Lower Efficacy in the Utilization of Dietary ALA as Compared to Preformed EPA + DHA on Long Chain n-3 PUFA Levels in Rats

We made a comparative analysis of the uptake, tissue deposition and conversion of dietary α-linolenic acid (ALA) to its long chain metabolites eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) with preformed EPA + DHA. Diets containing linseed oil [with ALA at ~2.5 (4 g/kg diet), 5 (8 g/kg diet), 10 (16 g/kg diet), 25% (40 g/kg diet)] or fish oil [with EPA + DHA at ~1 (1.65 g/kg diet), 2.5 (4.12 g/kg diet), 5% (8.25 g/kg diet)] or groundnut oil without n-3 polyunsaturated fatty acids (n-3 PUFA) were fed to rats for 60 days. ALA and EPA + DHA in serum, liver, heart and brain increased with increments in the dietary ALA level. When preformed EPA + DHA were fed, the tissue EPA + DHA increased significantly compared to those given ALA. Normalized values from dietary n-3 PUFA to tissue EPA + DHA indicated that 100 mg of dietary ALA lead to accumulation of EPA + DHA at 2.04, 0.70, 1.91 and 1.64% of total fatty acids respectively in liver, heart, brain and serum. Similarly 100 mg of preformed dietary EPA + DHA resulted in 25.4, 23.8, 15.9 and 14.9% of total fatty acids in liver, heart, brain and serum respectively. To maintain a given level of EPA + DHA, the dietary ALA required is 12.5, 33.5, 8.3 and 9.1 times higher than the dietary EPA + DHA for liver, heart, brain and serum respectively. Hence the efficacy of precursor ALA is lower compared to preformed EPA + DHA in elevating serum and tissue long chain n-3 PUFA levels.     

The Influence of n-3 PUFA Supplements and n-3 PUFA Enriched Foods on the n-3 LC PUFA Intake of Flemish Women

Food consumption data of Flemish women of reproductive age collected in 2002 showed a large deficit for ALA and n-3 LC PUFA compared to the recommendations (mean ALA and EPA + DHA intake 1.4 g/day and 209 mg/day, respectively) and indicated a need to tackle the problem of low n-3 PUFA intake. Another recent Belgian study demonstrated that enrichment of commonly eaten food items with n-3 PUFA provides the opportunity to increase the n-3 PUFA intake up to 6.5 g/day and decrease the n-6/n-3 ratio. Since a large supply of n-3 PUFA supplements and n-3 PUFA enriched foods exists on the Belgian market, this study aimed at assessing the influence of these products on the n-3 LC PUFA intake for Flemish women of reproductive age. It was found that n-3 supplements are consumed by 5% of the Flemish women. Of all the n-3 PUFA enriched foods on the Flemish market, margarines and cooking fat are most frequently consumed by young women. The results indicated that a big gap remains between the EPA&DHA intake (mean = 276 mg/day) and the recommendation. Seafood remains the most important source of EPA&DHA. Only 11.6% of the population sample reached an intake level of 500 mg EPA&DHA per day. The study showed that other strategies will be needed to increase the EPA&DHA intake in the long term.     

Uptake of α-Linolenic Acid and Its Conversion to Long Chain Omega-3 Fatty Acids in Rats Fed Microemulsions of Linseed Oil

The present work was designed to prepare linseed oil (LSO) microemulsion and explore the possibility of enhancing the uptake and utilization of α-linolenic acid (ALA) present in LSO. The bioavailability of encapsulated LSO as against native oil was monitored in rats by measuring the uptake in vitro using the intestinal everted sac model and in-vivo administration of microemulsions of LSO to rats for a period of 30?days. Microemulsions were prepared by using different binding materials such as gum acacia, whey protein and lipoid. When LSO was encapsulated with gum acacia, whey protein and lipoid, the levels of ALA uptake into intestinal sacs was increased by 6, 17 and 28?% as compared to oil given without encapsulation. EPA and DHA were not observed in the oil absorbed by intestinal everted sacs when given as emulsions with gum acacia or whey protein. When LSO was given as microemulsions with lipoid, EPA?+?DHA was observed in oil absorbed by intestinal sacs. Similarly when LSO was given as a lipoid emulsion by intubation to rats, the EPA and DHA in serum lipids were found to be 41 and 34?μg/ml, respectively while rats given LSO without encapsulation contained EPA and DHA at 9.1 and 8.8?μg/ml, respectively. Similar changes in omega-3 fatty acid content in liver lipids were observed when LSO was given as a microemulsion with lipoid. This study indicated that ALA was taken up and metabolized to long chain omega-3 PUFA when given as microemulsion with lipoid.     

