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

An esterification protocol for cis-parinaric acid-determined lipid peroxidation in immune cells

Loss of fluorescence from cis-parinaric acid (cPnA) is a sensitive indicator of lipid peroxidation. The purpose of this study was to utilize cPnA to determine, at the level of the intact immune cell, whether enrichment of membranes with polyunsaturated fatty acids (PUFA) increased lipid peroxidation. P388D1 macrophages were labeled by addition of cPnA as an ethanolic solution. Within two minutes of addition, in the absence-of serum, cPnA rapidly intercalated into the plasma membrane. Lipid peroxidation was initiated by addition of Fe(2+)-EDTA resulting in a dose-dependent decrease in fluorescence with increased oxidant concentration. Cells previously enriched with PUFA and labeled by intercalation showed no differences in spontaneous or Fe(2+)-induced lipid peroxidation. In separate experiments, 20 microM cPnA in ethanolic solution was injected into cell culture media containing 0.1% essentially fatty acid free bovine serum albumin (BSA). Cells were resuspended and incubated for 90 min at 37 degrees C. After washing with BSA to remove cPnA which had not incorporated, 0.5% (0.1 microM) of the added cPnA was found esterified within cellular lipids. This level of cPnA provided a 100-fold increase over basal autofluorescence levels. Cells labeled in this manner also lost fluorescence in a dose-dependent manner as levels of oxidant stress increased. Cells enriched with PUFA and labeled by esterification had significantly increased rates and total amounts of lipid peroxidation. Co-incubation with alpha-tocopherol and PUFA resulted in a decrease in lipid peroxidation which was not significantly different from control cells. In conclusion, esterification of cPnA into membrane phospholipids can sensitively detect changes in lipid peroxidation induced by alteration of membrane PUFA and/or vitamin E content.

Vitamins A1 (retinol), A2 (3,4-didehydroretinol) and E (alpha-tocopherol) in the liver and blubber of lacustrine and marine ringed seals (Phoca hispida sp.)

Concentrations of vitamins A1 (retinol), A2 (3,4-didehydroretinol) and E (alpha-tocopherol) in the liver and blubber of ringed seals from Lake Saimaa (Phoca hispida saimensis), Lake Ladoga (P. h. ladogensis), the Baltic Sea (P. h. botnica) and Spitsbergen (P. h. hispida) were determined by high-performance liquid chromatography. The freshwater seals had much lower levels of vitamin A1 but higher levels of vitamin A2 than the marine seals. The concentrations of vitamin E in the livers of the subspecies studied were high compared with earlier reports of seals, but the ranges were large. The livers of the marine seals contained more vitamin E than the livers of the freshwater seals, but the levels in the blubber were uniform in all populations, except in old specimens from the Baltic. The differences between the freshwater and marine seals are suggested to be due mainly to diet. The ratios of A1 to A2 in the liver and blubber and in the fish diet were similar for the marine seals and for the freshwater seals (but differed in the marine and freshwater populations), which suggests no great differences in the absorption, transport and metabolism of the two analogues. Blubber was an important storage site for the vitamins studied, and age-dependent increases were detected, especially for vitamin E. In the 2-month to 2-year-old ringed seals of Lake Saimaa, however, the vitamin E concentration in the blubber was not affected by age.

Vitamin E inhibits fish oil-induced hyperlipidemia and tissue lipid peroxidation in hamsters

Previous research has linked hyperlipidemia with increased serum concentrations of lipid peroxidation products; however, a specific association between diet-induced oxidative stress and hyperlipidemia has not been studied. In the present study, the relationship between tissue lipid peroxidation and hyperlipidemia induced by ingestion of fish oil was examined. In Experiment 1, male Golden Syrian hamsters were fed semipurified diets composed of 1.6 wt% safflower oil plus 15.0 wt% of either butterfat (BF), safflower oil (SAFF), or high-cholesterol menhaden oil [MHO(H-CHOL)] semipurified diets for 27 d. The cholesterol contents of the diets were adjusted to 0.088%. The MHO(H-CHOL)-fed hamsters exhibited higher serum concentrations of total cholesterol, triglycerides, apolipoprotein B, and lipid peroxides when compared to the BF and SAFF diet groups. In a further study (Experiment 2), hamsters were fed for 27 d three dietary treatments: (i) MHO(H-CHOL) with no vitamin E content; (ii) a low-cholesterol menhaden oil containing high concentrations of vitamin E (2.5 mg tocopherol/g oil or dietary concentrations of 375 mg/kg) [MHO(L-CHOL) + E]; and (iii) the MHO(L-CHOL + E) with added cholesterol (595 mg/kg) [MHO(L-CHOL) + CHOL + E] to match the cholesterol content of the MHO(H-CHOL). The MHO(L-CHOL) + E and MHO(L-CHOL) + CHOL + E diet groups showed lower concentrations of serum cholesterol, triglycerides, and hepatic lipid peroxides than the MHO(H-CHOL)-treated group. Moreover, in contrast to the hypercholesterolemia caused by the MHO(H-CHOL) feeding, the MHO(L-CHOL)+ E and MHO(L-CHOL) + CHOL + E diets did not show a serum cholesterol-elevating action. This study supports the hypothesis that oxidative stress in the Syrian hamster could play a causal role in dietary-induced hyperlipidemia which can be inhibited by high vitamin E intake.

