The data suggest that PL supplementation should be used with precaution in individuals with mitochondrial disorders.

Comprehensive Analysis of Fatty Acid and Oxylipin Patterns in n3-PUFA Supplements

Supplementing long-chain omega-3 polyunsaturated fatty acids (n3-PUFA) improves health. We characterized the pattern of total and non-esterified oxylipins and fatty acids in n3 supplements made of fish, krill, or micro-algae oil by LC-MS. All supplements contained the declared amount of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA); however, their content per capsule and the concentration of other fatty acids varied strongly. Krill oil contained the highest total n3 oxylipin concentration (6000 nmol/g) and the highest degree of oxidation (EPA 0.7%; DHA 1.3%), while micro-algae oil (Schizochytrium sp.) showed the lowest oxidation (<0.09%). These oils contain specifically high amounts of the terminal hydroxylation product of EPA (20-HEPE, 300 nmol/g) and DHA (22-HDHA, 200 nmol/g), which can serve as an authenticity marker for micro-algae oil. Refined micro-algae and fish oil were characterized by NEFA levels of ≤0.1%. Overall, the oxylipin and fatty acid pattern allows gaining new insights into the origin and quality of n3-PUFA oils in supplements.

Rapid quantification of fatty acids in plant oils and biological samples by LC-MS

Analysis of fatty acids (FA) in food and biological samples such as blood is indispensable in modern life sciences. We developed a rapid, sensitive and comprehensive method for the quantification of 41 saturated and unsaturated fatty acids by means of LC-MS. Optimized chromatographic separation of isobaric analytes was carried out on a C8 reversed phase analytical column (100 × 2.1 mm, 2.6 μm core–shell particle) with a total run time of 15 min with back pressure lower than 300 bar. On an old triple quadrupole instrument (3200, AB Sciex), pseudo selected reaction monitoring mode was used for quantification of the poorly fragmenting FA, yielding limits of detection of 5–100 nM. Sample preparation was carried out by removal of phospholipids and triglycerides by solid-phase extraction (non-esterified fatty acids in oils) or saponification in iso-propanol (fatty acyls). This is not only a rapid strategy for quantification of fatty acyls, but allows the direct combination with the LC-MS-based analysis of fatty acid oxidation products (eicosanoids and other oxylipins) from the same sample. The concentrations of fatty acyls determined by means of LC-MS were consistent with those from GC-FID analysis demonstrating the accuracy of the developed method. Moreover, the method shows high precisions with a low intra-day (≤ 10% for almost all fatty acids in plasma and ≤ 15% in oils) and inter-day as well as inter-operator variability (< 20%). The method was successfully applied on human plasma and edible oils. The possibility to quantify non-esterified fatty acids in samples containing an excess of triacylglycerols and phospholipids is a major strength of the described approach allowing to gain new insights in the composition of biological samples.

Reversed-phase and weak anion-exchange mixed-mode stationary phase for fast separation of medium-, long- and very long chain free fatty acids by ultra-high-performance liquid chromatography-high resolution mass spectrometry

Two commercial stationary phases allowing both reversed phase mechanism and anion-exchange with different selectivity, i.e. CSH C₁₈ and Atlantis PREMIER BEH C₁₈ AX, were tested for the separation of a complex mixture of 21 fatty acids (FAs) encompassing saturated medium-, long- and very long chain FAs, unsaturated long and very long chain FAs, cis/trans isomers, and isomers of odd- and branched-chain FAs. For this purpose, the role of surface area of stationary phase and the effect of pH of the mobile phase on the retention of the analytes were investigated. Separation was performed by ultra-high-performance liquid chromatography coupled with high resolution mass spectrometry (UHPLC-HRMS). BEH C₁₈ AX was shown to be more versatile and to offer superior retention of these analytes to CSH C₁₈ owing to a higher surface area and anion-exchange capacity up to pH 8.5. The UHPLC system allows shortening analysis time, the chromatographic analysis being accomplished in about 5 min, affording a high throughput of samples without the need for derivatization or ion-pairing reagents compared to techniques based upon gas chromatography approaches or LC. Finally, the application of the BEH C₁₈ AX column using UHPLC-HRMS was demonstrated for the separation and unambiguous identification of FAs of nutritional interest in a dietary supplement sample.

