Showing papers on "Fish oil published in 1997"

Randomized, double-blind, placebo-controlled trial of fish oil and mustard oil in patients with suspected acute myocardial infarction: the Indian experiment of infarct survival--4.

Abstract: In a randomized, placebo-controlled trial, the effects of treatment with fish oil (eicosapentaenoic acid, 1.08 g/day) and mustard oil (alpha-linolenic acid, 2.9 g/day) were compared for 1 year in the management of 122 patients (fish oil, group A), 120 patients (mustard oil, group B), and 118 patients (placebo, group C) with suspected acute myocardial infarction (AMI). Treatments were administered about (mean) 18 hours after the symptoms of AMI in all three groups. The extent of cardiac disease, rise in cardiac enzymes, and lipid peroxides were comparable among the groups at entry into the study. After 1 year total cardiac events were significantly less in the fish oil and mustard oil groups compared with the placebo group (24.5% and 28% vs. 34.7%, p < 0.01). Nonfatal infarctions were also significantly less in the fish oil and mustard oil groups compared with the placebo group (13.0% and 15.0% vs. 25.4%, p < 0.05). Total cardiac deaths showed no significant reduction in the mustard oil group; however, the fish oil group had significantly less cardiac deaths compared with the placebo group (11.4% vs. 22.0%, p < 0.05). Apart from the decrease in the cardiac event rate, the fish oil and mustard oil groups also showed a significant reduction in total cardiac arrhythmias, left ventricular enlargement, and angina pectoris compared with the placebo group. Reductions in blood lipoproteins in the two intervention groups were modest and do not appear to be the cause of the benefit in the two groups. Diene conjugates showed a significant reduction in the fish oil and mustard oil groups, indicating that a part of the benefit may be caused by the reduction in oxidative stress. The findings of this study suggest that fish oil and mustard oil, possibly due to the presence of n-3 fatty acids, may provide rapid protective effects in patients with AMI. However, a large study is necessary to confirm this suggestion.

Effect of dietary fish oil on body fat mass and basal fat oxidation in healthy adults.

Abstract: OBJECTIVE: To investigate whether the substitution of fish oil for visible fats in a control diet (52% carbohydrates, 16% protein, 32% fat; P:S 0.2) influences body fat mass and substrate oxidation in healthy adults. DESIGN: Six volunteers (5 men; 23±2 y; BMI: 21.9±1.6) were fed a control diet (C) ad libitum during a period of three weeks and, 10–12 weeks later, the same diet where 6 g/d of visible fat were replaced by 6 g/d of fish oil (FO) for another three weeks. RESULTS: Energy intakes (IKA-calorimeter) were unchanged. Body fat mass (Dual-energy X-ray absorptiometry) decreased with FO (−0.88±0.16 vs−0.3±0.34 kg; FO vs C; P<0.05). When adjusted for lean body mass (Ancova), resting metabolic rate (indirect calorimetry) was unchanged. Basal respiratory quotient decreased with FO (0.815±0.02 vs 0.834±0.02; P<0.05) and basal lipid oxidation increased with FO (1.06±0.17 vs 0.87±0.13 mg kg−1 min−1; P<0.05). CONCLUSION: Dietary FO reduces body fat mass and stimulates lipid oxidation in healthy adults.

n-3 Polyunsaturated fatty acids and cytokine production in health and disease

Abstract: Arachidonic-acid-derived eicosanoids modulate the production of pro-inflammatory and immunoregulatory cytokines. Overproduction of these cytokines is associated with both septic shock and chronic inflammatory diseases. The n-3 polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid, which are found in fish oils, suppress the production of arachidonic-acid-derived eicosanoids and EPA is a substrate for the synthesis of an alternative family of eicosanoids. Thus, dietary fats which are rich in n-3 PUFAs have the potential to alter cytokine production. Animal studies have provided a great deal of evidence that feeding plant or fish oils rich in n-3 PUFAs does alter the ex vivo production of tumour necrosis factor (TNF), interleukin 1 (IL-1), IL-6 and IL-2, but many contradictory observations have been made; it is most likely that the discrepancies in the literature result from differences in the cell types and experimental protocols used. Human studies provide more consistent data: several studies have shown that supplementation of the diet of healthy volunteers results in reduced ex vivo production of IL-1, IL-6, TNF and IL-2 by peripheral blood mononuclear cells. Similar findings have been made in patients with rheumatoid arthritis and multiple sclerosis. Animal studies indicate that dietary fish oil reduces the response to endotoxin and to pro-inflammatory cytokines, resulting in increased survival; such diets have been beneficial in some models of bacterial challenge, chronic inflammation and auto-immunity. These beneficial effects of dietary n-3 PUFAs may be of use as a therapy for acute and chronic inflammation and for disorders which involve an inappropriately activated immune response.

