Showing papers on "Fish oil published in 1993"

Does fish oil lower blood pressure? A meta-analysis of controlled trials.

Abstract: BACKGROUND In a meta-analysis of 31 placebo-controlled trials on 1356 subjects, we examined the effect of omega-3 fatty acids in fish oil on blood pressure by grouping studies that were similar in fish oil dose, length of treatment, health of the subjects, or study design. METHODS AND RESULTS The mean reduction in blood pressure caused by fish oil for the 31 studies was -3.0/-1.5 mm Hg (95% confidence intervals: systolic blood pressure: -4.5, -1.5; diastolic blood pressure: -2.2, -0.8). There was a statistically significant dose-response effect when studies were grouped by omega-3 fatty acid dose: -1.3/-0.7 mm Hg at doses < or = 3 g/d, -2.9/-1.6 mm Hg at 3.3 to 7 g/d, and -8.1/-5.8 mm Hg at 15 g/d. Both eicosapentaenoic acid and docosahexaenoic acid were significantly related to blood pressure response. There was no effect on blood pressure in eight studies of "healthy" persons (mean reduction, -0.4/-0.7 mm Hg) at an overall mean dose of 4.2 g omega-3 fatty acids/d. By contrast, there was a significant effect of -3.4/-2.0 mm Hg in the group of hypertensive studies with a mean fish oil dose of 5.6 g/d and on systolic blood pressure only in six studies of hypercholesterolemic patients (-4.4/-1.1 mm Hg) with a mean dose of 4.0 g/d. A nonsignificant decrease in blood pressure was observed in four studies of patients with atherosclerotic cardiovascular disease (-6.3/-2.9 mm Hg). Variations in the length of treatment (from 3 to 24 weeks), type of placebo, and study design (crossover or parallel groups) did not appear to account for inconsistent findings among studies. CONCLUSIONS There is a dose-response effect of fish oil on blood pressure of -0.66/-0.35 mm Hg/g omega-3 fatty acids. The hypotensive effect may be strongest in hypertensive subjects and those with clinical atherosclerotic disease or hypercholesterolemia.

Effects of dietary omega-3 fatty acids on human breast cancer growth and metastases in nude mice.

Abstract: BACKGROUND Diets rich in omega-6 polyunsaturated fatty acids stimulate the growth and metastases of transplantable mammary carcinomas in rodents, whereas fish oil-containing diets, rich in omega-3 fatty acids, suppress the growth of these mammary tumor cells. PURPOSE This study was performed to evaluate the effect of a diet rich in menhaden fish oil on the growth and metastases of MDA-MB-435 human breast cancer cells in a mouse model system. METHODS Ninety female athymic nude mice (Ncr-nu/nu) were fed a 23% (wt/wt) corn oil, omega-6 fatty acid-rich diet; after 7 days, 1 x 10(6) estrogen-independent MDA-MB-435 human breast cancer cells were injected into a thoracic mammary fat pad. The 23% corn oil diet was continued for a further 7 days, after which the mice were assigned randomly to one of three diets containing a total of 23% fat, but different proportions of corn oil and menhaden oil (diet Cm: 18% corn oil and 5% menhaden oil, diet CM: 11.5% corn oil and 11.5% menhaden oil, and diet cM: 5% corn oil and 18% menhaden oil). Animal body weights and the surface area of the mammary fat pad tumors were recorded weekly. The mice were killed after 12 weeks on the experimental diets. Primary tumor surface areas and body weights were compared by unpaired Student's t tests, the incidence of lung metastases by the chi-square test, and differences in the total volumes of lung metastases by the nonparametric Mann-Whitney U test. RESULTS Tumor growth rates in the mice of the group fed diet Cm were significantly greater than for mice of either of the two groups fed diets containing higher levels of menhaden oil. Of the mice with primary tumors, the incidence of macroscopic lung metastases was greater in those fed diet Cm, compared with those fed diet cM (57.7% versus 22.2%; P < .01), but not significantly different from the mice fed diet CM. When metastases did occur, their extent was significantly greater in mice fed diet Cm, compared with those fed diet cM (P < .001). CONCLUSION These results indicate that a high-fat diet rich in omega-3 fatty acids can suppress human breast cancer cell growth and metastases in this mouse model system. IMPLICATION Dietary intervention trials to reduce recurrence risk in the postsurgical breast cancer patient should take account not only of the level of fat consumed, but also its fatty acid composition.

