Showing papers on "Fish oil published in 1990"

Dietary fish oil and olive oil supplementation in patients with rheumatoid arthritis. Clinical and immunologic effects.

Abstract: Forty-nine patients with active rheumatoid arthritis completed a 24-week, prospective, double-blind, randomized study of dietary supplementation with 2 different dosages of fish oil and 1 dosage of olive oil. Clinical evaluations were performed at baseline and every 6 weeks thereafter, and immunologic variables were measured at baseline and after 24 weeks of study. The 3 groups of patients were matched for age, sex, disease severity, and use of disease-modifying antirheumatic drugs (DMARDs). Subjects continued receiving DMARDs and other background medications without change during the study. Twenty patients consumed daily dietary supplements of n3 fatty acids containing 27 mg/kg eicosapentaenoic acid (EPA) and 18 mg/kg docosahexaenoic acid (DHA) (low dose), 17 patients ingested 54 mg/kg EPA and 36 mg/kg DHA (high dose), and 12 patients ingested olive oil capsules containing 6.8 gm of oleic acid. Significant improvements from baseline in the number of tender joints were noted in the low-dose group at week 24 (P = 0.05) and in the high-dose group at week 18 (P = 0.04) and 24 (P = 0.02). Significant decreases from baseline in the number of swollen joints were noted in the low-dose group at weeks 12 (P = 0.003), 18 (P = 0.002), and 24 (P = 0.001) and in the high-dose group at weeks 12 (P = 0.0001), 18 (P = 0.008), and 24 (P = 0.02). A total of 5 of 45 clinical measures were significantly changed from baseline in the olive oil group, 8 of 45 in the low-dose fish oil group, and 21 of 45 in the high-dose fish oil group during the study (P = 0.0002). Neutrophil leukotriene B4 production decreased by 19% from baseline in the low-dose fish oil group (P = 0.0003) and 20% in the high-dose group (P = 0.03), while macrophage interleukin-1 production decreased by 38.5% in the olive oil group (P not significant), 40.6% in the low-dose group (P = 0.06), and 54.7% in the high-dose group (P = 0.0005). Tritiated thymidine incorporation in peripheral blood mononuclear cells after stimulation with concanavalin A increased significantly in all 3 groups after 24 weeks, compared with baseline values. We conclude that the clinical benefits of dietary supplementation with omega-3 fatty acids are more commonly observed in patients consuming higher dosages of fish oil for time intervals that are longer than those previously studied. Dietary supplementation with olive oil is also associated with certain changes in immune function, which require further investigation.

Effect of eicosapentaenoic and docosahexaenoic acids on blood pressure in hypertension. A population-based intervention trial from the Tromsø study.

Abstract: Studies of whether polyunsaturated fatty acids in fish oil--in particular, eicosapentaenoic and docosahexaenoic acids--lower blood pressure have varied in design and results. We conducted a population-based, randomized, 10-week dietary-supplementation trial in which the effects of 6 g per day of 85 percent eicosapentaenoic and docosahexaenoic acids were compared with those of 6 g per day of corn oil in 156 men and women with previously untreated stable, mild essential hypertension. The mean systolic blood pressure fell by 4.6 mm Hg (P = 0.002), and diastolic pressure by 3.0 mm Hg (P = 0.0002) in the group receiving fish oil; there was no significant change in the group receiving corn oil. The differences between the groups remained significant for both systolic (6.4 mm Hg; P = 0.0025) and diastolic (2.8 mm Hg; P = 0.029) pressure after control for anthropometric, lifestyle, and dietary variables. The decreases in blood pressure were larger as concentrations of plasma phospholipid n-3 fatty acids increased (P = 0.027). Dietary supplementation with fish oil did not change mean blood pressure in the subjects who ate fish three or more times a week as part of their usual diet, or in those who had a base-line concentration of plasma phospholipid n-3 fatty acids above 175.1 mg per liter. We conclude that eicosapentaenoic and docosahexaenoic acids reduce blood pressure in essential hypertension, depending on increases in plasma phospholipid n-3 fatty acids.

