Comparative effects of perilla and fish oils on the activity and gene expression of fatty acid oxidation enzymes in rat liver

The activity and mRNA level of hepatic enzymes in fatty acid oxidation and synthesis were compared in rats fed diets containing either 15% saturated fat (palm oil), safflower oil rich in linoleic acid, perilla oil rich in α-linolenic acid or fish oil rich in eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) for 15 days. The mitochondrial fatty acid oxidation rate was 50% higher in rats fed perilla and fish oils than in the other groups. Perilla and fish oils compared to palm and safflower oils approximately doubled and more than tripled, respectively, peroxisomal fatty acid oxidation rate. Compared to palm and safflower oil, both perilla and fish oils caused a 50% increase in carnitine palmitoyltransferase I activity. Dietary fats rich in n-3 fatty acids also increased the activity of other fatty acid oxidation enzymes except for 3-hydroxyacyl-CoA dehydrogenase. The extent of the increase was greater with fish oil than with perilla oil. Interestingly, both perilla and fish oils decreased the activity of 3-hydroxyacyl-CoA dehydrogenase measured using short- and medium-chain substrates. Compared to palm and safflower oils, perilla and fish oils increased the mRNA level of many mitochondrial and peroxisomal enzymes. Increases were generally greater with fish oil than with perilla oil. Fatty acid synthase, glucose-6-phosphate dehydrogenase, and pyruvate kinase activity and mRNA level were higher in rats fed palm oil than in the other groups. Among rats fed polyunsaturated fats, activities and mRNA levels of these enzymes were lower in rats fed fish oil than in the animals fed perilla and safflower oils. The values were comparable between the latter two groups. Safflower and fish oils but not perilla oil, compared to palm oil, also decreased malic enzyme activity and mRNA level. Examination of the fatty acid composition of hepatic phospholipid indicated that dietary α-linolenic acid is effectively desaturated and elongated to form EPA and DHA. Dietary perilla oil and fish oil therefore exert similar physiological activity in modulating hepatic fatty acid oxidation, but these dietary fats considerably differ in affecting fatty acid synthesis.     

Stimulation of acyl-CoA oxidase by alpha-linolenic acid-rich perilla oil lowers plasma triacylglycerol level in rats

The effect of dietary polyunsaturated fatty acids (PUFA) on hepatic peroxisomal oxidation was investigated with respect to the postprandial triacylglycerol levels. Male Sprague--Dawley rats were fed semipurified diets containing either 1% (w/w) corn oil, or 10% each of beef tallow, corn oil, perilla oil, and fish oil for 4 weeks and 4 days. Hepatic and plasma triacylglycerol levels were reduced in rats fed fish and perilla oil diets compared with corn oil and beef tallow diets. The peroxisomal beta-oxidation, catalase activity, and acyl-CoA oxidase (AOX) activity were markedly increased by fish oil feeding. To a lesser extent, perilla oil elevated AOX activity in a 4-day feeding although the effect gradually decreased in a 4-week feeding. Similarly, the mRNA levels were increased in rats fed fish and perilla oils. AOX activity was negatively correlated with postprandial triacylglycerol levels. In addition, the stimulation of AOX was highly associated with the content of long chain n-3 PUFA such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in hepatic microsome. These effects were evident within 4 days of initiating feeding. Therefore, alpha-linolenic perilla oil exerts a similar effect to fish oil in stimulating hepatic activity and gene expression of AOX by enriching long chain n-3 PUFA in hepatic membrane fraction, which can partly account for the reduction of postprandial triglyceridemia.     

