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PubMed1999

Effect of dietary hydrogenated fish oil on the plasma lipoprotein profile and on the fatty acid composition of different tissues on the rat.

Dietary fatty acids are actively incorporated into membrane lipids, and fat intake can modify the composition and the biochemical activity of cellular membranes and the pattern of plasma lipoproteins. Industrial hydrogenation of polyunsaturated oils leads to the formation of isomeric trans fatty acids which are incorporated into cellular membranes when they are present in the diet. The trans fatty acid amount present in hydrogenated oils depends on the degree of hydrogenation, being high for partially hydrogenated oils and low for highly hydrogenated oils. Hydrogenated fish oil is widely used in some countries for the production of margarine and industrial fats. This study compares the fatty acid composition of plasma, erythrocytes, subcutaneous adipose tissue, and hepatic microsomal membranes and the plasma lipoprotein profile after feeding rats with a synthetic diet containing either fish oil, partially hydrogenated fish oil, or highly hydrogenated fish oil. It is observed that the tissue content of monounsaturated fatty acids increases and that the content of polyunsaturated fatty acids decreases after an increase of the degree of hydrogenation of the dietary fat. Tissues from animals fed partially hydrogenated fish oil show significant amounts of trans fatty acids only. The plasma triacylglyceride composition and the lipoprotein profile are also altered by the degree of hydrogenation of the dietary fat. Triacylglycerides decrease after highly hydrogenated fat feeding only. Total cholesterol and low-density lipoprotein cholesterol are significantly increased after partially hydrogenated fat feeding. Although no direct evidence is presented, this effect may be attributable to the high content of trans isomers of this dietary fat which nutritionally may behave as saturated fatty acids.

Adipose Tissue↗

PubMed2006

Fish oil, insulin sensitivity, insulin secretion and glucose tolerance in healthy people: is there any effect of fish oil supplementation in relation to the type of background diet and habitual dietary intake of n-6 and n-3 fatty acids?

AIM: To evaluate whether a moderate supplementation of long-chain n-3 fatty acids is able to modulate insulin sensitivity, insulin secretion, beta-cell function and glucose tolerance in healthy individuals consuming a diet rich in either saturated or monounsaturated fat, also in relation to their habitual dietary intake of n-6 and n-3 fatty acid. METHODS AND RESULTS: One hundred and sixty-two healthy individuals were randomly assigned to follow either one of two isoenergetic diets for 3 months, one rich in monounsaturated fats and the other rich in saturated fats. Within each group there was a second randomisation to fish oil (n-3 fatty acids 3.6 g/day) or placebo. At the beginning and at the end of the treatment periods insulin sensitivity (SI), first phase insulin response (FPIR) and glucose tolerance (K(G)-value) were evaluated by the intravenous glucose tolerance test (IVGTT). Fish oil did not have any effect on SI, FPIR, K(G)-value and disposition index in either diet. Even after dividing subjects according to the median value of n-6/n-3 ratio of serum phospholipids at baseline, there was no change in SI (Delta SI 0.42+/-0.34 on fish oil vs 0.14+/-0.23 on placebo for those with n-6/n-3 <4.85; -1.03+/-0.47 on fish oil vs -0.27+/-0.32 on placebo for those with n-6/n-3 >4.85) (M+/-SE), FPIR (Delta FPIR 135.9+/-78.9 vs 157.2+/-157.5 pmol/L; 38.8+/-181.7 vs 357.1+/-181.7 pmol/L), K(G)-value (Delta K(G) 0.14+/-0.15 vs 0.12+/-0.11; -0.32+/-0.16 vs 0.15+/-0.15) or disposition index (Delta disposition index 1465.4+/-830.4 vs 953.8+/-690.0; -1641.6+/-1034.3 vs 446.6+/-905.1). Considering the 75th percentile of n-6/n-3 ratio (5.82) the results on insulin sensitivity, insulin secretion and disposition index were confirmed, while, in this more extreme situation, n-3 fatty acid supplementation induced a significant deterioration of K(G)-value (p=0.02). CONCLUSIONS: In healthy individuals a moderate supplementation of fish oil does not affect insulin sensitivity, insulin secretion, beta-cell function or glucose tolerance. The same is true even when the habitual dietary intake of n-6 and n-3 fatty acids is taken into account.

Adult↗

PubMed1993

Psychological stress reverses antiaggregatory effects of dietary fish oil.