Visual Acuity, Erythrocyte Fatty Acid Composition, and Growth in Term Infants Fed Formulas with Long Chain Polyunsaturated Fatty Acids for One Year

Abstract: The CNS and the retina are enriched in long chain polyunsaturated (LCP) fatty acids, specifically docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (AA, 20:4n-6), which are present in human milk but not in most infant formulas. In the present study of 134 formula-fed and 63 breast-fed infants, we prospectively evaluated whether providing a source of DHA and AA or DHA alone in formula would increase red blood cell (RBC) phospholipid levels of these fatty acids, enhance visual function, or affect growth during the first year. Healthy term infants < 7 d old were randomized to be fed formulas containing linoleic acid (approximately 10% kcal) and alpha-linolenic acid (approximately 1% kcal) plus (1) no added LCP fatty acids (control formula), (2) DHA (0.12 wt% fatty acids) and AA (0.43 wt%) from egg yolk phospholipid (AA + DHA formula), or (3) DHA (0.2 wt%) from fish oil (DHA formula). A breast-fed group was studied concurrently and permitted formula supplementation after 3 mo. Visual acuity was measured using both the acuity card procedure and a visual evoked potential method at 2, 4, 6, 9, and 12 mo. Infants fed the control formula had 10-40% lower RBC levels of DHA and AA than infants in the breast-fed group. Infants fed the AA + DHA formula had levels of both LCP within approximately 10% of the values for infants in the breast-fed group, and infants fed the DHA formula had 25-55% higher DHA levels and 15-40% lower AA levels. There were no differences in growth or in visual function during this 12-mo feeding study.

Incorporation of n‐3 fatty acids into plasma lipid fractions, and erythrocyte membranes and platelets during dietary supplementation with fish, fish oil, and docosahexaenoic acid‐rich oil among healthy young men

Abstract: The effects of n-3 fatty acid supplementation in the form of fresh fish, fish oil, and docosahexaenoic acid (DHA) oil on the fatty acid composition of plasma lipid fractions, and platelets and erythrocyte membranes of young healthy male students were examined. Altogether 59 subjects (aged 19-32 yr, body mass index 16.8-31.3 kg/m2) were randomized into the following diet groups: (i) control group; (ii) fish diet group eating fish meals five times per week [0.38 +/- 0.04 g elcosapentaenoic acid (EPA) and 0.67 +/- 0.09 g DHA per day]; (iii) DHA oil group taking algae-derived DHA oil capsules (1.68 g/d DHA in triglyceride form); and (iv) fish oil group (1.33 g EPA and 0.95 g DHA/d as free fatty acids) for 14 wk. The fatty acid composition of plasma lipids, platelets, and erythrocyte membranes was analyzed by gas chromatography. The subjects kept 4-d food records four times during the study to estimate the intake of nutrients. In the fish diet, in DHA oil, and in fish oil groups, the amounts of n-3 fatty acids increased and those of n-6 fatty acids decreased significantly in plasma lipid fractions and in platelets and erythrocyte membranes. A positive relationship was shown between the total n-3 polyunsaturated fatty acids (PUFA) and EPA and DHA intake and the increase in total n-3 PUFA and EPA and DHA in all lipid fractions analyzed. DHA was preferentially incorporated into phospholipid (PL) and triglyceride (TG) and there was very little uptake in cholesterol ester (CE), while EPA was preferentially incorporated into PL. and CE. The proportion of EPA in plasma lipids and platelets and erythrocyte membranes increased also by DHA supplementation, and the proportion of linoleic acid increased in platelets and erythrocyte membranes in the DHA oil group as well. These results suggest retroconversion of DHA to EPA and that DHA also interferes with linoleic acid metabolism.