Suppression of hepatic fatty acid synthase by feeding alpha-linolenic acid rich perilla oil lowers plasma triacylglycerol level in rats

This study was performed to determine the effects of dietary perilla oil, a n-3 alpha-linolenic acid (ALA) source, on hepatic lipogenesis as a possible mechanism of lowering triacylglycerol (TG) levels. Male Sprague-Dawley rats were trained for a 3-hour feeding protocol and fed one of five semipurified diets as follows: 1% (w/w) corn oil control diet, or one of four diets supplemented with 10% each of beef tallow, corn oil, perilla oil, and fish oil. Two separate experiments were performed to compare the effects of feeding periods, 4 weeks and 4 days. Hepatic and plasma TG levels were decreased in rats fed perilla oil and fish oil diets, compared with corn oil and beef tallow diets. The activities of hepatic lipogenic enzymes such as fatty acid synthase (FAS), glucose-6-phosphate dehydrogenase, and malic enzyme were suppressed in the fish oil, perilla oil, and corn oil-fed groups, and the effect was the most significant in the fish oil-fed group. Also, the activities of glycolytic enzymes, glucokinase, and L-pyruvate kinase showed the similar trend as that of lipogenic enzymes. The activity of FAS, the key regulatory enzyme in lipogenesis, was positively correlated with hepatic and plasma TG levels and reduced significantly in the perilla oil-fed group compared with corn oil-fed group. In addition, the FAS activity was negatively correlated with the hepatic microsomal content of EPA and DHA. In conclusion, suppression of FAS plays a significant role in the hypolipidemic effects observed in rats fed ALA rich perilla oil and these effects were associated with the increase of hepatic microsomal EPA and DHA contents.     

Low dietary fish-oil threshold for myocardial membrane n-3 PUFA enrichment independent of n-6 PUFA intake in rats

Long chain n-3 PUFA docosahexaenoic acid (DHA) is important for heart and brain function. Investigations of biologically plausible mechanisms using animal models associate cardioprotection with DHA incorporation into myocardial membranes that are largely derived from supra-physiological fish oil (FO) intake. We measured the incorporation of DHA into myocardial membranes of rats from low dietary FO intake within human dietary range and quantitatively assessed the influence of dietary n-6 PUFA. With rats fed diets containing 0.16%–5% FO, equal to 0.12%–8.7% energy (%en) as eicosapentaenoic acid (EPA) and DHA (EPA+DHA), and either 1.5%en or 7.5%en n-6 PUFA (linoleic acid) for four weeks, dietary n-6:n-3 PUFA ratios ranged from 74 to 0.3. Myocardial DHA concentration increased in a log-linear fashion with a dietary threshold of 0.019%en as EPA+DHA and half maximal dietary [EPA+DHA] equal to 0.29%en (95% CI, 0.23–0.35). Dietary linoleic acid intake did not influence myocardial DHA. Myocardial membranes are sensitive to absolute dietary intake of long chain n-3 PUFA at low %en in the rat, equivalent to a human intake of one meal of fatty fish per week or less. The dietary ratio of n-6:n-3 PUFA has no influence on long chain n-3 PUFA cellular incorporation from dietary fish oil.     

Dietary n-3 PUFAs affect the blood pressure rise and cardiac impairments in a hyperinsulinemia rat model in vivo

The cardiovascular consequences of eicosapentaenoic acid (EPA)- and docosahexaenoic acid (DHA)-specific intake were evaluated in vivo in a hyperinsulinemia (HI) model induced by dietary fructose intake. Wistar rats were fed a diet containing (or not for control) either EPA or DHA. The rise in blood pressure (BP), heart rate, and ECG were continuously monitored using an intra-abdominal telemetry system. The myocardial phospholipid fatty acid profile was significantly affected by DHA intake but less by EPA intake. The data indicated a reduced rise in BP in both DHA and EPA HI groups compared with controls. This result was confirmed by tail-cuff measurement after 5 wk [133.3 +/- 1.67 and 142.5 +/- 1.12 mmHg in n-3 polyunsaturated fatty acid (PUFA) and control groups, respectively], whereas n-3 PUFA did not affect BP in non-HI rats (116.3 +/- 3.33 mmHg). The heart rate was lower in the HI DHA group than in the other two dietary HI groups. Moreover, DHA induced a significantly shorter QT interval. It is concluded that the cardioactive component of fish oils is DHA through a mechanism that may involve the cardiac adrenergic system.     

