Tocopherol transport and absorption

Vitamin E as promising adjunct treatment option in the combat of infectious diseases caused by bacterial including multi-drug resistant pathogens - Results from a comprehensive literature survey

The use of antibiotics has provoked an emergence of various multidrug-resistant (MDR) bacteria. Infectious diseases that cannot be treated sufficiently with conventional antibiotic intervention strategies anymore constitue serious threats to human health. Therefore, current research focus has shifted to alternative, antibiotic-independent therapeutic approaches. In this context, vitamin E constitutes a promising candidate molecule due to its multi-faceted modes of action. Therefore, we used the PubMed database to perform a comprehensive literature survey reviewing studies addressing the antimicrobial properties of vitamin E against bacterial pathogens including MDR bacteria. The included studies published between 2010 and 2020 revealed that given its potent synergistic antimicrobial effects in combination with distinct antibiotic compounds, vitamin E constitutes a promising adjunct antibiotic treatment option directed against infectious diseases caused by MDR bacteria such as Pseudomonas aeruginosa, Burkholderia cenocepacia and methicillin-resistant Staphylococcus aureus (MRSA). In conclusion, the therapeutic value of vitamin E for the treatment of bacterial infections should therefore be investigated in future clinical studies.

Use of Natural Components Derived from Oil Seed Plants for Treatment of Inflammatory Skin Diseases

The incidence of inflammatory skin diseases is increasing, so the search for relevant therapeutics is of major concern. Plants are rich in phytochemicals which can alleviate many symptoms. In this review, we concentrate on compounds found in the seeds of widely cultivated plants, regularly used for oil production. The oils from these plants are often used to alleviate the symptoms of inflammatory diseases through synergetic action of unsaturated fatty acids and other phytochemicals most commonly derived from the terpenoid pathway. The knowledge of the chemical composition of oil seeds and the understanding of the mechanisms of action of single components should allow for a more tailored approach for the treatment for many diseases. In many cases, these seeds could serve as an efficient material for the isolation of pure phytochemicals. Here we present the content of phytochemicals, assumed to be responsible for healing properties of plant oils in a widely cultivated oil seed plants and review the proposed mechanism of action for fatty acids, selected mono-, sesqui-, di- and triterpenes, carotenoids, tocopherol and polyphenols.

Vitamin E plasma kinetics in swine show low bioavailability and short half-life of -α-tocopheryl acetate

Vitamin E is important for animal production because of its effects on health and product quality, but the amount and form required remains controversial. Our objective was to quantify the absolute bioavailability of oral -α-tocopheryl acetate (α-TAc) in swine (22 ± 1 kg and 8 wk old, fitted with jugular catheters) adapted to a diet supplemented with 75 mg/kg -α-TAc; 75 mg/kg was chosen because this level represents the nonweighted average inclusion level in piglet diets across Western key swine-producing countries. For this, a 350-g test meal (6% fat) was supplied at time 0 containing 75 mg deuterated (D9) -α-TAc to 9 animals, and 8 animals received an intravenous () dose containing deuterated (D6) RRR-α-tocopherol (α-T) at one-eighth the oral dose and a test meal without supplemental vitamin E. Plasma samples (12 to 13 per animal) were obtained at incremental intervals over 75 h for analysis of deuterated α-T using liquid chromatography-tandem mass spectrometry. Surprisingly, the i.v. dose rapidly disappeared from plasma and then reappeared. The half-life for this first peak was only 1.7 ± 0.3 min. The second peak had an appearance rate (Ka) of 0.10 ± 0.06 d and a half-life of 5.9 ± 1.2 h. Oral dosing resulted, after a lag of 56 min, in a Ka of 0.91 ± 0.21 d and a half-life of 2.6 ± 0.8 h. The bioavailability for oral α-TAc was 12.5%, whereas the area under the curve was only 5.4%. This low bioavailability, small area under the curve, and short half-life are likely because of various factors, that is, the use of only 6% fat in the diet, the use of the acetate ester and , and the high dose relative to requirements. In conclusion, i.v. dosed vitamin E shows both a rapid and a very slow pool, whereas orally dosed vitamin E shows a single slow pool. The oral material has a very short half-live (44% of i.v. or 2.6 h), low bioavailability (12.5%), and a very small area under the curve (5.4%), bringing into question the efficacy of typical doses of vitamin E in swine diets for alleviating oxidative stress.

