Tocopherols and Tocotrienols Are Bioavailable in Rats and Primarily Excreted in Feces as the Intact Forms and 13'-Carboxychromanol Metabolites.

BACKGROUND: Vitamin E α-, γ-, or δ-tocopherol (αT, γT, δT) and γ- or δ-tocotrienol (γTE, δTE) are metabolized to hydroxychromanols and carboxychromanols including 13'-carboxychromanol (13'-COOH), 11'-COOH, and carboxyethyl hydroxychroman (CEHC), some of which have unique bioactivities compared with the vitamers. However, the bioavailability of these metabolites has not been well characterized. OBJECTIVE: We investigated the pharmacokinetics (PK) of vitamin E forms and metabolites in rats. METHODS: Six-week-old male Wistar rats received 1-time gavage of γT-rich tocopherols (50 mg/kg) containing γT/δT/αT (57.7%, 21.9%, and 10.9%, respectively) or δTE-rich tocotrienols (35 mg/kg) containing δTE/γTE (8:1). We quantified the time course of vitamin E forms and metabolites in the plasma and their 24-h excretion to the urine and feces. The general linear model repeated measure was used for analyses of the PK data. RESULTS: In the rats' plasma, Cmax of γT or δTE was 25.6 ± 9.1 µM (Tmax = 4 h) or 16.0 ± 2.3 µM (Tmax = 2 h), respectively, and sulfated CEHCs and sulfated 11'-COOHs were the predominant metabolites with Cmax of 0.4-0.5 µM (Tmax ∼5-7 h) or ∼0.3 µM (Tmax at 4.7 h), respectively. In 24-h urine, 2.7% of γT and 0.7% of δTE were excreted as conjugated CEHCs. In the feces, 17-45% of supplemented vitamers were excreted as unmetabolized forms and 4.9-9.2% as unconjugated carboxychromanols, among which 13'-COOHs constituted ∼50% of total metabolites and the amount of δTE-derived 13'-COOHs was double that of 13'-COOH derived from γT. CONCLUSIONS: PK data of vitamin E forms in rats reveal that γT, δT, γTE, and δTE are bioavailable in the plasma and are mainly excreted as unmetabolized forms and long-chain metabolites including 13'-COOHs in feces, with more metabolites from tocotrienols than from tocopherols.

Modeling the dose effects of soybean oil in salad dressing on carotenoid and fat-soluble vitamin bioavailability in salad vegetables.

Background: Previously, we showed that vegetable oil is necessary for carotenoid absorption from salad vegetables. Research is needed to better define the dose effect and its interindividual variation for carotenoids and fat-soluble vitamins.Objective: The objective was to model the dose-response relation between the amount of soybean oil in salad dressing and the absorption of 1) carotenoids, phylloquinone, and tocopherols in salad vegetables and 2) retinyl palmitate formed from the provitamin A carotenoids.Design: Women (n = 12) each consumed 5 vegetable salads with salad dressings containing 0, 2, 4, 8, or 32 g soybean oil. Blood was collected at selected time points. The outcome variables were the chylomicron carotenoid and fat-soluble vitamin area under the curve (AUC) and maximum content in the plasma chylomicron fraction (Cmax). The individual-specific and group-average dose-response relations were investigated by fitting linear mixed-effects random coefficient models.Results: Across the entire 0-32-g range, soybean oil was linearly related to the chylomicron AUC and Cmax values for α-carotene, lycopene, phylloquinone, and retinyl palmitate. Across 0-8 g of soybean oil, there was a linear increase in the chylomicron AUC and Cmax values for ß-carotene. Across a more limited 0-4-g range of soybean oil, there were minor linear increases in the chylomicron AUC for lutein and α- and total tocopherol. Absorption of all carotenoids and fat-soluble vitamins was highest with 32 g oil (P < 0.002). For 32 g oil, the interindividual rank order of the chylomicron AUCs was consistent across the carotenoids and fat-soluble vitamins (P < 0.0001).Conclusions: Within the linear range, the average absorption of carotenoids and fat-soluble vitamins could be largely predicted by the soybean oil effect. However, the effect varied widely, and some individuals showed a negligible response. There was a global soybean oil effect such that those who absorbed more of one carotenoid and fat-soluble vitamin also tended to absorb more of the others. This trial was registered at clinicaltrials.gov as NCT02867488.

Effects of carotenoid and vitamin E supplementation on oxidative stress and plumage coloration in house finches (Haemorhous mexicanus).