reversibility of n-3 fatty acid deficiency and turnover of docosahexaenoic acid in the brain, erythrocytes, and plasma of rhesus monkeys'

Abstract: Rhesus monkeys given pre- and postnatal diets defi- cient in n-3 essential fatty acids develop low levels of docosahexa- enoic acid (22:6 n-3, DHA) in the cerebral cortex and retina and impaired visual function. This highly polyunsaturated fatty acid is an important component of retinal photoreceptors and brain synaptic membranes. To study the turnover of polyunsaturated fatty acids in the brain and the reversibility of n-3 fatty acid defi- ciency, we fed five deficient juvenile rhesus monkeys a fish oil diet rich in DHA and other n-3 fatty acids for up to 129 weeks. The results of serial biopsy samples of the cerebral cortex indi- cated that the changes of brain fatty acid composition began as early as 1 week after fish oil feeding and stabilized at 12 weeks. The DHA content of the phosphatidylethanolamine of the fron- tal cortex increased progressively from 3.9 + 1.2 to 28.4 + 1.7 percent of total fatty acids. The n-6 fatty acid, 22:5, abnormally high in the cerebral cortex of n-3 deficient monkeys, decreased reciprocally from 16.2 * 3.1 to 1.6 0.4%. The half-life (tl,*) of DHA in brain phosphatidylethanolamine was estimated to be 21 days. The fatty acids of other phospholipids in the brain (phosphatidylcholine, -serine, and -inositol) showed similar changes. The DHA content of plasma and erythrocyte phospho- lipids also increased greatly, with estimated half-lives of 29 and 21 days, respectively. a We conclude that monkey cerebral cortex with an abnormal fatty acid composition produced by dietary n-3 fatty acid deficiency has a remarkable capacity to change its fatty acid content after dietary fish oil, both to in- crease 22:6 n-3 and to decrease 22:5 n-6 fatty acids. The bio- chemical evidence of n-3 fatty acid deficiency was completely corrected. These data imply a greater lability of the fatty acids of the phospholipids of the cerebral cortex than has been hitherto appreciated. -Connor, W. E., M. Neuringer, and D. S. Lin. Dietary effects on brain fatty acid composition: the reversibility on n-3 fatty acid deficiency and turnover of docosahexaenoic acid in the brain, erythrocytes, and plasma of rhesus monkeys. J Lipid Res. 1990. 31: 237-247.

Dietary fish oil reduces progression of chronic inflammatory lesions in a rat model of granulomatous colitis.

Abstract: Eicosanoids are modulators of defensive and inflammatory processes in the gut mucosa, and may be involved in the pathogenesis of chronic inflammatory lesions of the bowel. As omega-3 fatty acids compete with the omega-6 as precursors of eicosanoid synthesis, we compared the effects of dietary supplementation with either sunflower (source of omega-6) or cod liver (source of omega-3) oil on the development of chronic granulomatous lesions in the rat colon. After four weeks on the supplemented diets, plasma omega-6 fatty acid content was significantly higher in the sunflower group, while omega-3 fatty acids predominated in the cod liver group. Inflammatory colitis was then induced by intracolonic administration of trinitrobenzene sulphonic acid. Luminal eicosanoid release, as measured by radioimmunoassay of intracolonic dialysis fluid, increased significantly after the challenge in both groups. Generation of prostaglandin E2 (PGE2) and leucotriene B4 (LTB4) peaked by day 3 and thereafter declined; thromboxane B2 (TXB2), instead, continued to increase from day 3 to 20 in sunflower fed rats, whereas this change was blunted in cod liver animals. The rats were killed 20, 30, or 50 days after the induction of colitis, and the colonic lesions were scored macroscopically (adhesions to surrounding tissues, strictures, ulcerations, and wall thickness) and histologically (ulceration, inflammation, depth of the lesions, and fibrosis). In cod liver animals, the damage score was markedly reduced by day 30, and inflammation and ulceration were almost absent by day 50. In conclusion, a fish oil diet prevents the increase in thromboxane in the chronic state of inflammation and shortens the course of the colonic disease by diminishing both the severity of the lesions and their progression to chronicity.