The importance of highly unsaturated fatty acids in zooplankton nutrition: evidence from experiments with Daphnia, a cyanobacterium and lipid emulsions

Abstract: 1. We used laboratory growth and feeding experiments to evaluate the role of ω3 highly unsaturated fatty acids (HUFA) in zooplankton nutrition. Polyunsaturated fatty acids (PUFA) comprised 40% of total fatty acids (FA) in the green alga Scenedesmus acutus but only 6% in the cyanobacterium Synechococcus elongatus.Scenedesmus contained modest amounts of the ω3 HUFA eicosapentaenoic acid (EPA, 20 : 5ω3) and docosahexaenoic acid (DHA, 22 : 6ω3), whereas Synechococcus contained only a trace of EPA and no DHA. 2. One-day-old Daphnia maintained high growth rates for 2–3 days on a diet of Synechococcus but exhibited reduced growth or even lost weight over the later part of the 6- or 7-day experiments. Daphnia magna grew better than D. galeata or D. pulicaria on a diet of pure Synechococcus. Daphnids fed the same concentration (0.5 mgC l–1) of green algae or a mixture of green algae and Synechococcus maintained high growth rates. 3. Supplementing Synechococcus with fish oil emulsions rich in ω3 HUFA markedly improved the growth and reproduction of all three Daphnia species. Supplementation with an emulsion of monounsaturated oleic acid (18 : 1ω9), however, did not affect the growth of D. galeata and caused a decrease in the growth of D. magna. 4. Short-term (7 min) and long-term (3 h) feeding trials with 14C-labelled Synechococcus were used to evaluate the effects of acclimation and mixed diets on carbon incorporation. D. galeata that had fed on unlabelled Synechococcus for 3 days exhibited no decline in clearance rate but a marked decline in carbon incorporation in comparison with animals acclimated with Scenedesmus or fed a mixture of Synechococcus and Scenedesmus. 5. Our results support the hypothesis that the poor nutritional quality of a cyanobacterium is at least partially due to a HUFA deficiency. Growth and feeding experiments both suggest that the utilization of Synechococcus is enhanced by HUFA from lipid reserves or a mixed diet.

Prevention of Cardiac Arrhythmia by Dietary (n-3) Polyunsaturated Fatty Acids and Their Mechanism of Action

Abstract: The role of marine fish oil (n-3) polyunsaturated fatty acids in the prevention of fatal ventricular arrhythmia has been established in experimental animals. Prevention of arrhythmias arising at the onset of ischemia and reperfusion is important because if untreated, they result in sudden cardiac death. Animals supplemented with fish oils in their diet developed little or no ventricular fibrillation after ischemia was induced. Similar effects have also been observed in cultured neonatal cardiomyocytes. Several mechanisms have been proposed and studied to explain the antiarrhythmic effects of fish oil polyunsaturated fatty acids, but to date, no definite mechanism has been validated. The sequence of action of these mechanisms and whether more than one mechanism is involved is also not clear. Some of the mechanisms suggested to explain the antiarrhythmic action of fish oils include the incorporation and modification of cell membrane structure by (n-3) polyunsaturated fatty acids, their direct effect on calcium channels and cardiomyocytes and their role in eicosanoid metabolism. Other mechanisms that are currently being investigated include the role of (n-3) polyunsaturated fatty acids in cell signalling mediated through phosphoinositides and their effect on various enzymes and receptors. This article reviews these mechanisms and the antiarrhythmic studies using (n-3) polyunsaturated fatty acids.

Dietary (n-3) Polyunsaturated Fatty Acids Suppress Murine Lymphoproliferation, Interleukin-2 Secretion, and the Formation of Diacylglycerol and Ceramide

Abstract: Elucidation of the mechanism(s) by which dietary fish oil, enriched in eicosapentaenoic acid (EPA, 20:5(n-3)] and docosahexaenoic acid [DHA, 22:6(n-3)], suppresses the inflammatory process is essential in maximizing this potentially therapeutic effect. Murine T-lymphocyte function and signal transduction were examined in response to a low fat, short term diet enriched in highly purified EPA or DHA ethyl esters. For 10 d, mice were fed comparable diets containing either 3% safflower oil ethyl esters (SAF), 2% SAF + 1% arachidonic acid triglyceride (AA), 2% SAF + 1% EPA, or 2% SAF + 1% DHA. Concanavalin A-induced T-lymphocyte proliferation in splenocyte cultures was significantly suppressed by dietary EPA and DHA while AA had no effect relative to the SAF control. The suppressed proliferative response in EPA- and DHA-fed mice was preceded temporally by a significant reduction in IL-2 secretion. Kinetics of mitogen-induced diacyl-sn-glycerol (DAG) and ceramide production did not differ significantly between SAF and AA diet groups. In contrast, DAG production was significantly suppressed in EP- and DHA-fed mice relative to the SAF and AA groups. The reduced DAG mass was paralleled by reduced ceramide mass following EPA and DHA feeding compared to the SAF and AA groups. Thus, low dose, short term dietary exposure to highly purified EPA or DHA appears to suppress mitogen-induced T-lymphocyte proliferation by inhibiting IL-2 secretion, and these events are accompanied by reductions in the production of essential lipid second messengers, DAG and ceramide.

