Tissue Alpha-tocopherol Concentrations Research Articles

Effect of vitamin E source, natural versus synthetic, and quantity on serum and tissue α-tocopherol concentrations in finishing swine

Relative vitamin E status of pigs fed natural or synthetic vitamin E was evaluated based on serum and tissue alpha-tocopherol concentrations. Individually fed finishing gilts at a BW of 70.5 kg (n = 24) were allotted to dietary treatments based on initial BW. The 5 dietary treatments consisted of a positive control diet using synthetic vitamin E acetate (Syn E Ac) supplemented at 22 mg/kg, and 4 dietary levels of natural vitamin E acetate (Nat E Ac) supplemented at 6.71, 8.33, 11.00, and 16.18 mg/kg of diet. Before initiation of the 32-d experiment, pigs were fed a non-vitamin E-fortified diet for 30 d. Diets were formulated to contain true ileal digestible lysine of 0.9 and 0.8% for the pretest and test diets. Serum samples were collected on d 15 and 32, whereas tissue samples were collected on d 32 for alpha-tocopherol analysis. Serum alpha-tocopherol concentrations on d 15 and 32 were greater (P < 0.05) in pigs fed 8.33, 11.00, or 16.18 mg/kg of Nat E Ac than in pigs fed 22 mg/kg of Syn E Ac. When compared with pigs fed 22 mg/kg of Syn E Ac, alpha-tocopherol concentrations were greater (P < 0.05) in 6 tissues (heart, kidney, spleen, liver, lung, and adipose) in pigs fed 16.18 mg/kg of Nat E Ac; greater (P < 0.05) in heart, kidney, spleen, liver, and adipose tissue in pigs fed 11.00 mg/kg of Nat E Ac; and greater (P < 0.05) in spleen, loin, and adipose tissue in pigs fed 8.33 mg/kg of Nat E Ac. As dietary Nat E Ac increased from 6.71 to 16.18 mg/kg, serum alpha-tocopherol increased linearly (P < 0.01) on d 15 and 32 of the experiment. Increasing dietary Nat E Ac linearly increased (P < 0.05) alpha-tocopherol concentrations for lung, heart, kidney, spleen, and liver. These results indicate that Nat E Ac was an effective vitamin E source and its relative bioavailability was substantially greater than 1.36 for finishing swine when compared with Syn E Ac.

An evaluation of natural (RRR-α-tocopheryl acetate) and synthetic (all-rac-α-tocopheryl acetate) vitamin E fortification in the diet or drinking water of weanling pigs1,2,3

Three experiments conducted with weanling pigs evaluated the effects of vitamin E added to the drinking water or diet on plasma and tissue alpha-tocopherol concentrations. When natural or synthetic vitamin E was used, it was added at an IU-equivalent basis, but natural vitamin E was 73.5% (mg basis) of the synthetic vitamin E. Experiment 1 used 18-d-old weanling pigs (n = 120) in a 3 x 2 factorial arrangement of treatments in a randomized complete block design with 4 replicates. The first factor evaluated the dietary levels of natural vitamin E (RRR-alpha-tocopheryl acetate) added at 0, 50, or 300 IU/kg, whereas the second factor was the natural vitamin E added to the drinking water at 0 or 100 IU/L. Pigs were bled at periodic intervals, and 1 pig per pen was killed at the end of the 21-d trial and tissues (liver, heart, lung, and loin) were collected for alpha-tocopherol analysis. When vitamin E was not added to the diet or water, plasma alpha-tocopherol declined over the 21-d period. Although there were some interactions (P < 0.01), tissue and plasma alpha-tocopherol concentrations increased linearly when vitamin E was added to the diet or water. Experiment 2 was a 3 x 2 factorial in a randomized complete block design with 4 replicates. A total of 96 pigs weaned at 18 d of age, with an initial BW of 6.2 kg, were fed a nonvitamin E fortified diet, but natural or synthetic (all-rac-alpha-tocopheryl acetate) vitamin E was added to their drinking water at 50, 100, or 150 IU/L. Pigs were bled at 0, 3, 7, 10, 14, and 21 d postweaning, with tissues (liver, lung, heart, and loin) collected for alpha-tocopherol analysis at d 21. The results indicated that plasma alpha-tocopherol concentrations increased (P < 0.01) as vitamin E increased, with greater tissue alpha-tocopherol concentrations (P < 0.01) when natural vitamin E was provided. Experiment 3 was conducted in 2 replicates, but pigs (n = 60) were not provided vitamin E in the diet or water for 7 d postweaning, and then natural or synthetic vitamin E was added to the drinking water as in Exp. 2 (50, 100, or 150 IU/L). Pigs were bled at 0, 2, 4, 6, 8, 10, and 24 h after being provided vitamin E to evaluate the absorption from each vitamin E source and level. Plasma alpha-tocopherol increased quadratically (P < 0.01) and plateaued at 8 to 10 h for each treatment group. These results indicate that adding vitamin E to the pig's water supply at weaning was more effective in increasing plasma alpha-tocopherol than when it was added to the diet during the initial 14 d postweaning, and that natural vitamin E was a superior source compared with synthetic vitamin E.

