Plasma Α-tocopherol Concentrations Research Articles

Effect of Vitamin E Supplementation on Plasma Antioxidant Vitamins and Immunity Status of Crossbred Cows

Twenty crossbred (HF×Tharparkar) dry pregnant cows were divided into four equal groups. They were supplemented with 1,000 I.U. α-tocopheryl acetate from 0 (group I), 15 (group II), 30 (group III) and 60 (group IV) days before parturition to 1month of lactation. All the cows were kept under similar feeding and management conditions. Blood plasma samples collected on specific days were analyzed for α-tocopherol, retinol, total antioxidant activity (FRAP), immunoglobulin and calcium. Plasma α-tocopherol concentration at 30 days prepartum averaged 3.5, 4.1, 4.4 and 3.9 µg/ml and decreased by 50.0, 41.4, 34.1 and 33.3 percent on the day of parturition in the four respective groups. After calving, plasma vitamin E started to recover earlier in groups II, III and IV as compared to group I. Mean plasma α-tocopherol concentration at 21 days postpartum was significantly higher in groups II, III and IV (2.9, 3.5 and 3.1 µg/ml) compared to group I (1.9 µg/ml) cows. Plasma retinol concentration also showed a substantial decrease in all the groups on the day of calving but recovered to its normal value at 3 weeks postpartum. Plasma total antioxidant activity averaged 901, 895, 859 and 875 µmol/l in the four respective groups on 30 days prepartum and decreased on the day of calving in all the groups, but the decrease was less in groups III and IV. Plasma immunoglobulin concentration was higher in group IV, followed by groups III, II and I, respectively, showing better immune status of vitamin E supplemented cows due to less oxidative stress. Supplementation of vitamin E resulted in higher plasma calcium concentration. The data showed that vitamin E supplementation should be started at least 30 days prepartum to reduce oxidative stress in periparturient cows. (Asian-Aust. J. Anim. Sci. 2003. Vol 16, No. 11 : 1614-1618)

Effect of fish oil on LDL oxidation and plasma homocysteine concentrations in health

Oxidation of low-density lipoprotein (LDL) and hyperhomocysteinemia are believed to play a role in therogenesis. Whether n-3 polyunsaturated fatty acids increase LDL susceptibility to oxidation or influence homocysteine (Hcy) metabolism has long been a subject of controversy. In this study, we evaluated the effect of 8 weeks of dietary supplementation with 6 g/day of fish oil (FO; 3 g of n-3 fatty acids) on plasma lipoproteins, in vitro LDL peroxidation, antioxidant status, and plasma Hcy concentrations in 16 normolipidemic subjects. FO rapidly and significantly (P <.01) decreased plasma total and very low density lipoprotein triglyceride concentrations and had no effect on LDL or high-density-lipoprotein cholesterol. The mean lag time before onset of Cu2+-induced LDL oxidation, as well as plasma and LDL α-tocopherol and β-carotene concentrations, was unchanged. However, changes in plasma aminothiol concentrations occurred during the study. Specifically, a progressive and significant increase in total Hcy plasma concentrations was observed (13.4% and 20% after 4 and 8 weeks, respectively; P <.01). Total glutathione concentrations were significantly higher after 8 weeks (P <.05). The tHcy increase was not associated with changes in plasma folate or vitamin B12 concentrations. However, concentrations of plasma nitric oxide metabolites (NOx = NO2 + NO3) were significantly higher than at baseline after 8 weeks of FO intake (74%; P <.01). Further, the changes in total Hcy and NOx plasma concentrations observed after 8 weeks of FO were found to be significantly correlated (r =.78, P <.001). With this study, we report for the first time the apparent interaction of n-3 fatty acids and nitric oxide on Hcy metabolism. (J Lab Clin Med 2003;141:41-9)

Measurement of oxysterols and α-tocopherol in plasma and tissue samples as indices of oxidant stress status

