Effects of dietary fish oil on lipid peroxidation and serum triacylglycerol levels in psychologically stressed mice

OBJECTIVE: The intake of omega-3 polyunsaturated fatty acids and psychological stress can each induce tissue lipid peroxidation. In our present study, we investigated their combined effects on the oxidative status of mouse tissues. METHODS: Mice were group-housed (four mice/cage) and fed a diet containing fish oil (as a source of omega-3 polyunsaturated fatty acids), soybean oil, or olive oil for 3 wk. These animals were then 1) housed under the same conditions (four per cage, control group) or 2) individually housed to generate psychological stress conditions (isolation stress). After 2 wk of isolation stress, the levels of thiobarbituric acid-reactive substances (an index of lipid peroxidation) and antioxidants in the liver and kidney and the serum levels of triacylglycerol were measured. RESULTS: Fish oil-fed mice showed increased levels of thiobarbituric acid-reactive substances in their livers and kidneys compared with soybean oil- or olive oil-fed mice. These increases in thiobarbituric acid-reactive substance levels in the fish oil-fed mice were less profound under isolation stress conditions when compared with the group-housed animals on the same diet. In the fish oil-fed mice, isolation stress led to an increase in liver vitamin E levels when compared with their group-housed counterparts. The fish oil-fed mice exhibited lower serum triacylglycerol levels compared with the soybean oil- or olive oil-fed mice, and this decrease was more profound under conditions of isolation stress when compared with group-housing conditions. CONCLUSION: Dietary fish oil combined with isolation stress results in lower levels of lipid peroxidation in the liver and kidney compared with dietary fish oil alone.     

Postprandial triacylglycerols from dietary virgin olive oil are selectively cleared in humans

The aims of the present study were to evaluate the effect of a meal rich in virgin olive oil on triacylglycerol composition of human postprandial triacylglycerol-rich lipoproteins (fraction Sf > 400), and to assess the role of the triacylglycerol molecular species concentration and polarity on lipoprotein clearance. Fasting (0 h) and postprandial blood samples were collected hourly for 7 h from eight healthy normolipidemic subjects after the ingestion of the meal. Plasma and lipoprotein triacylglycerol concentrations increased quickly over fasting values and peaked twice at 2 and 6 h during the 7-h postprandial period. The triacylglycerols in the lipoprotein fraction at 2 h generally reflected the composition of the olive oil, however, the proportions of the individualmolecular species were altered by the processes leading to their formation. Among the major triacylglycerols, the proportion of triolein (OOO; 43.6%) decreased (P < 0.05), palmitoyl-dioleoyl-glycerol (POO; 31. 1%) and stearoyl-dioleoyl-glycerol (SOO; 2.1%) were maintained and linoleoyl-dioleoyl-glycerol (LOO; 11.4%) and palmitoyl-oleoyl-linoleoyl-glycerol (POL; 4.6%) significantly increased (P < 0.05) compared with the composition of the triacylglycerols in the olive oil. Smaller amounts of endogenous triacylglycerol (0.8%), mainly constituted of the saturated myristic (14:0)and palmitic (16:0) fatty acids, were also identified. Analysis of total fatty acids suggested the presence of molecular species composed of long-chain polyunsaturated fatty acids of the (n-3) family, docosapentaenoic acid, [22:5(n-3)] and docosahexaenoic acid (DHA), [22:6(n-3)] and of the (n-6) family [arachidonic acid, [20:4(n-6)]. The fastest conversion of lipoproteins to remnants occurred from 2 to 4 h and was directly related to the concentration of the triacylglycerols in the lipoprotein particle (r = 0.9969, P < 0.05) and not with its polarity (r = 0.1769, P > 0.05). The rates of clearance were significantly different among the major triacylglycerols (OOO, POO, OOL and POL) (P < 0.05) and among the latter ones and PLL (palmitoyl-dilinoleoyl-glycerol, POS (palmitoyl-oleoyl-stearoyl-glycerol) and OLL (oleoyl-dilinoleoyl-glycerol) (P < 0.01). OOO was removed faster and was followed by POO, OOL, POL, PPO (dipalmitoyl-oleoyl-glycerol), SOO, PLL, POS and OLL.     