Comparative Effects of Sandalwood Seed Oil on Fatty Acid Profiles and Inflammatory Factors in Rats

The aim of the present study was to investigate the effect of sandalwood seed oil on fatty acid (FA) profiles and inflammatory factors in rats. Fifty male Sprague–Dawley rats were randomly divided into five different dietary groups: 10 % soybean oil (SO), 10 % olive oil (OO), 10 % safflower oil (SFO), 10 % linseed oil (LSO) and 8 % sandalwood seed oil blended with 2 % SO (SWSO) for 8 weeks. The SWSO group had a higher total n-3 polyunsaturated fatty acids (PUFA) levels but lower n-6:n-3 PUFA ratios in both adipose tissue and liver than those in the SO, OO and SFO groups (p < 0.05). Although the SWSO group had a much lower 18:3n-3 level (4.51 %) in their dietary lipids than the LSO group (58.88 %), the levels of docosahexaenoic acid (DHA: 22:6n-3) in liver lipids and phospholipids of the SWSO group (7.52 and 11.77 %) were comparable to those of the LSO group (7.07 and 13.16 %). Ximenynic acid, a predominant acetylenic FA in sandalwood seed oil, was found to be highly incorporated into adipose tissue (13.73 %), but relatively lower in liver (0.51 %) in the SWSO group. The levels of prostaglandin F_2α, prostaglandin E₂, thromboxane B₂, leukotriene B₄, tumor necrosis factor-α and interleukin-1β in both liver and plasma were positively correlated with the n-6:n-3 ratios, suggesting that increased n-6 PUFA appear to increase the formation of pro-inflammatory cytokines, whereas n-3 PUFA exhibit anti-inflammatory activity. The present results suggest that sandalwood seed oil could increase tissue levels of n-3 PUFA, DHA and reduce the n-6:n-3 ratio, and may increase the anti-inflammatory activity in rats.     

Metabolic Effects of Krill Oil are Essentially Similar to Those of Fish Oil but at Lower Dose of EPA and DHA,in Healthy Volunteers

The purpose of the present study is to investigate the effects of krill oil and fish oil on serum lipids and markers of oxidative stress and inflammation and to evaluate if different molecular forms, triacylglycerol and phospholipids, of omega-3 polyunsaturated fatty acids (PUFAs) influence the plasma level of EPA and DHA differently. One hundred thirteen subjects with normal or slightly elevated total blood cholesterol and/or triglyceride levels were randomized into three groups and given either six capsules of krill oil (N = 36; 3.0 g/day, EPA + DHA = 543 mg) or three capsules of fish oil (N = 40; 1.8 g/day, EPA + DHA = 864 mg) daily for 7 weeks. A third group did not receive any supplementation and served as controls (N = 37). A significant increase in plasma EPA, DHA, and DPA was observed in the subjects supplemented with n-3 PUFAs as compared with the controls, but there were no significant differences in the changes in any of the n-3 PUFAs between the fish oil and the krill oil groups. No statistically significant differences in changes in any of the serum lipids or the markers of oxidative stress and inflammation between the study groups were observed. Krill oil and fish oil thus represent comparable dietary sources of n-3 PUFAs, even if the EPA + DHA dose in the krill oil was 62.8% of that in the fish oil.     

Lymphatic Transport of α-Linolenic Acid and Its Conversion to Long Chain n-3 Fatty Acids in Rats Fed Microemulsions of Linseed Oil