Effect of fish oil on lipoproteins, lecithin:cholesterol acyltransferase, and lipid transfer protein activity in humans.

Abstract: A group of 33 mildly hypercholesterolemic men were stratified into three groups on diets closely matched except for the polyunsaturated fatty acid supplement The first group received 14 g/day of linoleic acid (safflower oil); the second group, 9 g of alpha-linolenic acid (linseed oil); and the third group, 38 g of n-3 fatty acids (fish oil) Only fish oil lowered plasma triglycerides (by 24% at 6 weeks, p less than 005 compared to safflower oil) Very low density lipoprotein (VLDL) apoprotein (apo) B, triglyceride, and cholesterol all fell significantly with the fish-oil diet (p less than 001) Low density lipoprotein (LDL) cholesterol fell by 018 and 010 mmol/l, respectively, with the safflower-oil and linseed-oil diets, but rose by 024 mmol/l with the fish-oil diet (p less than 005) There was a strong correlation between the changes in VLDL triglyceride and LDL cholesterol with the fish-oil diet (r = -084, p less than 0002) High density lipoprotein (HDL) cholesterol fell slightly in all three groups (p less than 002 with the linseed-oil diet only) However, the apo A-I/A-II ratio rose by 5% (p less than 005), and the HDL2/HDL3 protein ratio increased by 28% with the fish-oil diet (p less than 0005) Fish oil reduced the capacity for transfer of cholesteryl ester between LDL and HDL by 23% (p less than 002 compared to baseline), reduced plasma lecithin:cholesterol acyltransferase activity by 21% (p less than 005), and reduced maximal stimulated thromboxane production by 9% (p less than 005) Thus fish oil produced three potentially beneficial changes: significant decreases in VLDL concentration and in thromboxane production and an increase in the HDL2/HDL3 ratio The increase in the average HDL particle size probably reflected reduced cholesteryl ester acceptor capacity within the smaller pool of VLDL, as well as the decline in lipid transfer activity in plasma involving transfer protein itself, LDL, and HDL

Dietary polyunsaturated fats uniquely suppress rat liver fatty acid synthase and S14 mRNA content.

Abstract: The objective of these studies was to demonstrate that dietary polyunsaturated, but not saturated, fatty acids decrease mRNA abundance for fatty acid synthase (FAS) and S14. A series of experiments involving adult and weanling rats was designed to examine the ability of saturated (tripalmitin), (n-9) monounsaturated (triolein), (n-6) di-unsaturated (safflower oil), and (n-3) polyenic (fish oil) fatty acids to suppress the gene expression of FAS and S14. Dietary polyunsaturated fats reduced by 75-90% the hepatic abundance of FAS and S14 mRNA. Fish oil, rich in 20- and 22-carbon polyenic fatty acids, was more effective than safflower oil, whereas tripalmitin and triolein were without effect. Polyunsaturated fats were also very effective at preventing the rise in FAS and S14 mRNA associated with weaning. The inhibitory action of polyunsaturated fat was rapidly (less than 3 h) removed by deleting the fat from the meal. Regression analysis revealed a high correlation (0.81-0.94) between FAS and S14 expression among the various dietary studies. These data support the hypothesis that dietary polyunsaturated fats uniquely regulate the gene expression of lipogenic enzymes and that the mediator is likely a specific entity derived from the long-chain polyenic fatty acids. Moreover, the high correlation between FAS and S14 expression supports the hypothesis that S14 is a member of the lipogenic protein family and has potential as a model gene for the study of FAS expression.