Oral vitamin E absorption in English Cocker Spaniels with familial vitamin E deficiency and retinal pigment epithelial dystrophy

BACKGROUND

Retinal Pigment Epithelial Dystrophy (RPED) with neuroaxonal degeneration in English Cocker Spaniels (ECS) is associated with systemic vitamin E deficiency in the absence of dietary insufficiency.

OBJECTIVE

To evaluate the ability of ECS with RPED to absorb orally administered vitamin E and establish a basis for vitamin E supplementation in affected dogs.

ANIMALS STUDIED

8 RPED-affected ECS and five clinically normal dogs.

PROCEDURES

An oral vitamin E tolerance test (OVETT) was conducted in each dog. Blood samples were obtained prior to and at 3, 6, 9, 12, 24, 120, and 240 h following oral administration of 90 iu/kg of RRR-α-tocopherol. Plasma alpha tocopherol (αTOC) content was measured by normal phase, high-performance liquid chromatography, and indices of vitamin E absorption calculated.

RESULTS

There was marked variation in OVETT results between individuals. In RPED-affected ECS, mean peak plasma αTOC concentration (17.87 ± 13.21 μg/mL), attained after administration of a large oral dose of the vitamin, was significantly lower than the mean peak plasma αTOC concentration attained in normal dogs (47.61 ± 17.17 μg/mL; P < 0.005). However, the plasma concentrations achieved in 7/8 RPED-affected dogs remained within the normal reference range for plasma αTOC in vitamin E-replete dogs, for at least 12 h postdose.

CONCLUSIONS

Vitamin E-deficient ECS with RPED are capable of absorbing orally administered vitamin E. Twice daily administration of 600-900 iu tocopherol is likely to restore plasma vitamin E concentrations to the normal range in most affected dogs.

Soy constituents: modes of action in low-density lipoprotein management

Reviewed here are the modes of action of soy components used as ingredients in foods, which can lower plasma levels of low-density lipoprotein (LDL) and cholesterol, which are markers for the risk for atherosclerosis. Soy ingredients act via more than one mode of action including the following: LDL absorption suppression, cholesterol efflux stimulation, LDL resorption stimulation, LDL oxidation prevention, LDL particle size increase, cholesterol synthesis reduction, and bile secretion increase. Individual genetics, lifestyle, and nutrition habits alter LDL management and a better understanding of the various modes of actions of soy ingredients may facilitate the composition of effective ingredient cocktails. The optimization of food components offers further alternatives to LDL management to augment drug therapy for patients who are unable to reach their target LDL cholesterol levels or who are suffering from side effects or drug insensitivity.

Viability and permeability across Caco-2 cells of CBZ solubilized in fully dilutable microemulsions

The purpose of this study was to evaluate the viability and permeability of carbamazepine (CBZ) solubilized in fully dilutable non-ionic microemulsions across Caco-2 cells used as a model for intestinal epithelium. Maximum solubilization capacity (SC) of CBZ was determined within water-in-oil (W/O), bicontinuous and oil-in-water (O/W) structures formed upon dilution. The effect of the nature of the oil phase, surfactant type, and the ratio between the oil phase and surfactant on the quantity of solubilized CBZ, droplets size, the viability of the cells and drug permeability was elucidated. We found that: (1) several fully dilutable microemulsions based on pharma-grade ingredients can be loaded with very significant amounts of CBZ, (2) W/O microemulsions (10wt% water) exhibit up to 3-fold higher solubilization capacity over the drug's solubility in oil (triacetin), (3) CBZ in the O/W microemulsions (80wt% water) exhibit up to 29-fold higher solubilization than in water, (4) the O/W droplets of the examined systems are 9-11nm in size, (5) the highest permeability was obtained in systems containing triacetin/alpha-tocopherol acetate/ethanol in 3/1/4wt% ratio as oil phase and Tween 60 as surfactant, (6) the replacement of alpha-tocopherol acetate by alpha-tocopherol inhibits CBZ release, (7) replacement of a saturated chain of Tween 60 by an unsaturated (Tween 80) or shorter chain (Tween 40) inhibited drug release, (8) the decrease in the oil phase to surfactant ratio leads to enhancement of drug release (dilution line 64>dilution line 73).