Oxidant stress seems to play a role in several setting of human pathology, such as atherosclerosis, cancer, and aging. The study of oxidant stress in human disease should be based on the evaluation of either sensitive and specific markers of enhanced oxidant stress, such as oxysterols, or antioxidant defense, by measuring α-tocopherol. We have developed a rapid method to measure the oxysterols 7β-hydroxycholesterol and 7-ketocholesterol in plasma (50 healthy subjects) and tissue as an index of oxidant stress in vivo, and from the same sample α-tocopherol content. The mean plasma concentration of 7β-hydroxycholesterol and 7-ketocholesterol was 4.6±1.1 and 13.4±7.6 ng/mL, respectively. Plasma α-tocopherol concentration was 5.8±1.0 μ mol/mol cholesterol. Samples from atherosclerotic plaques contained 20 times more cholesterol, about 45 times higher oxysterols levels, and 600 times more α-tocopherol compared to normal arteries. No significant difference in cholesterol and oxysterol content was observed between cirrhotic and normal liver. However, cirrhotic liver contained significantly smaller concentration of α-tocopherol compared to normal liver. In conclusion, we have developed a rapid and reliable method for the assay of cholesterol oxidation products and α-tocopherol in plasma and tissue useful for estimation of oxidant stress/antioxidant balance.

Effects of Gossypol From Cottonseed on Hematological Responses and Plasma α-Tocopherol Concentration of Dairy Cows

The effects of feeding whole cottonseed (WCS) and bovine somatotropin (bST) administration on hematological responses and plasma α-tocopherol concentrations of lactating dairy cattle were examined. After parturition, multi and primiparous Holstein cows (n=159) were assigned randomly to a 2×2 factorial arrangement of treatments consisting of (0 or 15% WCS and 0 or 208mg of bST injected every 2 wk starting within 7 d after calving. Blood samples were collected from a subset group of 64 cows at 14, 28, 42, and 56 d postpartum. Blood was collected from all cows (n=159) at 75, 96 and 120 d postpartum. Blood samples were analyzed for α-tocopherol and total and (+)- and (−)-gossypol in plasma. Erythrocyte osmotic fragility, hemoglobin and hematocrit also were determined in blood. The mean concentrations of α-Tocopherol, total, and (+) - and (−) - gossypol were higher in cows fed WCS regardless of bST administration and plateaued by d 75 postpartum. Hematocrit and hemoglobin concentrations were not affected by treatments. Erythrocyte osmotic fragility was higher in cows fed WCS, but the increase was attenuated when bST was injected (diet×bST interaction). No clinical signs of gossypol toxicity were observed in the cows consuming the WCS.

Vitamin E deficiency in dogs with retinal pigment epithelial dystrophy

The role of vitamin E deficiency in the development of retinal pigment epithelial dystrophy was investigated in 11 cocker spaniels and four other dogs. The concentration of α-tocopherol was measured...

Procyanidins from Vitis vinifera seeds: in vivo effects on oxidative stress.

The purpose of this study was to evaluate the effect of supplementation with procyanidins from Vitis vinifera on markers of oxidative stress. Ten healthy volunteers received a daily dose of 110 mg of procyanidins for 30 days. Fasting venous blood samples were taken before and at the end of the supplementation period and after 7 days of wash-out. The total antioxidant activity and the plasma concentrations of alpha-tocopherol were not modified. Conversely, the levels of alpha-tocopherol in red blood cell membranes increased significantly from 1.8 +/- 0.1 to 2.8 +/- 0.2 mg/g. Similarly, the lymphocyte oxidized DNA [8-oxo-7,8-dihydro-2'-deoxyguanosine/2'-deoxyguanosine ratio] was reduced from 7.23 +/- 2.47 to 2.34 +/- 0.51, and the red blood cell membrane fatty acid composition shifted to a higher level of polyunsaturated fatty acids. On the basis of these results, it may be suggested that dietary procyanidins exert their antioxidant protection in vivo by sparing liposoluble vitamin E and reducing DNA oxidative damage.