Lipid accumulation and body fat distribution is influenced by type of dietary fat fed to rats.

Abstract: The amount of fat in the diet is known to influence body weight and body composition, but it is not clear whether dietary fat composition can affect body composition independently. We studied the effects of six months of feeding diets containing lard (L), corn oil (CO), fish oil (FO) or medium chain triglycerides (MCT) on body weight and body composition in adult male Wistar rats. Although FO fats ate slightly less total energy than the other groups, there were no differences among groups in body weight at any time during the study. However, body composition, the composition of depot triglyceride, body fat distribution and insulin resistance were all influenced by the type of fat in the diet. FO rats had less total body fat, less intra-abdominal fat, and less insulin resistance than all other groups. Although some of these metabolic effects may have been secondary to a slightly lower energy intake, we believe these data demonstrate the potential impact which dietary fat composition can have on metabolism and body weight regulation.

Dietary fish oil augments nitric oxide production or release in patients with type 2 (non-insulin-dependent) diabetes mellitus.

Abstract: Decreased release of nitric oxide from damaged endothelium is responsible for the impaired endothelium-dependent vasodilator responses found in animal models of vascular disease. Dietary supplementation with fish oils has been shown to augment endothelium-dependent relaxations, principally by improving the release of nitric oxide from injured endothelium. Using forearm venous occlusion plethysmography we studied vascular responses to 60, 120, 180 and 240 nmol/min of acetylcholine (an endothelium-dependent vasodilator) and 3, 6 and 9 nmol/min of glyceryl trinitrate (an endothelium-independent vasodilator) infused into the brachial artery in 23 patients with Type 2 (non-insulin-dependent) diabetes mellitus. NG monomethyl-L-arginine was employed to inhibit stimulated and basal release of nitric oxide from the endothelium. On completion of the baseline studies patients randomly received either fish oil or matching olive oil capsules in a double-blind crossover fashion for 6 weeks followed by a 6-week washout period and a final 6-week treatment phase. Studies, identical to the initial baseline studies, were performed at the end of the active treatment periods at 6 and 18 weeks. Fish oil supplementation significantly improved forearm blood flow responses to each dose of acetylcholine when compared to the vasodilator responses recorded at baseline and after olive oil administration (p < 0.01). Neither fish oil nor olive oil supplementation produced any significant changes in forearm blood flow to the incremental infusions of glyceryl trinitrate when compared with responses recorded during the baseline studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Fish oil n-3 fatty acids selectively limit the hypertrophy of abdominal fat depots in growing rats fed high-fat diets

Abstract: Because dietary n-3 polyunsaturated fatty acids (n-3 PUFA) from fish oils have profound effects on lipid metabolism, we examined whether they influence the growth of adipose tissue at different locations in growing rats. Rats were fed for 4 wk on high-fat (HF) diets (20% fat) containing very low (L), medium (M), and high (H) amounts of n-3 PUFA but similar amounts of saturated fatty acids and n-6 PUFA. A fourth group was fed a standard laboratory diet (control group) to estimate changes in adipose tissue mass related to growth. At the end of the dietary treatment, the lipid mass (LM) of the four major adipose depots (subcutaneous, SC; mesenteric, MES; retroperitoneal, RP; epididymal, EPI) and total adiposity were significantly higher in each of the three HF groups than in the control group. The lipid gain in EPI was due to fat cell hypertrophy alone, whereas RP showed both hypertrophy and hyperplasia. Energy intake, fatty acid excretion, and body mass were the same in the three groups fed HF diets. Similarly, there was no difference in the LM or in lipid gains specifically caused by HF feeding of SC and MES between the HF groups. In contrast, the LM of RP was significantly lower in the H than in the L and M groups (50 and 30%, respectively). The LM of EPI was also 30% lower in the H than in the L group.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary sunflower, linseed and fish oils affect phospholipid fatty acid composition, development of cardiac lesions, phospholipase activity and eicosanoid production in Atlantic salmon (Salmo salar)