Blood pressure-lowering effect of fish oil is independent of thromboxane A2 level in spontaneously hypertensive rats

Whether the alterations in the synthesis of thromboxane A2 (TXA2) is the direct mechanism underlying the blood pressure-lowering effect of fish oil was investigated in this study. Six groups of 11 male spontaneously hypertensive rats were fed semipurified diets containing corn or fish oils and graded levels (50, 5000 or 15,000 ppm) of dietary vitamin E for 8 weeks. Plasma TXA2, assayed by RIA, was significantly greater in the corn oil group than in the fish oil group (P < 0.05). Compared to 50 ppm dietary vitamin E, 5000 and 15 000 ppm dietary vitamin E, respectively, significantly decreased plasma TXA2 (P < 0.05). Systolic, mean or diastolic blood pressure, evaluated by the tail cuff method, were significantly higher in the corn oil group than in the fish oil group (P < 0.05). However, vitamin E had no effect on blood pressure. No relationship between TXA2 and blood pressure was found. Experimental results indicated that the alterations in the synthesis of TXA2 were not the direct antihypertensive effect of fish oil.

Lipid peroxidation status as an index to evaluate the influence of dietary fats on vitamin E requirements of young pigs

The aims of the present study were to establish a suitable criterion for estimating the vitamin E requirement for young pigs, and to investigate the influence of dietary fats on the requirement of this nutrient. In Expt 1 weaned pigs were given a semi-purified diet supplemented with 0, 20, or 100 mg DL-alpha-tocopheryl acetate/kg. Pigs in Expt 2 were fed on diets containing 10 g sunflower oil (SO) stripped of vitamin E/kg in diets 1 and 2, 100 g SO/kg in diets 3 and 4, and 100 g tallow/kg in diet 5. Diets 2, 4 and 5 were supplemented with DL-alpha-tocopheryl acetate at 20 mg/kg for 0-28 d and 50 mg/kg for 29-56 d of the experiment respectively. Results showed that vitamin E concentrations in plasma and tissues reflected dietary levels of vitamin E. No apparent clinical signs of vitamin E deficiency were observed, but pigs fed on diets without vitamin E supplementation showed a higher (P < 0.05) lipid peroxidation status as indicated by thiobarbituric acid-reactive substances in erythrocytes, and ethane and pentane levels in exhaled gases than those fed on supplemental diets. This indicated that the former was deficient in vitamin E. Data in Expt 1 suggested that supplementation with 20 mg DL-alpha-tocopheryl acetate/kg is adequate for young pigs when the diet contains 30 g lard/kg. However, results in Expt 2 showed that this level was inadequate when the diet contains 100 g SO/kg or its equivalent to 70 mg polyunsaturated fatty acids (PUFA)/g. Vitamin E and lipid peroxidation status of pigs were affected by both dietary vitamin E and dietary PUFA. This demonstrates that the requirement for vitamin E in young pigs increases as PUFA levels in the diet increase. The present study shows that lipid peroxidation response of pigs is a suitable index to evaluate vitamin E requirements.

Effects of vitamin E deficiency and dietary linoleate on serum thromboxane synthesis in male sprague-dawley rats

The aim of the present study was to examine whether vitamin E deficiency and dietary linoleate had additive or synergistic effects on serum thromboxane (TX) status and therefore on thrombogenesis. Eight groups of five male weaning Sprague-Dawley rats were fed semipurified diets containing 3.5 or 18.4% of energy from linoleate (en% linoleate) and 0, 100, 5000, 15,000 ppm vitamin E for 8 weeks. Rats fed no vitamin E had the lowest serum vitamin E while rats fed 15,000 ppm vitamin E had the highest serum vitamin E (p < 0.05). Serum 18:2, n-6 (linoleic acid; LA) and 20:4, n-6 (arachidonic acid; AA) were significantly greater in the 18.4 en% linoleate group than in the 3.5 en% linoleate group (p < 0.05). Serum TXA2, measured as its stable metabolite TXB2, was significantly greater in the vitamin E-deficient rats than in the vitamin E-adequate and vitamin E-supplemented rats (p < 0.05). Serum lipid peroxidation, measured as thiobarbituric acid reactive substances (TBARS), was significantly greater in the 0 and 100 ppm vitamin E groups than in the 5000 and 15,000 ppm vitamin E groups (p < 0.05). No interaction between dietary linoleate and vitamin E deficiency on serum TX status was found. However, it seemed that vitamin E deficiency had a more potent effect on TX synthesis than dietary linoleate. The result suggested that vitamin E deficiency may be prothrombogenic via its effect on TX synthesis.