In the present study we evaluated the uptake of ALA and its conversion to EPA + DHA in rats given linseed oil (LSO) in native form or as a microemulsion in whey protein or in lipoid. In a single oral dose study in which rats maintained on rodent pellets deficient in ω-3 fatty acids were intubated with 0.35 g LSO in lipoid, the amount of ALA present in lymph was increased reaching a maximum concentration of 16.23 mg/ml at 2.5 h. The amount of ALA present in lymph was increased to a maximum level of 10.95 mg/ml at 4 h in rats given LSO as a microemulsion in whey protein. When LSO was given without emulsification, the amount of ALA present in lymph was found to reach a maximum level of 7.08 mg/ml at 6 h. A similar result was observed when weaning rats were intubated with 0.15 g of LSO per day for a period of 60 days. Higher levels of ALA by 41 and 103 % were observed in lymph lipids of rats given microemulsions of LSO in whey protein and in lipoid respectively as compared to rats given LSO without pre-emulsification. Very little conversion of ALA to EPA and DHA was observed in lymph lipids but higher amounts of EPA + DHA was observed in liver and serum of rats given LSO in microemulsion form. This study indicated that ALA concentration in lymph lipids was increased when LSO was given in microemulsion form in lipoid and further conversion to EPA and DHA was facilitated in liver and serum.     

Structured lipids from rice bran oil and stearic acid using immobilized lipase from Rhizomucor miehei

The major objective of the present study was to prepare structured lipids rich in stearic acid from rice bran oil (RBO) using immobilized lipase (IM 60) from Rhizomucor miehei. The effects of incubation time and temperature, substrate molar ratio, and enzyme load on incorporation of stearic acid were studied. Acidolysis reactions were performed in hexane. Pancreatic lipase‐catalyzed sn‐2 positional analysis and tocopherol analyses were performed before and after enzymatic modification. The kinetics of the reaction was studied and maximum incorporation of stearic acid was observed at 6 h, at 37 °C, when the triacylglycerol and stearic acid molar ratio was maintained at 1 : 6 and the enzyme concentration was 10% of total substrates weight. Stearic acid in RBO after acidolysis was increased from 2.28 to 48.5%, with a simultaneous decrease in palmitic, oleic and linoleic acids. HPLC analysis of tocopherols and tocotrienols was carried out and their content in modified RBO was not significantly affected compared to that of native RBO. The oryzanol content of the modified RBO was reduced from 1.02 to 0.68%. Melting and crystallizing characteristics of the modified fat were studied using differential scanning calorimetry. The total solid fat content at 25 °C increased from 26.12 to 34.8% with an increase in stearic acid incorporation into RBO from 38 to 48%, but it was comparatively less than for cocoa butter and vanaspati. However, the modified RBO completely melted at 37 °C and was useful as plastic fat for various culinary purposes, bakery and confectionary applications. The results of the present study indicated that structured lipids prepared from RBO rich in stearic acid retained their beneficial nutraceuticals; in addition, they do not contain any trans fatty acids.     

Effects of dietary triacylglycerol structure on triacylglycerols of resultant chylomicrons from fish oil- and seal oil-fed rats

We investigated the influence of the intramolecular fatty acid distribution of dietary triacyl-sn-glycerols (TAG) rich in n-3 polyunsaturated fatty acids (PUFA) on the structure of chylomicron TAG. Fish oil and seal oil, comparable in fatty acid compositions but with different contents of major n-3 PUFA esterified at thesn-2 position (20:5n-3, 46.6%, and 5.3%; 22:6n-3, 75.5%, and 3.8%, respectively), were fed to rats. Mesenteric lymph was collected and the chylomicrons were isolated by ultracentrifugation. The fatty acid composition of chylomicrons largely reflected the fatty acid composition of the oils administered. The intramolecular fatty acid distributions of the TAG fed were reflected in the chylomicron TAG as the fraction of the total contents observed in thesn-2 position of 20:5n-3 were 23.6 and 13.3%, and of 22:6n-3 were 30.6 and 5.4% for resultant chylomicrons following fish oil and seal oil administration, respectively. Thus, after seal oil administration, significant higher load of n-3 PUFA was esterified in thesn-1,3 positions of chylomicron TAG compared with fish oil administration (P<0.05).     

Anti-Rancidity Effects of Sesame and Rice Bran Oils on Canola Oil During Deep Frying

In this study, the effect of sesame oil (SEO) and rice bran oil (RBO) on the rancidity of canola oil (CAO) during the process of frying potato pieces at 180 °C was investigated. The SEO and RBO were added to the CAO at levels of 3 and 6%. Frying stability of the oil samples during the frying process was measured on the basis of total polar compounds (TPC) content, conjugated diene value (CDV), acid value (AV), and carbonyl value (CV). In general, frying stability of the CAO significantly (P < 0.05) improved in the presence of the SEO and RBO. The positive effect of the SEO on the stability of the CAO was more than that of the RBO. Increasing the amounts of SEO and RBO from 3 to 6% led to decreases in the TPC and AV, and increases in the CDV and CV of the CAO during the frying process. The best frying performance for the CAO was obtained by use of 3% of both SEO and RBO together (CAO/SEO/RBO, 94:3:3 w/w/w).     