Abstract: Atlantic salmon (Salmo salar) post-smolts were fed practical-type diets in which the lipid was supplied either as fish oil (FO), sunflower oil (SFO) or linseed oil (LO) for 12 weeks. In general, the heart phospholipids from SFO-fed fish had increased 18:2n-6, 20:2n-6, 20:3n-6 and 20:4n-6 but decreased 20:5n-3 compared to both other dietary treatments. This was reflected in a decreased n-3/n-6 polyunsaturated fatty acid (PUFA) ratio and an increased 20:4n-6/20:5n-3 or eicosanoid precursor ratio in SFO-fed fish. While heart phospholipids of fish fed LO had increased levels of 18:2n-6, 20:2n-6 and 20:3n-6 compared to fish fed FO, 20:4n-6 levels were reduced, although only significantly in phosphatidylcholine (PC). Dietary-induced changes in phospholipid fatty acid compositions of blood leucocytes were similar to those in heart, although fish fed LO had increased 20:5n-3 compared to fish fed FO. Thromboxane B2 (TXB2) produced by stimulated blood cells was reduced in fish fed LO compared to those fed SFO. Prostaglandin E2 (PGE2) production was reduced in LO-fed fish compared to both other dietary treatments. Fish fed LO had reduced PC in heart membranes compared to the other two dietary treatments, resulting in a ratio of PC:PE (phosphatidylethanolamine) less than unity. Fish fed SFO developed a marked cardiac histopathology which, while present in FO-fed fish albeit in a less severe form, was virtually absent in fish fed LO. Fish fed SFO had increased heart phospholipase A activity compared to those given either FO or LO.

The effects of short- and long-term supplementation with fish oil on the incorporation of n-3 polyunsaturated fatty acids into cells of the immune system in healthy volunteers

Abstract: Eight healthy male volunteers supplemented their normal diet with 10-15 g/d of a fish oil supplement (MaxEPA) to provide 1.4-4.2 g/d of eicosapentaenoic acid (EPA; C20:5 n-3) for a period of 12 weeks. Blood samples were taken at weeks 0, 2 and 12 and the fatty acid compositions of the phospholipids of plasma, platelets, neutrophils, monocytes and T- and B-lymphocytes were determined. In all instances the level of EPA increased significantly (P < 0.05) by 2 weeks and remained so without a further increase for the ensuing 10 weeks. Beyond that, few consistent patterns in fatty acid composition were observed. Arachidonic acid (C20:4 n-6) fell significantly (P < 0.05) in plasma, platelets, neutrophils and T- and B-lymphocytes, but generally tended to do so only by week 12. Given the wide variability in the half-life of these cells (minutes for neutrophils, months for lymphocytes) it is evident that uptake of plasma EPA occurs by phospholipid exchange into preformed mature cells and does not require incorporation during cell genesis.

Effect of pravastatin and omega-3 fatty acids on plasma lipids and lipoproteins in patients with combined hyperlipidemia.

Abstract: This study compared the effects of a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, fish oil, and placebo on plasma lipids and lipoproteins in patients with mixed hyperlipidemia. After an initial run-in phase, 32 patients were randomized for 6 weeks to either (1) pravastatin 40 mg/d, n = 10; (2) fish oil (himega 6 g/d, equivalent to 3 g omega-3 fatty acids/d), n = 10; or (3) placebo. After single drug therapy, in the pravastatin group mean total plasma cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and apolipoprotein (apo) B fell significantly by 23% (P < .001), 30% (p < .001), and 26% (P < .01), respectively. LDL Stokes' diameter did not change. In the fish oil group mean plasma triglycerides (TG) fell 30% (P < .05), LDL Stokes' diameter increased from 25.0 to 25.9 nm (P < .05), and there was a nonsignificant increase in LDL-C. There were no changes in the placebo group. To assess the effect of the combination of pravastatin plus fish oil therapy, all patients, except one woman from the placebo group who developed nausea on fish oil, then took combined therapy of pravastatin 40 mg/d plus fish oil 6 g/d for an additional 12 weeks. In each case, there were no clinically significant episodes of muscle tenderness or elevation of creatine phosphokinase or alanine aminotransferase. After 12 weeks of combined therapy of pravastatin plus fish oil, there were significant reductions in the mean TC, TG, LDL-C, and apoB in the three groups compared with baseline levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Very long chain n-3 and n-6 polyunsaturated fatty acids inhibit proliferation of human T-lymphocytes in vitro.