Levels of lipid peroxidation and antioxidants in vegetarians

Age dependence of lipid peroxidation levels estimated as conjugated dienes (CD) of plasma fatty acids was investigated in vegetarian and non-vegetarian males and females aged 11-14, 15-18, 19-39 and 40-60 years. The increase of CD levels with age was found in probands on both types of nutrition up to the age of 40 years. In the first three age groups, lipid peroxidation was insignificantly lower in vegetarians when compared to nonvegetarians. The increase of conjugated dienes was on the level of significance (p < 0.05) in the oldest vegetarians vs nonvegetarians. Therefore, content of defense parameters--antioxidative vitamin and enzyme--was estimated in blood of vegetarians aged 40-60 years. Significantly higher levels of vitamin C and catalase activity were found in vegetarians (C-63.6 and 86.5 mumol/l; CAT-1497 and 1313 U/ml for males and females, respectively) when compared to nonvegetarians (C-41.3 and 54.4 mumol/l; CAT-1192 and 1086 U/ml). A significant negative linear correlation (p < 0.001) for CD-C and CD-CAT was found in both sexes of vegetarians and in nonvegetarian females (p < 0.05 for nonvegetarian males). Important finding is a more pronounced in vegetarians (2.5-3.4 times higher slope of regression lines) indicating positive effect of vegetarian nutrition on efficiency of protection system.

Influence of supplemental dietary fat on changes in vitamin E concentration in livers of poults

An experiment was conducted to determine the influence of supplemental dietary fat on alpha-tocopherol (TOC) stored in the livers of young turkeys during the first 21 d after hatching. The four dietary treatments were obtained by supplementing a corn-soybean meal diet with 8% sucrose (SUC), 8% animal-vegetable fat (AVF), 8% tallow (TAL), or 8% coconut oil (COC). All diets were supplemented with 12 IU of dl-alpha-tocopheryl acetate (vitamin E)/kg of diet. Body weight at 21 d of age was not affected by dietary fat, whereas feed efficiency was improved (P < .05) by added fat, irrespective of source. Liver TOC (micrograms per gram of liver and micrograms per total liver weight) decreased markedly between 1 to 14 d of age, irrespective of fat source. Average TOC concentration in liver was 78.9 micrograms/g at 1 d, but was only .5 microgram/g at 14 d. Between 14 and 21 d of age, total liver TOC increased slightly in all treatment groups. No diet effect was observed on the liver TOC concentration until 21 d of age. At this time, poults fed TAL had less (P < .05) TOC in liver than those fed COC and AVF. The data show that neither the presence of supplemental dietary fat nor fat source changed the pattern of marked decrease in liver TOC during the first 14 d after hatching.

n-3 fatty acids inhibit defects and fatty acid changes caused by phenytoin in early gestation in mice

Our previous work has shown that n-3 fatty acids exert a protective effect against phenytoin-induced cleft palate when phenytoin was administered midgestation [gestational days (GD) 12 and 13] to CD-1 mice. The effects of dietary n-3 fatty acids on phenytoin teratogenicity were investigated at an earlier gestational period (GD 9) to examine whether n-3 fatty acids could exert protective action against other teratogenic effects of phenytoin apart from cleft palate. The effect of phenytoin exposure on maternal hepatic polyunsaturated fatty acid composition was also studied since delta 6 desaturase activity has been shown to be modified by pharmacological action. Female CD-1 mice were fed a standard laboratory diet (SLD), safflower oil (SAFF) or a cod liver/linseed oil (CLO/LO)-based diet for three weeks prior to impregnation and throughout pregnancy. Pregnant mice were administered a single i.p. dose of phenytoin on GD 9, and teratological assessments were performed on GD 19. Tissues were harvested on GD 10 for maternal hepatic phospholipid fatty acid analysis from another group of phenytoin-treated mice. The CLO/LO and the SLD mice, as compared to the SAFF-fed animals, showed a reduction in total malformations and fetal growth retardation due to phenytoin. Open eye defect was the only anomaly induced by phenytoin in the CLO/LO fetuses while phenytoin produced a variety of malformations in the SAFF fetuses such as tail defects, cleft palate, open eye and absence or blockage of the ureter.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of n-3 and n-6 fatty acids on the activities and expression of hepatic antioxidant enzymes in autoimmune-prone NZBxNZW F1 mice

Menhaden fish oil (FO) containing n-3 fatty acids dramatically extends the life span and delays the onset and progression of autoimmune disease in (NZBxNZW)F1 (B/W) female mice as compared to those fed corn oil (CO) rich in n-6 lipids. As an inefficient antioxidant defense system has been linked to autoimmune diseases, the present study was undertaken to determine whether the protective action of n-3 lipids is mediated through their antioxidant defense system. Weanling B/W mice were fed a nutritionally adequate, semipurified diet containing CO or krill oil (KO) or FO at 10% level (w/w) ad libitum until the mice were 6.5 months old. All diets contained the same level of vitamin E (21.5 mg/100 g diet). We compared the effects of feeding n-6 and n-3 lipids on survival, kidney disease, hepatic microsomal lipid composition, peroxidation, and on the activity and mRNA expression of the antioxidant enzymes catalase, glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) in 6.5-month-old B/W mice. The results showed that when compared to livers from CO-fed mice, livers from KO- and FO-fed mice showed: (i) significantly higher (P < 0.001) activities and expression of CAT, GSH-Px and SOD; (ii) significantly lower (P < 0.001) arachidonic acid (20:4n-6) and linoleic acid (18:2n-6) and higher (P < 0.001) eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) levels in hepatic microsomes; and (iii) significantly lower (P < 0.001) estimated peroxidation indices and thiobarbituric acid reactive substances generation.(ABSTRACT TRUNCATED AT 250 WORDS)

Vitamin E deficiency increases serum thromboxane A2, platelet arachidonate and lipid peroxidation in male Sprague-Dawley rats

