Biomedical subjects

Brigitte M Winklhofer-Roob

Publications and source records attributed to Brigitte M Winklhofer-Roob.

10 recordsLinked to original sources

PubMed2006

Vitamin E content of foods: comparison of results obtained from food composition tables and HPLC analysis.

BACKGROUND & AIMS: Data on vitamin E content of foods are essential for nutrition research and its application. The aim of this study was to investigate the precision of calculated vitamin E content of prepared meals. METHODS: The vitamin E content of 69 dishes of a menu cycle sampled at two occasions were calculated using 4 different food composition tables (FCT) and measured by HPLC. RESULTS: Data were complete for 50-69 dishes. The proportion of dishes with differences between FCTs < or = 20% were 17-100%. Differences between HPLC and the Souci-Fachmann-Kraut table were < or = 20% in 8/46 dishes for alpha- and in 14/46 dishes for gamma-tocopherol. Differences fell in the order of baked > raw > fried/roasted > boiled > mixed prepared foods. The 2 samplings taken 6 months apart showed considerable differences. CONCLUSIONS: There are substantial differences in calculated/measured vitamin E content of prepared foods: (i) between different FCTs; (ii) between FCTs and HPLC, and (iii) between different seasons. This can be explained by intrinsic variability (breeding, season, country of origin, ripeness, freshness) and food processing, as well as selection of FCTs and should be taken into account when interpreting data of dietary intervention studies.

Chromatography, High Pressure Liquid↗

PubMed2004

In vivo and in vitro evidences that carotenoids could modulate the neutrophil respiratory burst during dietary manipulation.

BACKGROUND: The primary role of polymorphonuclear neutrophils (PMNs) is to destroy pathogenic microorganisms after phagocytosis by producing reactive oxygen species (ROS) and toxic molecules. However, PMNs produce sufficient amounts of ROS during an oxidative burst to be autotoxic and detrimental to their own functions and to possibly cause DNA damage, protein and lipid oxidation and cell membrane destructuration. OBJECTIVE: The aim of this study was to investigate in vivo the role of the antioxidant capacities of carotenoids in modulating ROS content in PMNs during oxidative burst. Moreover to investigate the direct or indirect effect of carotenoids, the modification of PMN ROS content was explored after in vitro supplementation with beta-carotene or lycopene, chosen taking account of their vitamin A and no vitamin A precursor effect, respectively. DESIGN: In vivo study: Venous blood was collected from 10 healthy male volunteers and ROS production from phorbol myristate acetate (PMA)-stimulated PMNs was determined, by flow cytometry using the fluorescent dye dihydrorhodamine 123, at baseline, after 3 weeks of carotenoid depletion (carotenoid intake limited to 25% of usual intake) and after 5 weeks of carotenoid repletion (30 mg beta-carotene, 15 mg lycopene and 9 mg lutein per day). In vitro study: ROS content in PMA-stimulated PMNs isolated from carotenoid depleted subjects and controls was quantified after an in vitro enrichment with beta-carotene (1 micromol/L) or lycopene (0.3 micromol/L). RESULTS: In vivo carotenoid depletion increased PMN H2O2 content after PMA activation by 38% (p < 0.05 vs baseline),while supplementation for 5 weeks restored basal H2O2 generation (p < 0.05 vs depletion). Although H2O2 measurement in PMNs from non-depleted subjects was not affected by an in vitro supply with beta-carotene or lycopene, a significant decrease in H2O2 content by 78.9 % and 81.2%, respectively, was observed in PMNs from carotenoid depleted subjects (p < 0.01 vs depleted control subjects). CONCLUSIONS: The carotenoid ROS quenching capacities control both in vivo and in vitro the PMNs ROS generation and probably protect these cells against DNA, membrane lipid and protein damages during oxidative burst. Moreover, these effects appear independent from the metabolic conversion of carotenoids to vitamin A.

Antioxidants↗

PubMed2004

Effects of LDL-immunoapheresis on plasma concentrations of vitamin E and carotenoids in patients with familial hypercholesterolemia.

Recently very potent extracorporeal cholesterol-lowering treatment options have become available for patients with hypercholesterolemia. LDL immunoapheresis treatment selectively removes LDL and lipoprotein(a) from the circulation. Since LDL is the major carrier of lipophilic antioxidants in plasma, the purpose of the present study was to assess the effects of a single LDL apheresis treatment on plasma concentrations of tocopherols (alpha- and gamma-tocopherol) and carotenoids (alpha- and beta-carotene, zeaxanthin, cryptoxanthin, canthaxanthin, lycopene, and retinol). Plasma antioxidant concentrations were determined by HPLC in 7 patients with familial hypercholesterolemia before and after LDL immunoapheresis treatment. Plasma concentrations of both alpha- and gamma-tocopherol and the different carotenoids were significantly reduced by LDL apheresis. However, when standardized for cholesterol to adjust for cholesterol removal, alpha- and gamma-tocopherol, retinol, and the more polar carotenoids lutein and zeaxanthin increased in response to apheresis treatment, while the more unpolar carotenoids such as beta-carotene and lycopene did not change. These data demonstrate that a single LDL immunoapheresis treatment affects tocopherols and individual carotenoids differently. This may be explained by differences in chemical structure and preferential association with different lipoproteins. These results further imply that tocopherols, lutein, zeaxanthin, and retinol, are associated in part with lipoproteins and other carriers such as retinol-binding protein that are not removed during apheresis treatment.