Effect of acute psychological stress on the inhibition of in vitro platelet aggregation by dietary long-chain n-3 fatty acids was studied in 20 adult males. Subjects were randomly divided into groups receiving either olive oil or fish oil (2.4 g long-chain n-3 fatty acids/day) for 4 weeks. In vitro aggregation responses to two doses of ADP collagen, and epinephrine were measured immediately prior to and following exposure to three psychological stressors (2 min each), before and after the supplementation period. Olive oil had no effect on baseline aggregatory responses, while fish oil reduced aggregatory responses to ADP and epinephrine. Exposure to the stressors had no effect upon presupplementation aggregation in either group or in the olive oil group postsupplementation. However, stress abolished antiaggregatory effects of fish oil. This reversal of the antiaggregatory effects of fish oil by mild stress suggests possible limitations of low-dose fish oil supplementation in clinical situations.

Adult↗

PubMed1992

Effects of a combination of evening primrose oil (gamma linolenic acid) and fish oil (eicosapentaenoic + docahexaenoic acid) versus magnesium, and versus placebo in preventing pre-eclampsia.

In a placebo controlled, partially double-blinded, clinical trial, a combination of evening primrose oil and fish oil was compared to Magnesium Oxide, and to a Placebo in preventing Pre-Eclampsia of Pregnancy. All were given as nutritional supplements for six months to a group of primiparous and multiparous pregnant women. Some of these women had personal or family histories of hypertension (21%). Only those patients who received prenatal care at the Central Maternity Hospital for Luanda were included in the study. Compared to the Placebo group (29%), the group receiving the mixture of evening primrose oil and fish oil containing Gamma-linolenic acid (GLA), Eicosapentaenoic acid (EPA), and Docosahexaenoic acid (DHA) had a significantly lower incidence of edema (13%, p = 0.004). The group receiving Magnesium Oxide had statistically significant fewer subjects who developed hypertension of pregnancy. There were 3 cases of eclampsia, all in the Placebo group.

Adolescent↗

PubMed1981

Changes in composition and enzyme activities of mitochondrial and post-mitochondrial fractions of tissues of rats given mustard oil diet with carnitine and/or fish oil.

The effects of short-term feeding of a 20% mustard oil (containing 47% erucic acid) diet with 0.1% carnitine and/or fish oil on the activity of enzymes of lipid metabolism in mitochondrial and post-mitochondrial fractions of heart, liver, and skeletal muscles of rats were determined to study the reversal of erucic acid-induced lipidosis. Histopathological changes were also studied. The inclusion of fish oil or fish oil plus carnitine in a mustard oil diet, especially the latter, eliminated the histopathologically detectable lipidosis in heart and skeletal muscles. The reason for this appears to be the increased activity of lipase and phospholipase in tissue homogenates and of cholesterol ester hydrolase in the post-mitochondrial fraction; and also an increase in mitochondrial succinate dehydrogenase which may increase the utilization of the liberated fatty acids. The results suggest that the erucic acid-induced lipidosis is prevented or eliminated by increased lipolysis and oxidation of fatty acids when such a diet is supplemented with carnitine and/or fish oil.

Animals↗

PubMed2002

Dietary fish oil and vitamin E enhance doxorubicin effects in P388 tumor-bearing mice.

In this study, four kinds of rodent diets, CO, FO, CVe, and FVe, were used by addition of canola oil, oil mixture (fish oil + canola oil), canola oil plus vitamin E, and oil mixture plus vitamin E, respectively, to a basic diet, AIN-93G, to investigate the influence of dietary fish oil and vitamin E on doxorubicin (DOX) treatment in P388 ascitic mice. Animal life span (LS) and heart damage were recorded in mice fed the four different diets and treated with different doses of DOX. The optimal doses of DOX for antitumor effect as manifested by increased LS were 6.0 and 9.0 mg/kg. Both fish oil and vitamin E significantly enhanced this effect. On the other hand, DOX at 12.0 mg/kg induced severe heart damage, which was also significantly aggravated by both fish oil and vitamin E, as shown by both decreased LS and increased serum creatine phosphokinase activity. Fish oil and vitamin E appeared to enhance the antitumor effect of optimal doses of DOX but to aggravate cardiotoxicity owing to DOX overdose.

Animals↗

PubMed1990

Changes in lipoprotein composition in hypertriglyceridemic patients taking cholesterol-free fish oil supplements.