There has been much recent interest from both applied and basic scientists in the broad series of benefits that animals reap from acquiring high concentrations of dietary antioxidants, such as carotenoids and vitamins (e.g., vitamin E, or tocopherol). Most attention has been paid to separate effects of these compounds on, for example, coloration, health state, development, and vision, but because of possible interactions between these lipid-soluble molecules, we are in need of more studies that co-manipulate these substances and examine their possible synergistic impacts on animal physiology and phenotype. We capitalized on a model avian system (the house finch, Haemorhous mexicanus), where extensive information is available on the fitness roles of carotenoids, to test how variation in carotenoid and/or vitamin E concentrations in the diet impacts body accumulation of these compounds, factors related to oxidative damage (e.g., breast muscle and plasma oxidative-stress susceptibility, plasma nitric-oxide levels), and plumage color development. As in a previous study of ours on carotenoids and health in finches, we employed a 2×2 factorial experimental design on birds in both molting and non-molting conditions, to understand how seasonal shifts in carotenoid use (i.e., pigment incorporation into plumage) might alter the accumulation and roles of carotenoids and vitamins. As expected, lutein supplementation increased the level of circulating carotenoids in both experiments and the color of newly molted plumage. By contrast, vitamin E provisioning did not significantly affect plasma carotenoid levels or plumage coloration in either experiment. Interestingly, carotenoid provisioning decreased circulating vitamin E levels during molt, which suggests either molecular competition between carotenoids and tocopherol at the absorption/transport stages or that vitamin E serves as an antioxidant to offset harmful actions that carotenoids may have at very high concentrations. Finally, in both experiments, we found a reduction in breast-muscle oxidative damage for tocopherol-supplemented birds, which constitutes the first demonstration of a protective effect of vitamin E against oxidative stress in wild birds. Taken together, these findings provide an interesting contrast with our earlier work on season-specific physiological benefits of carotenoids in finches and point to complex associations between indicators of antioxidant and oxidative state in wild-caught animals.

Bioavailability of phytochemical constituents from a novel soy fortified lycopene rich tomato juice developed for targeted cancer prevention trials.

Studies suggest that tomato and soy foods may contribute to a lower risk of certain cancers. We developed a novel soy germ tomato juice to be used in controlled cancer prevention trials. This study describes an initial test of compliance, phytochemical bioavailability, and effects on biomarkers of blood lipids. Healthy men and women (n = 18) consumed a soy germ-fortified juice daily (300 mL supplying 66 mg isoflavones and 22 mg lycopene) for 8 wk. A single-dose bioavailability study was completed on day 1 and isoflavones in plasma and urine, and lycopene in the plasma, were measured. All subjects completed the trial, with 97.7% ± 3.5% (mean ± SD) of the scheduled juice consumed. No adverse effects were documented. The postprandial study indicated that 3.1% ± 2.3% of lycopene was absorbed and that 49.3% ± 12.1% isoflavones ingested were recovered in 24-h urines. Lycopene plasma concentration changed from 0.60 ± 0.22 to 1.24 ± 0.30 µmol/L during 8 wk of consumption. Juice consumption significantly improved resistance of LDL+VLDL-C to Cu(2+)-mediated oxidation (P = 0.039), HDL-C (47.3 ± 15.8 to 51.7 ± 14.8 mg/dL, P < 0.001), and the ratio of total-C/HDL-C (4.25 ± 1.59 to 3.63 ± 1.16, P < 0.001) at 8 wk. A well-characterized soy-fortified tomato juice can be produced in large scale for multiinstitutional long-term cancer prevention trials and showed excellent compliance with no toxicity, while demonstrating absorption of biologically active phytochemicals.

Oral tocotrienols are transported to human tissues and delay the progression of the model for end-stage liver disease score in patients.