Influences of stearidonic acid-enriched soybean oil on the blood and organ biochemical parameters in rats

In this study, we administered various diets of stearidonic acid (SDA, 18:4n?3) soybean oil to rats and examined the subsequent blood and organ biochemical parameters. Male Wistar rats (seven rats/group, six groups total) were fed diets supplemented with a test oil for 4 weeks. Diets containing test oils were: FFC diet (fish-oil-free control diet), C diet (control group, assuming a Japanese diet), SDA25 diet (25% 18:4n?3 soybean oil in the C diet), SDA50 (50% 18:4n?3 soybean oil in the C diet), ALA diet (34% flaxseed oil in the C diet), and EPA+DHA diet (34% fish oil in the C diet). The intake of 18:4n?3 showed increased relative efficiency of 20:5n?3 accretions in serum and liver triacylglycerol and significantly decreased the serum triacylglycerol level in rats. The results suggested that the consumption of 18:4n?3 soybean oil may modify the lipid and fatty acid profiles of body fats, even when EPA and DHA derived from fish is consumed.     

Divergent effects of eicosapentaenoic and docosahexaenoic acid ethyl esters, and fish oil on hepatic fatty acid oxidation in the rat

The physiological activity of fish oil, and ethyl esters of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) affecting hepatic fatty acid oxidation was compared in rats. Five groups of rats were fed various experimental diets for 15 days. A group fed a diet containing 9.4% palm oil almost devoid of n-3 fatty acids served as a control. The test diets contained 4% n-3 fatty acids mainly as EPA and DHA in the form of triacylglycerol (9.4% fish oil) or ethyl esters (diets containing 4% EPA ethyl ester, 4% DHA ethyl ester, and 1% EPA plus 3% DHA ethyl esters). The lipid content of diets containing EPA and DHA ethyl esters was adjusted to 9.4% by adding palm oil. The fish oil diet and ethyl ester diets, compared to the control diet containing 9.4% palm oil, increased activity and mRNA levels of hepatic mitochondrial and peroxisomal fatty acid oxidation enzymes, though not 3-hydroxyacyl-CoA dehydrogenase activity. The extent of the increase was, however, much greater with the fish oil than with EPA and DHA ethyl esters. EPA and DHA ethyl esters, compared to the control diet, increased 3-hydroxyacyl-CoA dehydrogenase activity, but fish oil strongly reduced it. It is apparent that EPA and DHA in the form of ethyl esters cannot mimic the physiological activity of fish oil at least in affecting hepatic fatty acid oxidation in rat.     

Eicosapentaenoic and docosahexaenoic acids enriched polyunsaturated fatty acids from the coastal marine fish of Bay of Bengal and their therapeutic value

Eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA) enriched polyunsaturated fatty acids (PUFA) significantly present in marine fish oil emerge as preventive agents for combating many health problems specially in chronic or metabolic disorders. The fish in the coastal area of Bay of Bengal has remained unexplored with respect to EPA/DHA enriched PUFA content in its oils, although it may be a potential source in harnessing the health benefit. In this study, seven varieties of the coastal fish were analysed for the content of EPA/DHA. The one locally known as lotte, (Harpadon nehereus) though has low content of total lipids, was found to have high EPA/DHA in its oil. The phospholipids rich fraction was extracted from the total fish oil. The EPA/DHA enriched PUFA was isolated to investigate the potential use for health benefits. EPA/DHA is found to act as protective agent against mercury poisoning studied in cell culture as well as in animal mode. It is found to be highly preventive in diabetes. The lotte is available in the coastal area of Bay of Bengal adjoining West Bengal, India in large scale and it is the first report showing EPA/DHA enriched PUFA in these fish oil that can be availed to harness in important health benefits.     

Lipase specificity towards eicosapentaenoic acid and docosahexaenoic acid depends on substrate structure

The fatty acid specificity of five lipases towards eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) was evaluated in the hydrolysis of fish oil, squid oil and a model system. The model system contained methyl esters of EPA, DHA and palmitic acid. All the investigated lipases discriminated against both EPA and DHA more in the model system than in the natural oils. Thus both EPA and DHA were more easily hydrolysed from a glyceride than from a methyl ester. In the model system, the lipase from Candida rugosa showed the highest discrimination against DHA, while the lipases from Pseudomonas fluorescens and Pseudomonas cepacia discriminated against EPA the most. In a glyceride, the fatty acid specificity of lipases towards EPA and DHA was affected by the positional distribution of the fatty acids and the glyceride structure due to the regiospecificity and triglyceride specificity of the lipase. In the oils, the Pseudomonas lipases also discriminated against EPA the most, while DHA was initially discriminated the most by the lipase from Thermomyces lanuginosus. However, after longer reaction times the enrichment of DHA in the glyceride fraction of the oils was greatest for the lipase from C. rugosa.     