Fish oils rich in n - 3 fatty acids (FAs) have been shown to markedly lower levels of very low density lipoproteins (VLDL), but not the low density lipoproteins (LDL) which are derived from VLDL. Changes in the size and chemical composition of lipoproteins may affect their metabolism. In order to examine the effects of n - 3 FAs on lipoprotein metabolism, 6 patients with hypertriglyceridemia were given 6 g n - 3 FAs/day. Plasma lipid and apoprotein (apo A-I, A-II, B, E, C-II, C-III) levels (mg/dl) were measured before and after 4 weeks of treatment. Changes in lipoprotein size were assessed by gel chromatography. n - 3 FAs lowered VLDL cholesterol (58 +/- 35 to 40 +/- 30, P less than 0.01) and total triglyceride (410 +/- 170 to 236 +/- 114, P less than 0.01). In spite of this, LDL cholesterol levels did not decrease, and apo B levels increased (98 +/- 28 to 111 +/- 27, P less than 0.05). HDL cholesterol rose (31 +/- 5 to 34 +/- 7, P less than 0.05). The lipid content of smaller VLDL particles was reduced by over 40%, but the protein content was largely unchanged. Large triglyceride-rich lipoprotein particles were reduced to a greater extent than were small particles. These changes in VLDL particle size and composition may enhance the synthesis of LDL in hypertriglyceridemic patients taking n - 3 FA supplements.

Blood Proteins↗

PubMed1993

Lipoprotein lipases, lipoprotein density gradient profile and LDL receptor activity in miniature pigs fed fish oil and corn oil.

The effects of fish oil and corn oil on plasma lipoprotein concentrations, the lipolytic enzymes, lipoprotein lipase and hepatic triacylglycerol lipase, the density distribution of the plasma lipoproteins and LDL receptor activity were studied. These experiments were designed, in part, to define the mechanism(s) responsible for the increased conversion of plasma VLDL apolipoprotein B to LDL and a decreased LDL apolipoprotein B fractional catabolic rate described in previous apolipoprotein B kinetic studies. Miniature pigs were fed diets for 3 to 6 weeks containing supplements of corn oil or fish oil as Maxepa. Triacylglycerol and cholesterol in plasma and VLDL were significantly reduced by the fish oil diet. LDL and HDL cholesterol were not significantly changed. The fish oil diet significantly reduced post-heparin plasma lipoprotein lipase and hepatic triacylglycerol lipase activities, which may be an adaptive response to the low concentration of substrates (triacylglycerol-rich lipoproteins) for these enzymes. No differences were observed in the density of VLDL, LDL or HDL as determined by density gradient ultracentrifugation with the fish oil diet. No major changes in percent lipid composition of VLDL, LDL and HDL were observed. No differences were found with respect to LDL uptake by J774 macrophages. Receptor mediated clearance of LDL in vivo, as assessed by measuring the difference in fractional catabolic rate of native vs. methylated LDL decreased significantly by 17% (P < 0.032). We conclude that the increased conversion of VLDL apolipoprotein B to LDL in miniature pigs fed fish oil is not related to an increase in lipolytic enzymes or density distribution of VLDL, but may be due in part to a decrease in LDL receptor activity.

Animals↗

PubMed2000

Late feeding of dietary fish oil alleviates disease severity and affects macrophage function in autoimmune NZB/W F1 mice.

To investigate the influence of different saturations of dietary fat on autoantibody production and disease courses, autoimmune NZB/NZW F1 (NZB/W F1) mice were fed diets containing 20% palm oil, lard/soybean oil, soybean oil, canola oil or fish oil at 5 months of age. Sera levels of anti-DNA antibodies, proteinuria and life span were followed regularly. In addition, peritoneal resident cells were isolated and mediators such as interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), prostaglandin E2 (PGE2) and NO production were measured. The results show that mice fed a diet containing with fish oil had significantly decreased immunoglobulin G (IgG) anti-single strand (ss) or double strand (ds) DNA antibody levels, lessened proteinuria and prolonged life span compared to mice fed diets containing other types of dietary fat. TNF-alpha and PGE2 levels in mice fed a diet containing fish oil were significantly lower compared to the other dietary groups. IL-6 and NO produced by peritoneal resident cells were significantly higher in mice fed a diet containing lard/soybean oil in comparison with mice of the other groups. Hepatic ex vivo PGE2 level was significantly lower in mice fed fish oil compared to mice of the other dietary groups. These data suggested that dietary fish oil might affect either autoantibody production or macrophage function, contributing to alleviation of the autoimmune process in autoimmune-prone NZB/W F1 mice.