Adult↗

PubMed2004

The effect of age on vitamin E status, metabolism, and function: metabolism as assessed by labeled tocopherols.

The effects of age on vitamin E metabolism were studied in 97 healthy 20-75-year-old male nonsmoking Austrian volunteers of the VITAGE project. After a single oral intake of 30 mg d(6)-RRR-alpha- and d(2)-RRR-gamma-tocopheryl acetate, blood and 24-hour urine was collected. Deuterated tocopherols in plasma and deuterated urinary metabolites were analyzed by GC-MS. A first evaluation revealed a similar uptake of d(6)-alpha- and d(2)-gamma-tocopherol during the first 6 hours, and then d(2)-gamma-tocopherol started to decrease. Urinary d(2)-gamma- carboxyethyl hydroxychroman metabolites (CEHCs) exceeded those of d(6)-alpha-CEHCs by about 10 times. There was no effect of age. Thus, there might be no need for a higher vitamin E intake for healthy elderly nonsmoking men.

Absorption↗

PubMed2004

Effects of vitamin E depletion/repletion on biomarkers of oxidative stress in healthy aging.

The effects on ex vivo LDL resistance to oxidation and biomarkers of in vivo oxidative stress in response to 3-month dietary vitamin E restriction to 25% of recommended intake and 2-month unrestricted dietary intake and supplementation with 800 IU/d were studied in 100 healthy, nonsmoking 20-75-year-old volunteers. Significant changes in vitamin E status were associated with decreases and increases, respectively, in LDL resistance to oxidation in the depletion and supplementation period and with decreases in lipid peroxidation and oxidative DNA modification in the supplementation period. Healthy aging was not associated with enhanced susceptibility to oxidation in the depletion period.

Adult↗

PubMed2004

The decrease in gamma-tocopherol in plasma and lipoprotein fractions levels off within two days of vitamin E supplementation.

The effects of vitamin E supplementation on alpha- and gamma-tocopherol concentrations were studied in plasma and lipoprotein fractions of five healthy volunteers taking 1000 IU/day of RRR alpha-tocopherol for 4 days. Although plasma alpha-tocopherol increased, gamma-tocopherol decreased. Compared with baseline, gamma-/alpha-tocopherol ratios decreased from 48 h onward (P < 0.001). They all leveled off within 48 h. From 12 h onward, gamma-/alpha-tocopherol ratios were higher in VLDL and IDL than in LDL and HDL, indicating that gamma-tocopherol is better maintained in triglyceride-rich lipoprotein fractions. These data suggest that vitamin E supplementation exceeding 2 days does not further decrease gamma-tocopherol concentrations.

Adult↗

PubMed2004

Does aging affect the response of vitamin E status to vitamin E depletion and supplementation?

A vitamin E depletion/supplementation study was conducted in 100 healthy 20-75-year-old volunteers. The responses of vitamin E status to 3-week dietary vitamin E restriction to approximately 25% of recommended intake and 2-month unrestricted dietary intake plus 800 IU/d of RRR-alpha-tocopherol were studied as a function of age. Plasma alpha-tocopherol concentrations were closely related to cholesterol concentrations, which increased with age (P < 0.001). Upon dietary restriction, plasma alpha-tocopherol concentrations decreased significantly (P < 0.001) but independently of age. Plasma alpha-tocopherol responses to supplementation increased significantly with age, but this effect disappeared after standardization for cholesterol. gamma-Tocopherol concentrations decreased to less than 30% of baseline.

Adult↗

PubMed2003

Comparison of the postprandial chylomicron carotenoid responses in young and older subjects.