Dietary fat (virgin olive oil or sunflower oil) and physical training interactions on blood lipids in the rat

OBJECTIVE: We investigated whether the intake of virgin olive oil or sunflower oil and performance of physical exercise (at different states) affect plasma levels of triacylglycerols, total cholesterol, and fatty acid profile in rats. METHODS: The study was carried out with six groups of male rats subjected for 8 wk to a diet based on virgin olive oil (three groups) or sunflower oil (three groups) as dietary fat. One group for each diet acted as sedentary control; the other two groups ran in a treadmill for 8 wk at 65% of the maximum oxygen consumption. One group for each diet was killed 24 h after the last bout of exercise and the other was killed immediately after the exercise performance. Triacylglycerols, total cholesterol, and fatty acid profile were analyzed in plasma. Analysis of variance was used to test differences among groups. RESULTS: Animals fed on virgin olive oil had lower triacylglycerol and cholesterol values. Physical exercise reduced these parameters with both dietary treatments. Fatty acid profile showed higher monounsaturated fatty acid proportion in virgin olive fed oil animals and a higher omega-6 polyunsaturated fatty acid proportion in sunflower oil fed animals. Physical exercise reduced the levels of monounsaturated fatty acids with both diets and increased the proportions of omega-3 polyunsaturated fatty acids. CONCLUSIONS: Results from the present study supported the idea that physical exercise and the intake of virgin olive oil are very good ways of reducing plasma triacylglycerols and cholesterol, which is desirable in many pathologic situations. Concerning findings on fatty acid profile, we had results similar to those of other investigators regarding the effect of different sources of dietary fat on plasma. The most interesting results came from the effect of physical exercise, with significant increases in the levels of omega-3 polyunsaturated fatty acids, which may contribute to the antithrombotic state and lower production of proinflammatory prostanoids attributed to physical exercise.     

Effects of fish oil in parenteral nutrition

OBJECTIVE: Fish oil is a rich source of omega-3 fatty acids (FAs), especially eicosapentaenoic acid and docosahexaenoic acid. The existing data suggest that eicosapentaenoic acid and docosahexaenoic acid are the active agents in fish oil. A number of clinical trials have shown that dietary fish oil supplementation has antiatherogenic properties and immunomodulation effects. Fish oils are not used widely in parenteral nutrition because fish oil emulsions have not been commercially available until very recently. Studies concerning the use of fish oil in parenteral route are rare. METHODS: We reviewed the effect of parenteral fish oil infusion on lipid metabolism and immune response in normal and disease conditions. RESULTS: Studies showed that the main effects of parenteral infusion of fish oil are: 1) incorporation of omega-3 FAs into cellular membranes of many cell populations that consequently influence the disease process of some disease conditions, 2) an effect on eicosanoid metabolism leading to a decrease in platelet aggregation and thrombosis, 3) amelioration of the severity of diet-induced hepatic steatosis, 4) less accumulation of lipid peroxidation products in liver tissue, and 5) immunomodulation effects and therapeutic benefits in animal disease models or various disease conditions of humans. Most of these studies suggested that parenteral infusion of omega-3 FAs have clinical beneficial effects comparable to those of dietary administration. However, different effects of omega-3 and omega-6 FAs in some situations has been reported. For example, plasma triacylglycerol levels were not lowered after fish oil infusion in normal or diabetic rats when compared with those of safflower oil or soybean oil infusion. The reason for the difference remain unclear. CONCLUSION: The metabolic and immunologic effects of parenteral use of omega-3 FAs requires further evaluation, especially in some disease conditions.     