This study was designed to determine whether dietary linoleate and all-rac-alpha-tocopheryl acetate (vitamin E) interact to affect serum thromboxane A2 (TXA2) and prostacyclin (PGI2) status and therefore, thrombogenic potential. 6 groups of 12 weanling male Sprague-Dawley rats were fed semipurified diets containing 11 or 18% of energy from linoleate and 0, 100 or 5000 mg vitamin E/kg diet for 10 weeks. Platelet and serum alpha-tocopherol concentrations increased logarithmically with increasing dietary vitamin E. Serum TXA2, measured as TXB2, platelet arachidonate and thiobarbituric acid reactive substances were significantly greater in the vitamin E deficient groups than in groups receiving vitamin E (p < 0.05). Serum PGI2 levels, determined as 6-keto-PGF1 alpha, were not affected by diets. No interaction was found between dietary linoleate and vitamin E. However, vitamin E supplementation produced significantly less serum TXB2 than did vitamin E deficient diets (p < 0.05). Vitamin E deficiency may be prothrombogenic by increasing platelet arachidonate, lipid peroxidation and serum TXA2 levels while vitamin E supplementation at levels used in this study may decrease such effects.

Dietary fat effects on hepatic lipid peroxidation and enzymes of H2O2 metabolism and NADPH generation

The purpose of this study was to determine the effects of dietary fat quantity and fatty acid composition on hepatic H2O2-metabolizing systems, activities of NADPH-generating enzymes and lipid peroxidation. One-month-old male C57BL/6J mice were fed one of six diets: (i) 5% fat, rich in 18:2n-6 fatty acid (5% N-6); (ii) 20% fat, rich in 18:3n-3 (N-3); (iii) 20% fat, rich in 18:2n-6 (N-6); (iv) 20% fat, rich in 18:1n-9 (N-9); (v) 20% fat, rich in saturated fatty acids (SAT); and (vi) 20% fat, deficient in essential fatty acids (EFAD); for 11 wk. Comparisons between animal groups receiving different fat quantities showed that activities of glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) and malic enzyme (ME, EC 1.1.1.40) and the levels of conjugated dienes were significantly lower in the N-6 than in 5% N-6 group. Conversely, activities of catalase (CAT, EC 1.11.1.6) and selenium-glutathione peroxidase (SeGSHPx, EC 1.11.1.9) were higher in the N-6 than in 5% N-6 group. Among the five dietary groups receiving 20% fat but differing in fatty acid composition, CAT activity was lower in the N-9 group, SeGSHPx activity was lower in the EFAD group, and glutathione reductase (GSSGR, EC 1.6.4.2) activity was higher in the N-6 than in the N-3, N-9, SAT and EFAD group. The EFAD group had much higher levels of total lipids and conjugated dienes, as well as activities of NADPH-generating enzymes, including G6PDH, ME and isocitrate dehydrogenase (EC 1.1.1.42), than the other four high-fat groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunologic effects of national cholesterol education panel step-2 diets with and without fish-derived N-3 fatty acid enrichment

Reductions in dietary fat, saturated fat, and cholesterol have been recommended to reduce the risk of heart disease in our society. The effects of these modifications on human cytokine production and immune responses have not been well studied. 22 subjects > 40 yr of age were fed a diet approximating that of the current American (14.1% of calories as saturated fatty acids, [SFA], 14.5% monounsaturated fatty acids [MUFA], 6.1% [n-6] polyunsaturated fatty acids [PUFA], 0.8% [n-3] PUFA, and 147 mg cholesterol/1,000 calories) for 6 wk, after which time they consumed (11 in each group) one of the two low-fat, low-cholesterol, high-PUFA diets based on National Cholesterol Education Panel (NCEP) Step 2 recommendations (4.0-4.5% SFA, 10.8-11.6% MUFA, 10.3-10.5% PUFA, 45-61 mg cholesterol/1,000 calories) for 24 wk. One of the NCEP Step 2 diets was enriched in fish-derived (n-3) PUFA (low-fat, high-fish: 0.54% or 1.23 g/d eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA] [121-188 g fish/d]) and the other low in fish-derived (n-3) PUFA (low-fat, low-fish [0.13% or 0.27 g/d EPA and DHA] [33 g fish/d]). Measurements of in vivo and in vitro indexes of immune responses were taken after each dietary period. Long-term feeding of low-fat, low-fish diet enriched in plant-derived PUFA increased blood mononuclear cell mitogenic response to the T cell mitogen Con A, IL-1 beta, and TNF production and had no effect on delayed-type hypersensitivity skin response, IL-6, GM-CSF, or PGE2 production. In contrast, the low-fat, high-fish diet significantly decreased the percentage of helper T cells whereas the percentage of suppressor T cells increased. Mitogenic responses to Con A and delayed-type hypersensitivity skin response as well as the production of cytokines IL-1 beta, TNF, and IL-6 by mononuclear cells were significantly reduced after the consumption of the low-fat, high-fish diet (24, 40, 45, 35, and 34%, respectively; P < 0.05 by two-tailed Student's t test except for IL-1 beta and TNF, which is by one-tailed t test). Our data are consistent with the concept that the NCEP Step 2 diet that is high in fish significantly decreases various parameters of the immune response in contrast to this diet when it is low in fish. Such alterations may be beneficial for the prevention and treatment of atherosclerotic and inflammatory diseases but may be detrimental with regard to host defense against invading pathogens.

