Dietary echium oil increases plasma and neutrophil long-chain (n-3) fatty acids and lowers serum triacylglycerols in hypertriglyceridemic humans

Dietary intake of stearidonic acid-enriched soybean oil increases the omega-3 index: randomized, double-blind clinical study of efficacy and safety

BACKGROUND

The benefits of omega-3 (n-3) long-chain polyunsaturated fatty acids to heart health are well established. Stearidonic acid (SDA, 18:4n-3) may contribute to these benefits.

OBJECTIVE

The objective was to evaluate the ability of SDA-containing soybean oil to increase the omega-3 index [erythrocyte eicosapentaenoic acid (EPA) + docosahexaenoic acid, as a percentage of total fatty acids] and to affect other cardiovascular disease risk markers compared with EPA and regular soy oil (control).

DESIGN

This was a randomized, placebo-controlled, double-blind multicenter study in which 252 overweight subjects were randomly assigned to 1 of 3 treatments for 12 wk: 1 g encapsulated soybean oil/d plus 14.7 g liquid soybean oil/d to be mixed in food (control group), 1 g encapsulated EPA/d plus 14.7 g liquid soybean oil/d (EPA group), and 1 g encapsulated soybean oil/d plus 14.7 g liquid SDA-enriched soybean oil/d, providing 4.2 g SDA (SDA group). Subjects consumed treatment oils in exchange for other oils in their diet.

RESULTS

The mean (±SE) baseline omega-3 index was similar between treatments, but after 12 wk of treatment values for this index were 4.15 ± 0.12%, 4.84 ± 0.13%, and 4.69 ± 0.15% for control, EPA, and SDA groups, respectively. Values for the EPA and SDA groups were greater than those for control subjects in the intent-to-treat population (P < 0.001 and P = 0.006, respectively). No adverse treatment-related effects of SDA-enriched soybean oil were reported.

CONCLUSIONS

SDA-enriched soybean oil increased the omega-3 index by raising erythrocyte EPA concentrations. SDA-enriched soybean oil is a land-based n-3 fatty acid that is a sustainable approach to increasing tissue concentrations of long-chain polyunsaturated n-3 fatty acids.

Dietary Echium oil increases tissue (n-3) long-chain polyunsaturated fatty acids without elevating hepatic lipid concentrations in premature neonatal rats

Echium oil (EO) contains notable quantities of both (n-6) and (n-3) PUFA and has not, to our knowledge, been studied in neonates. We compared growth, tissue PUFA concentrations, and liver lipid profiles in premature neonatal Sprague-Dawley rats that were fed an EO diet with those that were dam-fed (DF) or fed rat milk substitute (RMS) or a fish oil (FO) diet. EO or FO comprised 10% of dietary fat. Rats were delivered prematurely at d 21 of gestation by caesarean section and then DF or fed one of the diets for 6 d. Rats were killed and the fatty acid (FA) concentrations in brain, liver, ileum, and serum and liver lipid profiles were analyzed. All diet-fed rats had similar weight gain and tissue protein concentrations. Compared with DF rats, EO-fed rats had similar brain docosahexaenoic acid (DHA) levels, similar brain and liver arachidonic acid (ARA) levels, higher liver and ileal eicosapentaenoic acid (EPA) levels (P < 0.05), and similar ARA:(EPA+DHA) ratios in brain, liver, and serum. Compared with RMS-fed rats, EO-fed rats had lower liver triglyceride FA and cholesterol ester concentrations (P < 0.05), higher EPA and DHA levels in liver, ileum, and serum, a higher DHA level in brain, and lower tissue and serum ratios of total (n-6):(n-3) PUFA and ARA:(EPA + DHA) (P < 0.05). Compared with FO-fed rats, EO-fed rats had higher ARA levels in brain, liver, ileum, and serum. In conclusion, dietary EO increases tissue EPA and DHA without reducing ARA in brain and liver and without elevating hepatic lipid concentrations of premature neonatal rats.

Do vegetarians have to eat fish for optimal cardiovascular protection?

