Showing papers on "Fish oil published in 1987"

Fish oil prevents insulin resistance induced by high-fat feeding in rats

Abstract: Non-insulin-dependent diabetes mellitus is an increasingly prevalent disease in Western and developing societies. A major metabolic abnormality of non-insulin-dependent diabetes is impaired insulin action (insulin resistance). Diets high in fat from vegetable and nonaquatic animal sources (rich in linoleic acid, an omega-6 fatty acid, and saturated fats) lead to insulin resistance. In rats fed high-fat diets, replacement of only 6 percent of the linoleic omega-6 fatty acids from safflower oil with long-chain polyunsaturated omega-3 fatty acids from fish oil prevented the development of insulin resistance. The effect was most pronounced in the liver and skeletal muscle, which have important roles in glucose supply and demand. The results may be important for therapy or prevention of non-insulin-dependent diabetes mellitus.

Fish oil inhibits development of atherosclerosis in rhesus monkeys.

Abstract: The effect of feeding fish oil (Menhaden) on the progression of rhesus monkey atherosclerosis was determined by feeding diets containing 2% cholesterol and either 25% coconut oil (Group I), 25% fish oil/coconut oil (1:1) (Group II), or 25% fish oil/coconut oil (3:1) (Group III) for 12 months (n = 8/group). The average serum cholesterol levels were 875 mg/dl for Group I, 463 mg/dl for Group II, and 405 mg/dl for Group III. HDL cholesterol levels were 49 mg/dl for Group I, 29 mg/dl for Group II, and 20 mg/dl for Group III. An average of 79% of the aortic intima was involved with atherosclerosis in Group I, 48% in Group II, and 36% in Group III. The aortas of both fish-oil groups (II or III) contained significantly less cholesterol (total, free, and esterified), as well as less acid lipase, cholesteryl esterase, and ACAT activities when compared to the coconut-oil group (I) (p less than 0.05). Microscopically, the aortic and carotid artery lesions were smaller in cross-sectional area and in thickness, and contained less macrophages in the fish-oil groups (II and III) when compared to the coconut-oil group (I) (p less than 0.05). This protective effect was not consistently enhanced by increasing the proportion of fish oil to 3:1 (Group III) over 1:1 (Group II). The results indicate that fish oil-containing diets reduce serum cholesterol levels and inhibit atherosclerosis even in the face of lowered HDL cholesterol levels when compared to a pure coconut oil/cholesterol diet in rhesus monkeys. Therefore, fish-oil diets exert effective protective control of progression of atherosclerosis during severe atherogenic stimuli.

Effects of dietary supplementation with marine fish oil on leukocyte lipid mediator generation and function in rheumatoid arthritis

Abstract: Twelve patients with active rheumatoid arthritis supplemented their usual diet with 20 gm of Max-EPA fish oil, daily, for 6 weeks. Following this supplementation, the ratio of arachidonic acid to eicosapentaenoic acid in the patients' neutrophil cellular lipids decreased from 81:1 to 2.7:1, and the mean generation of leukotriene B4 (with calcium ionophore stimulation) significantly declined by 33%. The mean neutrophil chemotaxis to both leukotriene B4 and FMLP significantly increased toward the normal range at week 6. The generation of 5-lipoxygenase products by calcium ionophore-stimulated monocytes was not significantly suppressed, but a significant decline (37%) in platelet-activating factor generation was noted at week 6. The modulation of these measures of leukocyte inflammatory potential suggests that fish oil supplementation may have an antiinflammatory effect.

Prophylaxis of atherosclerosis with marine omega-3 fatty acids. A comprehensive strategy

Abstract: Traditional approaches to prophylaxis of atherosclerosis have focused on one aspect of the pathogenesis of this multifactorial disease, such as platelet function or blood lipids, and therefore have had limited success. Epidemiologic studies show a striking inverse correlation of consumption of fish rich in the two omega-3 fatty acids, eicosapentaenoic acid and docosahexaenoic acid, and mortality from cardiovascular disease. In studies of volunteers and patients, reductions in platelet responsiveness, lowering of blood lipids, and improvements of blood flow, as well as improvements in other values implicated in the pathogenesis of atherosclerosis, were induced with eicosapentaenoic and docosahexaenoic acids. These findings indicate that these omega-3 fatty acids have a larger prophylactic potential than traditional approaches. This potential must be scrutinized in meticulously designed and conducted trials with clinical endpoints.

