Biopotency of vitamin E in barley

Monitoring of vitamin E status of dry, early and mid-late lactating organic dairy cows fed conserved roughages during the indoor period and factors influencing forage vitamin E levels

Analysis of blood plasma of 60 cows selected on six Flemish organic dairy farms revealed that on average 12% of all samples and on one farm up to 28% of the organic cows showed plasma vitamin E concentrations less than 3.0 μg/ml, which is considered the minimum level to avoid health risks due to vitamin E shortages. Furthermore, this study showed early lactating and dry cows to be more at risk in relation to animals in mid-late lactation. In European organic farming, vitamin supplements are only allowed if granted by the local authority to satisfy daily requirements. Therefore, the vitamin E content of the feedstuffs used on the farms was determined. Grass clover silage (GCS) and mixed silage had significantly more vitamin E than hay, maize or grain (p < 0.05) [mean (SD): 52 (35), 29 (20), 4.5 (1.7), 4.9 (4.4) and 7.1 (3.8) mg/kg DM, respectively]. Apparently, variation in the vitamin E content in the silage samples was huge. Hence, the vitamin E content of ryegrass, white and red clover was determined in a second lab scale experiment and the effects of wilting, DM content and supplementation of ensiling additives were investigated. Fresh ryegrass had a higher vitamin E content than white and red clover (p < 0.05) [156 (11.3), 49.3 (0.67) and 74.3 (5.73) μg/g DM, respectively]. These differences remained after the wilting or ensiling. Supplementation of formic acid or lactic acid bacteria at ensiling had no significant effect on the vitamin E content. Overall, it can be concluded that GCS is the most important source of vitamin E in organic dairy farming. A legal possibility for case-related supplementation should be retained in organic dairy farming as approximately 18% of all dry and early lactating cows were at risk of vitamin E shortage.

Tropical oils: Nutritional and scientific issues

Individually and in combination with other oils, the tropical oils impart into manufactured foods functional properties that appeal to consumers. The use of and/or labeling in the ingredient lists give the impression that these oils are used extensively in commercially processed foods. The estimated daily intake of tropical oils by adult males is slightly more than one fourth of a tablespoon (3.8 g), 75% of which consists of saturated fatty acids. Dietary fats containing saturated fatty acids at the beta-position tend to raise plasma total and LDL-cholesterol, which, of course, contribute to atherosclerosis and coronary heart disease. Health professionals express concern that consumers who choose foods containing tropical oils unknowingly increase their intake of saturated fatty acids. The saturated fatty acid-rich tropical oils, coconut oil, hydrogenated coconut oil, and palm kernel oil, raise cholesterol levels; studies demonstrating this effect are often confounded by a developing essential fatty acid deficiency. Palm oil, an essential fatty acid-sufficient tropical oil, raises plasma cholesterol only when an excess of cholesterol is presented in the diet. The failure of palm oil to elevate blood cholesterol as predicted by the regression equations developed by Keys et al. and Hegsted et al. might be due to the dominant alpha-position location of its constituent saturated fatty acids. If so, the substitution of interesterified artificial fats for palm oil in food formulations, a recommendation of some health professionals, has the potential of raising cholesterol levels. A second rationale addresses prospective roles minor constituents of palm oil might play in health maintenance. This rationale is founded on the following observations. Dietary palm oil does not raise plasma cholesterol. Single fat studies suggests that oils richer in polyunsaturated fatty acid content tend to decrease thrombus formation. Anomalously, palm oil differs from other of the more saturated fats in tending to decrease thrombus formation. Finally, in studies comparing palm oil with other fats and oils, experimental carcinogenesis is enhanced both by vegetable oils richer in linoleic acid content and by more highly saturated animal fats. The carotenoid constituents of red palm oil are potent dietary anticarcinogens. A second group of antioxidants, the tocotrienols, are present in both palm olein and red palm oil. These vitamin E-active constituents are potent suppressors of cholesterol biosynthesis; emerging data point to their anticarcinogenic and antithrombotic activities. This review does not support claims that foods containing palm oil have no place in a prudent diet.