Butter differs from olive oil and sunflower oil in its effects on postprandial lipemia and triacylglycerol-rich lipoproteins after single mixed meals in healthy young men

Accumulation of postprandial triacylglycerol-rich lipoproteins is generated by assimilation of ingested dietary fat and has been increasingly related to atherogenic risk. Nevertheless, the influence of different kinds of dietary fatty acids on postprandial lipid metabolism is not well established, except for (n-3) polyunsaturated long-chain fatty acids. Our goal was to evaluate the effects of test meals containing a common edible fat source of saturated (butter), monounsaturated (olive oil) or (n-6) polyunsaturated (sunflower oil) fatty acids on postprandial lipid and triacylglycerol-rich lipoprotein responses. After a 12-h fast, 10 healthy young men ingested mixed meals containing 0 g (control) or 40 g fat, provided as butter, olive oil or sunflower oil in a random order. Fasting and postmeal blood samples were collected for 7 h. The no-fat test meal did not elicit any change over baseline except for plasma phospholipids, insulin and nonesterified fatty acids. Conversely, the three fat-containing meals elicited bell-shaped postprandial changes (P < 0.05) in serum triacylglycerols, free and esterified cholesterol, and nonesterified fatty acids. The butter meal induced a lower postprandial rise of triacylglycerols in serum and chylomicrons (incremental AUC, mmol.h/L: 0.72) than the two unsaturated oils (olive oil: 1.6, sunflower oil: 1.8), which did not differ. Circulating chylomicrons were smaller after the butter meal than after the two vegetable oil meals. The in vitro susceptibility of circulating chylomicrons to hydrolysis by postheparin plasma was higher after sunflower oil than after butter or olive oil. We conclude that butter results in lower postprandial lipemia and chylomicron accumulation in the circulation of young men than olive or sunflower oils after consumption of a single mixed meal.     

Fatty acid composition and degradation level of the oils used in canned fish as a function of the different types of fish

An experimental investigation was carried out to assess the fatty acid composition and the degradation level of the covering oil present in canned fish. The most commonly marketed canned fish types were considered (tuna, sardines, anchovies, mackerels), as well as different kinds of covering oil: extra virgin olive oil, olive oil, refined seed oil. A total of 68 samples were analyzed. Two-way analysis of variance, followed by Fisher's Least Significant Difference test for multiple comparisons, and principal component analysis were carried out to compare the effect of both type of oil used and kind of fish on oil quality. The obtained results showed the lowest extent of both hydrolytic and oxidative degradation in samples containing extra virgin olive oil. In particular, the contents of triacylglycerol oligopolymers, imputable to secondary oxidative degradation, were equal to 0.17%, 0.50% and 0.74% for extra virgin olive oil, olive oil and refined seed oil, respectively. Olive oil showed significantly higher hydrolytic degradation, with diacylglycerols equal to 3.37%, but lower oxidative degradation and trans isomers content than refined seed oil. Finally, the type of fish did not seem to influence the extent of oxidative and hydrolytic degradation, with the only exception of sardines’ covering oil. This oil, characterized by the highest polyunsaturated fatty acid content, showed the highest values of oxidized triacylglycerols (1.32%) and specific absorption at 232 (K₂₃₂, 4.030), indices of primary oxidative degradation.     

Supplementation of fish oil and olive oil in patients with rheumatoid arthritis

OBJECTIVE: This study evaluated whether supplementation with olive oil could improve clinical and laboratory parameters of disease activity in patients who had rheumatoid arthritis and were using fish oil supplements. METHODS: Forty-three patients (34 female, 9 male; mean age = 49 +/- 19y) were investigated in a parallel randomized design. Patients were assigned to one of three groups. In addition to their usual medication, the first group (G1) received placebo (soy oil), the second group (G2) received fish oil omega-3 fatty acids (3 g/d), and the third group (G3) received fish oil omega-3 fatty acids (3 g/d) and 9.6 mL of olive oil. Disease activity was measured by clinical and laboratory indicators at the beginning of the study and after 12 and 24 wk. Patients' satisfaction in activities of daily living was also measured. RESULTS: There was a statistically significant improvement (P < 0.05) in G2 and G3 in relation to G1 with respect to joint pain intensity, right and left handgrip strength after 12 and 24 wk, duration of morning stiffness, onset of fatigue, Ritchie's articular index for pain joints after 24 wk, ability to bend down to pick up clothing from the floor, and getting in and out of a car after 24 wk. G3, but not G2, in relation to G1 showed additional improvements with respect to duration of morning stiffness after 12 wk, patient global assessment after 12 and 24 wk, ability to turn faucets on and off after 24 wk, and rheumatoid factor after 24 wk. In addition, G3 showed a significant improvement in patient global assessment in relation to G2 after 12 wk. CONCLUSIONS: Ingestion of fish oil omega-3 fatty acids relieved several clinical parameters used in the present study. However, patients showed a more precocious and accentuated improvement when fish oil supplements were used in combination with olive oil.     