Effects of fish oil supplementation in rheumatoid-arthritis

Abstract: Sixteen patients with rheumatoid arthritis entered a trial to determine the clinical and biochemical effects of dietary supplementation with fractionated fish oil fatty acids. A randomised, double blind, placebo controlled crossover design with 12 week treatment periods was used. Treatment with non-steroidal anti-inflammatory drugs and with disease modifying drugs was continued throughout the study. Placebo consisted of fractionated coconut oil. The following results favoured fish oil rather than placebo: joint swelling index and duration of early morning stiffness. Other clinical indices improved but did not reach statistical significance. During fish oil supplementation relative amounts of eicosapentaenoic acid and docosahexaenoic acid in the plasma cholesterol ester and neutrophil membrane phospholipid fractions increased, mainly at the expense of the omega-6 fatty acids. The mean neutrophil leucotriene B4 production in vitro showed a reduction after 12 weeks of fish oil supplementation. Leucotriene B5 production, which could not be detected either in the control or in the placebo period, rose to substantial quantities during fish oil treatment. This study shows that dietary fish oil supplementation is effective in suppressing clinical symptoms of rheumatoid arthritis.

Vascular prostacyclin is increased in patients ingesting omega-3 polyunsaturated fatty acids before coronary artery bypass graft surgery.

Abstract: Interest in the antithrombotic potential of diets enriched with fish oil-derived polyunsaturated fatty acids (omega-3 PUFAs) prompted us to examine how these fatty acids, when taken preoperatively, affect hemostasis, plasma lipid levels, and production of prostacyclin (PGI2) by vascular tissues in atherosclerotic patients undergoing coronary artery bypass graft surgery. Fifteen patients with angiographically proven coronary artery disease received 3 g/day eicosapentaenoic acid and 1.3 g/day docosahexaenoic acid as capsules of purified fish oil for 28 days before surgery. Platelet aggregation induced by low concentrations of ADP, collagen, and epinephrine decreased (p less than 0.05) and serum thromboxane B2 decreased 36% (p less than 0.01) from baseline values. Bleeding times increased 40% (p less than 0.01) from baseline. Serum triglycerides decreased 50% (p less than 0.05) without a change in total serum cholesterol. Spontaneous production of PGI2 measured as 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha), its stable hydrolytic product, by saphenous vein and aortic and atrial tissues obtained at surgery was greater in tissues from patients receiving omega-3 PUFA supplements than in tissues from matched controls (13.8 +/- 2.2 versus 8.6, 21.0 +/- 3.1 versus 11.5 +/- 2.1, and 166 +/- 13 versus 102 +/- 15 ng/g, respectively, all p less than 0.05). Arachidonate-stimulated production of PGI2, as indicated by increased levels of 6-keto-PGF1 alpha, was increased. Despite changes in platelet function, bleeding time, and vascular PGI2, the perioperative blood loss was not increased in subjects receiving fish oil supplements. Thus, omega-3 PUFAs at moderate dosages may exert antithrombotic effects by increasing prostacyclin production by vessel walls as well as by direct inhibition of platelet activity.

Dietary fish oils limit adipose tissue hypertrophy in rats

Abstract: Total body mass, fat pad mass, and fat cell size were examined after feeding rats diets containing 20% triglycerides from fish oil or lard. Although food consumption, weight gain, and fat balance on the two diets were similar, lard-fed rats had 77% more fat in perirenal fat pads and 51% more fat in epididymal fat pads compared with fish oil-fed rats. There was no difference between the two groups in fat cell number in each region; however, adipocytes were significantly smaller in fish oil-fed rats. Thus dietary fish oil appears to limit triglyceride accumulation in adipose tissue and thereby limit fat cell trophic growth.

Inhibition of weight loss by ω-3 fatty acids in an experimental cachexia model.