BACKGROUND: The plant carotenoids may contribute to the beneficial health effect of fruits- and vegetables-rich diet. Epidemiological studies consistently associated high plasma carotenoids status with reduced age-related diseases. However, the data concerning the bioavailability of carotenoids in the elderly are scarce. OBJECTIVE: To test whether there is an age effect on carotenoid bioavailability. DESIGN: Eight young (20-35 y) and eight older (60-75 y) healthy adults ingested three different meals containing 40 g triacylglycerols (TG) and vegetable sources of carotenoids. These sources were either 188 g carrot purée which provided 30 mg betacarotene as the main carotenoid, or 61 g tomato purée providing 30mg lycopene, or 260 g cooked chopped spinach providing 30 mg lutein. TG and carotenoids were assayed in chylomicrons (CM) collected for 9 h postprandially. RESULTS: There was no major effect of age on the postprandial CM/TG response (0-9 h area under the curve (AUC)). There was no major effect of age on the postprandial CM all- trans beta-carotene, cis betacarotene, alpha-carotene, and lutein responses. Adjustment of these responses by the CM TG responses did not reveal any age effect. While there was no significant effect of age on the CM lycopene response, the CM TG-adjusted lycopene response was significantly lower (-40 %) in the older than in the younger subjects (P < 0.04). The cis-trans ratios of CM betacarotene were not significantly different between the old and the young subjects. There was no significant effect of age on the ratio of CM retinyl-palmitate to the sum of alpha-carotene and beta-carotene measured after the carrot meal. CONCLUSIONS: The bioavailability of lycopene is apparently impaired in the old,while there is no major difference in the bioavailability of beta-carotene, alpha-carotene and probably lutein. There is also no major effect of age on the cis-trans isomerization of beta-carotene during absorption, and in the intestinal conversion of provitamin A carotenoids into vitamin A.

Adult↗

PubMed2003

Effects of vitamin E and carotenoid status on oxidative stress in health and disease. Evidence obtained from human intervention studies.

Vitamin E and carotenoids are known to act as antioxidants both in vitro and in vivo. In this review we present a series of studies in healthy subjects and in patients who exhibit either acute or chronic oxidative stress. In the EU-Commission funded VITAGE project we investigated the status and effects of vitamin E and carotenoids on oxidative stress in 300 healthy volunteers. Depletion studies limiting dietary vitamin E or carotenoid intake to approximately 25% of the dietary reference intakes and subsequent repletion by supplementation with either large doses of vitamin E or intermediate doses of carotenoids showed significant changes in ex vivo LDL oxidizability, total plasma peroxide concentrations and urinary 8-oxo-7,8-dihydro-2(')-deoxyguanosine excretion. Patients on chronic hemodialysis present with oxidative stress in the presence of normal vitamin E but impaired vitamin C status and, due to anemia, need to be treated with parenteral iron. We studied the effects of a single oral dose of vitamin E taken 6 h prior to intravenous infusion of 100 mg iron, which exceeded the iron-binding capacity of transferrin. Vitamin E significantly reduced and in combination with a single dose of vitamin C completely abrogated acute oxidative stress induced by the iron load. Patients with cystic fibrosis are exposed to chronic oxidative stress due to an overproduction of reactive oxygen species as a result of neutrophil-dominated lung inflammation and impaired antioxidant status. Biochemical vitamin E and carotenoid deficiencies could be fully corrected even in the presence of fat malabsorption using intermediate doses of either RRR alpha-tocopherol or all-rac alpha-tocopheryl acetate and water-miscible all-trans beta-carotene. Long-term supplementation reduced ex vivo LDL oxidizability, in vivo lipid peroxidation and lung inflammation.

Aging↗

PubMed2000

Vitamin E attenuates oxidative stress induced by intravenous iron in patients on hemodialysis.

Intravenous iron application to anemic patients on hemodialysis leads to an "oversaturation" of transferrin. As a result, non-transferrin-bound, redox-active iron might induce lipid peroxidation. To test the hypothesis that vitamin E attenuates lipid peroxidation in patients receiving 100 mg of iron(III) hydroxide sucrose complex intravenously during a hemodialysis session, 22 patients were investigated in a randomized cross-over design, either with or without a single oral dose of 1200 IU of all-rac-alpha-tocopheryl acetate taken 6 h before the hemodialysis session. Blood was drawn before and 30, 60, 90, 135, and 180 min after the start of the iron infusion, and areas under the curve (AUC0-180 min) of ratios of plasma malondialdehyde (MDA) to cholesterol and plasma total peroxides to cholesterol (two markers of lipid peroxidation) were determined as the outcome variables. At baseline of the session without vitamin E supplementation, plasma alpha-tocopherol concentrations (27.6 +/- 1.8 micromol/L) and ratios of alpha-tocopherol to cholesterol (5.88 +/- 1.09 mmol/mol) were normal, plasma MDA concentrations were above normal (1.20 +/- 0.28 micromol/ L), and bleomycin-detectable iron (BDI), indicating the presence of redox-active iron, was not detectable. Upon iron infusion, BDI and MDA concentrations increased significantly (P < 0.001). BDI concentrations explained the increase over baseline in MDA concentrations (MDA = 1.29 +/- 0.075 x BDI). Vitamin E supplementation, leading to a 68% increase in plasma alpha-tocopherol concentrations, significantly reduced the AUC0-180 min of MDA to cholesterol (P = 0.004) and peroxides to cholesterol (P = 0.002). These data demonstrate that a single oral dose of vitamin E attenuates lipid peroxidation in patients on hemodialysis receiving intravenous iron. Given that intravenous iron is applied repeatedly to patients on hemodialysis, this therapeutic approach may protect against oxidative stress-related degenerative disease in the long term.

Adult↗