High levels of dietary unsaturated fat decrease alpha-tocopherol content of whole body, liver, and plasma of chickens without variations in intestinal apparent absorption

An experiment was designed to assess the effect of dietary unsaturated fat inclusion level on alpha-tocopherol apparent absorption and deposition in broiler chickens at 2 ages (20 and 39 d). The dietary fat was a mixture of linseed and fish oil, rich in polyunsaturated fatty acids (PUFA). The experimental treatments were the result of 4 levels of supplementation with alpha-tocopheryl acetate (0, 100, 200, and 400 mg/kg; E0, E100, E200, and E400 treatments, respectively) and 4 dietary oil inclusion levels (2, 4, 6, and 8%; O2, O4, O6, and O8 treatments respectively). Almond husk was used as an energy dilutor in the high-fat diets. Apparent absorption of total fatty acids was high in all treatments averaging 88% and was higher with high fat dietary inclusion level. alpha-Tocopheryl acetate hydrolysis and apparent absorption of alpha-tocopherol were similar in both ages and were not affected by fat inclusion level, except for a reduction of the absorption in the low-fat diet (O2) in the E100 treatment at 20 d of age. Despite this lack of differences in hydrolysis and absorption, higher-fat PUFA diets induced lower concentrations of free alpha-tocopherol in the excreta, at high alpha-tocopherol doses, suggesting an increase in the destruction of alpha-tocopherol by lipid oxidation in the gastrointestinal tract. Similarly, total and hepatic alpha-tocopherol deposition was lower in the birds fed high-PUFA diets in the E200- and E400-supplemented birds, possibly due to a destruction of vitamin E when protecting these PUFA from lipid peroxidation. alpha-Tocopherol concentration in liver and, to a lesser extent, in plasma was a useful indicator of the degree of response of this vitamin to different factors that can affect its bioavailability; however, in the present experiment, CV were too high to use liver and plasma concentrations as estimators of total body vitamin E.

Enrichment of coenzyme Q10 in plasma and blood cells: defense against oxidative damage

Coenzyme Q10 (CoQ10) concentration in blood cells was analyzed by HPLC and compared to plasma concentration before, during, and after CoQ10 (3 mg/kg/day) supplementation to human probands. Lymphocyte DNA 8-hydroxydeoxy-guanosine (8-OHdG), a marker of oxidative stress, was analyzed by Comet assay.

Subjects supplemented with CoQ10 showed a distinct response in plasma concentrations after 14 and 28 days. Plasma levels returned to baseline values 12 weeks after treatment stopped. The plasma concentration increase did not affect erythrocyte levels. However, after CoQ10 supplementation, the platelet level increased; after supplementation stopped, the platelet level showed a delayed decrease. A positive correlation was shown between the plasma CoQ10 level and platelet and white blood cell CoQ10 levels. During CoQ10 supplementation, delayed formation of 8-OHdG in lymphocyte DNA was observed; this effect was long-lasting and could be observed even 12 weeks after supplementation stopped. Intracellular enrichment may support anti-oxidative defense mechanisms.

The absorption of vitamin E is influenced by the amount of fat in a meal and the food matrix

Vitamin E absorption requires the presence of fat; however, limited information exists on the influence of fat quantity on optimal absorption. In the present study we compared the absorption of stable-isotope-labelled vitamin E following meals of varying fat content and source. In a randomised four-way cross-over study, eight healthy individuals consumed a capsule containing 150 mg 2H-labelled RRR-α-tocopheryl acetate with a test meal of toast with butter (17·5 g fat), cereal with full-fat milk (17·5 g fat), cereal with semi-skimmed milk (2·7 g fat) and water (0 g fat). Blood was taken at 0, 0·5, 1, 1·5, 2, 3, 6 and 9 h following ingestion, chylomicrons were isolated, and 2H-labelled α-tocopherol was analysed in the chylomicron and plasma samples. There was a significant time (P<0·001) and treatment effect (P<0·001) in 2H-labelled α-tocopherol concentration in both chylomicrons and plasma between the test meals. 2H-labelled α-tocopherol concentration was significantly greater with the higher-fat toast and butter meal compared with the low-fat cereal meal or water (P<0·001), and a trend towards greater concentration compared with the high-fat cereal meal (P=0·065). There was significantly greater 2H-labelled α-tocopherol concentration with the high-fat cereal meal compared with the low-fat cereal meal (P<0·05). The 2H-labelled α-tocopherol concentration following either the low-fat cereal meal or water was low. These results demonstrate that both the amount of fat and the food matrix influence vitamin E absorption. These factors should be considered by consumers and for future vitamin E intervention studies.