Interactions Between Dietary Fat, Fish, and Fish Oils and Their Effects on Platelet Function in Men at Risk of Cardiovascular Disease

Abstract: Recent studies have suggested that omega 3-fats of marine origin may have a protective role in heart disease. This study aimed to compare the effects of fish or fish oil, in the setting of a high- or low-fat diet, on platelet aggregation and platelet thromboxane in men with increased risk of cardiovascular disease. One hundred twenty men who were nonsmokers, 30 to 60 years old, with mildly elevated blood pressure and cholesterol were randomly allocated to one of five high-fat (40% of daily energy) or two low-fat (30%) groups for 12 weeks. The five high-fat groups took either 6 or 12 fish oil capsules daily; fish; a combination of fish and fish oil; or placebo capsules. The two low-fat groups took either fish or placebo capsules. Fish meals provided 1.3 g of eicosapentaenoic acid daily, equivalent to 6 fish oil capsules, and contained an average of 3.65 g/d of omega 3-fatty acids. Multiple regression analysis of the combined groups showed that all groups taking omega 3-fatty acids reduced platelet aggregation to both collagen (P < .0001) and platelet-activating factor (PAF) (P < .05) and platelet thromboxane B2 responses (P < .05) to collagen-induced aggregation. The low-fat diet alone had no effect on PAF-induced platelet aggregation and only a small effect on platelet responses to collagen (P < .05). Platelet aggregation responses to PAF were reduced more by fish oil than fish in a high-fat diet, whereas fish had a greater effect when part of a low-fat rather than a high-fat diet. There was no significant difference in collagen-induced platelet aggregation or platelet thromboxane between fish and fish oils on a high or low fat intake. In conjunction with our previous findings of improvements in lipoproteins, blood pressure, and heart rate in this population, these results on platelet function suggest that dietary omega 3-fatty acids incorporated into a low- rather than a high-fat diet have a wider spectrum of more favorable effects on cardiovascular risk factors.

The Effect of Dietary Lipid on Polyunsaturated Fatty Acid Metabolism in Atlantic Salmon (Salmo salar) Undergoing Parr-Smolt Transformation

Abstract: The aim of this study was to measure the changes in lipid metabolism which occur during smoltification and seawater transfer in Atlantic salmon (Salmo salar). Duplicate groups of Atlantic salmon parr were fed diets containing either fish oil (FO) or a blend of linseed and rapeseed oils, vegetable oil (VO), from October (week 0) to seawater transfer in May (week 26). From May to August (weeks 26–43), all fish were fed a fish oil-containing diet. Fatty acyl desaturation and elongation activity were followed in isolated hepatocytes incubated with radioactive 18:3n−3 and 18:2n−6. Metabolism of 18:3n−3 was consistently around 5-fold greater than metabolism of 18:2n−6, and total metabolism of both substrate polyunsaturated fatty acids (PUFA) was increased in fish fed both VO and FO up to seawater transfer after which desaturation activities were reduced. Desaturation activities with both 18:3n−3 and 18:2n−6 were significantly greater in fish fed VO, compared to fish fed FO, at 22 and 26 wk. Arachidonic acid (20:4n−6; AA) in liver polar lipids (PL) of fish fed VO increased consistently from weeks 0–22 but varied after seawater transfer. In fish fed FO, AA in liver PL remained constant up to week 17 before increasing at seawater transfer and leveling off thereafter. Eicosapentaenoic acid (20:5n−3; EPA) in liver PL of fish fed VO decreased significantly from week 0–22 before rising at seawater transfer and increasing rapidly posttransfer. EPA in liver PL of fish fed FO showed a similar trend except EPA was always greater in the freshwater phase compared to fish fed VO. Docosahexaenoic acid (DHA) levels in liver PL of fish fed VO remained constant in the freshwater phase before increasing following seawater transfer. In fish fed FO, DHA in liver PL increased from weeks 0–17 reducing and leveling off postseawater transfer. The levels of PGF2α and PGF3α were measured in isolated gill cells stimulated with calcium ionophore A23187. PGF2α production in fish fed VO increased significantly between 0–7 wk before decreasing toward seawater transfer. After transfer, PGF2α production increased to a peak at 35 wk. PGF2α production in fish fed FO was not significantly altered during the trial period. The changes in PGF3α production were broadly similar to those occurring with PGF2α, but the latter was always in excess of the former (2-to 4-fold). Plasma chloride concentrations in fish subjected to seawater challenge at 20 wk were significantly lower in fish fed VO compared to those fed FO. This study has provided new information on the changes in lipid metabolism which accompany parr-smolt transformation and suggests that diets which have a fatty acid composition more similar to that in aquatic invertebrates may be beneficial in effecting successful seawater adaptation.