Vitamin E Trafficking

The alpha-tocopherol transfer protein (alpha-TTP) is required to prevent vitamin E deficiency in humans and in alpha-TTP null mice. Whereas alpha-TTP is not required to facilitate intestinal absorption of vitamin E, it is required to maintain normal alpha-tocopherol concentrations in plasma and extrahepatic tissues. alpha-Tocopherol secretion from the liver in very low density lipoproteins (VLDLs) is impaired in humans with a defect in the alpha-TTP gene. In perfusions of isolated cynomolgus monkey livers, VLDLs were preferentially enriched in RRR-alpha-tocopherol. The mechanism by which alpha-TTP incorporates alpha-tocopherol into nascent VLDLs is the topic of this report. VLDL assembly is a multistep secretory process that occurs within the membrane compartments of the endoplasmic reticulum and Golgi apparatus. Thus, we postulated that alpha-TTP might transfer alpha-tocopherol onto nascent VLDLs either in the endoplasmic reticulum or in the Golgi apparatus. To test these possibilities, we isolated nascent VLDLs from highly purified RER and Golgi apparatus membrane fractions from livers of rats fed equimolar ratios of RRR- and SRR-alpha-tocopherols labeled with different amounts of deuterium. Although the plasma was enriched in RRR-alpha-tocopherol 14 hours after the dose, no enrichment of nascent VLDL precursors from either of the secretory compartments was detected, indicating that VLDL enrichment with alpha-tocopherol may occur as a post-VLDL secretory process. Therefore, we hypothesize that alpha-TTP may facilitate movement of alpha-tocopherol to the hepatocyte plasma membrane (by unknown mechanisms) where newly secreted, nascent VLDLs could acquire both alpha-tocopherol and unesterified cholesterol while within the space of Disse. Clearly, critical information is lacking in our understanding of the mechanism by which alpha-TTP facilitates the preferential enrichment of VLDLs with alpha-tocopherol.

Ultraviolet-B Radiation Damage on Kentucky Bluegrass. I. Antioxidant and Colorant Effects

High ultraviolet-B (UV-B; 290-320nm wavelength) may significantly contribute to kentucky bluegrass (Poa pratensis L.) sod death at harvest and transplanting. As terrestrial UV-B levels continue to increase due to a depletion of the stratospheric ozone layer this problem may worsen. Epidermal attenuation from pigments and detoxification of reactive oxygen species by antioxidant metabolites and enzymes are involved in plant defense against oxidative stress caused by UV-B. Our objective was to determine whether the attenuation and detoxification systems of kentucky bluegrass could be artificially boosted by exogenous applications of ascorbic acid (AA), alpha-tocopherol (AT), or a colorant before exposure to high levels of UV-B. Ascorbic acid, AT, and the colorant Green Lawnger (GL), were applied to plugs of mature kentucky bluegrass alone or in combination, and then subjected to artificial, continuous UV-B exposure (70 μmol·m-2·s-1); three greenhouse experiments were conducted. By 3 to 5 days after UV-B initiation, visual quality and photochemical efficiency, as measured by chlorophyll fluorescence were significantly reduced. However, in Expt. 1, AA alleviated decline of visual quality, delayed loss of photochemical efficiency, and increased recovery relative to the control. In Expt. 3, decreased endogenous AT and antioxidant enzyme activities were measured due to UV-B stress. Application of AA, AA + AT, or GL partially alleviated photochemical efficiency decline from 4 to 12 days after initiation of UV-B. In addition, application of the chemical treatments increased leaf tissue AT concentrations by 32% to 42%, increased SOD activity by 30% to 33% and increased catalase activity by 37% to 59%, relative to the control as measured 10 days after UV-B initiation. Greater AT concentration and SOD and catalase activities were associated with greater visual quality under UV-B stress. The results of these studies indicate that kentucky bluegrass UV-B tolerance may be increased by supplementing its pigment and antioxidant defense systems with foliar applications of AA, AT or GL.

