Dietary effects of eicosapentaenoic and docosahexaenoic acid esters on lipid metabolism and immune parameters in Sprague-Dawley rats

Effect of fish paste products, fish balls 'tsumire', intake in Sprague-Dawley rats

The fish paste product, fish balls ‘tsumire’, is a traditional type of Japanese food made from minced fish as well as imitation crab, kamaboko and hanpen. Although tsumire is known as a high-protein and low-fat food, there is a lack of scientific evidence on its health benefits. Hence, we aimed to investigate the effects of tsumire intake on organ weight and biomarker levels in Sprague–Dawley rats for 84 d as a preliminary study. Six-week-old male Sprague–Dawley rats were divided into two groups: group I, fed normal diets, and group II, fed normal diets with 5 % dried tsumire. Throughout the administration period, we monitored their body weight and food intake; at the end of this period, we measured their organ weight and analysed their blood biochemistry. No significant differences were observed with respect to body weight, food intake, organ weight and many biochemical parameters between the two groups. It was found that inorganic phosphorus and glucose levels were higher in group II rats than in group I rats. On the other hand, sodium, calcium, amylase and cholinesterase levels were significantly lower in group II than in group I. Interestingly, we found that the levels of aspartate aminotransferase, alanine transaminase, lactate dehydrogenase and leucine aminopeptidase in group II were significantly lower than in group I, and that other liver function parameters of group II tended to be lower than in group I. In conclusion, we consider that the Japanese traditional food, ‘tsumire,’ may be effective as a functional food for human health management worldwide.

Effect of fish paste products "Hanpen" intake in Sprague-Dawley rats

Fish paste product, "Hanpen," is a traditional type of Japanese food made from minced fish as well as imitation crab and kamaboko, and a marshmallow-like soft texture is characteristic of hanpen. Hanpen is known as a high-protein and low-fat food. However, there is a lack of evidence on its health benefits. The aim of this study was to investigate the effects of hanpen intake on organ weight and biomarker levels in Sprague-Dawley rats with diets consisting of hanpen for 84 days as an initial study. Male, 6-week-old Sprague-Dawley rats were divided into two groups: group I, fed normal diets, and group II, fed normal diets with 5% dried hanpen. Throughout the 84-day treatment period, we checked body weight and food intake, and after 84 days, we performed organ weight and blood biochemical analyses. No significant differences were seen in body weight, food intake, organ weight, and most biochemical parameters between group I and group II. Interestingly, total cholesterol (T-CHO) and high-density lipoprotein cholesterol (HDL-C) levels of group II were significantly higher than those of group I after administration for 84 days. Moreover, lactate dehydrogenase (LDH) level of group II was marked lower than that of group I, and other liver function parameters of group II tended to be lower than those of group I. As conclusion, "Hanpen," a Japanese traditional food, could be effective as a functional food for human health management worldwide.

Development of multifunctional foods

Foods contain various biologically active substances with extent physiological effects. Among them, some substances, such as dietary fibers, polyunsaturated fatty acids, and antioxidants, exert multiple activities. In addition, combinational uses of some components, such as sesamin and α-tocopherol, enhance their biological effects each other. The expression of multiple effect leads to the production of multifunctional foods which prevent the occurrence of various diseases. Furthermore, synergic effects between biologically active substances allow us to decrease the dose of each component, which lead to the improvement of safety and reduction of production cost of multifunctional foods. To use these active components for human health, studies on their adsorption and transportation are important, since distribution of some components, such as tocotrienols, is limited to some tissues. In addition, extent safety studies are essential to use artificially synthesized substances such as 10t, 12c derivative of conjugated linoleic acid for human health.