Predictive value of proliferation, differentiation and apoptosis as intermediate markers for colon tumorigenesis

Abstract: In order to determine the prognostic significance of proliferation, differentiation, and apoptosis as intermediate markers for colon tumor development, these indices were measured during the promotion phase of tumorigenesis. Two hundred and sixty male Sprague-Dawley rats were provided with one of two fats (corn oil and fish oil) and two fibers (pectin and cellulose) plus or minus the carcinogen azoxymethane (AOM) and killed at two time points (18 and 36 wk) in a 2x2x2x2 factorial design. In vivo cell proliferation was measured immunohistochemically using incorporation of bromodeoxyuridine into DNA. Differentiation was assessed by binding of Dolichos biflorus agglutinin (DBA) to colonocytes. Apoptosis was measured by immunoperoxidase detection of digoxigenin-labeled genomic DNA. Adenocarcinoma incidence results at week 36 were 70.3% for corn oil + AOM and 56.1% for fish oil + AOM treatment (P < 0.05); no main effect of fiber was observed. At week 18, AOM treatment increased the number of cells per crypt column in the proximal colon compared with saline controls (P = 0.0358) and increased the proliferative zone in the distal colon compared with controls (P = 0.0073). However, changes in cell proliferation at week 18 did not predict the beneficial effect of fish oil versus corn oil. In contrast, DBA binding (the marker for differentiation) was higher in fish oil versus corn oil fed animals in both the proximal and distal colon and in each portion of the crypt (P = 0.0001). There were a greater number of apoptotic cells/crypt column in the proximal colon (P = 0.0019) and distal colon (P = 0.0358) with fish oil compared with corn oil, and indices of apoptosis also predicted certain fat/fiber interactions. Measurements of differentiation and apoptosis had greater prognostic value to detect dietary effects on tumor incidence than did measurements of cell proliferation.

Fish oils and human diet.

Abstract: Trends in global fish catches are described together with fish landings and fish consumption in the UK. The importance of n-6 and n-3 polyunsaturated fatty acids as essential constituents of human diets is considered and the role of oily fish as a dietary source of the long-chain n-3 polyunsaturates, docosahexaenoic acid and eicosapentaenoic acid, is emphasized. The origin of n-3 polyunsaturates in the marine phytoplankton and their transmission via zooplankton to fish is described as a means of understanding the composition of different fish body oils. The ease with which the fatty acid composition of fish body oils can be manipulated by altering the fatty acid composition of their feeds is emphasized and the dietary requirements of marine and freshwater fish for n-3 and n-6 polyunsaturates considered. Farming fish on diets containing principally fish meal and fish oil, as used in salmon production in Scotland, generates a high quality product with levels of long-chain n-3 polyunsaturates equalling or exceeding those of wild fish. Farming fish on high quality marine oils rich in docosahexaenoic and eicosapentaenoic acids is an efficient means of delivering these essential nutrients in human diets and also efficiently exploiting a strictly limited marine bioresource.