Absence of VLDL secretion does not affect alpha-tocopherol content in peripheral tissues

alpha-Tocopherol is a lipid-soluble antioxidant that helps to prevent oxidative damage to cellular lipids. alpha-Tocopherol is absorbed by the intestine and is taken up and retained by the liver; it is widely presumed that alpha-tocopherol is then delivered to peripheral tissues by the secretion of VLDL. To determine whether VLDL secretion is truly important for the delivery of alpha-tocopherol to peripheral tissues, we examined alpha-tocopherol metabolism in mice that lack microsomal triglyceride transfer protein (Mttp) expression in the liver and therefore cannot secrete VLDL (Mttp(Delta/Delta) mice). Mttp(Delta/Delta) mice have low plasma lipid levels and increased stores of lipids in the liver. Similarly, alpha-tocopherol levels in the plasma were lower in Mttp(Delta/Delta) mice than in controls, whereas hepatic alpha-tocopherol stores were higher. However, alpha-tocopherol levels in the peripheral tissues of Mttp(Delta/Delta) mice were nearly identical to those of control mice, suggesting that VLDL secretion is not critical for the delivery of alpha-tocopherol to peripheral tissues. When fed a diet containing deuterated alpha-tocopherol, Mttp(Delta/Delta) and control mice had similar incorporation of deuterated alpha-tocopherol into plasma and various peripheral tissues. We conclude that the absence of VLDL secretion has little effect on the stores of alpha-tocopherol in peripheral tissues, at least in the mouse.

Effect of dietary n−6 and n−3 polyunsaturated fatty acids on peroxidizability of lipoproteins in steers

The susceptibility of major plasma lipoproteins to lipoperoxidation was studied in relation to the FA composition of their neutral and polar lipids in steers given PUFA-rich diets. Two trials used, respectively, 18 ("sunflower" experiment, S) or 24 ("linseed" experiment, L) crossbred Salers x Charolais steers. Each involved three dietary treatments over a 70-d period: a control diet (CS or CL diets) consisting of hay and concentrate, or the same diet supplemented with oilseeds (4% diet dry matter) fed either as seeds (SS or LS diets) or continuously infused into the duodenum (ISO or ILO diets). Compared with control diets, ISO and ILO treatments tended to decrease the resistance time of LDL and HDL classes to peroxidation, mainly owing to the enrichment of their polar and neutral lipids with PUFA. With diets SS and LS, sensitivity of major lipoprotein classes (LDL, light and heavy HDL) was not affected because ruminal hydrogenation of dietary PUFA decreased their incorporation into lipoparticles. ISO and ILO treatments induced a more important production of conjugated dienes and hydroperoxides generated by peroxidation in the three lipoprotein classes due to the higher amounts of PUFA esterified in lipids of the core and the hydrophilic envelope of particles. The production of malondialdehyde (MDA) increased in steers fed linseed supplements, indicating that MDA production did not occur with linoleic acid provided by sunflower oil supplements. Thus, plasma peroxidation of PUFA generates toxic products in steers fed diets supplemented with PUFA and can be deleterious for the health of the animal during long-term treatment.

A carbohydrate-antioxidant hybrid polymer reduces oxidative damage in spermatozoa and enhances fertility

Gamete-gamete interactions are critically modulated by carbohydrate-protein interactions that rely on the carbohydrate-selective recognition of polyvalent carbohydrate structures. A galactose-binding protein has been identified in mammalian spermatozoa that has similarity to the well-characterized hepatic asialoglycoprotein receptor. With the aim of exploiting the ability of this class of proteins to bind and internalize macromolecules displaying galactose, we designed hybrid carbohydrate-antioxidant polymers to deliver antioxidant vitamin E (alpha-tocopherol) to porcine spermatozoa. Treatment of sperm cells with one hybrid polymer in particular produced large increases in intracellular sperm levels of alpha-tocopherol and greatly reduced endogenous fatty acid degradation under oxidative stress. The polymer-treated spermatozoa had enhanced physiological properties and longer half-lives, which resulted in enhanced fertilization rates. Our results indicate that hybrid polymer delivery systems can prolong the functional viability of mammalian spermatozoa and improve fertility rates, and that our functionally guided optimization strategy can be applied to the discovery of active glycoconjugate ligands.