Effect of randomized supplementation with high dose olive, flax or fish oil on serum phospholipid fatty acid levels in adults with attention deficit hyperactivity disorder

Dietary intake of omega-3 fatty acids has been positively correlated with cardiovascular and neuropsychiatric health in several studies. The high seafood intake by the Japanese and Greenland Inuit has resulted in low ratios of the omega-6 fatty acid arachidonic acid (AA, 20:4n-6) to eicosapentaenoic acid (EPA, 20:5n-3), with the Japanese showing AA:EPA ratios of approximately 1.7 and the Greenland Eskimos showing ratios of approximately 0.14. It was the objective of this study to determine the effect of supplementation with high doses (60 g) of flax and fish oils on the blood phospholipid (PL) fatty acid status, and AA/EPA ratio of individuals with Attention Deficit Hyperactivity Disorder (ADHD), commonly associated with decreased blood omega-3 fatty acid levels. Thirty adults with ADHD were randomized to 12 weeks of supplementation with olive oil (< 1% omega-3 fatty acids), flax oil (source of alpha-linolenic acid; 18:3n-3; alpha-LNA) or fish oil (source of EPA and docosahexaenoic acid; 22:6n-3; DHA). Serum PL fatty acid levels were determined at baseline and at 12 weeks. Flax oil supplementation resulted in an increase in alpha-LNA and a slight decrease in the ratio of AA/EPA, while fish oil supplementation resulted in increases in EPA, DHA and total omega-3 fatty acids and a decrease in the AA/EPA ratio to values seen in the Japanese population. These data suggest that in order to increase levels of EPA and DHA in adults with ADHD, and decrease the AA/EPA ratio to levels seen in high fish consuming populations, high dose fish oil may be preferable to high dose flax oil. Future study is warranted to determine whether correction of low levels of long-chain omega-3 fatty acids is of therapeutic benefit in this population.     

Docosahexaenoic acid (DHA) and cardiovascular disease risk factors

Numerous epidemiological and controlled interventional trials have supported the health benefits of long-chain omega-3 fatty acids in the form of docosahexaenoic acid (DHA, 22:6n-3) plus eicosapentaenoic acid (EPA, 20:5n-3) from fish and fish oils as well as from algal sources. The beneficial effects on cardiovascular disease and related mortality including various risk factors for cardiovascular disease (particularly lowering circulating triglyceride levels and the triglyceride:HDL-cholesterol ratio) have been observed in the absence of any concomitant blood cholesterol lowering. With appropriate dosages, consistent reductions in both fasting and postprandial triglyceride levels and moderate increases in fasting HDL-cholesterol levels have been observed with algal DHA in the majority of trials. These results are similar to findings for fish oils containing DHA and EPA. Related to greater fish intake, higher levels of DHA in circulating blood biomarkers (such as serum phospholipid) have been associated with reduced risks for the progression of coronary atherosclerosis and lowered risk from sudden cardiac death. Controlled clinical trials have also indicated the potential for algal DHA supplementation to have moderate beneficial effects on other cardiovascular disease risk factors including blood pressures and resting heart rates. Recommended intakes of DHA+EPA from numerous international groups for the prevention and management of cardiovascular disease have been forthcoming, although most have not offered specific recommendations for the optimal individual intake of DHA and EPA.     