Arterial Compliance in Obese Subjects Is Improved With Dietary Plant n-3 Fatty Acid From Flaxseed Oil Despite Increased LDL Oxidizability

Abstract: The compliance or elasticity of the arterial system, an important index of circulatory function, diminishes with increasing cardiovascular risk. Conversely, systemic arterial compliance improves through eating of fish and fish oil. We therefore tested the value of high intake of α-linolenic acid, the plant precursor of fish fatty acids. Fifteen obese people with markers for insulin resistance ate in turn four diets of 4 weeks each: saturated/high fat (SHF), α-linolenic acid/low fat (ALF), oleic/low fat (OLF), and SHF. Daily intake of α-linolenic acid was 20 g from margarine products based on flax oil. Systemic arterial compliance was calculated from aortic flow velocity and aortic root driving pressure. Plasma lipids, glucose tolerance, and in vitro LDL oxidizability were also measured. Systemic arterial compliance during the first and last SHF periods was 0.42±0.12 (mean±SD) and 0.56±0.21 units based on milliliters per millimeter of mercury. It rose significantly to 0.78±0.28 ( P <.0001) with ALF; systemic arterial compliance with OLF was 0.62±0.19, lower than with ALF ( P <.05). Mean arterial pressures and results of oral glucose tolerance tests were similar during ALF, OLF, and second SHF; total cholesterol levels were also not significantly different. However, insulin sensitivity and HDL cholesterol diminished and LDL oxidizability increased with ALF. The marked rise in arterial compliance at least with α-linolenic acid reflected rapid functional improvement in the systemic arterial circulation despite a rise in LDL oxidizability. Dietary n-3 fatty acids in flax oil thus confer a novel approach to improving arterial function.

The effect of dietary oil containing (n-3) fatty acids on the fatty acid, physicochemical, and organoleptic characteristics of pig meat and fat

Abstract: An investigation was made to alter the fatty acid composition of pork and a pork product in line with human dietary advice while not adversely affecting factors controlling consumer acceptability. Pigs (n = 150) were assigned to three dietary treatments with 25 intact male-female pairs per treatment. Diet A (control) contained 3% of a 4:1 (wt/ wt) tallow-soybean oil mixture. Diets B and C contained 2% rapeseed oil plus 1% fish oil. Diets A, B, and C were supplemented with 100, 100, and 250 mg of all-rac-alpha-tocopheryl acetate/kg of diet, respectively. Pigs were given ad libitum access to feed from 52 kg live weight until 95 kg (slaughter). Sausages were prepared from the resulting cuts. Tissues of pigs were evaluated in terms of fat firmness, color, fatty acid composition, and contents of alpha-tocopherol and thiobarbituric acid-reactive substances (TBARS). Organoleptic characteristics of chops and sausages were evaluated by a trained taste panel. Pigs fed Diets B and C had improved feed conversion ratios (P < .05) and ADG compared with control pigs. The levels of n-3 (omega-3) polyunsaturates were significantly increased in the tissues and sausage from pigs fed Diets B and C with associated alterations in n-6 to n-3 fatty acid ratios that accorded with contemporary human dietary recommendations. Levels of alpha-tocopherol and TBARS were significantly altered in the tissues. There were no appreciable differences between treatments in carcass characteristics, including color. The overall organoleptic acceptability of chops and sausages was not different between the treatments.

Dietary Fish Oil Alters Specific and Inflammatory Immune Responses in Chicks

Abstract: Two experiments were designed to determine the effects of dietary (n-3) fatty acids and grain source on the growth-suppressive effects of the inflammatory response and indices of specific immunity. In Experiment 1, chicks were fed diets containing 0.5, 1, or 2 g/100 g of either corn oil or fish oil. In Experiment 2, chicks were fed diets containing up to 2 g/100 g of either fish oil, linseed oil or corn oil as the source of dietary fat, in either cereal grain- or corn-based diets. In each experiment, subsets of chicks within each dietary treatment were either vaccinated with infectious bronchitis virus (IBV) vaccine, injected with Salmonella typhimurium lipopolysaccharide (LPS), heat-killed Staphylococcus aureus, or remained noninjected. Increasing dietary fish oil, but not corn oil increased body weight and lessened the growth-suppressing effect of heat-killed S. aureus or S. typhimurium LPS. Increasing the concentration of dietary fish oil decreased febrile response, circulating hemopexin and metallothionein concentrations. Dietary fish oil resulted in decreased release relative to dietary corn oil of interleukin-1 by peritoneal macrophages. Although IBV titers were not significantly affected by dietary oil treatment, phytohemagglutination-induced wattle swelling was greater among chicks fed fish oil. In Experiment 2, the modulating effects of fish oil on the immune system were dependent on the type of grain used in the diet, with fish oil/cereal diets resulting in greater cell-mediated immunity and lower indices of inflammation than fish oil/corn diets. Inclusion of increasing amounts of fish oil in the diet improved performance, decreased indices of the inflammatory response and either improved or did not change indices of the specific immune response of growing chicks.