Rat vitamin E status and heart lipid peroxidation: effect of dietary alpha-linolenic acid and marine n-3 fatty acids

Three groups of sixteen male rats each were fed semi-purified diets containing 15% by weight of lipid for a period of 4 wk. The diets contained the same amount of polyunsaturated fatty acids (PUFA) (20% of total fatty acids) and saturated fatty acids (19% of total fatty acids). Dietary PUFA were represented exclusively by linoleic acid (18:2 diet), or 10% linoleic acid and 10% linolenic acid (18:3 diet), or 10% linoleic acid and 10% long-chain n-3 fatty acids (LCn-3 diet). The overall amount of vitamin E was similar in the three diets, i.e., 140, 133 and 129 mg/kg diet, respectively. Following appropriate extraction, tocopherol levels in heart, liver, brain, adipose tissue (AT) and plasma were measured by high-performance liquid chromatography. The level of vitamin E in the heart decreased with n-3 PUFA diets, most markedly with LCn-3 PUFA. Liver and AT vitamin E contents also decreased with n-3 PUFA diets when expressed as micrograms/mg total lipids and micrograms/mg phospholipids, respectively. Total plasma vitamin E was lower in rats fed the LCn-3 diet, but there was no significant difference when expressed as microgram/mg total lipids. Brain vitamin E was not affected by the various diets. In vitro cardiac lipid peroxidation was quantified by the thiobarbituric acid reactive substances (TBARS) test. Heart homogenates were incubated at 37 degrees C for 15 and 30 min in both the absence (uninduced) or presence (induced) of a free radical generating system (1 mM xanthine, 0.1 IU per mL xanthine oxidase, 0.2 mM/0.4 mM Fe/ethylenediaminetetraacetic acid). TBARS release was time-independent but significantly higher when LCn-3 fatty acids were fed to rats in either the uninduced or induced system. The study demonstrated that n-3 PUFA diets can influence vitamin E status of rats even in short-term experiments and can change the susceptibility of the heart to in vitro lipid peroxidation.

Influence of dietary fatty acids on cytokine production and its clinical implications

Cytokines and eicosanoids are important biologic mediators with tightly regulated production. Overproduction contributes to pathogenesis of chronic and acute inflammatory, autoimmune, atherosclerotic, and neoplastic diseases. Animal and human studies have shown that production of cytokines and eicosanoids can be reduced by certain dietary fatty acids, specifically those containing long-chain (n-3) polyunsaturated fatty acids (PUFAs). This in turn results in reduction of the severity of certain autoimmune, inflammatory, and atherosclerotic diseases. Because these cytokines are also involved in control of the host defense, substantial reduction in their production could also result in the impairment of normal immune response. Increased intake of (n-3) PUFAs without adequate antioxidant protection could result in increased free radical formation and lipid peroxidation. Thus, when (n-3) PUFAs are used to reduce the pathogenesis of these diseases, its possible adverse effects should be considered and prevented.

Effects of dietary linseed oil and marine oil on lipid peroxidation in monkey liver in vivo and in vitro

Diets rich in linoleic acid (CO) from corn oil, or in linoleic acid and either alpha-linolenic acid (LO) based on linseed oil or n-3 fatty acids (MO) from menhaden oil were fed to male and female Cynomolgus monkeys for 15 wk. In the liver a 40% reduction of alpha-tocopherol occurred in the MO group relative to the CO and LO groups followed by increased formation of lipofuscin in vivo. A four-fold increase of alpha-tocopherol in the MO diet (MO + E) brought the level in the liver to that found with CO and LO. The increased peroxidation in the MO group in the liver phospholipids was associated with the replacement of 60% of the n-6 fatty acids by n-3 fatty acids from menhaden oil. Similar fatty acid profiles were found in groups fed MO and MO + E, respectively. Compared to the CO fed group, feeding alpha-linolenic acid only resulted in a slight incorporation of n-3 fatty acids in the liver membranes mainly due to a direct incorporation of alpha-linolenic acid. However, in monkeys fed menhaden oil more than 30% of the total fatty acids in the liver phospholipids were n-3 fatty acids. The various diets did not influence the activity of liver catalase (EC 1.11.1.6) nor superoxide dismutase (EC 1.15.1.1), but glutathione-peroxidase activity (EC 1.11.1.9) was higher in monkeys fed the MO diet. The catalase activity in females was 20% higher than in males.(ABSTRACT TRUNCATED AT 250 WORDS)

Vitamin E requirement in relation to dietary fish oil and oxidative stress in elderly

A growing body of evidence shows that oxygen radicals and other products of free radical reactions are involved in aging and age-related degenerative diseases. Recent studies have suggested that fish oils (FO) have a potentially beneficial effect on age-associated diseases. Consumption of FO may increase requirement for vitamin E, especially under conditions where oxidative stress is increased. Vitamin E requirement increases with increased intake of dietary polyunsaturated fatty acids (PUFA). This relationship may be exaggerated in elderly subjects. Our studies, as well as those of others, have shown that plasma lipid peroxides are significantly higher in older subjects compared to young subjects. Thus, in conditions where the percentage of highly unsaturated fatty acid increases in the membrane, older subjects may be more susceptible to oxidative damage. In a series of human studies, we found that older women, receiving FO supplements for 3 months exhibited a greater increase in plasma PUFA compared to young subjects. By substituting membrane fatty acids with the potentially unstable (n-3) fatty acids of FO, older subjects were found to be at greater risk of oxidative stress than young subjects. In addition, when exposed to eccentric exercise-induced oxidative stress, older men, receiving vitamin E supplements for 48 days, exhibited significantly lower levels of lipid peroxides in urine compared to placebo control. These data indicate that older subjects are more susceptible to oxidative stress and may benefit from the antioxidant protection provided by vitamin E.