Confusion over different types of n‐3 polyunsaturated fatty acids

There are two kinds of n‐3 polyunsaturated fatty acid (PUFA). Alpha‐linolenic acid (ALA) is the parent n‐3 PUFA; it cannot be synthesized by the human body and as a result is an essential fatty acid. The two long chain n‐3 PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can in principle be synthesized from ALA or obtained from the diet. While the cardioprotective effects of long chain n‐3 PUFA are well established the effects of ALA on the cardiovascular system are more controversial. The Lyon Diet Heart Study which it is claimed provides evidence for beneficial effects of ALA on the cardiovascular system is flawed. The argument that ALA conversion into EPA and DHA provides significant quantities of the two long chain n‐3 PUFA is unsustainable as rates of conversion are too low. To avoid confusion a distinction needs to be drawn between ALA and the long chain n‐3 PUFA. Health claims for foods rich in EPA and DHA cannot be extended to foods rich in ALA nor is ALA a substitute for EPA and DHA in vegetarian diets.     

Enzymatic incorporation of docosahexaenoic acid into borage oil

Lipase-catalyzed acidolysis of acylglycerols of borage (Borago officinalis L.) oil with a docosahexaenoic acid (DHA) concentrate, prepared from algal oil, in organic solvents was studied. Seven lipases were used as biocatalysts for the acidolysis reaction. Novozyme 435 from Candida antarctica, as compared to lipases from Mucor miehei and Pseudomonas sp., showed the highest degree of DHA incorporation into borage oil. Other lipases tested, such as those from Aspergillus niger, C. rugosa, Thermomyces lanuginousus and Achromobacter lunatus, were rather ineffective in the incorporation of DHA into borage oil. Effects of variation of reaction parameters, namely, enzyme load, temperature, time course, and type of solvent, were monitored for C. antarctica as the biocatalyst of choice. Incorporation of DHA increased with increasing amount of enzyme, reaching 27.4% at an enzyme concentration of 150 lipase activity units. As incubation time progressed, DHA incorporation also increased. After a reaction time of 24 h, the contents of total n-6 and n-3 polyunsaturated fatty acids in acylglycerols were 44.0 and 27.6%, respectively. The highest degree of DHA incorporation was achieved when hexane was used as the reaction medium. The positional distribution of DHA in modified borage oil was determined using pancreatic lipase hydrolysis. Results showed that DHA was randomly distributed over the sn-1, sn-2, and sn-3 positions of the triacylglycerol. Thus, preparation of modified borage oil acylglycerols containing both DHA (22:6n-3; 27.4%) and γ-linolenic acid (18:3n-6; 17.0%) was successfully achieved and products so obtained may have beneficial effects beyond simple physical mixtures of the two oils. The final oil had a ratio of n-3 to n-6 of 0.42–0.62 which is nutritionally more suitable than the original unaltered borage oil.     

Preparation of Infant Formula Fat Analog Containing Capric Acid and Enriched with DHA and ARA at the sn-2 Position

An infant formula fat analog with capric acid mostly esterified at the sn‐1,3 positions, and substantial amounts of palmitic, docosahexaenoic (DHA), and arachidonic (ARA) acids at the sn‐2 position, was prepared by physically blending enzymatically synthesized structured lipids (SL) with vegetable oils. The components of the blend included high sn‐2 palmitic acid SL enriched with capric acid (SL_CA), canola oil (CAO), corn oil (CO), high sn‐2 DHA (DHAO_m), and high sn‐2 ARA (ARAO_m) enzymatically modified oils. Each component was proportionally blended to match the fatty acid profile of commercial fat blends used for infant formula. The infant formula fat analog (IFFA₁) was characterized for total and positional fatty acids (FA), triacylglycerol (TAG) molecular species, thermal behavior, and tocopherol content. IFFA₁ contained 17.37 mol% total palmitic acid of which nearly 35 % was located at the sn‐2 position. The total capric acid content was 13.93 mol%. The content of DHA and ARA were 0.49 mol% (48.18 % at sn‐2) and 0.57 mol% (35.80 % at sn‐2), respectively. The predominant TAG were OPO (24.09 %), POP (15.70 %), OOO (11.53 %), and CLC (7.79 %). The melting completion and crystallization onset temperatures were 18.65 and ?2.19 °C, respectively. The total tocopherol content was 566.45 μg/g. This product might be suitable for commercial production of infant formulas.     