Effects of gossypol from cottonseed meal and dietary vitamin E on the reproductive characteristics of superovulated beef heifers12

Superovulated Hereford-Angus crossbred heifers (average 397 kg BW) were used to test the effect of feeding cottonseed meal (gossypol) and vitamin E on embryo quality and ovarian characteristics. Twenty-four heifers were assigned randomly to four treatments with six heifers per treatment. Treatments were the following dietary supplements: 1) SBM (soybean meal + 30 IU vitamin E/kg of diet DM); 2) SBM+E (soybean meal + 4,000 IU vitamin E • animal−1 • d−1); 3) CSM (cottonseed meal + 30 IU vitamin E/kg of diet DM); and 4) CSM+E (cottonseed meal + 4,000 IU vitamin E • animal−1 • d−1). Supplements based on cottonseed meal provided 43.5 g of total gossypol/d (37% negative isomer (−) and 63% positive isomer (+)). Blood samples were collected at the start of the experiment and every 3 wk thereafter up to 12 wk. Plasma α-tocopherol (α-T) concentration was affected by treatments (P < 0.05). Heifers supplemented with cottonseed meal had greater (P < 0.05) α-T concentration in plasma than heifers supplemented with soybean meal at each concentration of vitamin E. Supplementation at 4,000 IU vitamin E • animal−1 • d−1 increased (P < 0.05) the concentration of α-T in plasma. Weight gain, hemoglobin and hematocrit were not affected by treatment. Erythrocyte osmotic fragility (EOF) increased (P < 0.05) in cottonseed meal-fed animals; however, EOF was lowered (P < 0.05) with vitamin E supplementation. Heifers fed CSM and CSM+E supplements had greater (P < 0.01) concentrations of (−)-, (+)-, and total-gossypol in plasma, corpora lutea (CL), liver, and endometrium than heifers fed SBM and SBM+E supplements. Tissue α-T concentration increased with increased dietary supplemental vitamin E, particularly in great amounts in the CL. Because there was no adverse effect of gossypol on superovulation response or embryo development despite concentrations of gossypol in endometrium that are toxic to embryos, it is likely that systems exist in the reproductive tract to limit gossypol toxicity.

β-Carotene and α-tocopherol concentration and antioxidant status in buccal mucosal cells and plasma after oral supplementation

The uptake of α-tocopherol and β-carotene and their antioxidative effect in plasma and buccal mucosal cells after oral application in twelve subjects is demonstrated in our study. The effect on the antioxidative status was evaluated using a modified thiobarbituric acid-reactive substance (TBARS) method. As expected, the supplement of 134·2 mg α-tocopherol/d and 25 mg β-carotene/d for 7 d resulted in a significant increase of α-tocopherol and β-carotene concentration in plasma (P&lt;0·05). In buccal mucosal cells, the concentration of β-carotene increased after supplementation (P&lt;0·05), whereas the concentration of α-tocopherol remained constant. A decrease in TBARS (P&lt;0·05) was found in buccal mucosal cells but not in plasma. In conclusion, an uptake of the supplemented antioxidants was detected in plasma and in buccal mucosal cells. There was significant change in β-carotene concentration and oxidative stress as measured using a modified TBARS test in buccal mucosal cells, but not in the plasma.

THE RELATIONSHIP BETWEEN CAROTENOID STATUS AND GREEN AND YELLOW VEGETABLES INTAKE IN YOUNG SOCCER PLAYERS.