Effect of sesaminol on plasma and tissue alpha-tocopherol and alpha-tocotrienol concentrations in rats fed a vitamin E concentrate rich in tocotrienols.

We have shown that sesame lignans added to rat diet resulted in significantly greater plasma and tissue concentrations of alpha- and gamma-tocopherol concentrations in supplemented rats than in rats without supplementation. In the present studies we examined whether sesaminol, a sesame lignan, enhances tocotrienol concentrations in plasma and tissues of rats fed diets containing a tocotrienol-rich fraction of palm oil (T-mix). In Experiment 1, effects of sesaminol on tocotrienol concentrations in plasma, liver, and kidney were evaluated in rats fed diets containing 20 mg/kg of T-mix (20T) and 50 mg/kg of T-mix (50T) with or without 0.1% sesaminol. Although the T-mix contained 23% alpha-tocopherol, 22% alpha-tocotrienol, and 34% gamma-tocotrienol, alpha-tocopherol constituted most or all of the vitamin E in plasma and tissue (from 97% in kidney to 100% in plasma), with no or very little alpha-tocotrienol and no gamma-tocotrienol at all. Addition of sesaminol to the T-mix resulted in significantly higher plasma, liver, and kidney alpha-tocopherol concentrations compared to values for T-mix alone. Further, T-mix with sesaminol resulted in significantly higher alpha-tocotrienol concentrations in kidney, although the concentration was very low. In Experiment 2, we examined whether sesaminol caused enhanced absorption of alpha-tocopherol and alpha-tocotrienol in a dosage regimen supplying T-mix and sesaminol on alternating days and observed significantly higher levels of alpha-tocopherol and alpha-tocotrienol in rats fed sesaminol, even without simultaneous intake, compared to those in rats without sesaminol. In Experiment 3, alpha-tocopherol was supplied to the stomach with and without sesaminol, and alpha-tocopherol concentrations in the lymph fluid were measured. a-Tocopherol concentrations were not different between groups. These results indicated that sesaminol produced markedly higher alpha-tocopherol concentrations in plasma and tissue and significantly greater alpha-tocotrienol concentrations in kidney and various other tissues, but the concentrations of alpha-tocotrienol were extremely low compared to those of a-tocopherol (Exps. 1 and 2). However, the sesaminol-induced increases of a-tocopherol and a-tocotrienol concentrations in plasma and tissue were not caused by their enhanced absorption since sesaminol did not enhance their absorption.

Effect of dietary levels of vitamin E (all-rac-tocopheryl acetate) with or without added fat on weanling pig performance and tissue α-tocopherol concentration

Two experiments involving 496 cross-bred pigs evaluated the efficacy of various dietary levels of vitamin E, with or without supplemental fat, on postweaning pig performance and weekly serum and terminal tissue alpha-tocopherol concentrations. The first trial involved 248 pigs weaned at an average of 15 d of age and 4.8 kg BW. The experiment was a randomized complete block design conducted in seven replicates. Vitamin E was added as dl-alpha-tocopheryl acetate at 0, 20, 40, 60, 80, 100, 150, or 200 IU/kg diet. Pigs were bled initially and at 7-d intervals for a 42-d period. Liver and s.c. adipose tissue samples were collected from six pigs per treatment group at 42 d. In Exp. 2, a 2 x 4 factorial arrangement of treatments in a randomized complete block design was conducted in seven replicates. The experiment used a total of 248 pigs weaned at 19 d of age and averaged 6.4 kg BW. Four vitamin E levels (0, 20, 40, and 60 IU/kg diet) and two added fat levels of 0 or 5% were fed for 35 d. Four pigs per treatment pen were bled weekly, and at 35 d a total of four pigs per treatment group were killed and liver, heart, and s.c. adipose tissues were collected and analyzed for alpha-tocopherol. The basal diet in both experiments contained an average 7.9 IU for period 1, and later diets averaged 11.0 IU vitamin E/kg. In both experiments serum alpha-tocopherol concentrations declined from weaning to 7 d after weaning and continued to decline each week after weaning when the basal diets were fed. Serum alpha-tocopherol concentrations increased (P < 0.01) each week as the dietary vitamin E level increased in both experiments. In Exp. 2, when fat was added to the diet serum alpha-tocopherol concentrations were higher (P < 0.01) than in diets without added fat. Liver, heart muscle, and adipose tissue alpha-tocopherol concentrations increased (P < 0.01) as vitamin E level increased, but at the higher dietary vitamin E level the liver surpassed the adipose tissue in its alpha-tocopherol concentration. Liver and adipose alpha-tocopherol concentrations were higher (P < 0.01) when fat was added to the diet. These results indicate that supplementation of 40 to 60 IU/kg diet with added fat resulted in a relatively constant balance of serum and tissue concentration of alpha-tocopherol during the nursery period, but when fat was not supplemented a dietary vitamin E level of 80 to 100 IU/kg diet may be needed. The current NRC recommendations for vitamin E for the pig from 5 to 20 kg BW may need to be reevaluated.