The natural vitamin E family is composed of 8 members equally divided into 2 classes: tocopherols (TCP) and tocotrienols (TE). A growing body of evidence suggests TE possess potent biological activity not shared by TCP. The primary objective of this work was to determine the concentrations of TE (200 mg mixed TE, b.i.d.) and TCP [200 mg α-TCP, b.i.d.)] in vital tissues and organs of adults receiving oral supplementation. Eighty participants were studied. Skin and blood vitamin E concentrations were determined from healthy participants following 12 wk of oral supplementation of TE or TCP. Vital organ vitamin E levels were determined by HPLC in adipose, brain, cardiac muscle, and liver of surgical patients following oral TE or TCP supplementation (mean duration, 20 wk; range, 1-96 wk). Oral supplementation of TE significantly increased the TE tissue concentrations in blood, skin, adipose, brain, cardiac muscle, and liver over time. α-TE was delivered to human brain at a concentration reported to be neuroprotective in experimental models of stroke. In prospective liver transplantation patients, oral TE lowered the model for end-stage liver disease (MELD) score in 50% of patients supplemented, whereas only 20% of TCP-supplemented patients demonstrated a reduction in MELD score. This work provides, to our knowledge, the first evidence demonstrating that orally supplemented TE are transported to vital organs of adult humans. The findings of this study, in the context of the current literature, lay the foundation for Phase II clinical trials testing the efficacy of TE against stroke and end-stage liver disease in humans.

In vitro assessment of the bioaccessibility of fatty acids and tocopherol from soybean oil body emulsions stabilized with ι-carrageenan.

The present investigation aimed to expand the knowledge of the in vitro bioaccessibility of fatty acids and tocopherol from natural soybean oil body emulsions stabilized with different concentrations of ι-carrageenan. Several physicochemical parameters including proteolysis of the interfacial layer, interfacial composition, and microstructure were evaluated with regard to their impact on the bioaccessibility of fatty acids and tocopherol. Results from simulated human digestion in vitro indicated that the bioaccessibility of total fatty acids and tocopherol decreased (62.7-8.3 and 59.7-19.4%, respectively) with the increasing concentration of ι-carrageenan. During the in vitro digestion procedure, ι-carrageenan affected physicochemical properties of the emulsions, thereby controlling the release of fatty acids and tocopherol. These results suggested that soybean oil body emulsions stabilized with ι-carrageenan could provide natural emulsions in foods that were digested at a relatively slow rate, the important physiological consequence of which might be increasing satiety.

Repeat dose study of the novel proapoptotic chemotherapeutic agent alpha-tocopheryloxy acetic acid in mice.

Alpha-tocopheryloxy acetic acid (α-TEA) is an ether derivative of vitamin E and has been shown to suppress tumor growth in various murine and human xenograft tumor models, including melanoma, breast, lung, prostate, and ovarian cancers. The purpose of this study was to assess its safety and pharmacokinetics after repeat dosing in a preclinical murine model. Male and female mice received α-TEA doses of 100, 300, or 1500 mg/kg/day by daily oral gavage for 28 days. α-TEA serum levels were determined weekly by high-performance liquid chromatography with mass spectrometric detection. After 28 days of dosing, complete blood counts were taken, blood chemistry was analyzed, and histology was performed. Pharmacokinetic parameters were determined after single dosing. There was no mortality, and we found no clinical signs of toxicity in any of the α-TEA doses tested. Histopathological evaluation of major organs (heart, lung, kidney, liver, spleen, jejunum, ileum, and cecum) revealed no significant α-TEA treatment-related lesions. Blood counts revealed low-grade anemia but no other significant differences between treatment and control groups. Blood chemistry revealed moderate liver toxicity that was dose dependent and was absent in the lowest dose group. There were no significant sex-specific differences in the toxicity profile. The half-life of orally administered α-TEA was determined to be 52 h. This is the first report comprehensively evaluating the toxicity profile of this novel anticancer drug and will facilitate the design of clinical trials to evaluate the safety and antitumor efficacy of α-TEA in patients with cancer.

Relative bioavailability of all-rac and RRR vitamin E based on neutrophil function and total alpha-tocopherol and isomer concentrations in periparturient dairy cows and their calves.

The objective of this experiment was to determine whether source of supplemental alpha-tocopherol fed to periparturient dairy cows affects neutrophil function and vitamin E status of the cow and the neonatal calf. Starting 14 d before anticipated calving and continuing until 14 d post-parturition, cows were fed diets with no supplemental vitamin E or with 2,500 IU/d of vitamin E from all-rac alpha-tocopheryl acetate or RRR alpha-tocopheryl acetate. All-rac alpha-tocopherol contains equimolar amounts of all 8 stereoisomers, whereas the RRR contains only the RRR isomer. Concentrations of alpha-tocopherol in cow plasma, colostrum, milk, and blood neutrophils were greatest for the RRR treatment, intermediate for all-rac, and lowest for cows fed no supplemental vitamin E. The concentration of alpha-tocopherol in plasma of newborn calves was very low and not affected by treatment but after 6 feedings of their dam's colostrum or milk, concentrations in calf plasma followed the same treatment pattern as cow plasma. The number of bacteria phagocytized was greater by neutrophils from cows fed all-rac vitamin E than for the other 2 treatments, which resulted in a greater number of bacteria being killed. For cows fed all-rac vitamin E, the RRR isomer comprised about 20% of the alpha-tocopherol consumed but approximately 60% of the alpha-tocopherol in plasma and milk. This enrichment was caused mostly by an almost complete discrimination against the 2S isomers. Because all-rac alpha-tocopherol is 50% 2S isomers, these data suggest that 1 g of all-rac tocopheryl acetate is equivalent to 0.5 g of RRR tocopheryl acetate.