Ratio of oleic to palmitic acid is a dietary determinant of thrombogenic and fibrinolytic factors during the postprandial state in men

BACKGROUND: The nature of dietary fats affects the postprandial activation of the hemostatic system. OBJECTIVE: We investigated whether the ratio of oleic to palmitic acid [and that of monounsaturated to saturated fatty acids (MUFA:SFA)] in the diet affects postprandial concentrations of triacylglycerols, tissue factor (TF), fibrinogen, tissue-type plasminogen activator (t-PA), and plasminogen activator inhibitor 1 (PAI-1). DESIGN: We studied the effects of diets enriched in olive oil (ROO), high-palmitic sunflower oil (HPSO), butter, or a mixture of vegetable and fish oils (VEFO) on circulating concentrations of the aforementioned factors in 14 healthy men. The fats had ratios of oleic to palmitic acid (MUFA:SFA) of 6.83 (5.43), 2.36 (2.42), 0.82 (0.48), and 13.81 (7.08). RESULTS: The largest and longest-lasting postprandial changes in plasma triacylglycerol concentrations were found with the butter-based diet (all P < 0.05). No correlation was observed between the net incremental area under the curve (netAUC) for triacylglycerol and the ratio of oleic to palmitic acid (or MUFA:SFA) in the dietary fats. The netAUCs for TF and PAI-1, however, were inversely related to the ratio of oleic to palmitic acid (and MUFA:SFA) in ROO, HPSO, butter, and VEFO. Similar results were found for the fibrinogen netAUC when VEFO was omitted from the analysis. The netAUC for t-PA was inversely correlated with postprandial concentrations of triacylglycerol. CONCLUSIONS: Postprandial concentrations of TF, fibrinogen, and PAI-1 are associated with the ratio of oleic to palmitic acid (MUFA:SFA) in dietary fats. The postprandial t-PA response is related to postprandial concentrations of triacylglycerol.     

Evaluation of the composition of omega-3 fatty acids in dietary oil supplements

Aim: The aim of the present study was to determine the fatty acid composition of 19 dietary oil supplements that are commercially available in Australia, comparing findings with manufacturers' reported omega-3 fatty acid content. Methods: Fifteen fish oil supplements and four non-fish oil supplements were obtained from Australian retail stores. Fatty acids were derivatised, and fatty acid methyl esters were quantitated using classical GC-flame ionisation detection methods. Composition of eicosapentaenoic acid and docosahexaenoic acid reported by supplement manufacturers was compared with experimental values using the Bland-Altman plot. Results: The combined eicosapentaenoic acid and docosahexaenoic acid content in the fish oil and non-fish oil supplements was 17.63–71.45% and 0.00–0.05% respectively. A high level of congruency was observed for the composition of eicosapentaenoic acid and docosahexaenoic acid reported by manufacturers and determined experimentally (mean difference, eicosapentaenoic acid, 13.2 mg; docosahexaenoic acid, 12.8 mg). Conclusion: Current practice in pre-market assessment of complementary medicines in Australia is satisfactory for supplements examined in the present study. Intake of these fish oil supplements can be used to provide high levels of long-chain omega-3 fatty acids that would be otherwise difficult to achieve through normal dietary intake alone.     