Dietary palm oil level affects growth performance, protein retention and tissue vitamin E concentration of African catfish, Clarias gariepinus

A 9-week feeding trial was carried out to determine the effect of increasing dietary palm oil levels on growth, protein utilization efficiency and body composition of African catfish. Seven isonitrogenous and isoenergetic practical diets were formulated to contain 4%, 8%, 12% or 16% refined, bleached, deodorized palm olein (RBDPO) or 8%, 12% or 16% crude palm oil (CPO), in addition to a control diet which was not supplemented with palm oil. Growth performance of African catfish responded significantly ( P<0.05) in a positive manner to palm oil additions of up to 8% and no further improvement in growth was observed with higher levels of palm oil supplementation in the diet. Growth and protein utilization efficiency of African catfish fed diets with RBDPO or CPO at the same inclusion level were not significantly different. Significantly higher nitrogen retention was observed in catfish fed diets with 8%, 12% or 16% RBDPO compared to catfish fed 4% RBDPO or the control diet. Whole-body and muscle lipid content increased when fish were fed with increasing levels of dietary palm oil. Alpha-tocopherol concentrations in muscle and liver tissues increased linearly in response to increasing dietary α-tocopherol originating from RBDPO and CPO. Catfish fed CPO-supplemented diets had about three and five times higher concentrations of α-tocopherol in their muscle and liver tissues, respectively, compared to fish fed RBDPO-supplemented diets at all inclusion levels. It may be concluded that, under the present experimental conditions, the inclusion of at least 8% RBDPO or CPO in African catfish diets improves growth performance, protein retention and fillet vitamin E concentration of this fish.

Secretion of α-Tocopherol in VLDL Is Decreased by Dietary Protein Insufficiency in Young Growing Rats

The concentrations of alpha-tocopherol in plasma and most peripheral tissues were shown previously to be low in young growing rats fed a low protein diet. To examine the secretion rates of VLDL alpha-tocopherol and triglycerides, and lipoprotein lipase activity, weanling rats were fed a low protein (LP, 8 g/100 g lactalbumin) or a normal protein (NP, 20 g/100 g lactalbumin) diet for 6 wk. The absolute secretion rate of VLDL triglyceride (micromol/h) of the LP group was not significantly different from that of the NP group (P: > 0.05), but was significantly higher (P: < 0.05) when expressed relative to body weight [micromol/(h. kg)]. The secretion rates of VLDL alpha-tocopherol were significantly lower (P: < 0.05) in the LP group than in the NP group. The activities of hepatic lipase, lipoprotein lipase and total heparin-releasable lipase in plasma of the LP group were only 50-60% those of the NP group (P: < 0.05). The results demonstrated that the secretion rate of VLDL alpha-tocopherol and activities of lipases in postheparin plasma were significantly lower in rats fed a low protein diet. Thus, the redistribution of alpha-tocopherol from liver to peripheral tissues appears to have been impaired by dietary protein insufficiency.