Ischemic myocardial damage in spontaneously hypertensive rats (SHR) is enhanced after long-term feeding of an alpha-linolenic acid enriched diet

In this study the influence of long-term feeding of an alpha-linolenic acid (LNA) enriched diet on the sensitivity of SHR to catecholamine-induced myocardial injury was investigated. An enhanced ischemic vulnerability after LNA supplementation was observed as indicated both by a marked decrease of enzyme activities in the myocardium and by a pronounced elevation of plasma enzymes. Distinctly higher TBARS levels in heart tissue and plasma of LNA rich fed SHR suggest that an exaggerated lipid peroxidation might contribute to the increased ischemic vulnerability. Non-enzymatic lipid peroxidation is favoured by a feeding-provoked enrichment in highly unsaturated fatty acids in tissue phospholipids. Under such conditions of enhanced substrate availability for radical-induced lipid peroxidation an increased requirement for antioxidants can be assumed which might not sufficiently be met by tocopherol-supplementation in SHR because of their known defects in antioxidative defense mechanisms.

Effect of dietary menhaden, Canola and partially hydrogenated soy oil supplemented with vitamin E upon plasma lipids and platelet aggregation

Male Fisher rats were fed chow diets for two weeks after which they were divided into seven groups of ten rats each and fed 20% Canola, 20% menhaden, 20% partially hydrogenated soy oil (PHSO) or chow only, with or without 500 mg/Kg dietary vitamin E in chow containing 2% cholesterol for six weeks. Triglycerides were lower in the menhaden group and were essentially the same in the E supplemented groups as in their unsupplemented cohorts. Plasma cholesterol was higher in the Canola, and lower in the menhaden, groups, compared to the PHSO group. Cholesterol was the same in the E supplemented groups as in their unsupplemented cohorts. Plasma thiobarbituric acid reactant substances (TBARS) were higher in the menhaden group, compared to the chow group. Vitamin E supplementation lowered TBARS in the menhaden and PHSO groups, compared to the unsupplemented cohorts. Collagen induced platelet aggregation was lower in both Canola and menhaden groups, compared to the PHSO group. Vitamin E supplementation lowered collagen induced platelet aggregation only in the PHSO group. Thrombin induced platelet aggregation was lower in the Canola group, compared to the PHSO group. Vitamin E supplementation did not affect thrombin induced platelet aggregation compared to unsupplemented cohorts. Plasma vitamin E levels were lowest in the menhaden supplemented group compared to all other groups not receiving E, suggesting a greater requirement for E in this group. Finally, vitamin E supplementation raised the plasma E levels in all groups except the menhaden group when compared to unsupplemented cohorts.

Vitamin E and oxidative stress

Oxidative stress can result from or be enhanced by a large variety of conditions, including nutritional imbalance, exposure to chemical and physical agents in the environment, strenuous physical activities, injury, and hereditary disorders. While many enzymes and compounds are involved in protecting cells from the adverse effects of oxidative stress, vitamin E occupies an important and unique position in the overall antioxidant defense. The antioxidant function of vitamin E is closely related to the status of many dietary components. Vitamin E-depleted animals are generally more susceptible to the adverse effects of environmental agents than supplemented animals. Also, vitamin E supplementation is beneficial to certain groups of the population. However, supplementing vitamin E in experimental subjects maintained on a nutritionally adequate diet does not always provide additional protection. Differential metabolic responses in various organs and differences in experimental conditions often contribute in the discrepancies in the literature. The lack of clear evidence for the occurrence of lipid peroxidation or antioxidant function of vitamin E in vivo can be attributed partly to the presence of active pathways for metabolizing hydroperoxides, aldehydes, and other oxidation products. Specific and sensitive techniques for measuring lipid peroxidation products in biological systems are essential for understanding the role of free radical-induced lipid peroxidation in tissue damage and antioxidant function of vitamin E in vivo.