Seafoods and fish oils in human health and disease

Abstract: A reference text for food scientists, nutritionists, dietitians, pharmacologists, physicians, and other health professionals and biomedical researchers provides detailed discussions and information concerning the essential polyunsaturated fatty acids (PFA's) of the n-6 family and their metabolic conversion to eicosanoids, prostaglandins, and leukotrienes which evidently exert protective effects against cardiovascular disease (CD) and other diseases and disorders. Topics include the effects of omega-3 PFA's and their interactions in n-6 fatty acid metabolism, the effects of seafood and fish oil fatty acids on reducing CD risk based on clinical trials, and the nutritional value of fish and fish oils. Tabular data are provided throughout the text, and literature citations are appended to each of the 11 text chapters

Effect of dietary supplementation with eicosapentaenoic acid in the treatment of atopic dermatitis

Abstract: The effects of a dietary supplement of n-3 fatty acids in patients with atopic dermatitis were investigated in a 12-week, double-blind study. The experimental group received 10 g of fish oil daily, of which about 1.8 g was eicosapentaenoic acid. This amount of eicosapentaenoic acid can be obtained from a daily intake of fat fish. The controls received an iso-energetic placebo supplement containing olive oil. Compliance was monitored by gas-chromatographic analysis of the fatty acid pattern in serum phospholipids. Results favoured the experimental group with regard to scale (P less than 0.05), itch (P less than 0.05) and overall subjective severity (P less than 0.02) as compared to the controls.

Lipoprotein Lipases, Lipoproteins and Tissue Lipids in Rats Fed Fish Oil or Coconut Oil

Abstract: The effect of fish oil and coconut oil on plasma lipoproteins and lipoprotein-catabolizing enzymes [lipoprotein lipase (LPL) and hepatic endothelial lipase (HL)] was studied in rats. Male rats were fed for 4 wk purified diets containing equienergetic, amounts of either coconut oil (group A), coconut oil:fish oil, 50:50 (group B) or fish oil (group C). Whole plasma triacylglycerol, cholesterol and phospholipid concentrations were appreciably lower in group C than in group A, mainly due to a fall in very low density lipoprotein (VLDL) and subgroup 2 of high density lipoprotein (HDL2), with less consistent changes in LDL and HDL3. VLDL components of group B were also considerably lower than corresponding ones in group A. LPL and HL activities were about 50% lower in groups B and C than in group A. Increased hepatic triacylglycerol and cholesterol concentrations were observed in groups B and C. It is suggested that the decrease in LPL and HL activity of fish oil-fed rats may be an adaptive response to the low concentration of the substrate (triacylglycerols) for these enzymes.

The effects of dietary omega-3 fatty acids on the DU-145 transplantable human prostatic tumor.

Abstract: Two omega-3 fatty acids present in fish oil are effective inhibitors of some models of mammary and colon tumorigenesis in rodents. The present studies were conducted to determine if eicosapentaenoic and docosahexaenoic acids can modify the growth of DU-145 human prostatic tumor cells in nude mice. Two experimental diets tested contained either 23.52% corn oil or 20.52% fish oil, plus 3% corn oil (w/w). In the fish oil-fed group of mice: (a) tumor growth was significantly inhibited; (b) tumor cells in histological sections were smaller but more connective tissue was present; (c) immunochemical staining for human prostatic acid phosphatase was less intense, and (d) tumor content of PGE2 was smaller than in the 23.52% corn oil-fed group. Fatty acid composition of phosphoglyceride and neutral lipid fractions of liver, prostate, and tumor tissue reflect the dietary intake of omega-3 and omega-6 fatty acids. These results are consistent with a role for omega-3 fatty acids in the inhibition of growth of human prostatic tumor cells in nude mice by dietary modification.

Effect of age and dietary fat (fish, corn and coconut oils) on tocopherol status of C57BL/6Nia mice.