Increased bioavailability of a transdermal application of a nano-sized emulsion preparation.

The aim of this study was to compare the transdermal application of a nano-sized emulsion versus a micron-sized emulsion preparation of delta tocopherol as it relates to particle size and bioavailability. Two separate experiments were performed using seven F1B Syrian Golden hamsters, 1 week apart. Each emulsion preparation consisted of canola oil, polysorbate 80, deionized water and delta tocopherol; the only difference between the two preparations was processing the nano-sized emulsion with the Microfluidizer Processor. Both were formulated into a cream and applied to the shaven dorsal area. The particle size of the micron-sized emulsion preparation was 2788 nm compared to 65 nm for the nano-sized emulsion formulation. Two hours post-application, hamsters that were applied the nano-sized emulsion had a 36-fold significant increase of plasma delta tocopherol, where as hamsters that were applied the micron-sized emulsion only had a 9-fold significant increase, compared to baseline, respectively. At 3h post-application, plasma delta tocopherol had significantly increased 68-fold for hamsters applied the nano-sized emulsion, whereas only an 11-fold significant increase was observed in hamsters applied the micron-sized emulsion, compared to baseline, respectively. Significant differences were also observed between the nano-sized and micron-sized emulsion at 2 and 3h post-application. This study suggests that nano-sized emulsions significantly increase the bioavailability of transdermally applied delta tocopherol.

Bioavailability of a novel, water-soluble vitamin E formulation in malabsorbing patients.

In cystic fibrosis (CF), pancreatic insufficiency and a diminished bile acid pool cause malabsorption of important nutrients and dietary components leading to deficiency, poor nutritional status, and oxidative stress. Of particular significance is the malabsorption of fat-soluble nutrients and antioxidants, which are important for normal immune and neurologic function. Patients with CF often are deficient in these compounds despite supplementation with the current standard of care therapy. The objective was to compare the pharmacokinetic profile of this water-soluble vitamin E formulation (Aqua-E) with an oil-based softgel formulation in a malabsorbing patient population. Patients with CF who had documented malabsorption were recruited for participation in this pharmacokinetic study. Patients who met inclusion and exclusion criteria discontinued vitamin E supplementation, except for that in a multivitamin, for 7 to 21 days before the day of dosing. Patients were randomized to a single dose of 20 ml of Aqua-E or three oil-based softgels, which contained equivalent amounts of tocopherols. Blood was drawn from patients at time 0, 2, 4, 8, 24, 48, and 168 hr and analyzed for tocopherols. Eight patients were enrolled in the study and randomized to Aqua-E or softgels. The primary outcome, the absorption of gamma-tocopherol in Aqua-E (AUC=115 micro g/ml(*)hr), was significantly greater than that of oil-based softgels (AUC=25.3 micro g/ml(*)hr; P=0.013). Total-tocopherols (alpha+gamma+delta) in Aqua-E (AUC=294 micro g/ml(*)hr) showed a strong trend toward increased absorption compared with that of oil-based softgels (AUC=117 micro g/ml(*)hr; P=0.09). In conclusion, this novel, water-soluble formulation showed a marked and statistically significant increase in absorption of gamma-tocopherol in malabsorbing patients with CF compared with an oil-based formulation.

Dietary antibiotic growth promoters enhance the bioavailability of alpha-tocopheryl acetate in broilers by altering lipid absorption.