Animals↗

PubMed1993

Dietary non-starch polysaccharides interact with cholesterol and fish oil in their effects on plasma lipids and hepatic lipoprotein receptor activity in rats.

Male rats were fed the non-starch polysaccharides pectin, methylcellulose or guar gum with corn oil or with 60% of the corn oil replaced by fish oil. They were also fed these diets with or without cholesterol (+ cholic acid). Plasma total cholesterol concentration was higher overall in rats fed cholesterol and lower in those fed fish oil or fish oil + cholesterol. Plasma triacylglycerols were lower in rats fed fish oil with or without cholesterol. Hepatic LDL receptor activity was higher overall in rats fed fish oil or fish oil + cholesterol than in those fed cholesterol. Liver HDL receptor was lower overall in rats fed fish oil or cholesterol. Type of non-starch polysaccharide influenced these dietary effects so that in cholesterol-fed rats plasma cholesterol was highest in those fed methylcellulose, intermediate in those fed guar gum and in those fed pectin was unchanged from concentrations in rats fed pectin without cholesterol. Fish oil feeding lowered plasma cholesterol concentration in rats fed pectin or methylcellulose but not in those fed guar gum. Plasma triacylglycerols were lower in rats fed fish oil and all three non-starch polysaccharides, but concentrations were similar in rats fed pectin + fish oil + cholesterol and in those fed pectin. In rats fed methylcellulose + cholesterol and any non-starch polysaccharide + fish oils, HDL receptor activity was uniformly lower than in rats fed pectin, methylcellulose or guar gum. Low density lipoprotein receptor activity was higher in rats fed pectin + fish oil or pectin + fish oil + cholesterol than in rats fed pectin.

Animals↗

PubMed1998

Dietary fish oil appears to prevent the activation of phospholipase C-gamma in lymphocytes.

Rats were fed on a low fat diet or on high fat diets which included coconut oil, olive oil, safflower oil, evening primrose oil or fish oil as the principal fat source. The level of phosphatidylinositol-4, 5-bisphosphate in spleen lymphocytes was unaffected by diet. However, the fish oil diet significantly decreased the concentration of inositol-1,4,5-trisphosphate in stimulated lymphocytes; this concentration was also reduced following olive oil feeding. Diet did not significantly affect the level of phospholipase C-gamma1 in spleen lymphocytes but the tyrosine phosphorylation state of this enzyme in stimulated lymphocytes, as well as that of a range of other proteins, was decreased following feeding the fish oil and, to a lesser extent, the olive oil diets. It is concluded that fish oil feeding appears to result in inhibition of one or more tyrosine kinases.

Animals↗

PubMed1996

The desaturation and elongation of linolenic acid and eicosapentaenoic acid by hepatocytes and liver microsomes from rainbow trout (Oncorhynchus mykiss) fed diets containing fish oil or olive oil.

The products of desaturation and elongation of [1-14C]18:3(n - 3) and [1-14C]20:5(n - 3) were studied using hepatocytes and microsomes prepared from livers of trout maintained on diets containing either olive oil or fish oil, to establish the extent to which the formation of 22:6(n - 3) was enhanced in the absence of dietary 22:6(n - 3) and to investigate the pathway(s) of conversion of 18:3(n - 3) and 20:5(n - 3) to 22:6(n - 3). Levels of 20:5(n - 3) and 22:6(n - 3) in the total lipid of hepatocytes from trout fed olive oil were 20-fold and 10-fold, respectively, lower than in cells from trout fed fish oil. For both dietary groups, [1-14C]18:3(n - 3) was incorporated into hepatocyte lipid to a greater extent than [1-14C] 20:5(n - 3). Almost 70% of the total radioactivity from [1-14C]18:3(n - 3) was recovered in hepatocyte triacylglycerols, whereas radioactivity from [1-14C]20:5(n - 3) was recovered almost equally in neutral lipids (52%) and polar lipids (48%). The products of desaturation and elongation from both labelled substrates were esterified mainly into hepatocyte polar lipids, whereas elongation products of [1-14C]18:3(n - 3) were preferentially incorporated into neutral lipids. Radioactivity recovered in the 22:6(n - 3) of polar lipids of hepatocytes from trout fed olive oil, from both 14C substrates, was approximately double that in hepatocytes from trout fed fish oil. No radioactivity from either [1-14C]18:3(n - 3) or [1-14C]20:5(n - 3) was incorporated into 22:6(n - 3) by microsomes isolated from livers from either group of fish and incubated in the presence of acetyl-CoA, malonyl-CoA, NADH, NADPH, ATP and coenzyme A. However, significant radioactivity was recovered in 24:5(n - 3) and 24:6(n - 3) from [1-14C]20:5(n - 3) and more radioactive 24:6(n - 3) accumulated in microsomes from trout fed olive oil than from trout fed fish oil. The results establish that the formation of 22:6(n - 3) from both 18:3(n - 3) and 20:5(n - 3) in hepatocytes of rainbow trout is stimulated by omitting 22:6(n - 3) from the diet and are consistent with the biosynthesis of 22:6(n - 3) in trout liver cells proceeding via 24:5(n - 3) and 24:6(n - 3) intermediates.