Abstract: The effect of age and dietary fat type on tocopherol status was investigated using young and old C57BL/6Nia mice fed semipurified diets containing 5% (by weight) fish, corn or coconut oils and supplemented with 30, 100 or 500 ppm dl-α-tocopheryl acetate for 6 wk. Tocopherol levels in the diets, plasma, liver, kidney and lung were measured by high performance liquid chromatography following appropriate extractions. The results indicate that mice fed fish oil maintain lower plasma and tissue tocopherol concentrations than those fed corn and cononut oils (fish

Effect of fish oil supplementation on the n-3 fatty acid content of red blood cell membranes in preterm infants.

Abstract: Very low birth weight infants demonstrate significant reductions in red blood cell membrane docosahexaenoic acid (DHA, 22:6n-3) following delivery unless fed human milk. The purpose of the present study was to determine if a dietary source of DHA (MaxEPA, R. P. Scherer Corporation, Troy, MI) could prevent the decline in red blood cell phospholipid DHA in very low birth weight infants whose enteral feeding consisted of a preterm formula without DHA. Longitudinal data were obtained on membrane phospholipid DHA in both unsupplemented and MaxEPA-supplemented infants by a combination of thin-layer and gas chromatography. These infants (n = 39) ranged in age from 10 to 53 days at enrollment (0 time). At enrollment, phospholipid DHA and arachidonic acid (20:4n-6) were inversely correlated with age in days. During the study, mean red blood cell phospholipid DHA declined without supplementary DHA as determined by biweekly measurement, but infants supplemented with MaxEPA maintained the same weight percent of phospholipid (phosphatidylethanolamine, phosphatidylcholine, and phosphatidylserine) DHA as at enrollment. The pattern of red blood cell phospholipid fatty acids in supplemented infants was similar to that reported for preterm infants fed human milk.

The effects of N-3 polyunsaturated fatty acids on the generation of platelet-activating factor-acether by human monocytes.

Abstract: Human leukocytes generate platelet-activating factor (PAF-acether), a lipid mediator of inflammation, from membrane alkyl phospholipids through the release of arachidonic acid or other fatty acids at the 2-position and subsequent acetylation. Because it was previously demonstrated that fish oil fatty acids suppress human leukocyte arachidonic acid release and metabolism, separate experiments were conducted to investigate the effects of dietary fish oil supplementation and in vitro incubation with fish oil fatty acids on calcium ionophore-stimulated PAF-acether generation in human monocytes. In subjects on their regular diets, a 4-hr incubation of monocyte monolayers with an optimally effective concentration of arachidonic acid of 1 micrograms/ml resulted in a 64% increase of calcium ionophore-induced net PAF-acether generation from 7.75 +/- 0.78 ng/10(6) cells for untreated monolayers to 12.70 +/- 1.21 ng/10(6) cells (mean +/- SEM). Treatment of monolayers with eicosapentaenoic acid (EPA) at the optimal concentration of 1 micrograms/ml decreased net PAF-acether generation by 28%. However, treatment of monocyte monolayers with docosahexaenoic acid did not appreciably affect net PAF-acether generation. The changes in PAF-acether release with each fatty acid added in vitro paralleled those in total PAF-acether generation; the percentage PAF-acether release remained unaffected. Three weeks of dietary supplementation with 18 g MaxEPA daily, providing 3.2 g EPA did not affect the PAF-acether generation of calcium ionophore-stimulated human monocyte monolayers. However, 6 weeks of dietary supplementation resulted in a 47% decrease of net total PAF-acether generation and a concomitant 59% decline in net PAF-acether release; the percentage release of PAF-acether was not affected. Thus, whether added to the diet or introduced in vitro, fish oil-derived fatty acids suppress PAF-acether generation by human monocyte monolayers.

Ingestion of Fish Oil or a Derived n-3 Fatty Acid Concentrate Containing Eicosapentaenoic Acid (EPA) Affects Fatty Acid Compositions of Individual Phospholipids of Rat Brain, Sciatic Nerve and Retina