Interest in the cardiovascular protective effects of n-3 (omega-3) fatty acids has continued to evolve during the past 35 y since the original research describing the low cardiovascular event rate in Greenland Inuit was published by Dyerberg et al. Numerous in vitro experiments have shown that n-3 fatty acids may confer this benefit by several mechanisms: they are antiinflammatory, antithrombotic, and antiarrhythmic. The n-3 fatty acids that have received the most attention are those that are derived from a fish source: namely, the longer-chain n-3 fatty acids eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). More limited data are available on the cardiovascular effects of n-3 fatty acids derived from plants such as alpha-linolenic acid (ALA; 18:3n-3). Observational data suggest that diets rich in EPA, DHA, or ALA do reduce cardiovascular events, including myocardial infarction and sudden cardiac death; however, randomized controlled trial data are somewhat less clear. Several recent meta-analyses have suggested that dietary supplementation with EPA and DHA does not provide additive cardiovascular protection beyond standard care, but the heterogeneity of included studies may reduce the validity of their conclusions. No data exist on the potential therapeutic benefit of EPA, DHA, or ALA supplementation on those individuals who already consume a vegetarian diet. Overall, there is insufficient evidence to recommend n-3 fatty acid supplementation for the purposes of cardiovascular protection; however, ongoing studies such as the Alpha Omega Trial may provide further information.

Dietary stearidonic acid is a long chain (n-3) polyunsaturated fatty acid with potential health benefits

The therapeutic and health-promoting effects of (n-3) long-chain PUFA (LCPUFA) from fish are well known, although these same benefits may not be shared by their precursor, alpha-linolenic acid (ALA). World-wide agencies and scientific organizations (i.e. FDA, AHA, International Society for the Study of Fatty Acids and Lipids, Institute of Medicine, WHO, etc.) have made similar dietary recommendations for (n-3) LCPUFA; however, due to concerns regarding the safety of consuming fish, alternative sources of (n-3) LCPUFA are being investigated. One such lipid is stearidonic acid (SDA), a naturally occurring (n-3) PUFA that may have similar biological properties to eicosapentaenoic acid (EPA), a major (n-3) PUFA in fish oil. Existing and novel plant sources rich in SDA are being cultivated and promoted as potential alternatives to marine-based (n-3) PUFA. This critical review provides a direct comparison of SDA with other dietary (n-3) PUFA under similar experimental conditions. The comparative results suggest that SDA shares many of the biological effects of (n-3) LCPUFA and functions most similarly to dietary EPA compared with ALA when consumed in a typical Western diet. Therefore, although SDA may not replace fish as a major dietary source of (n-3) LCPUFA, it could become a prominent surrogate for EPA in the commercial development of foods fortified with (n-3) PUFA.

Stearidonic acid-enriched soybean oil increased the omega-3 index, an emerging cardiovascular risk marker

A plant source of omega-3 fatty acid (FA) that can raise tissue eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA) is needed. A soybean oil (SBO) containing approximately 20% stearidonic acid [SDA; the delta-6 desaturase product of alpha-linolenic acid (ALA)] derived from genetically modified soybeans is under development. This study compared the effects of EPA to SDA-SBO on erythrocyte EPA+DHA levels (the omega-3 index). Overweight healthy volunteers (n=45) were randomized to SDA-SBO (24 ml/day providing approximately 3.7 g SDA) or to regular SBO (control group) without or with EPA ethyl esters (approximately 1 g/day) for 16 weeks. Serum lipids, blood pressure, heart rate, platelet function and safety laboratory tests were measured along with the omega-3 index. A per-protocol analysis was conducted on 33 subjects (11 per group). Compared to baseline, average omega-3 index levels increased 19.5% in the SDA group and 25.4% in the EPA group (p<0.05 for both, vs. control). DHA did not change in any group. Relative to EPA, SDA increased RBC EPA with about 17% efficiency. No other clinical endpoints were affected by SDA or EPA treatment (vs. control). In conclusion, SDA-enriched SBO significantly raised the omega-3 index. Since EPA supplementation has been shown to raise the omega-3 index and to lower risk for cardiac events, SDA-SBO may be a viable plant-based alternative for providing meaningful intakes of cardioprotective omega-3 FAs.

Echium oil is better than rapeseed oil in enriching poultry meat withn-3 polyunsaturated fatty acids, including eicosapentaenoic acid and docosapentaenoic acid