The influence of parenterally administered alpha-tocopheryl acetate to sows on the vitamin E status of the sows and suckling piglets and piglets after weaning

The main aim of the study was to test if parenteral administration of alpha-tocopheryl acetate twice before farrowing and weaning could increase the vitamin E status of the newborn piglets and piglets after weaning. In Trial I eight sows were given 1.5 g alpha-tocopheryl acetate intramuscularly 7 and 2 days before farrowing. Eight sows were untreated controls. The experimental sows had a higher vitamin E concentration in colostrum than the controls. No significant difference between the groups existed in milk at weaning. The serum vitamin E concentration in the experimental piglets 2 and 5 days after farrowing was higher than in the controls. Fifteen days after farrowing the difference between the groups had nearly disappeared. The serum vitamin E concentration in the piglets in the control group was higher during the first days after farrowing than later, and was gradually reduced until at least 2 weeks after weaning. In Trial II, eight sows were given 1.5 g of alpha-tocopheryl acetate 7 and 2 days before weaning of their piglets. They had higher vitamin E concentrations in milk and serum than untreated control sows at weaning. The increase did not, however, influence the serum vitamin E concentration of the piglets. The lowest concentration of vitamin E in serum of the piglets was reached at 45 days after farrowing. The activity of the selenium-dependent enzyme glutathione peroxidase in the serum of piglets was very low during the first week of life in both groups despite the fact that the sows' feed had been supplemented with 0.35 mg selenium/kg. This indicates that the selenium status of newborn piglets might be more critical for their health than their vitamin E status.

Effect of selenium fertilization on selenium in feedstuffs and selenium, vitamin E, and beta-carotene concentrations in blood of cattle

Selenium (n = 56), total vitamin E, and homologues of natural vitamin E in feedstuffs (n = 52) and the concentrations of Se (n = 241), vitamin E (n = 244), and beta-carotene (n = 227) in blood were measured. The mean (+/- SD) Se content in hay, grass silage, oats, and barley produced using fertilizers enriched with Se was 0.13 (+/- 0.169), 0.17 (+/- 0.704), 0.23 (+/- 0.107) and 0.21 (+/- 0.119) mg/kg of DM, respectively, and the mean (+/- SD) vitamin E contents, calculated as dl-alpha-tocopherol acetate equivalents, were 39.7 (+/- 13.0), 120.0 (+/- 40.27), 24.4 (+/- 3.83) and 34.5 (+/- 3.57) IU/kg of DM, respectively. The mean Se concentrations in whole blood of cows, heifers, bulls and calves fed hay (n = 62), silage (n = 111), or pasture (n = 68) varied from 183 to 244 micrograms/l. The mean concentrations of total vitamin E in serum of lactating cows fed hay (n = 21), silage (n = 29) or pasture (n = 26) were 2.8 (+/- 1.43), 6.5 (+/- 3.03) and 8.2 (+/- 2.64) mg/l, respectively. For calves, concentrations of vitamin E in serum were as low as 0.25 mg/L. The mean concentration of beta-carotene in serum of lactating cows fed grass silage (n = 26) or pasture (n = 28) was 13.7 (+/- 6.61) and 15.4 (+/- 6.15) mg/L, respectively, but, in lactating cows fed hay (n = 20), concentrations were 2.5 (+/- 1.07) mg/L.

Blood-lipid and lactation-stage factors affecting serum vitamin E concentrations and vitamin E cholesterol ratios in dairy cattle