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

A wealth of evidence indicates that consumption of fish or dietary fish oils containing long-chain (n-3) PUFA such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is associated with cardiovascular benefit, including a reduction in circulating triacylglycerol concentrations and reduced mortality from coronary heart disease. Shorter-chain dietary (n-3) PUFA such as alpha-linolenic acid from vegetable oils are inefficiently converted to EPA and DHA and do not possess the hypotriglyceridemic properties attributed to fish oils. The objective of this study was to investigate the effect of dietary Echium oil, a plant oil containing the 18-carbon (n-3) PUFA stearidonic acid, on tissue fatty acid content and serum triacylglycerol concentrations in hypertriglyceridemic humans. Asymptomatic subjects with mild-to-moderate hypertriglyceridemia were enrolled in an open-labeled study. Subjects underwent a 4-wk lead-in period and were then instructed to follow the National Cholesterol Education Program Step 1 diet. Subjects (n = 11) whose serum triacylglycerol concentrations remained between 3.4 and 5.1 mmol/L (300 and 450 mg/dL) were instructed to consume 15 g of Echium oil daily for 4 wk. During the treatment period, serum triacylglycerol concentrations decreased by 21%, or 0.87 +/- 0.26 mmol/L (mean +/- SD) compared with baseline (P < 0.05); 8 of 11 subjects had a decrease in serum triacylglycerols ranging from 13 to 52% with a decrease from baseline of 30%, or 1.26 +/- 0.41 mmol/L (mean +/- SD). There were no significant changes in any other clinical laboratory variables. Concentrations of long-chain (n-3) PUFA, including EPA, increased (P < 0.05) in plasma and neutrophils when subjects consumed Echium oil. In conclusion, dietary plant oils rich in stearidonic acid are metabolized to longer-chain, more unsaturated (n-3) PUFA. These oils appear to possess hypotriglyceridemic properties typically associated with fish oils.     

Lymphatic transport in rats of several dietary fats differing in fatty acid profile and triacylglycerol structure

We examined in rats the intestinal absorption of nine very different dietary fats (two rapeseed oils, corn, olive, palm and menhaden oil, butter, cocoa butter and lard) to investigate the influence of fatty acid profile and triacylglycerol structure on absorption. Absorption was followed for 24 h after administration of similar amounts of fats, and the accumulated lymphatic transport and amount of triacylglycerols found in lymph in response to the administered fats were calculated, revealing major differences. The transport of olive and low alpha-linolenic rapeseed oil was significantly higher than that of the other fats (P < 0.05), except corn oil. The lymphatic transport of the other fats followed a slower course, with cocoa butter and menhaden oil having the lowest amounts transported. The amount of triacylglycerols found in lymph in response to the administered fats at 8 h ranged from 27.5% of the administered dose for cocoa butter to 72.1% for olive oil. The value for cocoa butter was significantly lower than that for most other fats. At 24 h, the values ranged from 66.5% for cocoa butter to 121.2% for olive oil. The high value for olive oil suggested transport of endogenous as well as exogenous fatty acids. The low value observed after cocoa butter resulted from decreased lipolysis and possibly also low absorption of triacylglycerols with high levels of long-chain saturated fatty acids in the sn-1/3 position. Furthermore, a low value was observed after menhaden oil administration, suggesting decreased absorption of fats containing (n-3) long-chain polyunsaturated fatty acids. Overall, these results demonstrate the influence of the fatty acid composition and triacylglycerol structure on the lymphatic absorption of dietary fat.     

Absorption of the n-3 eicosapentaenoic and docosahexaenoic acids as ethyl esters and triglycerides by humans.

Five normolipemic subjects received three test meals containing 28 g n-3 (omega-3) fatty acids provided as 1) triglycerides, 2) ethyl esters, and 3) ethyl esters + 12 g olive oil. The control meal contained olive oil. When equivalent amounts of fat were given, the increase in chylomicron and plasma triglycerides was similar; n-3 fatty acid contents were also similar after n-3 fatty acid intake as ethyl esters or triglycerides. Ethyl esters alone were well absorbed and produced similar n-3 fatty acid responses in plasma triglycerides and chylomicrons. At 24 h after the n-3 fatty acid-containing meals, the fatty acid plasma concentration of these acids was similar. This study showed that n-3 fatty acids in fish oil given as ethyl esters or triglycerides were equally well absorbed. Eicosapentaenoic and docosahexaenoic acids were also equally absorbed.     