Human plasma and tissue alpha-tocopherol concentrations in response to supplementation with deuterated natural and synthetic vitamin E

We report a comparison of natural and synthetic vitamin E in humans using deuterium labeling to permit the two forms of vitamin E to be measured independently in plasma and tissues of each subject. Differences in natural and synthetic vitamin E concentrations were measured directly under equal dosage conditions using an equimolar mixture of deuterated RRR-alpha-tocopheryl acetate and all-rac-alpha-tocopheryl acetate. Two groups of five adults took 30 mg of the mixture as a single dose and as eight consecutive daily doses, respectively. After a 1-mo interval the schedule was repeated but with a 10-fold higher dose (ie, 300 mg). In each case, the ratio of plasma d3-RRR-alpha-tocopherol to d6-all-rac-alpha-tocopherol (RRR:rac) increased from approximately 1.5-1.8 to approximately 2 after dosing ended. In an elective surgery study in which 22 patients were given 150 mg/d for up to 41 d before surgery, the RRR:rac in tissues was lower than in plasma and the percentage of deuterated alpha-tocopherol was lower in all tissues except gallbladder and liver. In a terminally ill patient given 30 mg/d for 361 d, plasma and tissue (x+/-SD) RRR-rac ratios (and % deuterated alpha-tocopherol) at autopsy were 2.06 (6.3%) and 1.71+/-0.24 (5.9+/-2.2%), respectively. In a second terminally ill patient given 300 mg/d for 615 d, the corresponding values were 2.11 (68%) and 2.01+/-0.17 (65+/-10%), respectively. The results indicated that natural vitamin E has roughly twice the availability of synthetic vitamin E. This 2:1 ratio is significantly higher than the currently accepted RRR:rac of 1.36:1.00. Gamma-Tocopherol, expressed as a fraction of total unlabeled tocopherols in 15 elective surgery patients, was 1.4-4.6 (mean: 2.6) times greater in adipose tissue, muscle, skin, and vein than in plasma, which is a substantially larger fraction than had been recognized previously.

Effect of injected vitamin A and level of dietary vitamin E on α-tocopherol status in gestating swine

A 2 x 2 trial was conducted to determine the effects of injected vitamin A and dietary level of vitamin E on blood serum and tissue concentrations of alpha-tocopherol during early gestation of gilts. Thirty-two crossbred gilts were fed a corn soybean meal basal diet supplemented with DL-alpha tocopheryl acetate to provide either 25 or 500 IU of vitamin E/kg of diet. Gilts were fed daily 1.9 kg/gilt beginning 7 days before breeding until day 25 of gestation. Sixteen gilts were injected (i.m.) with 350,000 IU of retinol palmitate 7 days before breeding, at the time of breeding (d0), and 7 days after breeding. Blood samples were collected on day -7, 0, 7, and 24, and all gilts were slaughtered on day 25 of gestation. Supplemental vitamin E at 500 IU/kg of diet increased alpha-tocopherol concentrations (P < 0.01) in blood serum in all tissues examined, including reproductive and embryonic, except fat. Vitamin A injections had no effect (P > 0.10) on blood serum alpha-tocopherol concentrations except on day 7 when a small increase (P < 0.06) was noted. Vitamin A injections had no effect (P > 0.10) on tissue alpha-tocopherol concentrations. Increasing dietary level of vitamin E increased blood serum and tissue alpha-tocopherol concentrations, and vitamin A injections had little or no effect on these concentrations during the early gestation of gilts.

A novel function for apolipoprotein B: lipoprotein synthesis in the yolk sac is critical for maternal-fetal lipid transport in mice

Apolipoprotein (apo) B, the principal structural component necessary for the synthesis and secretion of triglyceride-rich lipoproteins by the intestine and liver, is highly expressed in the yolk sac visceral endoderm of mammals, although its function in this tissue has been hitherto unclear. Disruption of the apoB gene in mice results in embryonic lethality (approximately 9.5 - 10.5 d). Here we demonstrate that apoB is normally expressed at early time points in embryonic development in yolk sac visceral endodermal cells, and that this expression is associated with the synthesis and secretion of apoB-containing lipoproteins. The lack of apoB in the visceral endoderm resulted in an accumulation of intracellular lipid droplets, an absence of lipoproteins from the secretory pathway, and reduced concentrations of cholesterol and alpha-tocopherol in tissues of apoB-/- embryos. Visceral endoderm of apoB+/- embryos exhibited an intermediate phenotype. Our results suggest that apoB plays an essential role in the transport of lipid nutrients to the developing mouse embryo via the yolk sac-mediated synthesis and secretion of apoB-containing lipoproteins.

Vitamin E supplementation and stress affect tissue alpha-tocopherol content of beef heifers.