The distribution of cholesterol and vitamin E among the various lipoprotein density fractions in bovine blood was measured. The percentage of total plasma vitamin E and cholesterol in the various lipoprotein fractions was very-low-density lipoprotein, 2% and 2%, respectively; low-density lipoprotein, 17% and 22%, respectively, and high-density lipoprotein. 77% and 72%, respectively. Only 3% of plasma vitamin E was not associated with the lipoproteins. Vitamin E cholesterol ratios were not significantly different among lipoprotein fractions (P = 0.3). These results indicate that vitamin E and cholesterol are distributed in equal proportions among lipoprotein fractions. Moreover, the results suggest that variation in the proportions of lipoproteins in the different density fractions would not affect the overall vitamin E cholesterol ratio of plasma. The results further imply that the total plasma vitamin E cholesterol ratio is a valid relative estimator of the vitamin E concentration per lipoprotein particle, regardless of the density distribution of particles. Total serum vitamin E and cholesterol concentrations and their ratio were then determined in commercial diary cattle in various phases of the lactation cycle. There was a significant lactation-stage effect on the serum concentration of each analyte, as well as on their ratio. However, the magnitude of the effect was much less for the ratio than for either vitamin E or cholesterol alone. These results imply that lactation stage affects serum vitamin E concentrations by influencing both the concentration of lipoprotein particles and the concentration of vitamin E within individual particles.

Biopotency of vitamin E in lucerne meal for chickens

In order to estimate the biopotency of vitamin E in lucerne/alfalfa meal in comparison to that of dl-alpha-tocopheryl acetate (dl-alpha-Ta; all-rac-alpha-Ta) a study was conducted with newly hatched White Leghorn male chicks. An increase in the vitamin E level in the liver and plasma, and the prevention of nutritional encephalomalacia (NE) were used as criteria for biopotency. After a vitamin E depletion period of one week posthatching, the chicks continued on a semipurified, vitamin E free basal diet without vitamin E supplementation, or were repleted with graded levels of that vitamin for six weeks, provided as extracted lucerne oil or as dl-alpha-Ta. High performance liquid chromatography (HPLC) with fluorescence detection was used for the analysis of the vitamin E homologues. The diagnosis of NE was based on clinical and histopathological observations. A significant increase (P < 0.05) in vitamin E content in the liver and plasma was observed in response to dietary supplementation with both vitamin E sources. The linear increase both in the liver and plasma storage assays was associated with a reduced incidence of NE. The disease was totally prevented by a dietary supplement of 7.50 and 5.40 mg vitamin E/Kg feed provided as dl-alpha-Ta or lucerne oil, respectively. The natural biopotency of the vitamin E in lucerne meal compared with that of dl-alpha-Ta in the liver and plasma storage assays and in the prevention of NE was 123, 105 and 99%, respectively, as calculated by the slope ratio technique.

Effect of vitamin E supplementation on weight gain, immune competence, and disease incidence in barley-fed beef cattle

The aim of the study was to investigate whether vitamin E supplements in larger amounts than recommended could reduce incidence of disease, improve immune competence, and increase rate of weight gain of conventionally barley-fed beef cattle. Mean daily intake of vitamin E by individual calves in the experimental group was 200 mg during the first 2 mo, 400 mg during the next 2 mo, and 600 mg during the rest of the period. Corresponding daily intakes of vitamin E for the control group were 50, 100, and 150 mg. Mean plasma vitamin E of the experimental group increased from .49 mg/L at the start of the trial to 2.03 mg/L at the end, but that of the control group was lower at the end (.36 mg/L) than at the beginning (.53 mg/L). No significant differences were observed between the groups concerning incidence of disease or magnitude of lymphocyte stimulation. The results indicated that there was a surprisingly poor biological availability of the dietary vitamin. Therefore, a comparison in reality was made between calves with inadequate and normal vitamin E status. The differences in daily BW gain and time to reach slaughter weight thus probably were effects of the low vitamin E status rather than positive effects of additional vitamin in the diet.