Abstract: The effect of feeding redfish (Sebastes marinus or mantella) oil or a derived n-3 fatty acid concentrate containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the fatty acid compositions of individual phospholipids in selected neural tissues was studied in growing male rats. Control animals were given sunflower oil in the diet for the 5-wk feeding trial. Lipid analyses revealed that EPA (20:5n-3) became significantly enriched in all phospholipid fractions (phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol) in the tissues studied (brain, retina and sciatic nerve) in the two n-3 fatty acid dietary groups relative to controls. Corresponding changes were also found in the 22:5n-3 contents of these tissues, whereas little or no significant elevation in DHA (22:6n-3) was found. In contrast, the percentages by weight of the n-6 fatty acids including 18:2n-6, 20:4n-6 (arachidonic acid, AA), 22:4n-6 and 22:5n-6 were generally lower in the various phospholipids/tissues of the animals given fish oil or the n-3 fatty acid concentrate; the levels of 22:5n-6 and 22:4n-6 were markedly affected in this regard. These results indicate that dietary n-3 fatty acids (as EPA plus DHA) can greatly affect the fatty acid compositions of the various membrane phospholipids in nervous tissues within a relatively short time. These biochemical alterations may be important for functional changes including altered membrane fluidity, cellular responses, ion transport and the biosyntheses of AA- and EPA-derived prostaglandins and leukotrienes.

The effects of dietary supplementation with fish oil in patients with psoriasis

Abstract: Ten patients with psoriasis resistant to conventional topical treatment were given dietary supplements of fish oil, providing approximately 12 g of eicosapentaenoic acid daily for a period of at least 6 weeks. In eight patients there was a modest improvement in their psoriasis, the principal effects being a diminution of erythema and scaling. The dietary treatment resulted in a substantial inhibition of leukotriene B4 production by the peripheral blood polymorphonuclear leukocytes in vitro. The discrepancy between the high degree of inhibition of leukotriene B4 synthesis and the modest therapeutic effect suggests that leukotriene B4 is not the only mediator involved in the development of the psoriatic lesion. Furthermore, the in vivo cutaneous levels of leukotriene B4 might not have been inhibited to the same extent as the polymorphonuclear leukocyte levels in vitro. Further studies on the use of fish oil supplements, both on their own and in conjunction with other forms of treatment in psoriasis are warranted. It will also be important to determine whether the altered profile of 5-lipoxygenase products found in the blood is also seen in the skin.

Modification of experimental nephrotoxicity with fish oil as the vehicle for cyclosporine.

Abstract: Cyclosporine-associated renal dysfunction is well recognized. While renal vasoconstriction appears to be a major pathogenic factor, the precise mechanism responsible for the altered hemodynamics is unclear. To investigate whether alterations in renal eicosanoid metabolism could be involved, we substituted fish oil rich in eicosapentaenoic acid (EPA), an inhibitor of cyclooxygenase metabolites, for the conventional olive oil cyclosporine vehicle. Male rats were pretreated with 1.0 cc fish oil or olive oil by gavage. After 14 days, cyclosporine (12.5 mg/cc vehicle) was added to the oil and animals received cyclosporine 50 mg/kg for an additional 14 days. Pair-fed control animals received fish oil or olive oil alone. Glomerular filtration rate (GFR) was severely reduced in the cyclosporine-in-olive-oil (CSA + OO) group (0.28 +/- .05 ml/min/100 g) vs. olive oil (OO) controls (0.70 +/- .04) (P less than 0.001). While GFR was reduced in the cyclosporine-in-fish oil group (CSA + FO) vs. fish oil (FO) controls (0.47 +/- .07 vs. 0.74 +/- .04), it was significantly higher than in the CSA + OO group (P less than 0.05). Trough whole-blood cyclosporine levels were not significantly different in the two groups. While CSA + OO appeared to elevate renal cortical content of thromboxane B2 (65.7 +/- 7.3 pg/mg tissue vs. 46.9 +/- 5.3 for OO), both the CSA + FO and FO groups had reduced levels (31.1 +/- 2.7 and 29.5 +/- 2.3, respectively). In addition, there was a striking reduction in proximal tubular vacuolar changes in the CSA +/- FO vs. CSA + OO group. We conclude that the use of EPA-rich fish oil as the vehicle for cyclosporine results in improved renal function and morphology and is associated with depressed renal cortical levels of vasoconstrictor thromboxane B2.

Effect of dietary fish oil on myocardial phospholipids and myocardial ischemic damage.

Abstract: The effect of dietary fish oil on myocardial phospholipids and ischemic damage to the heart was studied in the rat. Four weeks of feeding 5% (i.e., 12 energy percent) menhaden oil (MO) produced bot...