Animals↗

PubMed1992

Reduction of cholesterol absorption by dietary oleinate and fish oil in African green monkeys.

To determine whether diets enriched in monounsaturated or n-3 fatty acids cause a reduction in cholesterol absorption relative to those more enriched in saturated fatty acids, we measured cholesterol absorption in 18 African green monkeys fed diets enriched in lard, oleinate (oleic acid-rich safflower oil), or fish oil at two levels of dietary cholesterol (0.05 vs. 0.77 mg/kcal). All animals were initially challenged with the lard, high cholesterol diet to ascertain their responsiveness to dietary cholesterol. Based on the results of this challenge, low versus high responders were equally distributed in assignation to the low (n = 6) and high (n = 12) cholesterol regimens. Within each level of dietary cholesterol animals consumed all three dietary fats in random sequences during three experimental phases each lasting 9-12 months with a monkey chow washout period between each phase, so that each animal served as its own control. During each dietary phase measurements of plasma lipids and cholesterol absorption were performed. The animals fed the higher versus lower level of dietary cholesterol had significantly higher plasma total cholesterol and low density lipoprotein (LDL) cholesterol concentrations and lower percentage cholesterol absorption; high density lipoprotein (HDL) cholesterol levels were not affected by the level of dietary cholesterol. Dietary fish oil resulted in a 20-30% reduction (P less than 0.01) in total plasma and LDL cholesterol and a 30-40% reduction (P less than 0.01) in HDL cholesterol concentrations compared to lard and oleinate regardless of the level of dietary cholesterol. At the high level of cholesterol intake, the oleinate and fish oil diets resulted in significantly lower percentage cholesterol absorption compared to the lard fat diet (35 +/- 2%, 34 +/- 3%, 41 +/- 4%, respectively). At the lower level of dietary cholesterol, percentage cholesterol absorption values were higher than those at the high cholesterol intake (45-52% vs. 34-41%) but were not affected by the type of dietary fat. There was a significant positive correlation between plasma LDL cholesterol concentrations and percentage cholesterol absorption for the oleinate and lard diets at the high level of dietary cholesterol and a significant inverse association between plasma HDL cholesterol and percentage cholesterol absorption. We conclude that the type of dietary fat can influence cholesterol absorption in African green monkeys and that oleinate and fish oil reduce cholesterol absorption relative to lard when a high amount of cholesterol (0.77 mg/kcal) is present in the diet.

Analysis of Variance↗

PubMed1992

Comparison of the clinical efficacy of two commercial fatty acid supplements (EfaVet and DVM Derm Caps), evening primrose oil, and cold water marine fish oil in the management of allergic pruritus in dogs: a double-blinded study.

Twenty dogs with atopy or idiopathic pruritus were treated in a double-blinded clinical trial with computer-randomized and computer-generated sequences of 4 fatty acid-containing products: evening primrose oil, cold water marine fish oil, DVM Derm Caps, and EfaVet. Each dog received each product for a 2-week period. Five of 20 dogs (25%) had a good-to-excellent reduction in their level of pruritus with at least 1 of the products: evening primrose oil (2 dogs), DVM Derm Caps (1), EfaVet (1), DVM Derm Caps and cold water marine fish oil (1). Only 1 dog experienced a side effect (loose stools). Clinical response to fatty acid supplements appeared to be quite individualized, and independent of age, breed, sex, weight, duration of disease, specific diagnosis, or number of positive intradermal test reactions.

Animals↗

PubMed1997

Dietary fish oil blocks carcinogen-induced down-regulation of colonic protein kinase C isozymes.