Moringa oleifera-rich diet and T cell calcium signaling in spontaneously hypertensive rats

Moringa oleifera is a plant whose fruits, roots and leaves have been advocated for traditional medicinal uses. The physicochemical analysis shows that Moringa oleifera contains more dietary polyunsaturated fatty acids (PUFA) than saturated fatty acids (SFA). The consumption of an experimental diet enriched with Moringa oleifera extracts lowered blood pressure in spontaneously hypertensive rats (SHR), but not in normotensive Wistar-Kyoto (WKY) rats as compared to rats fed an unsupplemented control diet. Anti-CD3-stimulated T cell proliferation was diminished in both strains of rats fed the Moringa oleifera. The experimental diet lowered secretion of interleukin-2 in SHR, but not in WKY rats compared with rats fed the control diet. Studies of platelets from patients with primary hypertension and from SHR support the notion that the concentration of intracellular free calcium [Ca(2+)](i) is modified in both clinical and experimental hypertension. We observed that the basal, [Ca(2+)](i) was lower in T cells of SHR than in those of WKY rats fed the control diet. Feeding the diet with Moringa oleifera extracts to WKY rats did not alter basal [Ca(2+)](i) in T cells but increased basal [Ca(2+)](i) in SHR. Our study clearly demonstrated that Moringa oleifera exerts antihypertensive effects by inhibiting the secretion of IL-2 and modulates T cell calcium signaling in hypertensive rats.

Comparative Study of EPA-enriched Phosphatidylcholine and EPA-enriched Phosphatidylserine on Lipid Metabolism in Mice

Recent studies have shown that EPA enriched PLs have beneficial effects on lipid metabolism. Our previous study has demonstrated that the anti-obesity and hypolipidemic effects of EPA-PL were superior to DHA-PL. In the present study, we comparatively evaluated the effects of EPA-enriched phosphatidylcholine (EPA-PC) and EPA-enriched phosphatidylserine (EPA-PS) on lipid metabolism in mice. Both 2% dietary EPA-PC and EPA-PS significantly improved serum and hepatic lipid levels in mice. The HDL-c level in mice on EPA-PC diet was significantly higher than the other two groups. The level of DHA in hepatic TG and PL were significantly increased in both EPA-PC and EPA-PS fed groups (98.3 and 117.8%, respectively; p < 0.05). Notably, the proportion of DHA in EPA-PS group was significantly higher than the EPA-PC group. EPA-PC and EPA-PS suppressed hepatic SREBP-1c mediated lipogenesis and activated PPARα mediated fatty acid β-oxidation in the liver. These data are the first to indicate that EPA-PS has beneficial effects on lipid metabolism.

Eicosapentaenoic acid-enriched phospholipid ameliorates insulin resistance and lipid metabolism in diet-induced-obese mice

Background

Over the past two decades, a striking increase in the number of people with metabolic syndrome (MS) has taken place worldwide. With the elevated risk of not only diabetes but also cardiovascular morbidity and mortality, there is urgent need for strategies to prevent this emerging global epidemic. The present study was undertaken to investigate the effects of dietary eicosapentaenoic acid-enriched phospholipid (EPA-PL) on metabolic disorders.

Methods

Male C57BL/6J mice (n = 7) were fed one of the following 4 diets for a period of 4 weeks: 1) a modified AIN-96G diet with 5% corn oil (control diet); 2) a high fat (20%, wt/wt) and high fructose (20%, wt/wt) diet (HF diet); 3) the HF diet containing 1% SOY-PL (SOY-PL diet); 4) the HF diet containing 1% EPA-PL (EPA-PL diet). The oral glucose tolerance test was performed. Plasma TG, TC, glucose, NEFA, insulin, leptin, adiponectin, TNF-α and IL-6 levels were assessed. In addition, hepatic lipid levels, lipogenic, and lipidolytic enzyme activities and gene expressions were evaluated.

Results

Both EPA-PL and SOY-PL significantly inhibited body weight gain and white adipose tissue accumulation, alleviated glucose intolerance, and lowered both serum fasting glucose and NEFA levels substantially. Only EPA-PL significantly reduced serum TNF-α and IL-6 levels, and increased serum adiponectin level. EPA-PL was more effective in reducing hepatic and serum TG and TC levels than SOY-PL. Both EPA-PL and SOY-PL reduced the activities of hepatic lipogenic enzymes, such as FAS and G6PDH, but only EPA-PL significantly increased CPT, peroxisomal β-oxidation enzymes activities and CPT-1a mRNA level. Alterations of hepatic lipogenic gene expressions, such as FAS, G6PDH, ACC, SCD-1 and SREBP-1c were consistent with changes in related enzyme activities.