Lipase-assisted concentration of n-3 polyunsaturated fatty acids in acylglycerols from marine oils

Preparation of n-3 polyunsaturated fatty acid (PUFA) concentrates from seal blubber oil (SBO) and menhaden oil (MHO) in the form of acylglycerols was carried out by hydrolysis with a number of commercial microbial lipases. The lipases tested were Aspergillus niger, Candida cylindracea (CC), Chromobacterium viscosum, Geotrichum candidum, Mucor miehei, Pseudomonas sp., Rhizopus oryzae, and Rhizopus niveus. After lipase-assisted hydrolysis of oils, free fatty acids were removed, and fatty acid composition of the mixture containing mono-, di-, and triacylglycerols was determined. All lipases were effective in increasing the n-3 PUFA content of the remaining acylglycerols of both SBO and MHO. The highest concentration of n-3 PUFA was provided by CC lipase; 43.5% in SBO [9.75% eicosapentaenoic acid (EPA), 8.61% docosapentaenoic acid (DPA), and 24.0% docosahexaenoic acid (DHA)] and 44.1% in MHO (18.5% EPA, 3.62% DPA, and 17.3% DHA) after 40 h of hydrolysis. Thus, CC lipase appears to be most suitable for preparation of n-3 PUFA in the acylglycerol form from marine oils.     

Plasma Phospholipid Fatty Acid and Ex Vivo Neutrophil Responses are Differentially Altered in Dogs Fed Fish- and Linseed-Oil Containing Diets at the Same n-6:n-3 Fatty Acid Ratio

The effect of diets containing either 18-carbon n-3 fatty acids (FA) or 20/22-carbon n-3 FA on canine plasma and neutrophil membrane fatty acid composition, superoxide and leukotriene B₄ and B₅ production when fed at the same n-6:n-3 fatty acid ratio was investigated. Four groups of ten dogs each were fed a low fat basal diet supplemented with safflower oil (SFO), beef tallow (BTO), linseed oil (LSO), or Menhaden fish oil (MHO) for 28 days. Dietary fat provided 40.8% of energy and the n-6:n-3 of the diets were ~100:1, 9.7:1, 0.38:1, and 0.34:1 for the SFO, BTO, LSO and MHO groups, respectively. The MHO and LSO groups had increased incorporation of EPA and DPA in both the plasma and neutrophil membranes compared to the BTO and SFO groups. DHA was observed in the MHO but not in the LSO group. Neutrophils from the MHO diet fed dogs had less LTB₄ and greater LTB₅ than the other three groups. The LSO group also showed a reduction in LTB₄ and greater LTB₅ production compared to the SFO and BTO groups. Both LSO and MHO groups had lower superoxide production compared to the SFO and BTO groups. Diets containing 18 or 20/22 carbon n-3 FA fed at the same n-6:n-3 resulted in differential incorporation of long chain n-3 FA into neutrophil membranes. Thus, fatty acid type and chain length individually affect neutrophil membrane structure and function and these effects exist independent of dietary total n-6:total n-3 FA ratios.     

Increased α-linolenic acid intake increases tissue α-linolenic acid content and apparent oxidation with little effect on tissue docosahexaenoic acid in the guinea pig