Under normal circumstances, the body has adequate antioxidant reserves to deal with increased production of free radicals. However, if the production of free radicals is excessive as observed during strenuous aerobic exercise, the balance between prooxidants and antioxidants is lost. Taking exogenous antioxidants therefore is assumed to be of great importance in maintaining this balance. Carotenoids such as β-carotene (BC) and lycopene rich in green and yellow vegetables (GY) play an important role in oxidative damage prevention. However, relationship between daily carotenoid requirement and increasing physical activity level is not clear. Purpose: We examined the relationship between plasma carotenoid status and GY intake on young soccer players to assess the recommended amount of GY intake for young athletes. Methods: We studied 20 well-trained high school soccer players (3 hours/day, 6 times/week) and 34 age-matched untrained students. Blood samples were collected from an antecubital vein after an over night fast, after recording food intake for 3 days. Concentration of BC, α-carotene, lutein, lycopene, vitamin C, α-tocopherol and retinol in plasma were analyzed using HPLC. The average total energy and nutrient intakes for 3 days were calculated using Wellness2 for Windows 95 PC program. Results: Daily nutrient intakes of soccer players were significantly greater than the untrained group for all nutrients studied. Although the intake of GY in soccer players was significantly higher than that in untrained students (137 ± 60 g/day vs. 94 ± 59 g/day), the soccer players had a lower concentration of plasma BC, (0.48 ± 0.24 μM vs. 0.80 ± 0.39 μM). The data showed a good correlation between GY intake and plasma concentration of BC in the untrained group (r = 0.65, p < 0.05). However, there was no significant correlation between GY intakes and plasma BC in soccer players. There were no differences in the concentrations of other substrates (α-carotene, lutein, lycopene, vitamin C, α-tocopherol and retinol) between the two groups. Conclusion: These results suggest that athletes who regularly undergo vigorous exercise, need higher intakes of GY than untrained individuals for maintaining good antioxidant status within the blood.

Selective absorption of carotenoids in the common green iguana ( Iguana iguana)

In the animal kingdom, species-specific differences with regard to the absorption of intact carotenoids are observed. The causes of these differences are not entirely understood. To investigate the absorption of selected carotenoids, 20 juvenile green iguanas ( Iguana iguana) were fed a carotenoid deficient basal diet for 56 days. Thereafter, the iguanas were assigned to receive a basal diet supplemented with different carotenoids (80 mg/kg diet) such as β-carotene, canthaxanthin and apo-8′-carotenoic acid ethyl ester for 28 days. Changes in plasma carotinoid concentrations associated with the individual diets were used as indicators of carotenoid absorption. In both the experimental and control groups, only the oxygenated carotenoids (xanthophylls), lutein, zeaxanthin and canthaxanthin, were found in the plasma. Canthaxanthin and apo-8′-carotenoic acid ethyl ester were readily absorbed and recovered from the plasma. However, the supplementation of β-carotene caused no increase in plasma β-carotene concentration. Additionally, β-carotene, canthaxanthin or apo-8′-carotenoic acid ethyl ester did not affect the concentrations of retinol and α-tocopherol in plasma. In conclusion, the study demonstrates that iguanas appear to be selective accumulators of polar xanthophylls. The iguana might, therefore, be a valuable model to investigate the selectiveness of carotenoid absorption as well as the function of xanthophylls in animals.

Free radicals in alcoholic myopathy: indices of damage and preventive studies

Chronic alcoholic myopathy affects up to two-thirds of all alcohol misusers and is characterized by selective atrophy of Type II (glycolytic, fast-twitch, anaerobic) fibers. In contrast, the Type I fibers (oxidative, slow-twitch, aerobic) are relatively protected. Alcohol increases the concentration of cholesterol hydroperoxides and malondialdehyde-protein adducts, though protein-carbonyl concentration levels do not appear to be overtly increased and may actually decrease in some studies. In alcoholics, plasma concentrations of α-tocopherol may be reduced in myopathic patients. However, α-tocopherol supplementation has failed to prevent either the loss of skeletal muscle protein or the reductions in protein synthesis in alcohol-dosed animals. The evidence for increased oxidative stress in alcohol-exposed skeletal muscle is thus inconsistent. Further work into the role of ROS in alcoholic myopathy is clearly warranted.