Dietary docosahexaenoic acid ameliorates, but rapeseed oil and safflower oil accelerate renal injury in stroke-prone spontaneously hypertensive rats as compared with soybean oil, which is associated with expression for renal transforming growth factor-beta, fibronectin and renin

We have noted that n-3 fatty acid-rich oils, such as fish oil, perilla oil and flaxseed oil as well as ethyl docosahexaenoate (DHA) prolonged the survival time of stroke-prone spontaneously hypertensive rats (SHRSP) rats by approximately 10% as compared with linoleate (n-6)-rich safflower oil. Rapeseed oil with a relatively low n-6/n-3 ratio unusually shortened the survival time by approximately 40%, suggesting the presence of minor components unfavorable to SHRSP rats. This study examined the effects of dietary oils and DHA on renal injury and gene expression related to renal injury in SHRSP rats. Rats fed rapeseed oil- and safflower oil-supplemented diets developed more severe proteinuria than those fed soybean oil-supplemented diet used as a control, but there were no significant differences in blood pressure. In contrast, the DHA-supplemented diet inhibited the development of proteinuria and suppressed hypertension. The mRNA levels for renal TGF-beta, fibronectin and renin were higher in the rapeseed oil and safflower oil groups after 9 weeks of feeding of the experimental diet than in the soybean oil and DHA groups. The fatty acid composition of kidney phospholipids was markedly affected by these diets. These results indicate that the renal injury observed in the groups fed safflower oil with a high n-6/n-3 ratio and rapeseed oil with presumed minor components is accompanied by increased expression of the TGF-beta, renin and fibronectin genes, and that dietary DHA suppresses renal injury and gene expression as compared with soybean oil.     

Effect of rapeseed oil and dietary n-3 fatty acids on triacylglycerol synthesis and secretion in Atlantic salmon hepatocytes

Fish oil (FO) has traditionally been used as the dominating lipid component in fish feed. However, FO is a limited resource and the price varies considerably, which has led to an interest in using alternative oils, such as vegetable oils (VOs), in fish diets. It is far from clear how these VOs affect liver lipid secretion and fish health. The polyunsaturated fatty acids (PUFAs), eicosapentanoic acid (EPA) and docosahexanioc acid (DHA), reduce the secretion of lipoproteins rich in triacylglycerols (TAGs) in Atlantic salmon, as they do in humans. The mechanism by which n-3 fatty acids (FAs) in the diet reduce TAG secretion is not known. We have therefore investigated the effects of rapeseed oil (RO) and n-3 rich diets on the accumulation and secretion of (3)H-glycerolipids by salmon hepatocytes. Salmon, of approximately 90 g were fed for 17 weeks on one of four diets supplemented with either 13.5% FO, RO, EPA-enriched oil or DHA-enriched oil until a final average weight of 310 g. Our results show that the dietary FA composition markedly influences the endogenous FA composition and lipid content of the hepatocytes. The intracellular lipid level in hepatocytes from fish fed RO diet and DHA diet were higher, and the expressions of the genes for microsomal transfer protein (MTP) and apolipoprotein A1 (Apo A1) were lower, than those in fish fed the two other diets. Secretion of hepatocyte glycerolipids was lower in fish fed the EPA diet and DHA diet than it was in fish fed the RO diet. Our results indicate that EPA and DHA possess different hypolipidemic properties. Both EPA and DHA inhibit TAG synthesis and secretion, but only EPA induces mitochondrial proliferation and reduce intracellular lipid. Expression of the gene for peroxisome proliferator-activated receptor alpha (PPARalpha) was higher in the DHA dietary group than it was in the other groups.     