Abstract: The effect of marine n-3 polyunsaturated fatty acids on proliferation of human T-cells in vitro was compared to other polyunsaturated, monounsaturated and saturated fatty acids. Monoenes and saturated fatty acids had little effect on T-cell proliferation. Eicosapentaenoic acid and docosahexaenoic acid exerted a strong dose-dependent inhibitory effect on proliferation of mitogen- or antigen-stimulated T-cells, similar to that observed for arachidonic acid. Sixty microM of albumin-bound eicosapentaenoic acid or arachidonic acid promoted 25-40% inhibition of proliferation of T-cells stimulated with mitogen, whereas the same concentration of albumin-bound docosahexaenoic acid promoted 60% inhibition. When epidermal cells (Langerhans cells) were used as antigen-presenting cells, 100 microM of albumin-bound eicosapentaenoic acid or arachidonic acid caused 40% inhibition on T-cell proliferation. Low density lipoprotein (LDL), isolated after four months of dietary intake of fish oil or corn oil, inhibited mitogen-stimulated T-cell proliferation in a dose-dependent manner. Fish oil- and corn oil-enriched LDL showed similar ability to inhibit T-cell proliferation. Epidermal cells preincubated with docosahexaenoic acid, and extensively washed before adding purified T-cells and antigen, resulted in a strong inhibition of T-cell proliferation, whereas preincubation of purified T-cells with docosahexaenoic acid did not cause any inhibitory effect. Cyclooxygenase and lipoxygenase inhibitors (indomethacin, acetylsalicylic acid, nordihydroguaertic acid) did not affect the antiproliferative effect of eicosapentaenoic acid and arachidonic acid, neither did the antioxidants butylated hydroxytoluene or alpha-tocopherol. Eicosanoids, (PGE2, PGE3, LTB4, LTB5 and lipoxin A or lipoxin B) added directly to mitogen-stimulated peripheral blood mononuclear cells (PBMC) did not influence T-cell proliferation significantly. Decreased viability was observed when mitogen-stimulated lymphocytes were cultured with essential polyunsaturated fatty acids, whereas the viability of unstimulated lymphocytes was hardly influenced by the same fatty acids. We conclude that; (a) pharmacological albumin-bound concentrations of the highly unsaturated fatty acids eicosapentaenoic acid and docosahexaenoic acid promote a strong antiproliferative effect on mitogen- and antigen-stimulated human T-cells: (b) docosahexaenoic acid can suppress accessory cell function and consequently suppress T-cell activation; (c) physiologic concentration of LDL particles rich in n-3 and n-6 fatty acids, both promote a dose-dependent antiproliferative effect on mitogen-stimulated PBMC; (d) the inhibition is independent of eicosanoid metabolites; and (e) lipid peroxidation seems unlikely to be responsible for the antiproliferative effect.

Effects of alpha-tocopherol and dietary oxidized fish oil on the immune response of sea bass Dicentrarchus labrax

Abstract: Sea bass weighing about 35 g were reared on 6 experimental diets differing in the level of alpha-tocopherol (vitamin E) supplementation (0, 40 or 300 mg kg-') and fish oil quality (fresh or oxidized). After 35 wk, group comparisons of haematological parameters were made and alpha-tocopherol levels in anterior kidney, spleen, and thymus were assessed in pooled samples. Non-specific immune factors assayed were: (1) plasma lysozyme and complement activ~ties, (2) natural haemolysis of sheep red blood cells (SRBC), and (3) chemiluminescence (CL) response of head kidney phagocytes. Humoral antibody production was also assessed for each group after immunisation with Vibrio anguillarurn 408. Res~stance to bacterial infection was assessed comparatively according to diet. The levels of alphatocopherol in the different tissues were a funct~on of the dietary vitamin E concentrations and were lower when oxidized flsh oil was added to the diet. Erythrocyte fragility was raised in vitamin E depleted groups as well as in fish fed diets containing oxidized oil. Disease resistance, antibody response to V anguillarum antigen, and haemolytic activity of sera were not affected by dietary treatment. Plasma lysozyme activity was lower in groups fed diets containing oxidized oil or not supplemented with vitamin E, and complement activity was higher in the fish that were fed the diet containing fresh oil and 300 mg vitamin E kg-'. One month after vaccination, the CL peak response of head kidney phagocytes, stimulated by opsonized zymosan, was significantly lower in the fish that were fed the diet containing oxidized oil and not supplemented with vitamin E.