Bioactive Compounds in Edible Oils and Their Role in Oxidative Stress and Inflammation

Diet and inflammatory response are recognized as strictly related, and interest in exploring the potential of edible fats and oils for health and chronic diseases is emerging worldwide. Polyunsaturated fatty acids (PUFAs) present in fish oil (FO), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), may be partly converted into oxygenated bioactive lipids with anti-inflammatory and/or pro-resolving activities. Moreover, the co-presence of phenolic compounds and vitamins in edible oils may prevent the development of chronic diseases by their anti-inflammatory, antioxidant, neuroprotective, and immunomodulatory activities. Finally, a high content in mono-unsaturated fatty acids may improve the serum lipid profile and decrease the alterations caused by the oxidized low-density lipoproteins and free radicals. The present review aims to highlight the role of lipids and other bioactive compounds contained in edible oils on oxidative stress and inflammation, focusing on critical and controversial issues that recently emerged, and pointing to the opposing role often played by edible oils components and their oxidized metabolites.

Krill Oil Has Different Effects on the Plasma Lipidome Compared with Fish Oil Following 30 Days of Supplementation in Healthy Women: A Randomized Controlled and Crossover Study

This is a follow-up of our previous postprandial study and it focused on the plasma lipidomic responses to 30 days of krill oil (KO) versus fish oil (FO) supplementations in healthy women. Eleven women (aged 18–50 years) consumed KO or FO for 30 days in a randomized, cross-over study, with at least a four-week washout period between supplementations. The daily supplements provided 1.27 g/day of long-chain (LC) omega-3 polyunsaturated fatty acids (PUFA) from KO (containing 0.76 g eicosapentaenoic acid (EPA), 0.42 g docosahexaenoic acid (DHA)) and 1.44 g/day from FO (containing 0.79 g EPA, 0.47 g DHA). Fasting plasma samples at days 0, 15, and 30 were analyzed using gas chromatography and liquid chromatography electrospray ionisation-tandem mass spectrometry. KO resulted in a significantly greater relative area under the curve (relAUC) for plasma EPA after 30 days. Lipidomic analysis showed that 26 of 43 lipid molecular species had a significantly greater relAUC in the KO group, while 17/43 showed a significantly lower relAUC compared with the FO group. More than 38% of the lipids species which increased more following KO contained omega-3 PUFA, while where FO was greater than KO, only 12% contained omega-3 PUFA. These data show that KO and FO do not have equivalent effects on the plasma lipidome.

Internal Lamellar and Inverse Hexagonal Liquid Crystalline Phases During the Digestion of Krill and Astaxanthin Oil-in-Water Emulsions

Krill oil represents an important alternative natural source of omega-3 (ω-3) polyunsaturated fatty acids (PUFAs). Considering the beneficial health effects of these essential fatty acids, particularly in various disorders including cancer, cardiovascular, and inflammation diseases, it is of paramount importance to gain insight into the digestibility of krill oil. In this work, we study the fate of krill oil-in-water emulsion, stabilized by sodium caseinate, during lipolysis by coupling time-resolved synchrotron small-angle X-ray scattering (SAXS) to flow-through lipolysis model. For gaining further insight into the effect of ω-3 PUFA-containing oil type on the dynamic structural features occurring during lipolysis, two additional astaxanthin oil-in-water emulsions, stabilized using either sodium caseinate or citrem, were subjected to lipolysis under identical experimental conditions. In addition to the difference in lipid composition in both oils, ω-3 PUFAs in astaxanthin oil, similar to fish oil, exist in the form of triacylglycerols; whereas most of those in krill oil are bound to phospholipids. SAXS showed the formation of highly ordered nanostructures on exposure of these food emulsions to the lipolysis medium: the detection of a biphasic feature of coexisting inverse hexagonal (H₂) and lamellar (L_α) liquid crystalline phases in the digested krill oil droplets' interiors, as compared to a neat L_α phase in the digested astaxanthin oil droplets. We discuss the dynamic phase behavior and describe the suggested important role of these phases in facilitating the delivery of nutrients throughout the body. In addition, the potential implication in the development of food and drug nanocarriers is briefly described.