Free radical recycling and intramembrane mobility in the antioxidant properties of alpha-tocopherol and alpha-tocotrienol

d-Alpha-tocopherol (2R,4'R,8'R-Alpha-tocopherol) and d-alpha-tocotrienol are two vitamin E constituents having the same aromatic chromanol "head" but differing in their hydrocarbon "tail": tocopherol with a saturated and toctrienol with an unsaturated isoprenoid chain. d-Alpha-tocopherol has the highest vitamin E activity, while d-alpha-tocotrienol manifests only about 30% of this activity. Since vitamin E is considered to be physiologically the most important lipid-soluble chain-breaking antioxidant of membranes, we studied alpha-tocotrienol as compared to alpha-tocopherol under conditions which are important for their antioxidant function. d-Alpha-tocotrienol possesses 40-60 times higher antioxidant activity against (Fe2+ + ascorbate)- and (Fe2+ + NADPH)-induced lipid peroxidation in rat liver microsomal membranes and 6.5 times better protection of cytochrome P-450 against oxidative damage than d-alpha-tocopherol. To clarify the mechanisms responsible for the much higher antioxidant potency of d-alpha-tocotrienol compared to d-alpha-tocopherol, ESR studies were performed of recycling efficiency of the chromanols from their chromanoxyl radicals. 1H-NMR measurements of lipid molecular mobility in liposomes containing chromanols, and fluorescence measurements which reveal the uniformity of distribution (clusterizations) of chromanols in the lipid bilayer. From the results, we concluded that this higher antioxidant potency of d-alpha-tocotrienol is due to the combined effects of three properties exhibited by d-alpha-tocotrienol as compared to d-alpha-tocopherol: (i) its higher recycling efficiency from chromanoxyl radicals, (ii) its more uniform distribution in membrane bilayer, and (iii) its stronger disordering of membrane lipids which makes interaction of chromanols with lipid radicals more efficient. The data presented show that there is a considerable discrepancy between the relative in vitro antioxidant activity of d-alpha-tocopherol and d-alpha-tocotrienol with the conventional bioassays of their vitamin activity.

Histopathological and biochemical changes associated with selenium and vitamin E deficiency in chicks

One day old unsexed White Leghorn chicks obtained either from commercial hens fed adequate levels of selenium (Se) and vitamin E (VE) (Comm. chicks), or from hens depleted in both nutrients (Depl. chicks), were fed a low Se-VE semi-synthetic basal diet. The dietary Se content was kept constantly low, while graded levels of VE as dl-alpha-tocopheryl acetate (dl-alpha Ta), (0, 5, 10 or 15 mg VE/kg diet) were fed for six weeks. An efficient carry-over of Se and VE from hens to their progeny was observed by a significant increase in their muscle Se, liver Se-glutathione peroxidase (Se-GSH-Px), and VE content at hatching. In the Depl. chicks, signs of Se-VE deficiency, i.e. exudative diathesis (ED) were observed at hatching, indicating that the deficiency lesions had developed during the embryonic period, whereas these signs were not observed in Comm. chicks on the depletion diets until they were 2 weeks old. The VE supplemental level of 15 mg/kg was not adequate to provide a complete protection against ED. Exudative diathesis was associated with low levels of muscle Se, liver Se-GSH-Px and VE and was also accompanied by a simultaneous increase in the liver non-Se-GSH-Px. Autopsy findings and histopathological lesions were observed only in subcutaneous tissue and skeletal muscle. The subcutaneous tissue was edematous with hyaline vascular lesions and hemorrhages. The thigh muscles were more susceptible to deficiency lesions than were the breast muscles, and showed in acute stages degenerative processes of the muscle fibers including calcium deposits, vascular lesions and hemorrhages. In subacute and chronic cases, reparative changes and muscle damage may develop independently of the hyaline vasculosis. To prevent ED, adequate Se and VE in chick diet is essential after hatching, irrespective of their tissue reserves of both nutrients at 1 day of age.