The essential fatty acids do not have identical roles in nutrition. Linoleic acid (LA) accumulates throughout the body of most mammals, whereas α-linolenic acid (ALA) is rarely found in tissue lipids to the same extent as LA. It has been argued that this is the result of metabolism of ALA to docosahexaenoic acid (DHA) or that ALA is rapidly β-oxidized to acetyl CoA and CO₂. In this study, we consider the effect of high and low ALA levels on the tissue distribution of ALA and other n-3 polyunsaturated fatty acids (PUFA) in all tissues. Guinea pigs were fed one of two defined diets for 3 wk from wearning with both diets containing 1.8% (by weight) of LA and either 1.7% ALA or 0.03% ALA. The high ALA diet was associated with significantly increased ALA levels in all tissues except the brain and significantly increased levels of long-chain n-3 PUFA in all tissues except intestines, brain, carcass, and skin. The long-chain n-3 PUFA content of the whole body was less than 5% of that of the ALA content in both diet groups, and the major long-chain n-3 PUFA (>66% of total) in the body was 22∶5n−3. The brain was the only tissue where the DHA content exceeded that of 22∶5n−3. On the low ALA diet, there appeared to be conservation of ALA based on a comparison of the ratio of LA to ALA in the tissues compared with that in the diet. On the high ALA diet there was a loss of ALA relative to LA in the tissues compared with the diet. These studies suggest that the low levels of tissue ALA in the guinea pig are likely the result of β-oxidation or excretion via the skin and fur rather than metabolism to DHA.     

Enzymatic Modification of Anhydrous Milkfat with n-3 and n-6 Fatty Acids for Potential Use in Infant Formula: Comparison of Methods

A structured lipid (SL) with a high amount of sn‐2 palmitic acid was synthesized from anhydrous milkfat and was then enriched with docosahexaenoic (DHA) and arachidonic (ARA) acids using an immobilized lipase. Three different methods were compared including physical blending, enzymatic interesterification, and enzymatic acidolysis. Products were compared with respect to differences in fatty acid profiles, reaction times, antioxidant contents, oxidative stability, melting and crystallization profiles, and reaction yields. The acidolysis method was the least suitable for the synthesis of desired product because of a low reaction yield, low incorporation of DHA, low oxidative stability, and the extra processing steps required. The physical blending and interesterification methods were suitable, but the interesterification product (IE‐SL) had higher amounts of ARA at the sn‐2 position. The IE‐SL contained total ARA and DHA of 0.63 and 0.50 mol%, and 0.55 and 0.46 mol% at the sn‐2 position, respectively. The IE‐SL also contained 44.97 mol% sn‐2 palmitic acid. The reaction yield for the IE‐SL was 91.84 %, and its melting completion and crystallization onset temperatures were 43.1 and 27.1 °C, respectively. This SL might be totally or partially used in commercial fat blends for infant formula.     

Lipolysis of different oils using crude enzyme isolate from the intestinal tract of rainbow trout, <Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>

Crude enzyme isolate was prepared from the intestine of rainbow trout. Positional specificity of the crude enzyme isolate was determined from both 1(3)- and 2-MAG products after in vitro lipolysis of radioactive-labeled triolein. The ratio of 2-MAG/1(3)-MAG was 2∶1, suggesting that the overall lipase specificity of the enzyme isolate from rainbow trout tended to be 1,3-specific; however, activity against the sn-2 position also was shown. In vitro lipolysis of four different unlabeled oils was performed with the crude enzyme isolate. The oils were: structured lipid [SL; containing the medium-chain FA (MCFA) 8∶0 in the sn-1,3 positions and long-chain FA (LCFA) in the sn-2 position], DAG oil (mainly 1,3-DAG), fish oil (FO), and triolein (TO). MCFA were rapidly hydrolyzed from the SL oil. LCFA including n−3 PUFA were, however, preserved in the sn-2 position and therefore found in higher amounts in 2-MAG of SL compared with 2-MAG of FO, DAG, and TO. Lipolysis of the DAG oil produced higher amounts of MAG than the TAG oils, and 1(3)-MAG mainly was observed after lipolysis of the DAG oil. The positional specificity determined and the results from the hydrolysis of the different oils suggest that n−3 very long-chain PUFA from structured oils may be used better by aquacultured fish than that from fish oils.     

Accretion of Dietary Docosahexaenoic Acid in Mouse Tissues Did Not Differ between Its Purified Phospholipid and Triacylglycerol Forms