Fatty acid content of marine oil capsules

The use of dietary omega 3 fatty acid capsules has been associated with a decrease in plasma triglyceride levels. In addition, populations consuming diets rich in fish appear to have a decreased incidence of cardiovascular disease. Eicosapentaenoic acid (EPA, 20:5 omega 3) and docosahexaenoic acid (DHA, 22:6 omega 3) are major fatty acids in fish oils. It is believed that fish oils exert their biologic effect through these fatty acids. Many individuals are currently taking fish oil capsules to lower lipids, increase bleeding time, and possibly decrease cardiovascular risk. These capsules also have been classified as food additives with less stringent controls on content. We assessed the fatty acid, cholesterol, and vitamin A and E content of eight commercially available capsules along with cod liver oil. The content of EPA was found to range from 8.7-26.4% (wt %) with a mean of 17.3% (82.4% of labeled content), and that of DHA from 8.9-17.4% with a mean of 11.5% (90.0% of labeled content) as assessed by capillary column gas-liquid chromatography. The mean content of the polyunsaturated omega 3 fatty acids was 31.9%, and that of the omega 6 fatty acids was 1.4%. The content of saturated fatty acids was 32.0%, and that of monounsaturated fatty acids was 25.1%. Cholesterol content was low, with a range of 0.7-8.3 mg/g, the alpha-tocopherol range was 0.62-2.24 mg/g, and the range of retinyl esters was 0.4-298.4 micrograms/g. Cod liver oil had substantially more retinyl esters (2450.1 micrograms/g) than did fish oil capsules.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary canola and reference oils upon serum lipids and platelet aggregation

To compare Canola a terrestrial (n-3) oil with fish oil (n-3) and common vegetable oil (n-6) in decreasing serum lipids and platelet aggregation, various oils were included in Chow-based diets and fed to rats in an eight-weeks feeding trial. The Chow diet contained 2% cholesterol along with either Canola, menhaden, safflower, or partially hydrogenated soy oil, or no oil addendum. The menhaden oil group was the only one to show a significant reduction in serum cholesterol and triglycerides and at the same time yielded the most uniform decrease in platelet aggregability. However, this same group was also the only one to show a decrease in serum tocopherol levels, suggesting that improving an atherogenic risk profile may require antioxidant supplementation. In these rat trials, Canola oil supplementation did not yield the same results measured during menhaden supplementation.

Identification of hydroxyalkenals formed from omega-3 fatty acids

The highly toxic lipid peroxidation product, 4-hydroxynonenal, is formed from the decomposition of hydroperoxides of omega-6 fatty acids. In this study the analogous hydroxyalkenals formed from the decomposition of hydroperoxides of omega-3 fatty acids (eicosapentaenoic acid and docosahexaenoic acid) were isolated and identified using TLC densitometry, HPLC and GC/Mass Spectrometry. The major hydroxyalkenal formed from both fatty acids was a diene analog of 4-hydroxynonenal, 4-hydroxynona(2,6)dienal, while 4-hydroxyhexanal was a minor product. Measurement of specific omega-3 lipid peroxidation products may be important in studies using dietary fish oil.

Plasmodium yoelii: comparative antimalarial activities of dietary fish oils and fish oil concentrates in vitamin E-deficient mice

Feeding vitamin E-deficient diets containing either fish oils such as menhaden, salmon, or anchovy oil or fish oil concentrates based on n-3 ethyl esters or free fatty acids protected mice against Plasmodium yoelii as indicated by decreased parasitemia and improved survival. The fish oil concentrates depressed plasma tocopherol levels more strongly in vitamin E-supplemented mice than the menhaden oil. The free fatty acid concentrate appeared to suppress parasitemia in vitamin E-deficient mice better than the menhaden oil, although ultimate survival was similar in both groups. Dietary manipulation of host antioxidant status offers promise as a possible means of malaria control.

Vitamin E status in Sudanese children with protein-energy malnutrition

Total tocopherols and alpha-tocopherols were estimated in the plasma of children with severe malnutrition (14 marasmus; 11 marasmic kwashiorkor; five kwashiorkor) and related to the total plasma lipids and different plasma lipid classes. If the mere plasma concentrations were taken as an index of the vitamin E status, five children with marasmus, five children with marasmic kwashiorkor, and two children with kwashiorkor would have been regarded as deficient (less than 500 micrograms/dl). However, if total tocopherols and alpha-tocopherols were related to the total plasma lipids, all malnourished children--except one--showed values within the limits found in healthy American children. The study shows that low tocopherol/lipid ratios are not a constant feature in severely malnourished children.

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

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 less than or equal to 5 IU or less than or equal to 2 IU/kg vitamin E, respectively, or the same diets supplemented with d-alpha-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 peroxidation in vitro. Thiobarbituric acid-reactive substances (TBARS) were measured in the medium after incubation of the slices at 37 degrees 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 less than 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.(ABSTRACT TRUNCATED AT 250 WORDS)

N-3 and N-6 phosphoglyceride fatty acids in relation to in vitro erythrocyte haemolysis induced by hydrogen peroxide in captive common marmosets (Callithrix jacchus)

1. Hydrogen peroxide-induced haemolysis (HPIH) was studied in the red blood cells of the common marmoset monkey (Callithrix jacchus) in relation to the composition of the membrane fatty acids. HPIH (%) was surprisingly high (mean 41% +/- 34; median 33.4%) and significantly different (P less than 0.001) from the corresponding value in healthy human subjects (mean 0.98% +/- 0.6; median 1.3%). 2. It was negatively correlated with 18:2n-6 (r = -0.76, P less than 0.001), 18:2n-6/20:4n-6 (r = -0.70, P less than 0.005) and 18:2n-6/22:6n-3 (r = -0.44, P less than 0.025) in the ethanolamine phosphoglycerides of the erythrocytes. 3. A shift in the n-6/n-3 balance in favour of the n-3 in the fatty acid composition of the membrane may have predisposed the red blood cells to haemolysis. 4. An increase in 22:6n-3, and a decrease of 20:4n-6 and 18:2n-6, may have been the result of feeding a diet containing fish products rich in long chain n-3 fatty acids.