The influence of intestinal microbial bile salt deconjugation on absorption of fatty acids and alpha- and gamma-tocopherol was investigated in a trial with Ross 208 broilers. Birds (n = 1600) were assigned to 4 dietary treatments: no supplementation or supplementation of antibiotics (salinomycin, 40 mg/kg feed and avilamycin, 10 mg/kg feed), and inclusion of either animal fat (10 g/100 g feed) or soybean oil (10 g/100 g feed) in the diet. At d 7, 14, 21, and 35 of age, the intestinal number of the bile salt hydrolase-active bacteria Clostridium perfringens, the concentration of conjugated and unconjugated bile salts, the ileal absorption of fatty acids and tocopherols, and the blood plasma concentrations of tocopherols were measured. All variables were significantly influenced by bird age. C. perfringens counts were lower and bile salt concentrations were greater in birds fed soybean oil. The supplementation of antibiotics reduced the numbers of C. perfringens in the small intestine and reduced the concentration of unconjugated bile salts. The ileal absorption of fatty acids and alpha-tocopherol, as well as the plasma concentration of alpha-tocopherol, was greater in birds fed antibiotics. The absorption and plasma concentration of gamma-tocopherol were not influenced by antibiotics. Unlike gamma-tocopherol, which is present solely as the free alcohol, the major proportion of dietary alpha-tocopherol is present as alpha-tocopheryl acetate, which requires a bile salt-dependent enzymatic hydrolysis before absorption. In conclusion, proper digestion of lipid-soluble compounds is highly dependent on an adequate concentration of bile salts in the small intestine to provide proper lipid emulsification and activation of lipolytic enzymes.

Early modifications of fatty acid composition in plasma phospholipids, platelets and mononucleates of healthy volunteers after low doses of n-3 polyunsaturated fatty acids.

OBJECTIVES: Although previous data suggested that only doses of 4 g/day or higher of n-3 polyunsaturated fatty acids (PUFA) have had a beneficial effect in the prevention of atherosclerosis and cardiovascular diseases, the GISSI-Prevenzione Study in a 3-year trial showed that 1 g/day reduced total and cardiovascular mortality in over 11,000 post-infarction patients. The aim of this study was to investigate the time course and the extent of incorporation of n-3 fatty acids in plasma and blood cells after 1 g/day of n-3 PUFA, the dose effective in the GISSI-Prevenzione in comparison with higher doses. METHODS: Thirty-six healthy volunteers were given 1, 2 and 4 g/day of n-3 PUFA ethyl esters for 12 weeks, followed by a 4-week washout. Blood was collected at weeks 0, 1, 2, 4, 8, 12 and 16 and used for lipid profile analysis and measurement of fatty acid composition in plasma phospholipids, platelets and mononucleates. RESULTS: Total n-3 PUFA increased by 2.0-, 2.2- and 2.9-fold versus baseline after 12-week treatment with 1, 2 and 4 g respectively. A statistically significant raise of total n-3 PUFA was seen in platelets and mononucleates. Among individual n-3 PUFA, 22:5 n-3 was enriched early and dose dependently in plasma phospholipids, platelets and mononucleates; the raise of 22:6 n-3 was less marked especially in platelets and mononucleates. CONCLUSIONS: One gram per day of n-3 PUFA induces fast (within 1 week) and striking changes in blood composition of PUFA that may well explain their beneficial effects against cardiovascular diseases.

Maternal and posthatch dietary polyunsaturated fatty acids alter tissue tocopherol status of chicks.

The effects of maternal and starter diet polyunsaturated fatty acid (PUFA) composition on the tocopherol (TOC) status of posthatch chicks were investigated. Fertile eggs enriched with long chain n-3, 18:3 n-3 or 18:2 n-6 PUFA were incubated. The eggs were collected from hens fed diets containing 3.5% menhaden oil (MO), linseed oil (LO), or sunflower oil (SO) and a vitamin E mix containing 400 microg/g total TOC. Posthatch chicks from MO, LO, or SO were fed starter diets containing 3.5% MO, LO, or SO along with vitamin E mix containing 48 microg/g total TOC. Tissues (liver, blood, brain) were collected on d 0 (day of hatch), 7, 14, and 21 posthatch. On d 0, MO chicks had the lowest liver and plasma TOC (P < 0.05). A rapid depletion of liver and plasma TOC was observed on d 7 and 14 posthatch (P < 0.001) and was lower in MO chicks (P < 0.05) than LO. When compared with d 0, a 98% decrease of tocopherol on d 7 was observed for chicks from all treatments. No changes due to age or diet PUFA was observed in the brain TOC status. Data showed that maternal and starter diet PUFA could alter the TOC status of chicks in early life.