Differential effects of saturated and monounsaturated fatty acids on postprandial lipemia and incretin responses in healthy subjects.

BACKGROUND: Elevations of postprandial triacylglycerol-rich plasma lipoproteins and suppressions of HDL-cholesterol concentrations are considered potentially atherogenic. Long-term studies have shown beneficial effects of monounsaturated fatty acids (eg, oleic acid) on fasting lipid and lipoprotein concentrations in humans. A direct stimulatory effect of oleic acid on the secretion of glucagon-like peptide 1 (GLP-1) was shown in animal studies. OBJECTIVE: We compared the postprandial responses of glucose, insulin, fatty acids, triacylglycerol, gastric inhibitory polypeptide (GIP), and GLP-1 to test meals rich in saturated and monounsaturated fatty acids. DESIGN: Ten young, lean, healthy persons ingested 3 meals: an energy-free soup consumed with 50 g carbohydrate (control meal), the control meal plus 100 g butter, and the control meal plus 80 g olive oil. Triacylglycerol and retinyl palmitate responses were measured in total plasma, in a chylomicron-rich fraction, and in a chylomicron-poor fraction. RESULTS: No significant differences in glucose, insulin, or fatty acid responses to the 2 fat-rich meals were seen. Plasma triacylglycerol responses were highest after the butter meal, with chylomicron triacylglycerol rising 2.5-5-fold. Retinyl palmitate responses were higher and more prolonged after the butter meal than after the control and olive oil meals, whereas both postprandial HDL-cholesterol concentrations and GLP-1 and GIP responses were higher after the olive oil meal than after the butter meal. CONCLUSIONS: Olive oil induced lower triacylglycerol concentrations and higher HDL-cholesterol concentrations than butter, without eliciting differences in concentrations of glucose, insulin, or fatty acids. Furthermore, olive oil induced higher concentrations of GLP-1 and GIP than did butter, which may point to a relation between fatty acid composition, incretin responses, and triacylglycerol metabolism in the postprandial phase.     

Acute postprandial effect of hydrogenated fish oil, palm oil and lard on plasma cholesterol, triacylglycerol and non-esterified fatty acid metabolism in normocholesterolaemic males

The majority of research has focused on the association between trans unsaturated fatty acids (TUFA) from hydrogenated vegetable oils and heart disease even though TUFA are also produced from hydrogenated fish oil. We compared the acute effect of three solid fats on postprandial cholesterol, triacylglycerol (TAG) and NEFA concentrations in normocholesterolaemic males. Eight healthy male volunteers consumed each of the three 40 g fat meals (partially hydrogenated fish oil (PHFO), palm oil and lard) in random order and blood samples were drawn at 2, 4, 6 and 8 h thereafter for lipid analysis. The postprandial response in plasma TAG, TAG-rich lipoprotein-TAG (TRL-TAG), total cholesterol and plasma NEFA, measured as the area under the postprandial curve, was not significantly different between the three meals (P>0.05), which varied in MUFA, PUFA and TUFA content. There was no marked elevation of longer-chain fatty acids (C20-22, cis or trans isomers) into the TRL-TAG fraction following the PHFO meal even though they provided 40 % of the total fatty acids in the PHFO meal. The postprandial TRL-TAG response to PHFO was expected to be higher, as it is higher in TUFA, lower in PUFA and similar in saturated fatty acid composition compared with the lard and palm oil test meals. The absence of a higher postprandial response following ingestion of PHFO could be as a result of reduced absorption and increased oxidation of long-chain fatty acids (both cis and trans isomers).     