Utilization of dietary sodium selenite, barley, oats and meat meal selenium by the chick

The biological availability of selenium (Se) in barley, oats and meat meal as compared to that in sodium selenite was determined by whole blood glutathione peroxidase (GSH-Px) activity and Se concentration depletion-repletion bioassays. One day old White Leghorn chicks, initially of low-Se status, were further depleted for Se by feeding a low-Se casein basal diet (0.03 mg Se/kg diet) adequate in vitamin E for the first two weeks of life. Repletion treatments of Se at graded levels supplemented by the natural sources or sodium selenite were then provided for 4 weeks. A multiple regression equation was calculated to relate the final whole blood GSH-Px activity and Se concentration to the dietary intake of Se. The percent biological availability of Se present in the natural sources was evaluated by slope ratio analyses in comparison to the standard, sodium selenite (100%). The activity of whole blood GSH-Px established a relative bioavailability for barley, oats and meat meal Se of 85, 41 and 25%, respectively (as mu kat/l), and 81, 51 and 17%, respectively (as mu kat/g Hb). The estimated bioavailability of Se in the different natural sources, as measured by blood Se concentration was: barley, 104%; oats, 99% and meat meal, 69% in comparison to that of sodium selenite. Thus, selenite Se was superior to the natural Se sources for the induction of GSH-Px activity. Barley Se appeared to be of higher biological value to chicks than did oats and meat meal Se. Even though meal Se was retained in appreciable amounts in chick blood, it showed the poorest utilization for the synthesis of blood GSH-Px.

Response of whole blood, erythrocyte and plasma vitamin E content to dietary vitamin E intake in the chick

Whole blood, red blood cells (RBC), and plasma vitamin E (VE) levels in chicks fed dietary VE (dl-alpha-tocopheryl acetate, dl-alpha Ta) supplementation in steps of 0.0, 5.0, 10.0, 15.0, 20.0 and 30.0 mg/Kg were determined to examine their usefulness as an index of VE status. The increase in VE level was significant and linear in whole blood (r = 0.90), RBC (r = 0.89) and plasma (r = 0.93) in response to dietary VE intake. There was a close correlation between VE in plasma vs whole blood (r = 0.90), plasma vs RBC (r = 0.91) and whole blood vs RBC (r = 0.95). The plasma VE content was 1.2-1.8 times greater than that of whole blood, and 6.6-12.5 times greater than that of RBC. The plasma total lipids content was not affected by the dietary VE intake, whereas the level of VE in the plasma total lipids was significantly increased with increasing supplementation. Alpha tocopherol was the major isomer (ca 92%) of VE in whole blood, RBC and plasma at hatching. The small proportions of beta-tocopherol (ca 2%), gamma-tocopherol (ca 5%) and alpha-tocotrienol (ca 1%) observed at 1 day of age had decreased or totally disappeared by 7 days of age after feeding the VE-free basal diet. The data showed that in the chick, the whole blood and RBC levels of VE were as sensitive and reliable indexes of dietary VE status as was that of the plasma.

Vitamin E requirements of adult Standardbred horses evaluated by tissue depletion and repletion

Vitamin E requirements of adult Standardbred horses were evaluated by tissue depletion and repletion. All the horses used in the study were given the same basal feed low in vitamin E during the eight months of the experiment. After an initial depletion period of two-and-a-half months the horses were divided into groups according to the amounts of DL alpha-tocopheryl acetate given (0 mg, control; 200, 600, 1800 and 5400 mg, respectively) as a daily oral supplement. The supplement study was followed by a second depletion period. Total vitamin E content and individual natural tocopherol isomers and tocotrienol isomers were measured both in the feed (hay and oats) and in tissue (serum, liver, skeletal muscle and adipose tissue) using high performance liquid chromatography with fluorescent detection. Tissue vitamin E response to different dietary vitamin E levels were studied. The serum total lipid content remained unchanged during the experiment; serum vitamin E levels were expressed per gram serum lipid. The total vitamin E levels in serum, liver, skeletal muscle and fat reflected the supplement levels. The highest vitamin E levels were seen in fat tissue, followed by the liver and by skeletal muscle. In spite of the wide occurrence of the different vitamin E isomers in the feed, alpha-tocopherol was almost the only isomer detected in the tissues. To ensure nutritional adequacy, 600 and 1800 mg of DL alpha-tocopheryl acetate was suggested as an optimal oral daily supplement of vitamin E to adult Standardbred horses given feed low in vitamin E; this corresponds to 1.5 to 4.4 mg/kg bodyweight.(ABSTRACT TRUNCATED AT 250 WORDS)