Conclusions

According to our study, EPA-PL supplementation was efficacious in suppressing body fat accumulation, and alleviating insulin resistance and hepatic steatosis by modulating the secretion of adipocytokines and inflammatory cytokines, suppression of SREBP-1c mediated lipogenesis and enhancement of fatty acid β-oxidation. These results demonstrate that EPA-PL is a novel beneficial food component for the prevention and improvement of metabolic disorders.

Ingestion of (n-3) fatty acids augments basal and platelet activating factor-induced permeability to dextran in the rat mesenteric vascular bed

Loss of intestinal barrier function and subsequent edema formation remains a serious clinical problem leading to hypoperfusion, anastomotic leakage, bacterial translocation, and inflammatory mediator liberation. The inflammatory mediator platelet activating factor (PAF) promotes eicosanoid-mediated edema formation and vasoconstriction. Fish oil-derived (n-3) fatty acids (FA) favor the production of less injurious eicosanoids but may also increase intestinal paracellular permeability. We hypothesized that dietary (n-3) FA would ameliorate PAF-induced vasoconstriction and enhance vascular leakage of dextran tracers. Rats were fed either an (n-3) FA-rich diet (EPA-rich diet; 4.0 g/kg EPA, 2.8 g/kg DHA) or a control diet (CON diet; 0.0 g/kg EPA and DHA) for 3 wk. Subsequently, isolated and perfused small intestines were stimulated with PAF and arterial pressure and the translocation of fluid and macromolecules from the vasculature to lumen and lymphatics were analyzed. In intestines of rats fed the EPA-rich diet, intestinal phospholipids contained up to 470% more EPA and DHA at the expense of arachidonic acid (AA). The PAF-induced increase in arterial pressure was not affected by the EPA-rich diet. However, PAF-induced fluid loss from the vascular perfusate was higher in intestines of rats fed the EPA-rich diet. This was accompanied by a greater basal loss of dextran from the vascular perfusate and a higher PAF-induced transfer of dextran from the vasculature to the lumen (P = 0.058) and lymphatics. Our data suggest that augmented intestinal barrier permeability to fluid and macromolecules is a possible side effect of (n-3) FA-rich diet supplementation.

Effects of three different highly purified n-3 series highly unsaturated fatty acids on lipid metabolism in C57BL/KsJ-db/db mice

Triglycerides (TG) consisting of highly purified (>97%) n-3 series highly unsaturated fatty acids, eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA), were administered to C57BL/KsJ-db/db mice for 4 weeks by pair-feeding to compare their effects on lipid metabolism and to evaluate the effects of DPA on lipid metabolism. The hepatic TG level and total amount was decreased by treatment with DHA and DPA compared to the control. The efficacy of DPA was greater than that of EPA, but less than that of DHA. In contrast, EPA had the greatest serum TG reducing effect. The hepatic cytosol fraction of the DHA-treated group contained the lowest fatty acid synthase (FAS) and malic enzyme (ME) activity levels. Furthermore, the DHA-treated group contained the highest serum adiponectin concentrations. These findings indicate that the strong hepatic TG-lowering effect of DHA is due to the suppression of TG synthesis. The same tendencies were observed in DPA-treated mice, and the effect was stronger than that observed in EPA-treated mice, but equivalent to that observed in DHA-treated mice. Based on these results, DPA possesses lipid metabolism-improving effects. The beneficial effects of DPA for lipid metabolism were not superior to those of EPA and DHA, and the effect was always intermediate between those of EPA and DHA.