Effect of dietary supplementation with very-long-chain n-3 fatty acids in patients with psoriasis.

Abstract: Background In several studies dietary fish oil has been found to have a beneficial effect on psoriasis, but the results are contradictory and based mainly on open studies or studies of small numbers of patients. Methods In a four-month double-blind, multicenter trial, we randomly assigned 145 patients with moderate-to-severe psoriasis to receive in their diet either highly purified ethyl esters of n-3 fatty acids (“fish oil”; 6 g of oil per day, containing 5 g of eicosapentaenoic and docosahexaenoic acid) or an isoenergetic amount of corn oil containing mainly n-6 fatty acids. All the patients were advised to reduce their intake of saturated fatty acids. A 48-hour dietary recall was performed, and the fatty-acid pattern in the serum phospholipids was monitored in a subgroup of patients. Results In the fish-oil group, n-3 fatty acids were increased in serum phospholipids (P<0.001), the ratio of arachidonic acid to eicosapentaenoic acid decreased (P<0.001), and the level of n-6 fatty acids decreased (P<0.00...

N‐3 Fatty Acids from Fish Oil

Abstract: In the experimental studies reported in this review, dietary n-3 fatty acids from fish and fish oil had profound hypolipidemic effects in normal subjects and in hypertriglyceridemic patients with combined hyperlipidemia (type II-b) and types IV and V hyperlipidemia. In these carefully controlled metabolic experiments, dramatic reductions occurred in plasma triglycerides and to a lesser extent in plasma total cholesterol. Reductions in VLDL, chylomicrons, remnants, LDL, apo B, and apo E were also noted. HDL changes varied from subject to subject. These plasma lipoprotein changes occurred in subjects with non-insulin-dependent diabetes mellitus as well, without deterioration of diabetic control. Similar results are reported in two other papers in this volume. Fish oil did not cause deterioration of diabetic control. Whereas the mechanism of the hypolipidemic action of the n-6 rich vegetable oils containing linoleic acid such as corn or safflower oil still remains obscure, the mechanism of the hypolipidemic action of the n-3 fatty acids in fish oil is well documented. The synthesis of triglyceride and VLDL in the liver is greatly reduced by n-3 fatty acids. At the same time, the turnover of VLDL in plasma is shortened. In another study, LDL production was decreased. Combined with other dietary manipulations, such as a reduction in saturated fat and dietary cholesterol, the use of n-3 fatty acids to treat hyperlipidemia, especially hypertriglyceridemia, appears to have a well-supported rationale. Fish oil combined with a low cholesterol, low saturated fat diet has been shown to produce complementary effects. Total plasma cholesterol and LDL cholesterol were lowered by the low cholesterol, low saturated fat diet, whereas plasma triglyceride and VLDL were decreased by the fish oil. In most situations, the use of fish oil supplements should be regarded as pharmacologic therapy, particularly effective in severe hypertriglyceridemic states (e.g., chylomicronemia). However, a lifelong diet rich in fish may be protective against atherosclerosis as well. Further studies are required to delineate exact doses and precise indications for the use of fish oil in different types of hyperlipidemias and to differentiate the effects, if any, of the two major n-3 fatty acids in fish oil, EPA and DHA. The hypolipidemic effects of n-3 fatty acids coupled with their known antithrombotic actions (secondary to changes in prostaglandin secretion, platelet function, inhibition of growth factors, and enhancement of endothelial-derived relaxation factor) appear to have an important potential role in the control of coronary heart disease and other atherosclerotic disorders. Moreover, fish oil may prevent the "chylomicronemia" syndrome of type V hyperlipidemia.

Dietary fish oil effects on seasonal hay fever and asthma in pollen-sensitive subjects