Omega-3 polyunsaturated fatty acid profiling using fingertip-prick whole blood does not require overnight fasting before blood collection

Fatty acid profiling through the rapid analysis of capillary blood collected by fingertip prick could enable economical screening for omega-3 polyunsaturated fatty acid (PUFA) status, although the typical requirement of fasting prior to sample collection may limit application. We hypothesize that moderate changes in omega-3 biomarkers determined from fingertip-prick blood will occur and correspond to omega-3 PUFA content of the meals. Eight participants consumed a single breakfast with high fat, high fat with omega-3 functional foods, and low fat and low fat with fish oil capsules in a cross-over design. The fatty acid composition of fingertip-prick blood total lipid and venous blood erythrocyte total lipid, plasma total lipid, plasma triacylglycerol, and plasma phospholipids were analyzed at baseline and 1, 2, 3 and 4 hours after each single breakfast consumption. Omega-3 blood biomarkers; % of omega-3 highly unsaturated fatty acid (HUFA) in total HUFA, weight % of eicosapentaenoic acid+docosahexaenoic acid, weight % of eicosapentaenoic acid+omega-3 docosapentaenoic acid+docosahexaenoic acid, and the ratio of total omega-6 PUFA to total omega-3 PUFA in fingertip-prick blood, did not change from baseline during the postprandial period (P > .05). However, meal type yielded lower (P < .05) % omega-3 HUFA in total HUFA in the low fat meal (22.8 ± 3.9) as compared with the low fat with omega-3 (24.2 ± 3.9) and, the high fat (23.8 ± 4) meals. The ratio of total omega-6 PUFA to total omega-3 PUFA was generally higher in meals without omega-3 compared with omega-3. In conclusion, determinations of omega-3 status by fingertip-prick blood sampling may not require prior overnight fasting.     

Effect of dietary seal and fish oils on lipid metabolism in hamsters

Eicosapentaenoic and docosahexaenoic acids were distributed mainly in the sn-1 and 3 positions of seal oil triacylglycerols and in the sn-2 position of fish oil triacylglycerols. Seal oil-rich or fish oil-rich fats having constant polyunsaturated (PUFAs)/monounsaturated/saturated fatty acids and n-6/n-3 PUFAs ratios were fed to hamsters for 3 weeks. The control fat contained linoleic acid as the sole PUFA. The concentration of triacylglycerols in the liver was significantly lower in the fish oil group than in the control group. Phospholipid concentration in serum was lower and that in the liver was higher in the seal oil group compared with the fish oil group. The activities of fatty acid synthase (FAS), glucose-6-phosphate dehydrogenase (G6PDH), and the malic enzyme were significantly lower in both the fish and seal oil groups than in the control group. Dietary seal oil more effectively reduced arachidonic acid content in liver phosphatidylcholine and phosphatidylethanolamine and serum phosphatidylcholine than fish oil. These results showed that different intramolecular distribution of n-3 PUFAs influenced glycerolipid metabolism and arachidonic acid content in serum and liver phospholipids of hamsters.     

Differential effects of saturated and monounsaturated fats on postprandial lipemia and glucagon-like peptide 1 responses in patients with type 2 diabetes

BACKGROUND: Postprandial lipemia is important in the development of coronary artery disease because of elevated postprandial triacylglycerol-rich plasma lipoproteins and suppressed HDL-cholesterol concentrations. We showed in healthy subjects a possible association between postprandial lipid metabolism and the responses of the duodenal incretin hormones glucagon-like peptide 1 (GLP-1) and gastric inhibitory polypeptide after meals rich in saturated and monounsaturated fatty acids (oleic acid), respectively. OBJECTIVE: The objective was to compare the postprandial responses (8 h) of glucose, insulin, fatty acids, triacylglycerol, gastric inhibitory polypeptide, and GLP-1 to saturated- and monounsaturated-rich test meals. DESIGN: Twelve overweight patients with type 2 diabetes ingested 3 meals randomly: an energy-free soup with 50 g carbohydrate (control meal), the control meal plus 100 g butter, and the control meal plus 80 g olive oil. Triacylglycerol responses were measured in total plasma and in a chylomicron-rich and a chylomicron-poor fraction. RESULTS: No significant differences in the glucose, insulin, or fatty acid responses to the 2 fat-rich meals were seen. The plasma triacylglycerol and chylomicron triacylglycerol responses were highest after the butter meal. HDL-cholesterol concentrations decreased significantly after the butter meal but did not change significantly after the olive oil meal. GLP-1 responses were highest after the olive oil meal. CONCLUSIONS: Olive oil induced lower triacylglycerol concentrations and higher HDL-cholesterol concentrations than did butter, without eliciting significant changes in glucose, insulin, or fatty acids. Furthermore, olive oil induced higher concentrations of GLP-1, which may indicate a relation between fatty acid composition, incretin responses, and triacylglycerol metabolism postprandially in patients with type 2 diabetes.     