Update on oxidative stress and inflammation in pregnant women, unborn children (nasciturus), and newborns - Nutritional and dietary effects

The scientific background of perinatal pathology, regarding both mother and offspring, from the lipidomic perspective, has highlighted the possibility of identifying new, promising clinical markers of oxidative stress and inflammation, closely related to the normal development of unborn and newborn children, together with their application. In this regard, in recent years, significant advances have been achieved, assisted by both newly developed analytical tools and basic knowledge on the biological implications of oxylipins. Hence, in the light of this recent progress, this review aims to provide an update on the relevance of human oxylipins during pregnancy and in the unborn and newborn child, covering two fundamental aspects. Firstly, the evidence from human clinical studies and dietary intervention trials will be used to shed light on the extent to which dietary supplementation can modulate the lipidomic markers of oxidative stress and inflammation in the perinatal state, emphasizing the role of the placenta and metabolic disturbances in the mother and fetus. The second part of this article comprises a review of existing data on specific pathophysiological aspects of human reproduction, in relation to lipidomic markers in pregnant women, unborn children, and newborn children. The information reviewed here evidences the current opportunity to correct reproductive disturbances, in the framework of lipidomics, by fine-tuning dietary interventions.

Supersaturable Self-Emulsifying Drug Delivery System of Krill Oil with Improved Oral Absorption and Hypotriglyceridemic Function

This study aimed to develop a supersaturable self-emulsifying drug delivery system (S-SEDDS) of krill oil (KO), a rich source of docosahexaenoic acid and eicosapentaenoic acid (EPA), to improve its hypotriglyceridemic function. S-SEDDS of KO (KO/S-SEDDS) was prepared by the addition of lysolecithin, glycerin, and hydroxypropyl methylcellulose (HPMC). Self-emulsifying drug delivery system of KO (KO/SEDDS) and KO with HPMC (KO/HPMC) were also prepared for comparison purposes. The physicochemical and pharmacokinetic properties of KO samples were characterized, and the hypotriglyceridemic function of KO/S-SEDDS was evaluated. Micronized droplets in KO/SEDDS and KO/S-SEDDS with a mean diameter of ca. 270 nm could be observed in comparison to KO and KO/HPMC. Both KO/HPMC and KO/S-SEDDS tended to enhance the dissolution behavior of KO, and the S-SEDDS formulation improved the dissolution behavior of KO as a result of micronized droplets and the addition of HPMC. KO/S-SEDDS (60 mg of EPA/kg) improved the oral absorption of KO based on the pharmacokinetic profiling of EPA, and repeated oral administration of KO/S-SEDDS (250 mg of KO kg^-1 day^-1) for 7 days had a potent hypotriglyceridemic effect on rats with corn-oil-induced hypertriglyceridemia compared to orally administered KO. On the basis of these findings, the S-SEDDS approach might be an efficacious dosage option to enhance the nutraceutical properties of KO.

Examination of marine and vegetable oil oxidation data from a multi-year, third-party database

Fish oil (FO) products constitute good sources of omega-3 fats. Oxidation data from a large third-party database of 1900 + globally-sourced FO samples were assessed. In FO products, for peroxide value (PV), 13.9% exceeded 5 mEq O₂/kg (2.2% >10); for acid value (AcV) 2.1% exceeded 3 mg KOH/g, while for p-anisidine value (pAV) in unflavoured oils, 6.1% exceeded 20, (3.8% >30), and 8.8% exceeded TOTOX limits (26). Additionally, we compared FO with other dietary oils. The FO median PV was similar to those of algal and sunflower oils, 4.8-fold greater than krill oil, and 5.2-fold less than extra-virgin olive oil. The median pAV differed non-significantly among oils. The FO median AcV was similar to those of algal and extra-virgin olive oils, 3.4-fold greater than sunflower oil, and 11.9-fold less than krill oil. This study has provided new insight that retail FO products predominantly meet regulatory guidelines and are comparable in oxidative status to other dietary oils.

Modulation of the endogenous omega-3 fatty acid and oxylipin profile in vivo-A comparison of the fat-1 transgenic mouse with C57BL/6 wildtype mice on an omega-3 fatty acid enriched diet

Dietary intervention and genetic fat-1 mice are two models for the investigation of effects associated with omega-3 polyunsaturated fatty acids (n3-PUFA). In order to assess their power to modulate the fatty acid and oxylipin pattern, we thoroughly compared fat-1 and wild-type C57BL/6 mice on a sunflower oil diet with wild-type mice on the same diet enriched with 1% EPA and 1% DHA for 0, 7, 14, 30 and 45 days. Feeding led after 14–30 days to a high steady state of n3-PUFA in all tissues at the expense of n6-PUFAs. Levels of n3-PUFA achieved by feeding were higher compared to fat-1 mice, particularly for EPA (max. 1.7% in whole blood of fat-1 vs. 7.8% following feeding). Changes in PUFAs were reflected in most oxylipins in plasma, brain and colon: Compared to wild-type mice on a standard diet, arachidonic acid metabolites were overall decreased while EPA and DHA oxylipins increased with feeding more than in fat-1 mice. In plasma of n3-PUFA fed animals, EPA and DHA metabolites from the lipoxygenase and cytochrome P450 pathways dominated over ARA derived counterparts.Fat-1 mice show n3-PUFA level which can be reached by dietary interventions, supporting the applicability of this model in n3-PUFA research. However, for specific questions, e.g. the role of EPA derived mediators or concentration dependent effects of (individual) PUFA, feeding studies are necessary.