Functions and tocopherol content of blood platelets from elderly people after low intake of purified eicosapentaenoic acid

Elderly people present an increased incidence of atherosclerosis and vascular cerebral damages, associated with blood platelet hyperactivity and a stimulation of arachidonic acid metabolism in vivo. The effects of a low intake of purified eicosapentaenoic acid (EPA) on platelet hyperactivity in old human subjects has been investigated. In a randomized, double blind study, 8 people took during 2 months a daily intake of 100 mg of eicosapentaenoic acid (EPA) given as a triglyceride (1,3-dioctanoyl,2-eicosapentaenoyl-glycerol), and 8 other subjects ingested a placebo. A slight, but significant reduction of platelet-rich plasma aggregation in response to epinephrine and arachidonic acid occurred after EPA intake, as well as a decreased aggregation of washed platelets induced by thrombin, although collagen- and U-46619-induced aggregations were not significantly modified. EPA intake failed to affect arachidonic acid metabolism in thrombin-stimulated platelets or in clotted venous blood. The urinary excretion of thromboxane, 6-keto-PGF1 alpha and their 2,3-dinor-metabolites was also not modified. Similarly, no change in the plasma and platelet lipid fatty acid compositions could be observed. Platelet, but not plasma, alpha- and gamma-tocopherol were enhanced by EPA intake. An increase of platelet vitamin E has been associated with a decrease of aggregation, especially in vitamin E-deficient subjects, like elderly people. Therefore, low intake of EPA might have contributed to inhibit platelet aggregation by increasing cellular vitamin E.

Interleukin-1-induced anorexia in the rat. Influence of prostaglandins

The anorexia associated with acute and chronic inflammatory or infectious conditions is poorly understood. Our objectives were to explore the anorexigenic effects of interleukin-1 (IL-1) in the rat. Recombinant human (rh) IL-1 beta, murine (rm) IL-1 alpha and to a lesser extent rhIL-1 alpha significantly reduced food intake at greater than or equal to 4.0 micrograms/kg i.p. but not at lower doses, in young (200-250 g) meal-fed rats on chow diets. The anorexic effect appears to be mediated by prostaglandins since pretreatment with ibuprofen completely blocked it, and a fish oil based diet abolished it, in comparison to corn oil or chow diets. Fish oil feeding also decreased basal and IL-1 stimulated prostaglandin E2 production by tissues in vitro (liver, brain, peritoneal macrophages) and in the whole body. Constant intravenous infusions of lower doses of IL-1 also diminished food intake, though intravenous boluses did not (reflecting rapid renal clearance). Chronic daily administration of IL-1 caused persistent inhibition of food intake for 7-17 d in chow and corn oil fed rats, but had no effect in fish oil fed rats. There was an attenuation of the effect (tachyphylaxis) after 7 d in corn oil and chow fed rats, but slowed weight gain and lower final weights were observed after 17-32 d of daily IL-1. Old (18-20 mo Fisher 344) rats showed less sensitivity to IL-1 induced anorexia. In conclusion, IL-1 is anorexigenic in the rat, but this is influenced by the structural form of IL-1, the route and chronicity of administration, the source of dietary fat, and the age of the animal. The ability of prior fat intake to influence the anorexic response to IL-1 represents a novel nutrient-nutrient interaction with potential therapeutic implications.

Effects of fish oil, corn oil and lard diets on lipid peroxidation status and glutathione peroxidase activities in rat heart

In this study, we investigated the effect of various types of fats on heart lipid peroxidation status and on blood lipid parameters. Rats were fed either a low-fat diet (2.2% lard plus 2.2% corn oil), a corn oil diet (17%), a salmon oil diet (12.5%) supplemented with 4.5% corn oil, or a lard diet (15%) supplemented with 2% corn oil. All diets were supplemented with 1% cholesterol. Rats were fed for eight weeks. When compared with the low-fat diet, the salmon oil-diet intake resulted in a lower blood cholesterol, triglyceride and phospholipid concentrations (-50, -56 and -30%, respectively). Corn oil only tended to lower blood lipids; this decrease was significant for triglycerides only (-40%). The hypocholesterolemic effect of salmon oil diet is even more pronounced, if blood cholesterol values are compared with those of rats fed the lard diet. Heart lipid composition was not affected by dietary manipulations. Fatty acid composition of cardiac phosphatidylcholines and phosphatidylethanolamines, however, were altered by high-fat diets. In phosphatidylcholine, salmon oil induced a twelvefold decrease in the n-6/n-3 ratio and a 26% increase in the unsaturation index. For phosphatidylethanolamine, the n-6/n-3 ratio decreased 7.7-fold and the unsaturation index increased by 13%. A 50% decrease of the n-6/n-3 ratio was observed in animals fed the lard diet. Ultramicroscopic examination of ventricles revealed that those of the salmon oil group significantly accumulated lipofuscin-like or ceroid material, whereas this accumulation was barely detectable in hearts of the other groups.(ABSTRACT TRUNCATED AT 250 WORDS)