Digestion, absorption and effects on cholesterol absorption of menhaden oil, fish oil concentrate and corn oil by rats.

Abstract: Adult male rats were surgically provided with a drainage catheter in the left thoracic lymphatic channel and an indwelling duodenal catheter for constant infusion of physiological saline-5% glucose. After an overnight fast, animals were given a single duodenal dose of an aqueous emulsion containing one of the following: oleic acid, corn oil, menhaden oil or a fish oil concentrate (FOC) and [1,2-3H]cholesterol. Digestion and absorption were estimated by recovering the total fatty acids in the thoracic duct lymph over a 24-h collection period (after subtraction of the "baseline" endogenous fatty acids in the lymph). Cholesterol absorption in the thoracic duct lymph was significantly reduced (P less than 0.05) in the presence of menhaden oil or FOC compared to that in the presence of corn oil. With various fat feedings, the major increases in lymph fatty acids were directly related to the dietary fatty acid content. The relative amounts of eicosapentaenoic acid (EPA) and arachidonic acid (AA) in the thoracic lymph were influenced by the lipid content of the emulsion. The EPA/AA ratio in control, oleic acid and corn oil feedings ranged from 0.12 to 0.25. When marine oil was administered, the EPA/AA ratio was 0.78-0.98. The total amount of fatty acids found in the lymph after marine oil feeding was significantly less (P less than 0.01) than that found after corn oil feeding. The results suggested that the digestion and absorption of menhaden oil and FOC were decreased as compared with corn oil. The EPA/AA ratio was increased in the thoracic lymph after dietary fish oil feeding.

Biologic Significance of Polyunsaturated Fatty Acids in the Skin

Abstract: • Deficiency of essential fatty acid (EFA) containing linoleic acid (18:2n-6) in humans or animals induces morphologic changes characterized by severe scaly dermatosis, extensive percutaneous water loss, and hyperproliferation of the epidermis. Microscopically, the epidermis is characterized by hyperkeratosis and acanthosis. The refeeding of safflower oil containing linoleic acid or primrose oil (containing linoleic acid [18:2n-6] and γ-linolenic acid [18:3n-6]) acids to EFA-deficient guinea pigs reverses the EFA-deficiency symptoms. In contrast, replacement of safflower oil with menhaden fish oil, (containing eicosapentaenoic acid [20:5n-3] and docosahexaenoic acid [22:6n-3]) did not reverse the symptoms of EFA deficiency. These results indicate: (1) that an understanding of the roles of vegetable or fish oil in skin must evolve from an understanding of the roles of each constituent n-6 or n-3 fatty acid, and (2) that the n-3 fatty acids may function to modulate the metabolism and function of the n-6 fatty acids in vivo. ( Arch Dermatol 1987;123:1686a-1690)

Effects of polyunsaturated fatty acids on factors related to cardiovascular disease.

Abstract: Dietary fats play a critical role in atherogenesis and thrombosis. Both the amount of fat consumed and its composition affect various events associated with coronary artery disease. Dietary unsaturated fatty acids appear to reduce the incidence of these events, in particular polyunsaturated fatty acids (PUFAs), which exert markedly different effects on risk factors related to heart disease. The omega-3 (n-3) PUFAs, at high levels of dietary intake, significantly reduce hyperlipidemia and the production of the prothrombotic substance thromboxane, and they enhance the production of the platelet-antiaggregatory substance prostacyclin. Data from clinical trials indicate a significant reduction of levels of very low density lipoprotein (VLDL). The n-3 PUFAs also depress hepatic fatty acid and triglyceride synthesis and VLDL secretion. The n-3 PUFAs of fish oils displace arachidonic acid from tissue phospholipids and concomitantly increase n-3 PUFA levels, which inhibit thromboxane synthesis. Most significantly, in human subjects the antiaggregatory prostacyclin PGI3 is also synthesized and the net effect is enhanced antiaggregatory/antiadhesive activity. In addition, the chemotactic platelet adhesion-promoting substance leukotriene B4 is suppressed. These composite effects reduce atherogenesis and thrombosis. Fish oil n-3 PUFAs may also reduce blood pressure and blood viscosity. Through the combined vasodilatory effects via prostacyclin (PGI2 and PGI3), fish oils may improve peripheral circulation and thereby facilitate VLDL removal. The n-3 PUFAs of fish oils, by altering membrane fluidity in a specific manner, alter the activities of membrane-bound enzymes and may change receptor activity, specificity and signal transduction. Overall, these data indicate a beneficial role for n-3 PUFAs as part of a dietary approach to minimizing coronary artery disease.