Abstract: The effects of taking 18 capsules a day of Max-EPA (3.2 g/day eicosapentaenoic acid) on clinical symptoms and bronchial hyperresponsiveness were studied in pollen-sensitive subjects over a pollen season in a parallel, double-blind, placebo-controlled (olive oil) fashion. The study was conducted over the 1990 and 1991 pollen seasons in London, England. A total of 37 nonsmoking pollen-sensitive asthmatic subjects were entered into the trial, and 25 completed the 6-month study period over the 2 yr. The preseasonal geometric mean PD35 SGaw of histamine for the fish oil (n = 12) and placebo (n = 9) groups were 0.62 and 0.42 mumol, respectively. During the middle of the pollen season, histamine PD35 SGaw fell significantly for both the fish oil (0.11 mumol, p < 0.0001) and placebo groups (0.10 mumol, p < 0.007), indicating increased bronchial reactivity compared with preseasonal values, but there was no significant difference between the groups. Similarly, morning and evening peak expiratory flow (PEF), diurnal variability in PEF, nocturnal cough and wheeze, daytime wheeze, and activity, as well as nasal symptoms and increased usage of medication, were not significantly different between the groups. Compliance was confirmed by neutrophil and plasma phospholipid analysis, which showed significant rises in eicosapentaenoic acid content in the fish oil group but not in the placebo group. We conclude that dietary fish oil supplementation does not prevent seasonal hay fever and asthma in pollen-sensitive subjects during the pollen season.

Dietary Fatty Acid Composition Influences Energy Accretion in Rats

Abstract: To study the influence of dietary fatty acid composition on energy metabolism, forty male rats were fed elemental diets containing 42% of energy as fish oil, safflower oil, olive oil or beef tallow for 12 wk Food intakes and body weights were measured daily Energy expenditure and body composition were determined using doubly labeled water on the final 2 d Pooled fecal energy losses differed in response to dietary manipulation, with losses greatest in rats fed beef tallow and least in those fed olive oil Higher lean body mass gains and lower fat mass gains were observed in rats fed diets containing fish oil, compared with rats fed olive oil or beef tallow Total energy gains in rats fed olive oil (3632 +/- 145 kJ) and beef tallow (3850 +/- 136 kJ) were higher than those in rats fed fish oil (2905 +/- 196 kJ) Energy efficiency in both the olive oil and beef tallow groups was also higher than that in the fish oil group There were no differences in energy expenditure measured by doubly labeled water technique among the four groups The data suggest that dietary fatty acid composition alters the efficiency of energy substrate accretion in rats

Flavonoids as stabilizers of fish oil: An alternative to synthetic antioxidants

Abstract: The antioxidant activities against fish oil oxidation of six commercially available flavonoids and of five flavonoids purified from two Chilean native plants were compared to those ofdl-α-tocopherol and of two synthetic antioxidants, butylated hydroxytoluene and butylated hydroxyanisole. Among the commercial flavonoids, catechin, morin and quercetin showed a higher activity when fish oil oxidation (either spontaneous or Fe2+-induced) was assessed from the formation of peroxides or thiobarbituric acid-reactive substances. Among the native flavonoids, the 5,3′,4′-trihydroxy-7-methoxy flavanone (designated as Pt-2) showed the highest antioxidant activity. Mixtures of quercetin or of Pt-2 withdl-α-tocopherol produced better inhibitory effects when compared to that of each substance assayed by itself. Also, when Pt-2 and quercetin were assayed in combination (0.3 g/kg oil and 0.7 g/kg oil, respectively), a synergistic antioxidant effect was observed. Results indicate that several flavonoids could be used as natural antioxidants as a means to replace those synthetic antioxidants, the use of which has been questioned.

Essential fatty acid requirement of juvenile red drum (Sciaenops ocellatus).

Abstract: Feeding experiments and laboratory analyses were conducted to establish the essential fatty acid (EFA) requirement of red drum (Sciaenops ocellatus). Juvenile red drum were maintained in aquaria containing brackish water (5 ± 2‰ total dissolved solids) for two 6-week experiments. Semipurified diets contained a total of 70% lipid consisting of different combinations of tristearin [predominantly 18:0] and the following fatty acid ethyl esters: oleate, linoleate, linolenate, and a mixture of highly unsaturated fatty acids (HUFA) containing approximately 60% eicosapentaenoate plus docosahexaenoate. EFA-deficient diets (containing only tristearin or oleate) rapidly reduced fish growth and feed efficiency, and increased mortality. Fin erosion and a “shock syndrome” also occurred in association with EFA deficiency. Of the diets containing fatty acid ethyl esters, those with 0.5–1% (n-3) HUFA (0.3–0.6% eicosapentaenoate plus docosahexaenoate) promoted the best growth, survival, and feed efficiency; however, the control diet containing 7% menhaden fish oil provided the best performance. Excess (n-3) HUFA suppressed fish weight gain; suppression became evident at 1.5% (n-3) HUFA, and was pronounced at 2.5%. Fatty acid compositions of whole-body, muscle and liver tissues from red drum fed the various diets generally reflected dietary fatty acids, but modifications of these patterns also were evident. Levels of saturated fatty acids appeared to be regulated independent of diet. In fish fed EFA-deficient diets (containing only tristearin or oleate), monoenes increased and (n-3) HUFA were preferentially conserved in polar lipid fractions. Eicosatrienoic acid [20:3(n-9)] was not elevated in EFA-deficient red drum, apparently due to their limited ability to transform fatty acids. Red drum exhibited some limited ability to elongate and desaturate linoleic acid [18:2(n-6)] and linolenic acid [18:3(n-3)]; however, metabolism of 18:3(n-3) did not generally result in increased tissue levels of (n-3) HUFA. Based on these responses, the red drum required approximately 0.5% (n-3) HUFA in the diet (approximately 7% of dietary lipid) for proper growth and health.