The effect of stress on tissue alpha-tocopherol was investigated in 16 crossbred heifers fed a corn/corn silage-based diet. For 28 d, eight heifers (379 +/- 10 kg BW) received a dietary supplement of 1,000 IU of dl-alpha-tocopheryl acetate, whereas the controls (375 +/- 10 kg BW) received no supplemental vitamin E. Tissue samples of plasma, red blood cells, liver, trapezius, and longissimus muscles and subcutaneous fat immediately dorsal to each muscle were taken on d 1 for determination of alpha-tocopherol concentration. On d 2 through 4 each heifer was restricted to 2.61 kg of grass hay and allowed water. On d 5, 6, and 7 no feed or water was given, 100 IU of ACTH and .0024 mg of epinephrine/kg BW were given every 8 h, and biopsies for alpha-tocopherol content were again taken on d 7. The stress reduced (P < .01) mean BW, increased (P < .01) serum cortisol, creatine kinase, and urea. After stress, supplemental vitamin E reduced (P < .13) the increase in creatine kinase relative to that in heifers not supplemented with vitamin E. Stress also increased (P < .04) serum Se in heifers fortified with the vitamin E. Alpha-tocopherol content of plasma, red blood cells, liver, and subcutaneous fat dorsal to the trapezius muscle was increased (P < .01) by supplemental vitamin E. The stress treatment reduced (P < .01) alpha-tocopherol content of plasma in those fed the vitamin E and increased it (P < .05) in the nonsupplemented vitamin E-deficient heifers. Stress also decreased red blood cell (P < .01) and liver (P < .05) alpha-tocopherol content in cattle supplemented with vitamin E. Tissue alpha-tocopherol concentrations were reduced by stress only when a diet adequate in vitamin E was fed. In addition, in most sampled tissues, stress did not affect alpha-tocopherol concentrations.

Growth and fresh meat quality characteristics of pigs supplemented with vitamin E.

Crossbred pigs (n = 30) were fed to determine the influence of supplementation with vitamin E on growth and slaughter characteristics of swine and on the quality characteristics of fresh pork. Pigs received either a control diet containing no vitamin E (CON) or a diet formulated to contain 100 mg of vitamin E/kg feed (VITE). During 84 d of feeding, feed intake and weight gain were measured every 2 wk. After the feeding period, pigs were slaughtered and the loin from the left side of each carcass was removed 4 d after death. Alpha-Tocopherol concentration and proximate composition of the longissimus muscle were determined. Loins were sliced into 10-cm sections and stored under vacuum (2 degrees C) for 0, 14, 28, and 56 d. After storage, loins were sliced into 2.54-cm chops, wrapped in polyvinyl chloride film and stored in a retail case (2 to 4 degrees C) for 5 d. Thiobarbituric acid (TBA) values, Hunter L, a, and b values, total plate counts, pH, purge loss, drip loss, cook loss, taste panel characteristics, and visual panel characteristics were evaluated. Growth traits, slaughter characteristics, and proximate composition did not differ (P > .05) between dietary treatment groups. Alpha-Tocopherol concentrations were greater (P < .05) and TBA values during extended retail display were less (P < .05) for VITE chops than for CON chops. Overall palatability ratings were more desirable (P < .05, at 14 d of vacuum storage) for VITE chops than for CON chops. Color measurements, sensory characteristics, total plate counts, pH, purge loss, drip loss, and cook loss were not influenced (P > .05) by vitamin E supplementation. These results indicated that at the tissue alpha-tocopherol concentrations of the present study, vitamin E supplementation of the growing-finishing diet of hogs reduced lipid oxidation in fresh pork but did not influence pork color or tissue drip loss.

Assessment of vitamin E nutritional status in yearling beef heifers.

Effects of four dietary levels of DL-alpha-tocopheryl acetate (0, 500, 1,500, and 3,000 IU.animal-1.d-1) on serum, red blood cell (RBC), and tissue alpha-tocopherol concentrations were investigated in 32 yearling cattle during an 84-d trial. Supplemental vitamin E was fed for 28 d, withdrawn for 28 d, and then resumed for another 28 d. Blood was collected on d 1 before treatment administration, d 3, and biweekly thereafter. Serum alpha-tocopherol increased rapidly from pretreatment values (1.8 micrograms/mL) with linear (P < .05) treatment effects on d 3 and 14 and cubic treatment effects on d 28. Upon withdrawal of vitamin E supplementation, serum tocopherol concentrations declined and again increased rapidly and linearly by d 84 after supplementation was resumed. Concentration of alpha-tocopherol in RBC did not respond appreciably to supplemental vitamin E. There were no vitamin E treatment effects on blood lipid fractions (cholesterol and triglycerides). When serum tocopherol was expressed relative to the sum of cholesterol and triglycerides, response to vitamin E intake followed similar trends as serum alpha-tocopherol. The relationship between serum alpha-tocopherol concentrations or serum tocopherol:cholesterol plus triglycerides ratio and vitamin E intake was linear (P < .05) for d 14, 28, and 84 and linear with liver for d 84. Serum and liver tocopherol reflected vitamin E intake and can be used reliably to estimate vitamin E status in young cattle.