The effect of feeding structured triacylglycerols enriched in eicosapentaenoic or docosahexaenoic acids on murine splenocyte fatty acid composition and leucocyte phagocytosis

The effects of altering the type of n-3 polyunsaturated fatty acid (PUFA) in the mouse diet on the ability of monocytes and neutrophils to perform phagocytosis were investigated. Male weanling mice were fed for 7 d on one of nine diets which contained 178 g lipid/kg and which differed in the type of n-3 PUFA and in the position of these in dietary triacylglycerol (TAG). The control diet contained 4·4 g α-linolenic acid/100 g total fatty acids. In the other diets, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) replaced a proportion (50 or 100 %) of the α-linolenic acid, and were in the sn-2 or the sn-1(3) position of dietary TAG. There were significant increases in the content of n-3 PUFA in spleen-cell phospholipids when EPA or DHA was fed. These increases were largely independent of the position of EPA or DHA in dietary TAG except when EPA was fed at the highest level, when the incorporation was greater when it was fed in the sn-2 than in the sn-1(3) position. There was no significant effect of dietary DHA on monocyte or neutrophil phagocytic activity. Dietary EPA dose-dependently decreased the number of monocytes and neutrophils performing phagocytosis. However, when EPA was fed in the sn-2 position, the ability of active monocytes or neutrophils to engulf bacteria was increased in a dose-dependent fashion. This did not occur when EPA was fed in the sn-1(3) position. Thus, there appears to be an influence of the position of EPA, but not of DHA, in dietary TAG on its incorporation into cell phospholipids and on the activity of phagocytic cells.

Chemical compositions, antioxidant capacities, and antiproliferative activities of selected fruit seed flours

Seed flours from black raspberry, red raspberry, blueberry, cranberry, pinot noir grape, and chardonnay grape were examined for their total fat content, fatty acid composition, total phenolic content (TPC), total anthocyanin content (TAC), radical scavenging capacities against the peroxyl (ORAC) and stable DPPH radicals, chelating capacity against Fe(2+), and antiproliferative activities using the HT-29 colon cancer cell line. Significant levels of fat were detected in the fruit seed flours and their fatty acid profiles may differ from those of the respective seed oils. Cranberry seed flour had the highest level of alpha-linolenic acid (30.9 g/100 g fat) and the lowest ratio of n-6/n-3 fatty acids (1.2/1). The ORAC value of the chardonnay seed flour was 1076.4 Trolox equivalents mumol/g flour, and its TPC was 186.3 mg gallic acid equivalents/g flour. These values were 3-12 times higher than the other tested fruit seed flours. Furthermore, the ORAC value was significantly correlated to the TPC under the experimental conditions (P < 0.05). These fruit seed flours also differed in their TAC values and Fe(2+)-chelating capacities. In addition, black raspberry, cranberry, and chardonnay grape seed flour extracts were evaluated for their antiproliferative effects using HT-29 colon cancer cells. All three tested seed flour extracts significant inhibited HT-29 cell proliferation. The data from this study suggest the potential of developing the value-added use of these fruit seed flours as dietary sources of natural antioxidants and antiproliferative agents for optimal human health.

Fatty acid composition and antioxidant properties of cold-pressed marionberry, boysenberry, red raspberry, and blueberry seed oils

Cold-pressed marionberry, boysenberry, red raspberry, and blueberry seed oils were evaluated for their fatty acid composition, carotenoid content, tocopherol profile, total phenolic content (TPC), oxidative stability index (OSI), peroxide value, and antioxidant properties. All tested seed oils contained significant levels of alpha-linolenic acid ranging from 19.6 to 32.4 g per 100 g of oil, along with a low ratio of n-6/n-3 fatty acids (1.64-3.99). The total carotenoid content ranged from 12.5 to 30.0 micromoles per kg oil. Zeaxanthin was the major carotenoid compound in all tested berry seed oils, along with beta-carotene, lutein, and cryptoxanthin. Total tocopherol was 260.6-2276.9 mumoles per kg oil, including alpha-, gamma-, and delta-tocopherols. OSI values were 20.07, 20.30, and 44.76 h for the marionberry, red raspberry, and boysenberry seed oils, respectively. The highest TPC of 2.0 mg gallic acid equivalents per gram of oil was observed in the red raspberry seed oil, while the strongest oxygen radical absorbance capacity was in boysenberry seed oil extract (77.9 micromol trolox equivalents per g oil). All tested berry seed oils directly reacted with and quenched DPPH radicals in a dose- and time-dependent manner. These data suggest that the cold-pressed berry seed oils may serve as potential dietary sources of tocopherols, carotenoids, and natural antioxidants.