Abstract: The effect of substitution of the carbohydrate component of the diet by calories derived from fish oil on host body weight loss and tumor growth rate has been studied in an experimental colon adenocarcinoma (MAC16). This tumor produces extensive host weight loss and reductions in both total body fat and muscle dry weight, without a reduction in food intake. Diets containing fish oil significantly reduced host body weight loss, with almost complete protection occurring when the fish oil comprised 50% of the calories, without an alteration of total calorie consumption or nitrogen intake. There was also a significant reduction in tumor growth rate, although the reduction in host weight loss was greater than might be expected from a smaller tumor burden. The reduction of host body weight loss was associated with an increase in total body fat and muscle mass. The effect appears specific to the type of fat since comparable results were not obtained with a gamma-linolenic acid-enriched diet. When compared with cyclophosphamide and 5-fluorouracil the fish oil diet exerted a similar antitumor effect at the maximum dose. Whereas the antitumor effect of the former agents was achieved with considerable host toxicity, the latter produced no toxicity and almost completely abolished the cachectic effect of the tumor. These results suggest that fish oil is a nontoxic, highly effective anticachectic agent with the added advantage of antitumor activity.

Selective Hydrolysis of Fish Oil by Lipase to Concentrate n-3 Polyunsaturated Fatty Acids

Abstract: Six lipases were examined for concentrating the n-3 polyunsaturated fatty acid (n-3 PUFA) of two kinds of fish oil (cod liver oil and refined sardine oil). Although all lipases could increase the n-3 PUFA content of the remaining glycerides, Candida cylindracea and Aspergillus niger lipases gave glycerides with a more than two-fold increase in n-3 PUFA content over the original fish oils.Candida cylindracea lipase seems the most promising with respect to recovery of triacylglycerol. Aspergillus niger lipase increased not only the docosahexaenoic acid (DHA) content but also eicosapentaenoic acid (EPA) and docosapentaenoic acid (DPA), although the absolute value of the latter was quite low. The effects of temperature (15–40 °C) on the concentration of n-3 PUFA were investigated. Lower temperatures did not improve the concentration of n-3 PUFA, but prevented the development of an unpleasant odor in the product.

Seafood lipids and fatty acids

Abstract: The consumer is very inadequately informed on seafood composition because of variable fat levels in some species, confusion in species nomenclature, failure to recognize the increasing proportion of imports, influence of aquaculture practices, and the actual fish contents of convenience foods. Concerns about safety considerations are primed by the controversy between advocates of fish as food and marketers of fish oil concentrates in capsules. There are in fact very few problems with fish and shellfish, when these are carefully inspected, or with fish oil concentrates, which are prepared from highly purified natural materials. The bioavailability of different forms of omega‐3 fatty acids attached to glycerol, or sold as ethyl esters or free fatty acids, must be addressed. Therefore, the absorption and distribution in the body of various forms of omega‐3 fatty acids is outlined.

Effect of dietary fish oil on coronary artery and aortic atherosclerosis in African green monkeys.