α-Linolenic acid (ALA; 18 : 3n-3) and stearidonic acid (SDA; 18 : 4n-3) are on the biosynthetic pathway of EPA (20 : 5n-3) and DHA (22 : 6n-3). Then-3 fatty acid in rapeseed oil is ALA while Echium oil contains both ALA and SDA. To determine the comparative efficacy of ALA- and SDA-rich oils in enriching broiler meat withn-3 PUFA, we offered diets supplemented with rapeseed oil (rapeseed group) or Echium oil (Echium group) for 35 d to two groups of chicks (age 21 d). There were no differences in carcass weight (2·20 (sem0·06)v.2·23 (sem0·05) kg), boned, skinless thigh muscle (494 (sem20·5)v.507 (sem16·7) g), boned, skinless breast muscle (553 (sem13·4)v.546 (sem11·6) g) or organ weights (heart, liver and gizzard) between the two groups. The total intramuscular fat (IMF) percentage of thigh (8·0 (sem0·64)v.8·1 (sem0·62) %) and breast muscles (2·3 (sem0·24)v.2·0 (sem0·19) %) were also similar between the groups. In contrast, the concentrations of most of the individualn-3 fatty acids (ALA, SDA, EPA and docosapentaenoic acid) were all higher in the Echium than the rapeseed group (P < 0·05). However, differences in DHA concentrations were significant in breast but not thigh muscle IMF. The totaln-3 yields/100 g serve thigh muscle were 265 and 676 mg for the rapeseed and Echium groups, respectively (P < 0·0001). The corresponding values for equivalent breast muscles were 70 and 137 mg, respectively (P < 0·01). We conclude that Echium oil is a better lipid supplement than rapeseed oil in changing the concentration and yield ofn-3 fatty acids, except DHA, in broiler meat.

Mechanisms by which botanical lipids affect inflammatory disorders

Changes in diet over the past century have markedly altered the consumption of fatty acids. The dramatic increase in the ingestion of saturated and n-6 fatty acids and concomitant decrease in n-3 fatty acids are thought to be a major driver of the increase in the incidence of inflammatory diseases such as asthma, allergy, and atherosclerosis. The central objective of the Center for Botanical Lipids at Wake Forest University School of Medicine and the Brigham and Women's Hospital is to delineate the mechanisms by which fatty acid-based dietary supplements inhibit inflammation leading to chronic human diseases such as cardiovascular disease and asthma. The key question that this center addresses is whether botanical n-6 and n-3 fatty acids directly block recognized biochemical pathways or the expression of critical genes that lead to asthma and atherosclerosis. Dietary supplementation with flaxseed oil, borage oil, and echium oil affects the biochemistry of fatty acid metabolism and thus the balance of proinflammatory mediators and atherogenic lipids. Supplementation studies have begun to identify key molecular and genetic mechanisms that regulate the production of lipid mediators involved in inflammatory and hyperlipidemic diseases. Echium oil and other oils containing stearidonic acid as well as botanical oil combinations (such as echium and borage oils) hold great promise for modulating inflammatory diseases.

Echium oil reduces plasma lipids and hepatic lipogenic gene expression in apoB100-only LDL receptor knockout mice

We tested the hypothesis that dietary supplementation with echium oil (EO), which is enriched in stearidonic acid (SDA; 18:4 n-3), the product of Delta-6 desaturation of 18:3 n-3, will decrease plasma triglyceride (TG) concentrations and result in conversion of SDA to eicosapentaenoic acid (EPA) in the liver. Mildly hypertriglyceridemic mice (apoB100-only LDLrKO) were fed a basal diet containing 10% calories as palm oil (PO) and 0.2% cholesterol for 4 weeks, after which they were randomly assigned to experimental diets consisting of the basal diet plus supplementation of 10% of calories as PO, EO or fish oil (FO) for 8 weeks. The EO and FO experimental diets decreased plasma TG and VLDL lipid concentration, and hepatic TG content compared to PO, and there was a significant correlation between hepatic TG content and plasma TG concentration among diet groups. EO fed mice had plasma and liver lipid EPA enrichment that was greater than PO-fed mice but less than FO-fed mice. Down-regulation of several genes involved in hepatic TG biosynthesis was similar for mice fed EO and FO and significantly lower compared to those fed PO. In conclusion, EO may provide a botanical alternative to FO for reduction of plasma TG concentrations.

Important differences exist in the dose-response relationship between diet and immune cell fatty acids in humans and rodents

Omega-3 polyunsaturated fatty acids (n-3 PUFA) are noted for their ability to diminish inflammatory and immune responses in vitro and in a variety of animal-based models of autoimmunity and inflammation. Yet, recent systematic reviews suggest that the evidence for these fatty acids having beneficial effects on inflammation or autoimmunity in humans is equivocal. A possible explanation for these disappointing and somewhat paradoxical findings emerged from the analyses described in this review. The available data on the changes in immune cell fatty acid profiles in mice, rats and humans, fed various forms and amounts of n-3 PUFA are summarized and displayed graphically. The dose-response curves generated provide new insights into the relationship between dietary n-3 PUFA and immune cell fatty acid profiles. The author suggests that the poor predictive value of most in vitro as well as many animal trials may, in part, be a consequence of the frequent adoption of experimental conditions that create differences in immune cell fatty acid profiles that far exceed what is possible in free-living humans through dietary intervention. Recommendations for improving the preclinical value of future in vitro and animal-based studies with n-3 PUFA are provided.