The effect of excessive dietary vitamin A on performance and vitamin E status in swine fed diets varying in dietary vitamin E

A study was conducted to evaluate the effects of high dietary vitamin A on vitamin E status and performance of growing-finishing pigs fed diets supplemented with varying levels of vitamin E. Treatments consisted of corn-soybean meal-based diets supplemented with retinyl acetate to provide 2,000 or 20,000 IU of vitamin A/kg of diet and with DL-alpha-tocopheryl acetate to provide 0, 15, or 150 IU of added vitamin E/kg in a 2 x 3 factorial arrangement. The trial involved 84 crossbred pigs (26 kg initial BW) allotted to pens of two pigs each (one gilt, one barrow). Serum was obtained from all pigs on d 0, 3, 7, 21, 35, 63, and 77 of the 83- or 90-d feeding period. Tissue samples (liver, leg, and neck muscle, backfat, and leaf fat) were collected from one pig (barrow) in each pen at the end of the feeding period. Average daily gain and gain:feed were .93 kg and .30, respectively, without treatment differences (P > .10). Serum alpha-tocopherol increased linearly (P < .01) by d 3 with increasing level of dietary vitamin E supplementation. High dietary vitamin A resulted in a small decrease (P < .01) in serum alpha-tocopherol on d 3, but serum alpha-tocopherol concentration was not affected (P > .10) on other days. Tissue alpha-tocopherol increased linearly (P < .001) as dietary vitamin E increased in all tissues examined. No consistent evidence was found to indicate that a high level of dietary vitamin A interfered with performance or with blood serum or tissue alpha-tocopherol concentrations in growing-finishing swine.

A review of dietary vitamin E supplementation for improvement of beef quality.

Color is a primary factor used by consumers to judge beef quality, especially freshness. Recent studies indicate that dietary supplementation of vitamin E to beef cattle increases the alpha-tocopherol concentration in muscle and its membranous subcellular fractions. The increased tissue alpha-tocopherol concentration protects not only membranal lipids but also myoglobin from oxidation. This results in delayed onset of discoloration in fresh, ground, and frozen beef and in suppression of lipid rancidity, especially in fresh, ground, and frozen beef and less so in cooked beef. Extension of beef color display life depends on dose level and duration of dietary vitamin E, muscle, and aging period. Cumulative results of experiments conducted to date indicate that beef from animals that receive 500 IU/steer daily of vitamin E for 126 d could assuredly benefit the domestic retail market by extending color display life. Implementation of this technology by the beef industry requires development of a method for rapid determination of alpha-tocopherol concentration in muscle samples collected on the day of harvest.

Efficacy of water-soluble vitamin E in the treatment of vitamin E malabsorption in short-bowel syndrome

A water-soluble form of vitamin E, tocopheryl succinate polyethylene glycol 1000 (TPGS), was used as an oral vitamin E supplement in a 71-y-old patient with severe fat malabsorption and vitamin E deficiency secondary to short-bowel syndrome. An absorption test with deuterium-labeled TPGS demonstrated that TPGS was absorbed and the released alpha-tocopherol was transported normally in lipoproteins. The disappearance portion of the deuterated alpha-tocopherol curves were parallel to those in control subjects, suggesting normal metabolic turnover of alpha-tocopherol. Long-term (3 y) supplementation with orally administered TPGS (10,360 mg or 4000 IU/d) maintained normal plasma alpha-tocopherol concentrations, raised adipose tissue alpha-tocopherol concentrations, and prevented further progression of the neurological abnormalities resulting from vitamin E deficiency. Thus, TPGS can be an effective vitamin E supplement in short-bowel syndrome despite severe fat malabsorption.

Tissue vitamin E status is compromised by dietary protein insufficiency in young growing rats.