Abstract: Studies were carried out for 2.5 to 3 years in adult male African green monkeys (grivet subspecies) fed diets containing 22% of calories as lard or fish oil with 40% of calories as fat and 0.75 mg cholesterol/Kcal to determine if isocaloric substitution of menhaden fish oil for lard affects coronary artery atherosclerosis. The average total plasma cholesterol concentrations during the experimental period were significantly lower for the fish-oil group (231 +/- 37 mg/dl) compared to the lard group (360 +/- 44 mg/dl), but this difference did not become apparent until after 5 months of experimental diet consumption. High density lipoprotein cholesterol concentrations were 30% lower (p less than 0.01) for the fish-oil group also (57 +/- 5 vs. 82 +/- 6 mg/dl). Plasma triglyceride concentrations were low for both groups, but after about 5 months of diet consumption, they were higher for the animals fed fish oil (25 +/- 2 mg/dl) compared to their lard-fed counterparts (15 +/- 1 mg/dl). Coronary artery intimal area (in this case a measure of early atherosclerotic lesion size) was low in all animals but was significantly less (p less than 0.03) for the fish oil vs. lard groups (0.01 +/- 0.002 vs. 0.03 +/- 0.009 mm2). More atherosclerosis was found in other arteries, and a trend was seen of less atherosclerosis in the thoracic aorta and common carotid arteries of the fish-oil group. The size of lesions in the abdominal aorta was similar between diet groups, but microscopic examination of arteries of the lard group revealed relatively more cholesterol monohydrate crystals compared to the arteries of the fish-oil group. Chemical analysis showed that there was less esterified cholesterol (1.46 +/- 0.71 vs. 3.43 +/- 0.74 mg/g, p = 0.04) and free cholesterol (3.7 +/- 2.15 vs. 7.05 +/- 1.68 mg/g, p = 0.08) in the abdominal aortas taken from the animals fed fish oil. There was a significant correlation between low density lipoprotein (LDL) cholesteryl ester (CE) fatty acid ratio (i.e., saturated + monounsaturated/polyunsaturated species) and the amount of esterified (r = 0.59) and free (r = 0.63) cholesterol in the abdominal aortas. Compared to the lard group, animals fed fish oil had significantly lower LDL CE melting temperatures (26 +/- 1 vs. 38 +/- 1 degree C) and significantly smaller LDL particles (2.68 +/- 0.10 vs. 3.25 +/- 0.38 g/mumol). Therefore, the potentially antiatherogenic effects of dietary fish oil include its ability to decrease the concentration, size, CE content, and CE melting temperature of plasma LDL.

Lipid peroxidation in rat tissue slices: effect of dietary vitamin E, corn oil-lard and menhaden oil.

Abstract: Rats were fed for 5 weeks either 10% (w/w) menhaden oil (MO) or a 10% corn oil-lard (COL) mixture (1∶1) in diets with ≤5 IU or ≤2 IU/kg vitamin E, respectively, or the same diets supplemented with d-α-tocopheryl succinate to a total of 35 and 180 IU vitamin E/kg, respectively. Slices of liver and heart from these rats were used to study lipid peroxidationin vitro. Thiobarbituric acid-reactive substances (TBARS) were measured in the medium after incubation of the slices at 37°C for 1 hr in the absence (uninduced) and presence of 0.5 mM tert-butyl hydroperoxide (induced). The release of TBARS from slices of heart and liver from rats fed either lipid decreased with increasing levels of dietary vitamin E. At the same level of dietary vitamin E, TBARS release was greater for slices of liver and heart from the MO-fed rats than from the COL-fed rats. Application of the TBARS data to a model simulating the experimental conditions showed a good correlation (r=0.95, p<0.001) between experimental and simulated values. Of the 16∶0–22∶6 fatty acids measured in liver from MO-fed rats, 15.4% was n−6 fatty acids and 29.9% was n−3 fatty acids; in liver from COL-fed rats, the respective values were 37.4% and 3.7%. Liver and kidney vitamin E levels were unaffected by the dietary lipid. This study demonstrated that a dietary fish oil increased the susceptibility of rat liver and heart toin vitro lipid peroxidation, and that vitamin E decreased TBARS in tissues from rats fed COL to lower levels than for tissues from rats fed MO. The results suggest that there might also be an increased requirement for dietary antioxidants by humans using fish oil supplements.

Nutritional immunomodulation in burn patients.

Abstract: A series of laboratory experiments in thermally injured guinea pigs has shown that feeding by the enteral route immediately after injury results in a decreased metabolic response by preventing loss of the GI barrier to the entrance of intestinal endotoxin and bacteria. Feeding by the iv route or giving crystalline amino acids instead of intact protein does not prevent atrophy of the intestine, nor does it prevent the hypermetabolic response. Optimal diets for nutritional support of burn patients contain 20% of energy from whey protein, 2% from arginine, 0.5% from cysteine, and 0.5% from histidine. Lipids comprise 15% of nonprotein calories with 50% fish oil (high in omega-3 fatty acids) and 50% safflower oil (high in linoleic acid). In a prospective clinical study, administration of this new diet was found to reduce wound infection (p less than .03), shorten hospital stay (p less than .02), and reduce death (p less than .06) when compared to other standard enteral formulations.