Regulation of cell signalling by vitamin E

Vitamin E, the most important lipid-soluble antioxidant, was discovered at the University of California at Berkeley in 1922. Since its discovery, studies of the constituent tocopherols and tocotrienols have focused mainly on their antioxidant properties. In 1991 Angelo Azzi's group (Boscoboinik et al. 1991a,b) first described non-antioxidant cell signalling functions for alpha-tocopherol, demonstrating that vitamin E regulates protein kinase C activity in smooth muscle cells. At the transcriptional level, alpha-tocopherol modulates the expression of the hepatic alpha-tocopherol transfer protein, as well as the expression of liver collagen alphal gene, collagenase gene and alpha-tropomyosin gene. Recently, a tocopherol-dependent transcription factor (tocopherol-associated protein) has been discovered. In cultured cells it has been demonstrated that vitamin E inhibits inflammation, cell adhesion, platelet aggregation and smooth muscle cell proliferation. Recent advances in molecular biology and genomic techniques have led to the discovery of novel vitamin E-sensitive genes and signal transduction pathways.

Interaction of dietary vitamin E with Eimeria maxima infections in chickens

In two trials, broiler chickens, processed similarly to those placed in commercial operation, were fed, from 1 d of age, a range (13 to 200 ppm) of DL-alpha-tocopheryl acetate (VE-AC) levels, and the effects on the pathology of Eimeria maxima infections were assessed at 6 d postinoculation (PI). In Trial 1, dietary levels of VE-AC had little significant effect on variables characterizing pathology except for the number of oocysts shed, which was significantly increased in chicks treated with higher VE-AC levels. The infection was judged to be mild based on moderate lesion scores (2.2+/-0.2), lack of significant effects on weight gain (7+/-1.6% decrease), moderate reduction in plasma carotenoids (21+/-2%) and small increases in plasma NO2-+NO3- (141+/-12%). In uninfected and infected chickens, plasma alpha-tocopherol (AT) increased with dietary levels of VE-AC; however, E. maxima infection caused a fairly constant decrease in AT of 35.3+/-3.2% across these levels. Plasma gamma-tocopherol (GT) levels were unaffected by dietary VE-AC or E. maxima infection. In Trial 2, pathology, again, was relatively unaffected by dietary VE-AC level. The infection was judged to be severe based on lesion scores (3.5+/-0.1), reduction in weight gain (30.7+/-3%), plasma carotenoids (72.4+/-1.5%), uric acid (16.3+/-3.4), albumin (37.8+/-2.8%), large increases (261+/-8%) in plasma NO2-+NO3-, and high numbers of oocysts shed per chick (4.12+/-0.4 x 10(7)). Plasma AT again increased with increasing dietary VE-AC levels in uninfected and infected chicks, but the mean decrease across VE-AC levels caused by E. maxima infection was 73.14+/-3.3%. GT levels were erratic and unrelated to dietary VEAC or infection. Thus, in processed broiler chickens, high dietary VE-AC did not prevent or lessen the pathology caused by mild or severe infections with E. maxima. The main effect of E. maxima infection appeared to be reduction in plasma AT levels. We postulate that this reduction may be due to malabsorption of AT, which results from physical damage to the absorptive mucosa, reduction in esterases required to hydrolyze the VE-AC, and a generalized lipid malabsorption, preventing movement of the free AT to circulating blood and infected tissues.