Antioxidant nutrient supplementation and brachial reactivity in patients with coronary artery disease

Epidemiologic studies have shown a correlation between antioxidant intake and coronary artery disease (CAD); however, the results of clinical trials have been inconsistent. We evaluated the effect of combined antioxidant supplementation on endothelial function and its correlation with change in low-density lipoprotein cholesterol (LDLC) oxidation in patients with established CAD. In a double-blind, placebo-controlled 12-week trial, 18 nonsmoking, nondiabetic patients (mean age 62.4 ± 8.1 years) were randomized to receive placebo or antioxidant supplementation consisting of (a) 400 IU of vitamin E, 500 mg of vitamin C, and 12 mg of β-carotene; or (b) 800 IU of vitamin E, 1000 mg of vitamin C, and 24 mg of β-carotene daily. Endothelial function was evaluated on the basis of percent and absolute changes in brachial artery diameter in response to reactive hyperemia induced by occlusion-release. Baseline and 12-week values of LDL oxidation (measured on the basis of lag phase), endothelial function, dietary composition, serum antioxidants, and lipids were measured. We noted a significant between-group difference at 12 weeks for change in plasma concentrations of α-tocopherol, vitamin C, and β-carotene between the placebo and antioxidant groups (p <.05). Both placebo and treatment groups demonstrated a significant improvement in lag phase; however, the treatment group achieved a greater, although nonsignificant, magnitude of change compared with the placebo group (181.3 ± 177.8 minutes vs 80.6 ± 63.0 minutes, P =.06). Within-group change in brachial reactivity from baseline to follow-up in the treatment group did not reach statistical significance (1.7% ± 3.2% and 0.07 mm ± 0.13 mm, P =.08 and P =.09, respectively), whereas an improved change in brachial reactivity was observed in the placebo group (2.2% ± 1.9%, 0.09 mm ± 0.06 mm, P <.05). No significant correlation was found between change in lag phase and change in endothelial function. On adjustment for confounders, antioxidant supplementation was found not to be a significant predictor of brachial reactivity. We conclude that antioxidant supplementation did not significantly alter brachial reactivity, despite significantly increased plasma levels of antioxidants and improved lag phase. These data should be confirmed in larger-scale trials and examined in studies evaluating individual dietary antioxidant supplementation. (J Lab Clin Med 2002;139:133-9)

Influence of dietary vitamin E and selenium on muscle fatty acid composition in pigs

A total of 28 female pigs were fed a basal diet containing a low amount of α-tocopherol (10.3 mg/kg; control), and diets supplemented with 0.3 mg selenium/kg (group Se) or with 200 mg α-tocopherol/kg (group V) at the growing-finishing period. Increasing dietary level of vitamin E resulted in higher concentration of α-tocopherol in plasma and muscle immediately after slaughter and 4 h later ( P⩽0.05). The fatty acid composition of muscle microsomes and mitochondria was slightly affected by the diet. Corresponding to the minor changes of the membrane fatty acid composition the fluidity was unaffected by the diet. A positive relationship was observed between the resistance to in vitro stimulation of peroxidation and the vitamin E content of the muscle samples. Supplementation with selenium did not reduce the lipid oxidation after stimulation. In conclusion, even though the effect was minor, vitamin E improved the antioxidative status in pork.

Influence of dietary long-chain n-3 fatty acids from Menhaden fish oil on plasma concentrations of α-tocopherol in geriatric Beagles