Stearidonic Acid Increases the Red Blood Cell and Heart Eicosapentaenoic Acid Content in Dogs

Plant sources of omega-3 fatty acids (FA) are needed that can materially raise tissue levels of long-chain omega-3 FA [i.e., eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 20:6n-3)]. Stearidonic acid (SDA; 18:4n-3) is the delta-6 desaturase product of alpha-linolenic acid (ALA; 18:3n-3), and when fed to humans, increases red blood cell (RBC) content of EPA to a greater extent than does ALA. This study was undertaken to determine the dose-dependence and time course of the increase in the EPA and DHA content of the heart and RBC in dogs. Adult male Beagles were fed 21, 64, or 193 mg/kg of SDA in in their food daily for up to 12 weeks. Positive and negative controls were given EPA (43 mg/kg) or high oleic acid sunflower oil, respectively. The baseline EPA content of RBC was 0.38 +/- 0.03% which increased (P<0.01) in a dose-dependent manner, with the high dose of SDA and EPA achieving levels of 1.33 +/- 0.26 and 1.55. +/- 0.28%, respectively. In the heart, the content of EPA rose from 0.06 +/- 0.01 to 1.24 +/- 0.22% in the EPA group and to 0.81 +/- 0.32% in the high SDA group (both P<0.01). In both tissues, DHA did not change. Compared to dietary EPA, SDA was 20-23% as efficient in raising tissue EPA levels. In conclusion, SDA supplementation increased the EPA content of RBC and heart and may have utility as a plant-based source of omega-3 FA.

Effect of eicosapentaenoic/docosahexaenoic fatty acids and soluble fibers on blood lipids of individuals classified into different levels of lipidemia

OBJECTIVE

This study evaluated the effect of a formulation containing eicosapentaenoic acid and docosahexaenoic acid combined with soluble fibers (beta-glucan and guar gum) on fasting blood lipids used as coronary heart disease biomarkers of individuals classified into different levels of lipidemia by multivariate techniques.

METHODS

Serum total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triacylglycerol, plasma glucose concentrations, body mass index, age, and waist circumference were determined in 99 healthy volunteers. Three clusters or subgroups were identified according to coronary heart disease risk levels. Within each cluster, individuals were randomly assigned to one of four experimental groups, with each group receiving samples of a functional formulation containing 460 mg of omega-3 polyunsaturated fatty acids and/or 580 mg of soluble fibers, and placebo to be consumed in one bottle per day (200 mL) for 6 wk.

RESULTS

No significant changes were observed for triacylglycerol (P = 0.281) and total cholesterol (P = 0.082) concentrations across the three subgroups. Soluble dietary fibers improved the sensory quality of the formulation containing eicosapentaenoic acid and docosahexaenoic acid. The efficiency of cluster analysis to discriminate individuals in subgroups was confirmed by one-way analysis of variance (P < 0.003).

CONCLUSION

The omega-3 polyunsaturated fatty acid supplementation equivalent to fish consumed 2.5 to 3 times per week by a functional food-containing soluble dietary fiber showed no beneficial result in terms of changes in blood lipids in individuals classified according to different levels of lipidemia. Small numbers of patients in each cluster and possibly the low dose of fish oil and soluble dietary fibers used in this study may have also contributed to the lack of these differences. Multivariate techniques proved to be a very efficient tool to solve the heterogeneity problem usually observed in human designs and to evaluate the results within subgroups categorized by n variables extracted from the same population.

Innovative Dietary Sources of N-3 Fatty Acids

It is now established that dietary n-3 polyunsaturated fatty acids (PUFAs) are involved in health promotion and disease prevention, particularly those traditionally derived from marine sources (e.g., eicosapentaenoic acid and docosahexaenoic acid). A number of organizations have made specific recommendations for the general population to increase their intakes of these nutrients. In response to and along with these recommendations, n-3 PUFAs are being incorporated into nontraditional food sources because of advances in the technology to safely enrich/fortify our food supply. Fatty acid compositions of traditional oils (e.g., canola and soybean) are being genetically modified to deliver more highly concentrated sources of n-3 PUFA. The advent of algal sources of docosahexaenoic acid provides one of the few terrestrial sources of this fatty acid in a concentrated form. All of this is possible because of newer technologies (microencapsulation) and improved processing techniques that ensure stability and preserve the integrity of these unstable fatty acids.