Serum phospholipid fatty acid composition and habitual intake of marine foods registered by a semi-quantitative food frequency questionnaire.

Abstract: Objective: To examine the relation between consumption of fish and fish products registered by a comprehensive food frequency questionnaire and the composition of fatty acids in serum phospholipids. Design: Cross-section study. Setting: Cardiovascular screening centre in Trondheim, Mid-Norway. Subjects: Of 256 eligible women 242 agreed to participate in the present study. Altogether 234 middle-aged women (91.4%) completed the questionnaire and gave a valid blood sample. Results: Total frequency consumption of fish for dinner showed only weak association with serum phospholipid fatty acid composition. In separate analyses of lean and fatty fish, consumption of fatty fish was negatively associated with n-6 and positively associated with n-3 fatty acids in serum phospholipids, while no significant associations were found for lean fish consumption. Cod liver oil consumption was strongly related to the phospholipid fatty acid composition. The associations improved moderately when adding portion size information. Spearman’s correlation coefficient between dietary intake of eicosapentaenoic acid (EPA) and serum phospholipid EPA was 0.58, and Spearman’s correlation coefficient between intake of docosahexaenoic acid (DHA) and serum phospholipid DHA was 0.53. Conclusions: This study suggests that in populations with a high consumption of fish and cod liver oil, habitual intake can be reflected in serum phospholipids. However, as the fat content of fish is highly variable, separate registration of lean and fatty fish consumption is needed. Sponsorship: Erna and Olav Aakre’s Foundation, Tromso, and the Norwegian Cancer Society (E96071).

Nutritional factors affecting the fatty acid composition of bovine milk

Abstract: The predominant fatty acids in milk are the long-chain fatty acids myristic, palmitic and stearic. These saturated fatty acids account for 75% of the total fatty acids, with a further 21% occurring as monounsaturated fatty acids of which the most prevalent is oleic acid. Only 4 g/100 g of the milk fatty acids are polyunsaturated, occurring mainly as linoleic and linolenic acids. All milk fatty acids are derived, almost equally, from either de novo synthesis or directly from preformed fatty acids in the diet. There are four main dietary sources of fatty acids: forages, oilseeds, fish oil and fat supplements. The digestive tract exerts a profound influence on the fate of dietary fatty acids. The short-chain saturated free fatty acids are absorbed through the walls of the rumen or abomasum into the bloodstream. The medium- and longer-chain saturated fatty acids pass into the small intestine, diffuse across the membrane wall where they are incorporated into lipoproteins and enter the bloodstream via the lymphatic system. The majority of unsaturated fatty acids are extensively hydrogenated in the rumen. However, recent work has shown that the levels of certain saturated fatty acids can be reduced and the levels of oleic, linoleic and linolenic fatty acids increased by feeding oilseeds rich in mono- or polyunsaturated fatty acids. In addition, work reported here has confirmed that eicosapentaenoic and docosahexaenoic acids can be transferred to milk when a diet containing fish oil is fed, but the transfer efficiencies are low.

Effects of ruminal or postruminal fish oil supplementation on intake and digestion in dairy cows.

Abstract: The effect of fish oil supplementation on intake, digestibility and the volatile fatty acid profile in dairy cows was investigated in two trials. In each of the two trials, six cows received a diet based on maize silage in a latin square design. In the first trial, the cows were fitted with ruminal and duodenal cannulae and their diet was either supplemented or not with 300 mL fish oil and infused either into the rumen or the duodenum. In the second trial, the cows were not cannulated and their diet was either supplemented or not with 200 or 400 mL fish oil given orally. In both trials, the fish oil reaching the rumen decreased (P < 0.01) feed intake, increased (P < 0.01) the organic matter and fibre digestibility, and the percentage of propionate in the volatile fatty acid profile. These increases were higher for the 400 mL supplement than for the 200 mL one. The long-chain fatty acid pattern in the duodenum showed a high degree of hydrogenation of 20- and 22-carbon fatty acids. All these results demonstrated the particular action of fish oil on ruminal digestion when compared to other lipid sources.