Vitamin E status during dietary fish oil supplementation in rheumatoid arthritis.

Abstract: The primary objective of this study was to determine whether it is the fish oil itself or the alpha-tocopherol that is added to the fish oil preparations (to prevent peroxidation) that is responsible for the beneficial effects of dietary supplementation with fish oil in patients with rheumatoid arthritis (RA). One group of RA patients took fish oil supplements and another group took alpha-tocopherol-enriched coconut oil supplements (placebo controls), both for 3 months. Clinical and laboratory indices of RA activity in relation to cellular and plasma vitamin E levels were assessed at the beginning and the end of the trial. The results of the study provide evidence that the beneficial effects of fish oil supplementation cannot be ascribed to the antioxidizing properties of the alpha-tocopherol per se.

Effects of dietary n-3 fatty acids on the phospholipid molecular species of monkey brain

Abstract: We examined the changes in the molecular species of brain ethanolamine glycerophospholipids of monkeys fed diets containing widely ranging amounts of n-3 fatty acids. Two groups of rhesus monkeys were fed pre- and postnatally either a control diet (soy oil; containing 8% of fatty acids as 18:3n-3) or a deficient diet (safflower oil; containing less than 0.3% 18:3n-3). The brains of these animals were analyzed at 22 months of age. A third group of monkeys was fed the safflower oil diet to 22 months of age and then switched to a fish oil diet (28% long-chain n-3 fatty acids) for 1-2 years before autopsy. The molecular species of the diacyl, alkylacyl, and alkenylacyl ethanolamine glycerophospholipids from frontal cortex were separated by HPLC. A total of 24 molecular species were identified. Fatty acids in the sn-2 position differed markedly among the diet groups, but the sn-1 position always contained only 16:0, 18:0, or 18:1. In the diacyl subclass of the control brain, the n-3 molecular species represented 41% of total and the n-6 species 45%, whereas in the deficient brain the n-3 molecular species decreased to 9% and n-6 molecular species increased to 77%. The fatty acid 22:5n-6 did not replace 22:6n-3 in a symmetrical fashion in the molecular species of the deficient brain. In the brains of the fish oil-fed monkeys, the n-3 molecular species amounted to 61% and n-6 molecular species were reduced to 25%. The species 18:1-22:6, 16:0-22:6, and 18:0-22:6 generally changed proportionally in response to diet.(ABSTRACT TRUNCATED AT 250 WORDS)

Failure to demonstrate an effect of dietary fatty acid composition on body weight, body composition and parameters of lipid metabolism in mature rats

Abstract: The objectives of the present study were to examine the effects of dietary fatty acid composition on body composition and on several parameters of lipid metabolism in adipose tissue and to assess the ease of weight loss with restricted dietary intake. Rats were fed diets containing 14% fish oil, safflower oil or beef fat plus 2% corn oil. These diets were fed ad libitum for 4 wk (first phase). A number of the animals from each group were killed, and the others were fed 50% of their first-phase food intake for an additional 4 wk (second phase). The diets used in the second phase contained 3% of the above fats plus 2% corn oil. Food consumption, food efficiency and body weights were monitored. After the rats were killed, fatty acid composition of epididymal fat pads was examined. In addition, in vivo lipolysis and in vitro lipogenesis in epididymal fat pads were examined. The results indicate that dietary fatty acid composition had no effect on body weight, food consumption, in vivo lipolysis and in vitro lipogenesis in epididymal fat pads. In addition, although dietary fatty acid manipulation resulted in alteration in adipose tissue fatty acid composition, it had no effect on the rate of weight loss, body composition, in vivo lipolysis and in vitro lipogenesis in epididymal fat pads. It is concluded that dietary fatty acid composition does not play a role in body composition and in lipid metabolism in adipose tissue of mature rats.