The effect of alpha-tocopherol on the in vitro solubilisation of lipophilic drugs

alpha-Tocopherol is an excellent solvent for many poorly soluble drugs. The aim of this work was to study whether or not the presence of alpha-tocopherol has an influence on the solubilisation of poorly soluble drugs in simulated intestinal fluids (SIF). The solubilizing capacity of mixed micelles containing alpha-tocopherol towards three lipophilic drugs was investigated. The solubilisation of alpha-tocopherol in an aqueous micellar phase was increased by the addition of monoglycerides (MG) and free fatty acids (FFA), preferably of medium chain length, as compared to a simple bile salt solution. The addition of alpha-tocopherol to mixed micellar solutions seems to have an effect on the solubilizing capacity, which can be correlated to the partition coefficient of the drug to be solubilised. A positive effect on the solubilisation of griseofulvin and felodipine was found. For a highly lipophilic drug (Lu28-179), a positive effect on solubilisation was observed only in media containing MG and FFA of medium chain length. Generally, alpha-tocopherol cannot be considered an important factor for the solubilisation of highly lipophilic drugs in SIF. The presence of lipolytic digestion products (LDP) of the proper chain length in relation to the drug to be solubilised is much more important.

alpha-Tocopherol concentrations in plasma but not in lipoproteins fluctuate during the menstrual cycle in healthy premenopausal women

Because premenopausal women experience cyclic fluctuations of plasma carotenoids and their lipoprotein carriers, it was hypothesized that plasma alpha-tocopherol (A-T) fluctuates by phase of the menstrual cycle. Twelve free-living women, with a confirmed ovulatory cycle, were given a controlled diet for two consecutive menstrual cycles. Blood was drawn during the menses, early follicular, late follicular and luteal phases to simultaneously measure serum hormones, plasma lipoproteins and A-T concentrations, and A-T distribution in the lipoprotein fractions. Plasma A-T concentrations were significantly lower during menses than during the luteal phase by approximately 12% in each controlled diet cycle (P < 0.001). Adjustment for serum cholesterol and triglyceride concentrations did not alter these findings. The distributions of A-T in lipoprotein cholesterol fractions were not significantly different by menstrual phase. From 61 to 62% of A-T was concentrated in the LDL fraction, with another 9-14% in HDL2, 17-22% in HDL3 and the remaining 6-8% in VLDL+ IDL. There were no significant differences in lipoprotein cholesterol fractions by menstrual phase, except for a significant increase (P = 0.03) in HDL2 cholesterol from the early follicular to the late follicular phase. Spearman rank correlations from data during the second controlled diet month showed A-T in HDL2 in the late follicular phase was positively correlated with HDL cholesterol in the early follicular (r = 0.88), late follicular (r = 0.86) and luteal phases (r = 0.86) and with luteal apolipoprotein (ApoA-1) level (r = 0.90), and luteal HDL2 cholesterol (r = 0.83). A-T in HDL3 in the early follicular phase was negatively correlated with HDL2 cholesterol (r = -0.96) and ApoA-1 (r = -0.85), whereas luteal A-T in HDL3 was correlated with luteal HDL3 cholesterol (r = -0.79). Late follicular A-T in VLDL was positively correlated with early follicular HDL3 cholesterol and late follicular HDL3 cholesterol (r = 0.83). Fluctuations of A-T concentrations by phase of the menstrual cycle should be taken into consideration in future research concerning premenopausal women and the risk of chronic disease.

Delaying colostrum intake by one day impairs plasma lipid, essential fatty acid, carotene, retinol and alpha-tocopherol status in neonatal calves

To study whether a delayed start of colostrum feeding in calves affects plasma lipids, fatty acids and fat-soluble vitamins, one group was fed colostrum (milkings 1-4) on d 1 and 2, then mature milk up to d 7, whereas two other groups were fed glucose or water on d 1, colostrum (milkings 1-4) on d 2 and 3 and then mature milk up to d 7. In calves fed colostrum on d 1, starting 5-7 h after birth, plasma concentrations of triglycerides, phospholipids, total cholesterol and of essential and nonessential fatty acids in triglyceride, phospholipid and cholesterol ester fractions as well as of carotene, retinol and alpha-tocopherol up to d 7 were significantly higher than in calves in which colostrum feeding started after >24 h of life. On the other hand, plasma concentrations of vitamin B-6, vitamin B-12 and folic acid were not influenced. Results indicated reduced efficiency of absorption of colostral fatty acids and of fat-soluble vitamins, but not of (selected) water-soluble vitamins, if colostrum is not fed on d 1 of life. In conclusion, colostrum intake within the first 24 h of life is required for an adequate plasma lipid, essential fatty acid, carotene, retinol and alpha-tocopherol status in the first week of life of calves.