To determine effects of dietary n-3 fatty acids from Menhaden fish oil on plasma alpha-tocopherol concentrations in Beagles. 32 female Beagles. For 82 days, dogs were fed diets that contained 1 of 2 ratios of n-6:n-3 fatty acids (40:1 [low n-3] and 1.4:1 [high n-3]) and 1 of 3 concentrations of all-rac-alpha-tocopheryl acetate (low, 17 mg/kg of diet; medium, 101 mg/kg; and high, 447 mg/kg) in a 2 X 3 factorial study. Diets high in n-3 fatty acids significantly increased total content of n-3 fatty acids in plasma (17.0 g/100 g of fatty acids), compared with low n-3 diets (2.02 g/100 g of fatty acids). Mean +/- SEM plasma concentration of cholesterol was significantly lower in dogs consuming high n-3 diets (4.59 +/- 0.48 mmol/L), compared with dogs consuming low n-3 diets (5.71 +/- 0.48 mmol/L). A significant interaction existed between the ratio for n-6 and n-3 fatty acids and amount of alpha-tocopheryl acetate in the diet (plasma alpha-tocopherol concentration expressed on a molar basis), because the plasma concentration of alpha-toco-pherol was higher in dogs consuming low n-3 diets, compared with those consuming high n-3 diets, at the 2 higher amounts of dietary alpha-tocopheryl acetate. Plasma alpha-tocopherol concentration expressed relative to total lipid content did not reveal effects of dietary n-3 fatty acids on concentration of alpha-tocopherol. Plasma alpha-tocopherol concentration is not dependent on dietary ratio of n-6 and n-3 fatty acids when alpha-tocopherol concentration is expressed relative to the total lipid content of plasma.

α-tocopherol concentrations, lipid peroxidation and superoxide dismutase and glutathione peroxidase activities in rat heart and liver after feeding stabilized and unstabilized fish oil

To further examine the relationship between increased consumption of n-3 polyunsaturated fatty acids (PUFAs), antioxidant defence systems and lipid peroxidation, for 6 weeks adult male rats were fed fish oil (FO)-rich diets containing one of two levels of α-tocopherol (4.5 or 1.9 IU vitamin E/g fish oil) either with or without the addition of the antioxidant mix PUFANOX® in order to stabilize the FO; rats fed corn oil or butter served as controls. Feeding FO resulted in increased proportions of the n-3 PUFAs eicosapentaenoic and docosahexaenoic acids in the phospholipids of the plasma, myocardium and liver. Rats fed the PUFANOX®-stabilized FO had higher plasma, myocardial and liver α-tocopherol concentrations compared to those fed the unstabilized FO; α-tocopherol concentrations were highest in rats fed the higher level of α-tocopherol in combination with PUFANOX®. FO feeding increased lipid peroxidation in myocardial and liver extracts. This was highest after feeding the FO diet which contained the lower amount of α-tocopherol and no PUFANOX® and was positively correlated with the n-3 PUFA content of the phospholipids. FO feeding did not alter myocardial and liver superoxide dismutase activity. Myocardial glutathione peroxidase activity was lower after feeding FO, except that containing the higher amount of α-tocopherol plus PUFANOX®. Glutathione peroxidase activity in the liver was lower after FO feeding than after corn oil with no significant differences among the different FO diets. Thus, insufficient antioxidant protection in FO results in decreased antioxidant defences and increased lipid peroxidation. Increasing the content of α-tocopherol and including a stabilizing agent (e.g. PUFANOX®) in FO can prevent at least some of these effects. The results of the present study do not support the idea that intake of FO, by increasing tissue lipid peroxidation, induces the body’s antioxidant defence system.

Vitamin E sparing effect by dietary vitamin C in juvenile hybrid tilapia, Oreochromis niloticus× O. aureus