In order to elucidate the influence of dietary constituents on colonic intracellular signal transduction, the effect of different fats on rat colonic epithelial protein kinase C (PKC) alpha (classical), delta (novel) and lambda-zeta (atypical) expression was determined in carcinogen-treated animals. Sprague-Dawley rats were provided with one of two fats (corn oil and fish oil); plus or minus the carcinogen azoxymethane (AOM) and killed at two time points (15 and 37 weeks) in a 2x2x2 factorial design. At 5 and 6 weeks of age, animals were injected s.c. with either AOM at a dose of 15 mg/kg body weight or saline once a week for 2 weeks and continued on the same diet until termination of the study. At 15 and 37 weeks after the second injection, 10 rats from each treatment group were killed. Colonic PKC alpha, delta and lambda-zeta steady-state protein and mRNA levels were determined using immunoblotting and relative quantitative polymerase chain reaction, respectively. Colonic mucosa from rats injected with AOM had significantly suppressed membrane and cytosolic PKC alpha and cytosolic lambda-zeta protein levels (P < 0.05) as compared to saline-injected control animals at both time points. In contrast, rats fed fish oil diets had significantly higher (P < 0.05) cytosolic PKC delta and lambda-zeta protein levels relative to animals fed corn oil diets. However, the effect of diet and AOM on the steady-state expression of PKC alpha, delta and zeta mRNA was not consistent with changes in the respective isozyme protein levels, suggesting regulation at the post-transcriptional level. These data demonstrate that dietary fish oil blocks the carcinogen-induced decrease in the steady-state levels of colonic mucosal PKC delta and lambda-zeta, which may in part explain why this fat source protects against colon cancer development.

Animals↗

PubMed1999

Multidimensional gas chromatographic enantiomer quantification of some chlorinated xenobiotics in cod liver and fish oils.

Four chiral HRGC column systems for the separation of selected organochlor pesticides and photoconversion products (heptachlor, cis- and trans-chlordane, o,p'-DDT, o,p'-DDD, and alpha-HCH) were tested. Cod hver oil and fish oil samples from different countries were comparatively analyzed. Of all these columns, the fourth was the most suitable one for the analysis of the selected compounds. The enantiomer ratios [ER] of cis-chlordane, trans-chlordane, photodieldrin, alpha-HCH, and o,p'-DDD in fish oils are nearly 1.0, while the ERs of the same substances are significantly different from 1.0 in cod liver oils. Contrary to that, the ER values of o,p'-DDT are remarkable different from 1 in the cod liver oils as well as in the fish oils.

Animals↗

PubMed1990

The role of fish oil in psoriasis. A randomized, double-blind, placebo-controlled study to evaluate the effect of fish oil and topical corticosteroid therapy in psoriasis.

In a randomized, double-blind, placebo-controlled study, patients received 10 fish or olive oil capsules three times daily for the whole study in addition to applying betamethasone diproprionate to their psoriatic plaques for the first 3 weeks. Most patients gradually worsened upon discontinuation of corticosteroids. Using survival analysis methods, no significant difference was found between the fish and olive oil groups. The authors attempt to put the role of fish oil in the therapy of psoriasis into perspective and discuss the efficacy of fish oil when used alone versus in combination therapy.

Adult↗

PubMed1988

A fish oil diet reduces the severity of collagen induced arthritis after onset of the disease.

We have previously reported that compared to a corn oil diet a fish oil diet (5% by weight) fed to B10R.III mice before the induction of collagen induced arthritis markedly reduced disease severity. In this study we determine whether a fish oil diet could reduce the severity of collagen induced arthritis if begun after the arthritis was clinically apparent. Mice were initially fed either a fish oil or corn oil diet and immunized with bovine type II collagen 4 weeks later. At the onset of collagen-induced arthritis, half of the corn oil fed mice were switched to fish oil and arthritis assessed on a weekly basis. Four weeks after the diet change until killing 5 weeks later, the mice switched to fish oil developed much less severe arthritis than the corn oil fed controls. Thus the severity index of corn oil fed mice ranged between 9.4 and 7.1; the severity index of fish oil fed mice was between 6.8 and 4.3 while the mice switched to fish oil ranged between 7.2 and 5.6. Analysis of peritoneal macrophages 13 weeks after immunization showed that macrophages from fish oil fed mice incorporated eicosapentaenoic acid into phospholipids and produced less arachidonate products than corn oil fed mice. There was no difference between macrophages obtained from mice switched from corn oil to fish oil and those maintained on fish oil with respect to fatty acid composition of membrane phospholipids or prostaglandin profile. These results suggest that arthritis severity may be modulated after the onset of CIA by altering the PG profile of macrophages present at inflammatory sites.

Animals↗