Effect of fish oil pretreatment on isoproterenol-induced changes in myocardial membrane phospholipids

OBJECTIVE: In the present study, the protective effect of fish oil treatment on the fatty acid composition in isoproterenol (IPH)-induced myocardial infarction was studied in male albino Wistar rats. METHODS: Rats were injected for 2 consecutive days with IPH (60 mg/kg body weight) at 24-h intervals to induce myocardial infarction. Fish oil was administered orally at a dose of 0.05 mL/d for 45 d, after which serum and heart tissue were assayed for lipid profile, lipoprotein changes, and myocardial membrane phospholipid fatty acid composition. RESULTS: Biochemical assessment of myocardial infarction was done by measuring the activities of creatinine kinase and lactate dehydrogenase, which were significantly elevated in the rats administered with IPH. Further, the administration of IPH modified the fatty acid composition and analysis of fatty acids showed there was an increase in the omega-3/omega-6 ratio in phospholipid pool. In addition, increased levels of total cholesterol, free cholesterol, ester cholesterol, phospholipids, triacylglycerols and free fatty acid was observed in serum and heart tissue of IPH-induced rats. The fish oil treatment for a period of 45 d decreased the levels of cardiac markers (creatinine kinase and lactate dehydrogenase) and reversed the biochemical lesions induced by IPH. CONCLUSION: Our study suggests that fish oil treatment has a hypolipidemic effect and has potential use in the treatment of myocardial infarction.     

Olive oil- and fish oil-enriched diets modify plasma lipids and susceptibility of LDL to oxidative modification in free-living male patients with peripheral vascular disease: the Spanish Nutrition Study

The present study describes a clinical trial in which Spanish patients suffering from peripheral vascular disease (Fontaine stage II) were given specific lipid supplements. Designed as a longitudinal intervention study, patients were provided with olive oil for 3 months, followed by a 3 month wash-out period, then supplemented with a combination of fish oil and olive oil for the final 3 months. Changes in plasma and lipoprotein fatty acid composition and susceptibility of LDL to in vitro oxidation were examined. Furthermore, lipid-supplement-induced changes in LDL properties were measured as relative electrophoretic mobility and macrophage uptake. In addition, thirteen patients not provided with olive oil and fish oil were included as a control group and twenty healthy age-matched individuals were used as a reference group. A complete clinical study and a nutritional survey concerning food habits and lifestyle were performed every 3 months. Yao indices and claudicometry did not change significantly with dietary intervention although changes in plasma lipid composition suggested an improvement in the condition of the patients. The intake of the fish-oil supplement resulted in significantly increased plasma levels of eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) in comparison with baseline concentrations, olive-oil and control groups. Fish-oil consumption significantly decreased plasma triacylglycerol levels compared with the olive-oil period, control and reference groups. The susceptibility of LDL to Cu-mediated oxidation was lower in the patients consuming olive oil and the fish-oil supplement than in the control group, and the uptake of LDL by macrophages was significantly lower in the group supplemented with fish oil. In conclusion, consumption of olive oil together with a dietary supplement of fish oil may be useful in the nutritional management of patients suffering from peripheral vascular disease in terms of increasing plasma n-3 long-chain polyunsaturated fatty acids and decreasing susceptibility of LDL to oxidation.