In order to investigate sparing effects of vitamin C on vitamin E for juvenile hybrid tilapia, fish were fed diets with or without vitamin E each supplemented with either adequate or a high (3× adequate) level of two ascorbate sources, l-ascorbic acid (AA) and its derivative, l-ascorbyl-2-monophosphate-Mg (C2MP-Mg). Each diet was fed to three replicate groups of fish initially weighing a mean value of 0.54±0.01 g/fish in a closed-recirculated rearing system for 8 weeks. Weight gain and feed efficiency of fish fed the vitamin E-deficient diet supplemented with adequate levels of either AA or C2MP-Mg were significantly lower ( P<0.05) than fish fed the other diets. Plasma and liver α-tocopherol concentrations were lower in fish fed vitamin E-deficient diets regardless of the level or source of supplemented ascorbate. Gill α-tocopherolxxxxxxxx concentration was highest in fish fed vitamin E-adequate diets, intermediate in fish fed vitamin E-deficient diets supplemented with a high level of AA or C2MP-Mg and lowest in fish fed a vitamin E-deficient diet supplemented with an adequate level of AA or C2MP-Mg. Fish fed a vitamin E-deficient diet supplemented with an adequate level of AA or C2MP-Mg had higher hepatic thiobarbituric acid-reactive substances than fish fed the other diets. These data suggest that the high supplementation level (3× adequate) of ascorbate could spare vitamin E in diets for hybrid tilapia and that both AA and C2MP-Mg exhibits the same sparing effect.

Erythrocyte, but not plasma, vitamin E concentration is associated with carotid intima–media thickening in asymptomatic men at risk for cardiovascular disease

Epidemiological data regarding the preventive role of vitamin E in the pathogenesis of atherosclerosis have yielded conflicting results, possibly because endpoints considered were clinical events but not detection of atherosclerosis per se. Otherwise, it has been suggested that the measure of the erythrocyte α-tocopherol level may be more suitable to assess the human tocopherol status than its plasma level. We investigated the association between early atherosclerosis in superficial arteries assessed noninvasively and the α-tocopherol status in 261 asymptomatic men at risk for cardiovascular disease. α-Tocopherol concentrations in plasma, HDL, and erythrocytes were determined using a reverse-phase HPLC method. Detection of carotid plaques and measure of carotid intima–media thickness (IMT) were performed using high-resolution B-mode ultrasonography. The main result of this study is the observation of a negative correlation ( P<0.01) between carotid IMT and erythrocyte α-tocopherol concentration, independently of conventional cardiovascular risk factors, whereas no such association has been found with plasma (total or HDL) α-tocopherol concentrations. No association has been evidenced between α-tocopherol concentrations and carotid plaques. These results emphasize the primary protective role of vitamin E in the early phases of atherosclerosis and the significance of the erythrocyte α-tocopherol concentration as a marker of atherosclerosis.

Antioxidative Power of Plant Oils in Humans: The Influence of α- and γ-Tocopherol

Background: The daily diet is usually comprised of a varying antioxidant and fatty acid content acquired from plant oils. The present study was performed to evaluate the antioxidative effects of a plant oil mixture rich in α-tocopherol (olive/sunflower oil) in comparison with a single γ-tocopherol-rich corn oil used in a normal, balanced human diet. Methods: In the context of a double-blind study 28 healthy nonsmoking male volunteers aged between 19 and 31 years were investigated. After 2 weeks of adjustment on a mixed, balanced diet (average 11.6 MJ, average fat intake ∼105 g/day), a 2-week test period with a diet of 80 g corn oil (CO)/day vs. a mixture of 68 g olive and 12 g sunflower oil/day (MO; total 80 g) as the main fat source, was followed by a crossover after 2 weeks. Blood samples were collected at the beginning of the study and at 2-week intervals. Results: The main carriers of tocopherol in blood are low-density lipoproteins (LDLs). A highly significant correlation (r² = 0.73, p < 0.001) was found between plasma and LDL γ-tocopherol concentrations in the CO group, and a significant correlation was found between plasma and LDL α-tocopherol concentrations only in the MO group. Plasma and LDL total antioxidative capacity values could only be improved insignificantly in both groups to comparable extents, although the MO group had a twofold higher α-tocopherol equivalent/diene equivalent ratio (1.13 mg/g) than the CO group (0.55 mg/g). Conclusion: In spite of the higher P/S ratio (CO 4.2 vs. MO 1.2) and lower α-tocopherol equivalent/diene equivalent ratio, the antioxidant potential of CO in vivo (total antioxidative capacity in plasma and LDL) was as efficient as the MO. This positive finding might be explained by a synergism between α- and γ-tocopherol in the CO diet.