Vitamin E incorporated into a very-low-fat meal is absorbed from the intestine of young rats

Vegetable fats and oils are major sources of dietary vitamin E. Consequently the current trend to reduce fat consumption is accompanied by a reduction of the intake of vitamin E. In addition, the absorption of vitamin E is thought to be dependent on the hydrolysis of dietary lipids in the small intestine. It is therefore conceivable that a lower dietary fat intake also diminishes the intestinal absorption of vitamin E. The present 3-week feeding study in young male rats was designed to investigate whether different concentrations of vitamin E added to a very-low-fat product (0, 330 or 1350 mg DL-alpha-tocopheryl acetate/kg product) were absorbed. We therefore incorporated these products into a very-low-fat meal (final fat concentration: 7 g/kg) or a low-fat meal containing 52 g fat/kg. The magnitude of vitamin E absorption from these meals was compared with that from meals containing similar amounts of vitamin E, but a high fat concentration of 190 g/kg. Apparent vitamin E absorption was defined as intake of alpha-tocopherol equivalents (alpha TE) minus faecal alpha TE excretion over 4 d during week 3 of the experimental period. The results of this study showed that apparent absorption of vitamin E from a very-low-fat meal varied, depending on the vitamin E concentration, from 73 to 83%. The magnitude of this vitamin E absorption was not significantly different from that from meals containing a high amount of fat. Liver vitamin E status was equal in rats fed on the very-low-fat meals compared with those fed on the high-fat meals. We conclude that, when very-low-fat or low-fat products are used as a replacement for full-fat products, addition of vitamin E to these products, as DL-alpha-tocopheryl acetate, might be useful in meeting the vitamin E requirements.

Pharmacokinetics and tissue uptake of D-alpha-tocopherol in sheep following a single intraperitoneal injection

D-alpha-Tocopherol in an emulsible base was administered i.p. to four groups of five sheep each at doses of 0, 1250, 2500, and 5000 IU. Blood was sampled regularly until slaughter at 7 d after administration. Plasma and tissue concentrations of D-alpha-tocopherol were measured by HPLC. Pharmacokinetic analysis of plasma concentrations, for the three tested doses, showed an absence of significant difference for lag time to absorption (.9 to 2.5 h), half-time of absorption (15 to 30 h), plasma half-life (31 to 42 h), and time of maximal concentration (18 to 31 h). In contrast, dose had a significant effect on area under the tocopherol plasma curve and on the maximal concentration. For both parameters, statistical evidence indicated nonlinearity for disposition of D-alpha-tocopherol, but without biological significance; by 7 d after dosing, amounts of residue of tocopherol were highest in the pancreas and adrenal glands (approximately 65 and 47 micrograms/g, respectively, for the 5000 IU dose) and lowest in neck muscle (approximately 4 micrograms/g for the 5000 IU dose). Kidney had an intermediate level of tocopherol. The intraperitoneal route is an efficient route for tocopherol administration in sheep.

Transport of alpha-tocopherol in Atlantic salmon (Salmo salar) during vitellogenesis

The transport of α-tocopherol was studied during vitellogenesis in Atlantic salmon that were fed diets with two levels of α-tocopherol. α-Tocopherol levels were measured in the flesh, liver, ovary and serum, and in the serum the α-tocopherol levels in the very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein (HDL) and very high density lipoprotein (VHDL or vitellogenin) were also measured.Atlantic salmon store α-tocopherol mainly in their flesh because the muscle mass comprises 50% or more of live weight. During vitellogenesis the α-tocopherol content declined to about 10% of the level prior to maturation. The relative range of level of α-tocopherol in the lipoproteins was: HDL> LDL> VLDL> VHDL, irrespective of dietary levels of α-tocopherol.From the recent knowledge on lipid transport during vitellogenesis and the present data, we hypothesize that α-tocopherol is transported from peripheral tissues to liver by HDL and further transported from liver to ovary by LDL. Vitellogenin appears to play a minor role in the transportation of vitamin E to the ovary.