Dietary docosahexaenoic acid is more optimal than eicosapentaenoic acid affecting the level of cellular defence responses of the juvenile grouper Epinephelus malabaricus

The combined effects of dietary docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids on phagocytic, respiratory burst, and leucocyte proliferative activities of the juvenile grouper, Epinephelus malabaricus, were investigated. The test fish were fed for 12wk on test diets containing 1g 100g(-1) diet of DHA and EPA in combinations (DHA/EPA: 3/1, 2/1, 1/1, 0.7/1, 0.3/1). In addition to promoting fish growth, high dietary DHA/EPA ratio significantly enhanced phagocytic and respiratory burst activities of grouper head-kidney leucocytes compared with low ratio. Significant correlations were found between leucocyte phagocytic or respiratory burst activities and concentrations of 20:3(n-3), DHA and EPA in fish liver and muscle tissues. Leucocyte proliferation was significantly higher (P< 0.05) when the diets were high in DHA/EPA ratio than low in DHA/EPA ratio, when stimulated by Con A and PHA-P, but not by LPS. Tissue DHA concentrations and leucocyte proliferation were significantly and positively correlated. Fortification of dietary DHA, thus increased T-cell proliferation and phagocytic function of grouper leucocytes. DHA is the only member in the (n-3) highly unsaturated fatty acid family that stimulated phagocytic functions of leucocytes and T-cell proliferation, and is more optimal than EPA affecting the cellular defence responses of the E. malabaricus juveniles.

Food restriction and fish oil suppress atherogenic risk factors in lupus-prone (NZB x NZW) F1 mice

Atherosclerosis-mediated coronary artery disease is a significant cause of mortality in lupus patients. Both an activated immune system and hyperlipidemia are implicated in the pathogenesis of the atherosclerotic lesions of lupus. In this study, the increases in anticardiolipin antibodies, total cholesterol, and LDL cholesterol with age were significantly lowered by fish oil and food restriction, either alone or in combination. Food restriction also significantly decreased the elevation in anti-dsDNA antibody production seen with age in ad libitum groups. Interestingly, effects of food restriction and fish oil on both lipid profile and autoantibody production were seen from a young age. Accumulation of leukocytes in the blood vessels and deposition of IgG in the glomerular mesangium also were suppressed by food restriction. Thus, beneficial effects of fish oil and food restriction on lupus nephritis and survival could be, at least in part, due to their selective effect on atherogenic risk factors.

Dietary gamma-linolenic acid dose-dependently modifies fatty acid composition and immune parameters in rats

gamma-linolenic acid (GLA) has been reported to improve several inflammatory disorders through regulation of eicosanoid production. However, since GLA is a precursor of arachidonic acid, it may bring about increasing tissue arachidonic acid levels with subsequent pro-inflammatory events. To explore this possibility, we examined the effect of high-dose GLA acid on the fatty acid profile of immune cells, leukotriene B4 production by peritoneal exudate cells and immunoglobulin productivity of mesenteric lymph node lymphocytes of Sprague-Dawley rats. Male rats were fed 10% fat diets containing graded levels, 0, 20, 40 and 60% of GLA for 3 weeks. The results showed the distinction in activity of metabolizing GLA between immune cells and liver. Thus, in immune cells such as mesenteric lymph node and spleen lymphocytes and peritoneal exudate cells, more dihomo-gamma-linolenic acid was found than in the liver. Leukotriene B4 production by peritoneal exudate cells was significantly suppressed when fed the highest level of GLA suggesting a lower risk of allergic reaction. Moreover, immunoglobulin productivity in mesenteric lymph node lymphocytes was promoted by dietary GLA. The present study indicates that a high dose of GLA may exert anti-inflammatory effects through suppression of leukotriene B4 release and strengthening of gut immune system, thus ameliorating allergic reaction.