Effect of diets enriched in Δ6 desaturated fatty acids (18:3n−6 and 18:4n−3), on growth, fatty acid composition and highly unsaturated fatty acid synthesis in two populations of Arctic charr (Salvelinus alpinus L.)

This study aimed to test the hypothesis that diets containing relatively high amounts of the Delta6 desaturated fatty acids stearidonic acid (STA, 18:4n-3) and gamma-linolenic acid (GLA, 18:3n-6), may be beneficial in salmonid culture. The rationale being that STA and GLA would be better substrates for highly unsaturated fatty acid (HUFA) synthesis as their conversion does not require the activity of the reputed rate-limiting enzyme, fatty acid Delta6 desaturase. Duplicate groups of two Arctic charr (Salvelinus alpinus L.) populations with different feeding habits, that had been reported previously to show differences in HUFA biosynthetic capacity, were fed for 16 weeks on two fish meal based diets containing 47% protein and 21% lipid differing only in the added lipid component, which was either fish oil (FO) or echium oil (EO). Dietary EO had no detrimental effect on growth performance and feed efficiency, mortalities, or liver and flesh lipid contents in either population. The proportions of 18:2n-6, 18:3n-3, 18:3n-6, 18:4n-3, 20:3n-6 and 20:4n-3 in total lipid in both liver and flesh were increased by dietary EO in both populations. However, the percentages of 20:5n-3 and 22:6n-3 were reduced by EO in both liver and flesh in both strains, whereas 20:4n-6 was only significantly reduced in flesh. In fish fed FO, HUFA synthesis from both [1-(14)C]18:3n-3 and [1-(14)C]20:5n-3 was significantly higher in the planktonivorous Coulin charr compared to the demersal, piscivorous Rannoch charr morph. However, HUFA synthesis was increased by EO in Rannoch charr, but not in Coulin charr. In conclusion, dietary EO had differential effects in the two populations of charr, with HUFA synthesis only stimulated by EO in the piscivorous Rannoch morph, which showed lower activities in fish fed FO. However, the hypothesis was not proved as, irrespective of the activity of the HUFA synthesis pathway in either population, feeding EO resulted in decreased tissue levels of n-3HUFA and 20:4n-6. This has been observed previously in salmonids fed vegetable oils, and thus the increased levels of Delta6 desaturated fatty acids in EO did not effectively compensate for the lack of dietary HUFA.

Biological effects of a dietary omega-3 polyunsaturated fatty acids supplementation in cystic fibrosis patients: a randomized, crossover placebo-controlled trial

BACKGROUND AND AIMS

Various anti-inflammatory therapies, including dietary omega-3 polyunsaturated fatty acids (PUFA) supplementation, have been investigated in cystic fibrosis (CF) patients. To further explore this nutritional approach, biological effects of an omega-3 PUFA oral liquid supplementation were measured in 17 CF patients in a double-blind, randomized, crossover without a washout period and placebo-controlled study.

METHODS

CF patients (age: 18+/-9 year; weight: 43+/-13 kg) received a liquid dietary supplementation either enriched or not in omega-3 PUFA (390-1170 mg/day according to patient weight) during two 6-month periods.

RESULTS

Increase in eicosapentaenoic acid was observed in neutrophil membrane following omega-3 PUFA dietary supplementation (from 0.7+/-0.6 to 1.6+/-0.6 micromol%, P<0.01). The leukotriene B(4) (LTB(4))/leukotriene B(5) (LTB(5)) ratio was decreased (from 72+/-27 to 24+/-7, P<0.001) in CF patients taking omega-3 PUFA supplements. In contrast, omega-3 PUFA supplementation affected neither internalization of IL-8 receptors following IL-8 exposure, nor IL-8-induced neutrophil chemotaxis.

CONCLUSION

Our results show that omega-3 PUFA are incorporated in neutrophil membranes. The subsequent decrease in LTB(4)/LTB(5) ratio suggests that, in such conditions, neutrophils may produce less pro-inflammatory mediators from the acid arachidonic pathway. These data indicate that omega-3 PUFA intake may have anti-inflammatory effect that still need to be assessed by long-term studies following large groups of patients.