Red wine mitigates the postprandial increase of LDL susceptibility to oxidation

The aim of the present study was to verify the extent of oxidative stress induced by a meal at plasma and LDL level, and to investigate the capacity of red wine to counteract this action. In two different sessions, six healthy men ate the same test meal consisting of “Milanese” meat and fried potatoes. The meal was taken either with 400 ml red wine or with an isocaloric hydroalcoholic solution. Oxidative stress at plasma level was estimated through the measure of ascorbic acid, α-tocopherol, protein SH groups, uric acid, and antioxidant capacity, measured before and 1 and 3 h after the meal. The change in the resistance of LDL to oxidative modification was taken as an index of exposure to pro-oxidants. The susceptibility to Cu(II)-catalyzed oxidation of baseline and postprandial LDL was measured as conjugated dienes formation, tryptophan residues, and relative electrophoretic mobility. The experimental meal taken with wine provoked a significant increase in the total plasma antioxidant capacity and in the plasma concentration of α-tocopherol and SH groups. Postprandial LDL was more susceptible to metal-catalyzed oxidation than the homologous baseline LDL after the ethanol meal. On the contrary, postprandial LDL obtained after the wine meal was as resistant or more resistant to lipid peroxidation than fasting LDL.

Effects of supplementation with vitamin E on the performance and the tissue peroxidation of broiler chicks and the stability of thigh meat against oxidative deterioration

Two experiments were conducted: Expt 1 determined the optimal allowance of vitamin E in the diet for broiler chicks aged 0–3 weeks; Expt 2 investigated the effects of different dietary levels of vitamin E (α-tocopherol) on the performance and the oxidative stability of thigh meat of broiler chicks during storage. In Expt 1, 1-day-old 900 broiler chicks were allocated to five treatments, each with six replicates (cages) of 22 as-hatched chicks for performance evaluation, and another cage of 45 male chicks for determining plasma and hepatic α-tocopherol and thiobarbituric acid reactive substances (TBARS) concentration in blood and liver. The basal dietary α-tocopherol concentration was 13 mg/kg, and the five α-tocopherol acetate supplementation levels were 0, 5, 10, 50 and 100 mg/kg. For 0–3-week-old broiler chicks fed with maize–soya bean meal–soya oil type diet, supplementation of vitamin E did not influence the feed intake, but tended to improve growth and feed utilization, however there was no significant correlation between performance and vitamin E supplementation level. Significant positive correlations existed between dietary supplemental vitamin E level and plasma or hepatic α-tocopherol concentrations ( P<0.05), and a negative correlation with hepatic TBARS levels no matter at what age (11, 16 and 21 days). In Expt 2, 2200 broiler chicks were randomly allocated to five treatments with four replicates (pens) in each. Chicks were fed ad libitum five pellet diets supplemented with vitamin E at 5, 10, 20, 50 and 100 mg/kg of diet, respectively. The basal dietary α-tocopherol level of grower and finisher diets were 7 and 6 mg/kg, respectively. Supplementation of vitamin E tended to improve growth and feed utilization of birds during 0–3 weeks of age, but the performance from 0 to 6 weeks of age were not influenced. The hepatic α-tocopherol concentrations of 6-week-old chicks linearly increased with the dietary vitamin E levels ( R 2=0.98, P<0.001). The content of TBARS in the thigh meat over 4 days of storage under 4°C was significantly decreased by increasing dietary vitamin E level ( P<0.05). There was a significant inverse relationship between TBARS value in the thigh meat and the dietary vitamin E level ( R 2=0.93, P<0.01). Supplementation of vitamin E significantly improved the meat quality stability substantially against oxidative deterioration. Comparing the hepatic α-tocopherol levels of chicks in Expts 1 and 2, total allowance of dietary α-tocopherol of 20–30 mg/kg could sustain relatively constant hepatic α-tocopherol level at round about 2–2.5 μg/kg.