Recent studies suggest that dietary krill oil leads to higher omega-3 polyunsaturated fatty acids (n-3 PUFA) tissue accretion compared to fish oil because the former is rich in n-3 PUFA esterified as phospholipids (PL), while n-3 PUFA in fish oil are primarily esterified as triacylglycerols (TAG). Tissue accretion of the same dietary concentrations of PL- and TAG-docosahexaenoic acid (22:6n-3) (DHA) has not been compared and was the focus of this study. Mice (n = 12/group) were fed either a control diet or one of six DHA (1%, 2%, or 4%) as PL-DHA or TAG-DHA diets for 4 weeks. Compared with the control, DHA concentration in liver, adipose tissue (AT), heart, and eye, but not brain, were significantly higher in mice consuming either PL- or TAG-DHA, but there was no difference in DHA concentration in all tissues between the PL- or TAG-DHA forms. Consumption of PL- and TAG-DHA at all concentrations significantly elevated eicosapentaenoic acid (20:5n-3) (EPA) in all tissues when compared with the control group, while docoshexapentaenoic acid (22:5n-6) (DPA) was significantly higher in all tissues except for the eye and heart. Both DHA forms lowered total omega-6 polyunsaturated fatty acids (n-6 PUFA) in all tissues and total monounsaturated fatty acids (MUFA) in the liver and AT; total saturated fatty acid (SFA) were lowered in the liver but elevated in the AT. An increase in the DHA dose, independent of DHA forms, significantly lowered n-6 PUFA and significantly elevated n-3 PUFA concentration in all tissues. Our results do not support the claim that the PL form of n-3 PUFA leads to higher n-3 PUFA tissue accretion than their TAG form.     

Effects of Seal Oil and Tuna-Fish Oil on Platelet Parameters and Plasma Lipid Levels in Healthy Subjects

Fish are a rich source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), two long-chain polyunsaturated n-3 fatty acids (LC n-3 PUFA) with cardiovascular benefits. A related but less-investigated LC n-3 PUFA, docosapentaenoic acid (DPA), is more common in seal oil and pasture-fed red meats. This study compared indicators of platelet function and plasma lipids in healthy volunteers given supplements containing these different fatty acids (FA) for 14 days. Subjects, randomised into three groups of ten, consumed capsules of tuna oil (210 mg EPA, 30 mg DPA, 810 mg DHA), seal oil (340 mg EPA, 230 mg DPA, 450 mg DHA) or placebo (sunola) oil. Supplementary LC n-3 PUFA levels were approximately 1 g/day in both fish and seal oil groups. Baseline dietary FA and other nutrient intakes were similar in all groups. Both fish and seal oil elevated platelet DHA levels (P < 0.01). Seal oil also raised platelet DPA and EPA levels (P < 0.01), and decreased p-selectin (P = 0.01), a platelet activation marker negatively associated with DPA (P = 0.03) and EPA (P < 0.01) but not DHA. Plasma triacylglycerol decreased (P = 0.03) and HDL-cholesterol levels increased (P = 0.01) with seal oil only. Hence, seal oil may be more efficient than fish oil at promoting healthy plasma lipid profiles and lowering thrombotic risk, possibly due to its high DPA as well as EPA content.     

Decreasing the Linoleic Acid to α-Linolenic Acid Diet Ratio Increases Eicosapentaenoic Acid in Erythrocytes in Adults

The n-6/n-3 fatty acid (FA) ratio has increased in the Western-style diet to ~10–15:1 during the last century, which may have contributed to the rise in cardiovascular disease (CVD). Prior studies have evaluated the effects on CVD risk factors of manipulating the levels of n-6 and n-3 FA using food and supplements or investigated the metabolic fate of linoleic acid (LNA) and α-linolenic acid (ALA) by varying the n-6/n-3 ratios. However, no previous studies have investigated the potential interaction between diet ratios and supplementation with eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). We used a factorial design approach with adults (n = 24) in a controlled feeding trial to compare the accretion of EPA and DHA into red blood cell membranes (RBC) by adding a direct source (algal oil supplement) of EPA and DHA in a diet with a 10:1 versus 2:1 ratio of n-6/n-3 FA. Subjects were randomized into 8-week crossover diet sequences and each subject consumed three of four diets [10:1, 10:1 plus supplement (10:1 + S), 2:1 and 2:1 + S]. LNA and ALA intakes were 9.4 and 7.7%, and 1.0 and 3.0% during the low and high ALA diets, respectively. Compared to the Western-style 10:1 diet, the 2:1 diet increased EPA by 60% (P < 0.0001) in RBC membranes without the direct EPA source and a 34% increase (P = 0.027) was observed with the 10:1 + S diet; however, DHA levels increased in both diet ratios only with a direct DHA source. Shifting towards a 2:1 diet is a valid alternative to taking EPA-containing supplements.