Reduced protein oxidation in Wistar rats supplemented with marine ω3 PUFAs

The potential effects of various dietary eicosapentaenoic acid (EPA; 20:5) and docosahexaenoic acid (DHA; 22:6) ratios (1:1, 2:1, and 1:2, respectively) on protein redox states from plasma, kidney, skeletal muscle, and liver were investigated in Wistar rats. Dietary fish oil groups were compared with animals fed soybean and linseed oils, vegetable oils enriched in ω6 linoleic acid (LA; 18:2) and ω3 α-linolenic acid (ALA; 18:3), respectively. Fish oil treatments were effective at reducing the level of total fatty acids in plasma and enriching the plasmatic free fatty acid fraction and erythrocyte membranes in EPA and DHA. A proteomic approach consisting of fluorescein 5-thiosemicarbazide (FTSC) labeling of protein carbonyls, FTSC intensity visualization on 1-DE or 2-DE gels, and protein identification by MS/MS was used for the protein oxidation assessment. Albumin was found to be the most carbonylated protein in plasma for all dietary groups, and its oxidation level was significantly modulated by dietary interventions. Supplementation with an equal EPA:DHA ratio (1:1) showed the lowest oxidation score for plasma albumin, followed in increasing order of carbonylation by 1:2 <2:1 ≈ linseed < soybean. Oxidation patterns of myofibrillar skeletal muscle proteins and cytosolic proteins from kidney and liver also indicated a protective effect on proteins for the fish oil treatments, the 1:1 ratio exhibiting the lowest protein oxidation scores. The effect of fish oil treatments at reducing carbonylation on specific proteins from plasma (albumin), skeletal muscle (actin), and liver (albumin, argininosuccinate synthetase, 3-α-hydroxysteroid dehydrogenase) was remarkable. This investigation highlights the efficiency of dietary fish oil at reducing in vivo oxidative damage of proteins compared to oils enriched in the 18-carbon polyunsaturated fatty acids ω3 ALA and ω6 LA, and such antioxidant activity may differ among different fish oil sources because of variations in EPA/DHA content.     

Omega-3 fatty acids from fish oils and cardiovascular disease

Fish and fish oils contain the omega-3 fatty acids known as eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA). Epidemiological studies have shown an inverse relation between the dietary consumption of fish containing EPA/DHA and mortality from coronary heart disease. These relationships have been substantiated from blood measures of omega-3 fatty acids including DHA as a physiological biomarker for omega-3 fatty acid status. Controlled intervention trials with fish oil supplements enriched in EPA/DHA have shown their potential to reduce mortality in post-myocardial infarction patients with a substantial reduction in the risk of sudden cardiac death. The cardioprotective effects of EPA/DHA are widespread, appear to act independently of blood cholesterol reduction, and are mediated by diverse mechanisms. Their overall effects include anti-arrhythmic, blood triglyceride-lowering, anti-thrombotic, anti-inflammatory, endothelial relaxation, plus others. Current dietary intakes of EPA/DHA in North America and elsewhere are well below those recommended by the American Heart Association for the management of patients with coronary heart disease. (Mol Cell Biochem 263: 217–225, 2004)     

Utilisation of fish oil in ruminants: II. Transfer of fish oil fatty acids into goats’ milk

A study was conducted to determine the transfer of eicosapentaenoic acid (EPA, 20:5) and docosahexaenoic acid (DHA, 22:6) from fish oil into goats’ milk. Goats were sequentially offered three diets: control (C) pellets (lucerne hay-oat grain: 60/40 w/w), C plus tuna oil protected against ruminal biohydrogenation (PTO pellets), and C plus unprotected tuna oil (UTO pellets). In supplemented diets, tuna oil constituted 3% of total dry matter (DM), and each supplement was fed for 7 days, with 12 days allowed between the two fish oil feeding periods to minimise carry-over effects. Dry matter intake, milk yield, protein and fat yield were reduced by feeding UTO, but not PTO, pellets. Goats produced ω-3 enriched milk (0.3–0.5% EPA and 1.01–1.12% DHA) when fed either supplement. The rate of transfer of dietary EPA and DHA to milk ranged from 3.5 to 7.6%. Significant transfer of EPA and DHA from tuna oil into goat milk, without deleterious effects on intake or milk yield is possible, provided that the oil supplement is substantially protected against ruminal biohydrogenation.     