Effects of fish oil on postburn metabolism and immunity.

Abstract: The metabolic effects and immune responses of different levels of fish oil in enteral formulas for postburn nutritional support were studied. Thirty-seven burned guinea pigs with previously placed gastrostomy feeding tubes were given diets containing 5, 15, 30, or 50% of nonprotein calories as fish oil. These diets were isonitrogenous, isocaloric, and contained identical amounts of vitamins and minerals. After 14 days of enteral feeding, there were no significant differences in resting metabolic expenditure, serum transferrin, and albumin levels. Weight loss was significantly greater in groups receiving 30 and 50% of fish oil compared to groups which received 5 and 15% of fish oil. Carcass weights and liver weights of animals in the two groups that received diets with higher lipid content were also significantly lower. Cell-mediated immunity, macrophage bactericidal indices, and opsonic indices were not different among the groups. This study confirms that diets containing lower levels of lipids are more e...

Effect of a fish-oil-supplemented diet on inflammation and immunological processes in rats.

Abstract: The effect of a diet enriched in fish-oil-derived fatty acids including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DCHA) in inflammation and immunological processes in rats has been investigated. Rats on a normal chow diet were given 500 mg/kg/day EPA and 333 mg/kg/day DCHA by gavage over a period of 50 days. Control groups received water, oleic acid or safflower oil. Acute and chronic phases of inflammation induced by antigenic challenge with bovine serum albumin were examined in the rat air-pouch model. In rats receiving fish-oil-derived fatty acids, there was a reduced production of the arachidonic acid metabolites, prostaglandin E2 and leukotriene B4, in the exudate in the chronic phase of inflammation, but not in the acute phase. This was associated with an increased infiltration of leukocytes, especially monocytes and macrophages, in the chronic inflammatory phase. The fish-oil-supplemented diet showed no effect on the volume of inflammatory exudate, the amount of protein in the exudate and connective tissue proliferation. Carrageenin-induced paw edema in the animals was not influenced by the diet. There was no effect of the dietary fish oil on production of antibodies to bovine serum albumin in the rats. However, the diet appeared to suppress a delayed-type skin reaction in the animals. These studies suggest that fish-oil-derived fatty acids may modulate chronic inflammation and a cellular-mediated immunological reaction by reducing the synthesis of arachidonic acid metabolites.

New findings in the fatty acid composition of individual platelet phospholipids in man after dietary fish oil supplementation.

Abstract: Nine healthy male volunteers were given 15 Max EPA fish oil capsules providing 2.67 g of eicosapentaenoic acid (EPA, 20:5 omega 3) and 1.72 g of docosahexaenoic acid (DHA, 22:6 omega 3) daily for 3 wk. Measurements were taken at baseline, at the end of the fish-oil period, and at 2 and 6 wk postsupplementation. The effect of fish oil on plasma lipids and the fatty acid composition of individual platelet phospholipids was studied. In general, the proportions of 20:5 omega 3 and 22:6 omega 3 in platelet phosphoglycerides were substantially increased mainly at the expense of arachidonic acid (AA, 20:4 omega 6). A large and significant increase in the relative EPA content of phosphatidylcholine (PC) (P less than 0.001) and phosphatidylethanolamine (PE) (P less than 0.001) was noted at the end of the 3 wk supplementation. We have also shown for the first time a small but significant (P less than 0.001) incorporation of EPA in phosphatidylserine (PS). Incorporation of DHA was also detected in PC, PE and PS, whereas the relative AA content of these phospholipids was significantly reduced. Fish oil supplementation led to a significant increase of 22:5 omega 3 in PS and decreases of 20:3 omega 6 in PC and 22:4 omega 6 in PE. Postsupplementation measurements showed a gradual return of all fatty acids to baseline levels. The fatty acid composition of the phosphatidylinositol (PI) fraction remained unchanged throughout the trial period. We conclude that in humans omega 3 fatty acids are incorporated into platelet membrane phospholipid subclasses with a high degree of specificity.