Effects of omega-3 fatty acid supplementation on the pattern of oxylipins: a short review about the modulation of hydroxy-, dihydroxy-, and epoxy-fatty acids

A growing body of evidence suggests that the intake of the long chain omega-3 polyunsaturated fatty acids (n3-PUFA) eicosapentaenoic acid (C20:5 n3, EPA) and docosahexaenoic acid (C22:6 n3, DHA) is linked to beneficial health effects, particularly in the prevention of cardiovascular and inflammatory diseases. Although the molecular mode of action of n3-PUFA is still not fully understood, it is not controversial that a significant portion of the (patho)-physiological effects of PUFA are mediated by their oxidative metabolites, i.e. eicosanoids and other oxylipins. Quantitative targeted oxylipin methods allow the comprehensive monitoring of n3-PUFA supplementation induced changes in the pattern of oxylipins in order to understand their biology. In this short review, results from intervention studies are summarized analyzing >30 oxylipins from different PUFAs in response to n3-PUFA supplementation. The results are not only qualitatively compared with respect to the study design, n3-PUFA dose and trends in the lipid mediators, but also quantitatively based on the relative change in the oxylipin level induced by n3-PUFA. The evaluation of the data from the studies shows that the change in oxylipins generally corresponded to the observed changes in their precursor PUFA, i.e. the lower the individual n3-status at the baseline, the higher the increase in EPA and DHA derived oxylipins. The strongest relative increases were found for EPA derived oxylipins, while changes in arachidonic acid (C20:4 n6, ARA) derived eicosanoids were heterogeneous. After 3-12 weeks of supplementation, similar relative changes were observed in free and total (free + esterified) oxylipins in plasma and serum. Regarding EPA derived oxylipins, the results indicate a trend for a linear increase with dose. However, the interpretation of the quantitative oxylipin patterns between studies is hampered by strong inter-individual variances in oxylipin levels between and also within the studies. In the future, the reason for these varying oxylipin plasma concentrations needs to be clarified in order to understand oxylipin and n3-PUFA biology.

Effect of DHA supplementation on oxylipin levels in plasma and immune cell stimulated blood

INTRODUCTION

EPA and DHA cause different physiological effects, which are in many cases mediated via their oxidative metabolites (oxylipins). However, metabolism studies investigating the effect of either EPA or DHA on comprehensive oxylipin patterns are lacking.

MATERIAL AND METHODS

The short and long term (1, 3, 6, and 12 week) effect of 1076mg/d DHA (free of EPA) on free (unesterified) oxylipin concentrations in plasma and lipopolysacharid (LPS) stimulated blood of 12 healthy men (mean age 25.1 ± 1.5 years) was investigated.

RESULTS

After DHA supplementation, plasma levels of all DHA-oxylipins (HDHAs, EpDPEs, DiHDPEs) significantly increased (up to 600%) in a time-dependent fashion. Oxylipins of EPA and arachidonic acid (AA) were also affected. Whereas a slight increase in several EPA-derived hydroxy-FAs (including the RvE1 precursor 18-HEPE) and dihydroxy-FAs was observed after DHA supplementation, a trend to a slight decline in AA-derived oxylipin levels was found. In LPS stimulated blood, it is shown that DHA supplementation significantly reduces the ability of immune cells to form AA-derived COX (TXB2 and PGB2) and 12-LOX (12-HETE) eicosanoids. While no increase in EPA COX metabolites was found, n-3 PUFA 12-LOX metabolites of EPA (12-HEPE) and DHA (14-HDHA) were highly induced.

CONCLUSION

We demonstrated that DHA supplementation causes a time-dependent shift in the entire oxylipin profile suggesting a cross-linked metabolism of PUFAs and subsequent formation of oxygenated lipid mediators.