Modulating effect of amount and types of dietary fat on ornithine decarboxylase, tyrosine protein kinase and prostaglandins production during colon carcinogenesis in male F344 rats.

Abstract: Epidemiological and laboratory animal model studies suggest that the effect of dietary fat on colon carcinogenesis depends on the amount and its type. In the present study, we investigated the modulating effect of high-fat diets rich in omega-3, omega-6 and omega-9 fatty acids on liver, colon and small intestine mucosal ornithine decarboxylase (ODC) and tyrosine-specific protein kinase (TPK) activities and plasma, liver and colon mucosal prostaglandin E2 (PGE2) and 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha) levels in male F344 rats. At 6 weeks of age, groups of animals were fed the low-fat diet containing 5% corn oil (LFCO), or high-fat diets containing 23.5% corn oil (HFCO), 23.5% olive oil (HFOO) and 20.5% fish oil + 3% corn oil (HFFO). Two weeks later, all animals except the vehicle-treated groups received azoxymethane (AOM) s.c. once weekly for 2 weeks at a dose rate of 15 mg/kg body wt. All animals were killed 5 days later and liver, colon and small intestine mucosa were analyzed for ODC, TPK and PGs and plasma for PGs. Carcinogen treatment enhanced the ODC and TPK activities (P < 0.0001) in the liver and colon of animals, irrespective of dietary treatment. Dietary HFCO compared with LFCO significantly increased the ODC (P < 0.01) and membrane TPK (P < 0.05) activities in the liver and colon of carcinogen-treated animals, whereas the HFOO and HFFO diets significantly (P < 0.002) suppressed the ODC and membrane TPK (P < 0.05) activities in the liver and colon mucosa compared with the HFCO diet. Carcinogen treatment also significantly (P < 0.01) increased the PG levels in plasma, liver and colon. Feeding of the HFFO diet significantly suppressed both the basal levels and ex vivo production of PGE2 and 6-keto PGF1 alpha levels compared with the HFCO diet, whereas the HFOO diet only decreased PGE2 in liver and colon. These results thus demonstrate that high levels of corn oil in the diet increase colon and liver ODC, TPK and PGs whereas high dietary levels of fish oil and olive oil suppress these activities.

Regulation of plasma oestrogen by dietary fats in the laying hen: Relationships with egg weight

Abstract: 1. Feeding a diet supplemented with maize oil was found to elevate plasma oestradiol concentration in laying hens. 2. In a larger-scale experiment, isoenergetic and isonitrogenous diets containing 10, 20, 40 or 60 g/kg supplemental maize oil, tallow, coconut oil or fish oil were fed for 5 weeks. 3. Egg weights showed very different responses to the different fats. The responses could be described by quadratic functions that all gave optimum responses with supplemental dietary fat concentrations of about 40 g/kg. Egg weight increased the most with maize oil and was decreased with fish oil at the highest inclusion rate. 4. Measurements of egg components showed a relatively larger increase in albumen weights with maize oil than with other fats. 5. Across treatments, mean plasma oestradiol concentrations were very highly correlated (r = 0.96) with the changes in egg weights over the experimental period. 6. It is concluded that oestrogen is important in controlling egg weight and that the effect of dietary fats in influencing egg weight is mediated by an effect of the fats on oestrogen metabolism.