In vitro erythrocyte hemolysis previously has been found to be significantly elevated in rats fed a low protein diet. To investigate the effects of dietary protein insufficiency on tissue vitamin E status, four groups of male weanling Long-Evans rats were given free access to either an 8% (wt/wt) lactalbumin diet containing 50 (L50) or 500 (L500) mg/kg diet of all-rac-alpha-tocopheryl acetate, or a 20% (wt/wt) lactalbumin diet containing 50 (N50) or 500 (N500) mg/kg of all-rac-alpha-tocopheryl acetate for 6 wk. A fifth group (P50) was pair-fed to the L50 group with the N50 diet. The L50 and L500 groups showed signs of protein malnutrition such as growth retardation as well as lower hematocrit and plasma protein and albumin concentrations. The alpha-tocopherol concentrations of plasma, heart, lung, kidney and muscle were significantly lower in the L50 group compared with the N50 group. The L500 group showed significantly less alpha-tocopherol in heart, kidney, muscle, brain and adipose tissue compared with the N500 group. The alpha-tocopherol concentrations in liver, testis, spleen and adrenal gland did not significantly differ either between the L50 and N50 groups or between the L500 and N500 groups. Supplementation with 500 mg/kg diet of all-rac-alpha-tocopheryl acetate resulted in significantly higher tissue alpha-tocopherol concentration in all tissues except muscle. The tissue alpha-tocopherol concentrations of the P50 group were not significantly different from those of the N50 group. The results indicated that protein insufficiency resulted in significantly lower alpha-tocopherol concentrations in most tissues in young growing rats.

Tissue alpha-tocopherol concentrations following supplementation with various forms of vitamin E in sheep.

Tissue alpha-tocopherol concentrations were determined in 40 lambs following oral supplementation of various forms of vitamin E. Lambs were allocated to 8 dietary groups of 5 animals each and supplemented with or without equimolar amounts (300 mg equivalence) of different vitamin E compounds daily for 60 d as follows: 1) control, no supplemental vitamin E; 2) D-alpha-tocopheryl acetate; 3) DL-alpha-tocopheryl acetate; 4) DL-alpha-tocopheryl nicotinate; 5) D-alpha-tocopheryl polyethylene glycol 1,000 succinate (TPGS); 6) DL-alpha-tocopheryl nicotinate+TPGS; 7) D-alpha-tocopheryl acetate+TPGS; and 8) D-alpha-tocopheryl succinate. At the end of the 60 d the lambs were killed and portions of adrenal, fat, heart, kidney, liver, lung, skeletal (brachiocephalicus and gluteus) muscles, pancreas and spleen were removed. Daily supplementation with various vitamin E compounds (equivalence) in lambs resulted in significant differences in tissue alpha-tocopherol concentration in heart, liver, gluteus medius muscle, and spleen. Correlations between the plasma and tissue alpha-tocopherol levels were highly significant for all tissues except adrenal, fat, and pancreas.

α‐tocopherol concentrations of the nervous system and selected tissues of adult dogs fed three levels of vitamin E

The effects of dietary vitamin E levels on tissue alpha-tocopherol (alpha-T) concentrations in different parts of the nervous system are largely unknown. Therefore, we measured the alpha-T contents of nervous and other tissues obtained from beagle dogs fed for two years a vitamin E-deficient diet (-E, 0.05 +/- 0.02 mg vitamin E/kg diet, n = 2), a vitamin E-supplemented diet (+E, 114 +/- 14 mg/kg, n = 2), or a standard chow diet (En, 74 +/- 6 mg/kg, n = 3). Brain regions and spinal cords of +E dogs contained about double the alpha-T concentrations of En dogs, and about 10-fold those of -E dogs. The various brain regions of -E dogs, compared with En dogs, retained 12-18% of the alpha-T concentrations, with the exception of the caudal colliculus, which retained 48%. Peripheral nerve alpha-T concentrations in +E dogs (67 ng/mg wet weight) were nearly 5-fold higher than in En dogs (13.4 +/- 5.9 ng/mg) and 80-fold higher than in -E dogs (0.8 ng/mg). Within each dietary group, the lowest alpha-T concentrations in the central nervous system (CNS) were in the spinal cord. Peripheral nerves were the most susceptible to vitamin E repletion or depletion: in +E dogs, nerves contained higher concentrations of alpha-T than most brain regions; in En dogs, they contained similar concentrations; but in -E dogs, they contained less alpha-T than most brain regions. Muscles and other tissues of -E dogs retained from 1 to 10% of En values.(ABSTRACT TRUNCATED AT 250 WORDS)