Associations between omega-3 poly-unsaturated fatty acids from fish consumption and severity of depressive symptoms: an analysis of the 2005-2008 National Health and Nutrition Examination Survey

Fish is the primary source of dietary omega-3 poly-unsaturated fatty acids EPA and DHA, which have been reported to reduce depressive symptoms in clinical trials. We assessed the association between fish consumption and depressive symptoms in a nationally representative sample of 10,480 adults from the 2005-2008 National Health and Nutrition Examination Survey. Depressive symptoms were classified by severity using the Patient Health Questionnaire. Fish meal consumption reported in 30-day food frequency questionnaires, and EPA+DHA intake computed from 24-h dietary recalls were evaluated in relation to depressive symptoms using multivariable ordinal logistic regression. Consumption of breaded fish showed an increased risk of greater depressive symptom severity, while all fish, non-breaded fish, and shell fish were not associated. Any EPA+DHA intake was significantly associated with fewer depressive symptoms. Exposure-response analyses revealed no clear patterns for any intake measures. Inconsistent patterns of associations in our study may be partially explained by exposure misclassification.     

Dietary effect of EPA-rich and DHA-rich fish oils on the immune function of Sprague-Dawley rats

The dietary effect of fish oils (FOs) rich in eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) on the immune function of Sprague-Dawley rats was compared with that of safflower oil. After 3 weeks of feeding at the 10% level of a dietary fat, the IgG and IgM production by splenocytes and IgG production by mesenteric lymph node (MLN) lymphocytes were significantly higher in the FO-fed rats, while no significant difference was found in IgA or IgE productivity by both the spleen and MLN lymphocytes. In the FO-fed rats, peritoneal exudate cells released a lower amount of LTB4, reflecting their lower arachidonic acid level, and a higher amount of LTB5, reflecting their higher EPA level in phospholipids. On these EPA-rich FO exerted a stronger effect than DHA-rich FO immune functions.     

Increased uncoupling protein2 mRNA in white adipose tissue, and decrease in leptin, visceral fat, blood glucose, and cholesterol in KK-Ay mice fed with eicosapentaenoic and docosahexaenoic acids in addition to linolenic acid.

The effects of n-3 polyunsaturated fatty acids (n-3PUFA) on obesity and diabetes were examined using KK-Ay mice fed with perilla oil (P), soybean oil (S), or lard (L), and those containing 30% fish oil (PF, SF, or LF), containing eicosapentaenoic acid (EPA = 9.9%) and docosahexaenoic acid (DHA = 18.0%). Perilla oil contained the largest proportion of linolenic acid (LNA = 61.9%). Computerized tomography (CT) scans showed narrower areas of visceral fat in the abdominal cross sections of groups given fish oil (PF, SF, and LF) and lower leptin levels (p < 0.05-p < 0.001) compared with controls (P, S, and L), without significant changes in energy intake and body weight. The highest plasma n-3PUFA content (21.31 +/- 0.35%) was attained with PF. This group contained 2.6-fold more plasma DHA (p < 0.001), and expressed 2.7-fold more UCP2 mRNA in white adipose tissue (p < 0.01) than in the P group. The epididymal fat pad (p < 0.05) weighed less, and levels of blood glucose (p < 0.05) and total cholesterol (p < 0.01) were reduced in PF compared with P.     

Erythrocyte eicosapentaenoic acid versus docosahexaenoic acid as a marker for fish and fish oil consumption.

The fatty acid composition of erythrocyte membranes was investigated in 21 healthy men after 6 wk of varying intakes of eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). In one experiment, 12 subjects were fed three diets in a 3 x 3 crossover design: an essentially fish-free control diet, a fish diet (0.15 g EPA/d, 0.41 g DHA/d) and the same fish-based diet supplemented with 5 g/d fish oil (Fish + Oil: 0.99 g EPA/d, 0.99 g DHA/d). A 6 wk wash-out period was allowed between each diet. In another experiment, 11 subjects were supplemented with 5 g/d fish oil alone for 6 wk (0.84 g EPA/d, 0.48 g DHA/d). After fish or fish oil feeding, the percent proportion of EPA and DHA in the erythrocyte membranes rose at the expense of linoleic and arachidonic acids. After 6 wk on the fish-based diets, EPA incorporation approached saturation, with the incremental increases being proportional to the amounts supplied by the diets. In contrast, parallel increases were observed for erythrocyte DHA even though the Fish + Oil diet was supplying twice as much DHA as the fish alone diet. These observations imply different metabolic rates for EPA and DHA and their importance is discussed in terms of the value of erythrocyte EPA versus DHA as markers for fish and fish oil consumption.