Vitamin E: Not only a single stereoisomer.

The recent publication by Azzi and colleagues puts forth the argument that only RRR-α-tocopherol should be considered as vitamin E from a physiological point of view. They base their argument primarily on the assertion that only this form has been used to treat stark vitamin E deficiency in humans (known as AVED, or Ataxia with Vitamin E Deficiency). Azzi et al. also argue that other chemically similar molecules, such as tocopherols other than α-tocopherol and tocotrienols do not provide vitamin E activity. Azzi and colleagues are correct on this second point. An investigation into the biological activities of vitamin E, and the mechanisms behind these activities, confirms that physiological vitamin E activity is limited to certain α-tocopherol forms. However, it is also clear that these activities are not restricted only to the RRR-form but include other 2R-forms as well. Indeed, the α-tocopherol transfer protein (α-TTP), which is critical to mediate vitamin E trafficking and biological activity, and genetic defects of which lead to vitamin E deficiency, binds well to all 2R-forms of α-tocopherol. Furthermore, both RRR-α-tocopherol and the other 2R-forms are maintained in human plasma and distributed to tissues and organs, whereas the 2S-stereoisomers are excreted quickly. As such, in recent years the definition of vitamin E including both 2R- and RRR-α-tocopherol has gained both broad scientific and regulatory acceptance. Consistent with this understanding, we provide evidence that AVED has indeed been treated successfully with forms in addition to RRR-α-tocopherol, again arguing against the restriction of the definition to RRR-α-tocopherol only. Finally, we provide evidence against any safety concerns utilizing the currently accepted definition of vitamin E.

Inflammatory disease processes and interactions with nutrition.

Inflammation is a stereotypical physiological response to infections and tissue injury; it initiates pathogen killing as well as tissue repair processes and helps to restore homeostasis at infected or damaged sites. Acute inflammatory reactions are usually self-limiting and resolve rapidly, due to the involvement of negative feedback mechanisms. Thus, regulated inflammatory responses are essential to remain healthy and maintain homeostasis. However, inflammatory responses that fail to regulate themselves can become chronic and contribute to the perpetuation and progression of disease. Characteristics typical of chronic inflammatory responses underlying the pathophysiology of several disorders include loss of barrier function, responsiveness to a normally benign stimulus, infiltration of inflammatory cells into compartments where they are not normally found in such high numbers, and overproduction of oxidants, cytokines, chemokines, eicosanoids and matrix metalloproteinases. The levels of these mediators amplify the inflammatory response, are destructive and contribute to the clinical symptoms. Various dietary components including long chain omega-3 fatty acids, antioxidant vitamins, plant flavonoids, prebiotics and probiotics have the potential to modulate predisposition to chronic inflammatory conditions and may have a role in their therapy. These components act through a variety of mechanisms including decreasing inflammatory mediator production through effects on cell signaling and gene expression (omega-3 fatty acids, vitamin E, plant flavonoids), reducing the production of damaging oxidants (vitamin E and other antioxidants), and promoting gut barrier function and anti-inflammatory responses (prebiotics and probiotics). However, in general really strong evidence of benefit to human health through anti-inflammatory actions is lacking for most of these dietary components. Thus, further studies addressing efficacy in humans linked to studies providing greater understanding of the mechanisms of action involved are required.

Competitive and seasonal oxidative stress in elite alpine ski racers.

We investigated competitive- and long-term oxidative stress during a competition season in eight top-ranked members of the Austrian Men's Alpine Ski Team. Serum total peroxides, antibody titers against oxidized LDL (oLAb) and lag time of the degradation of the fluorophore 1-palmitoyl-2-((2-(4-(6-phenyl-trans-1,3,5-hexatrienyl)phenyl)ethyl)-carbonyl)-sn-glycero-3-phosphocholine were measured, along with plasma concentrations of ascorbate, alpha- and gamma-tocopherol, beta-carotene, uric acid and the lipid status. Competitive stress was indicated through an increased post-race uric acid level (286 +/- 50 microM pre-race vs 456 +/- 77 microM post-race, P<0.001) in December. Long-term effects were already apparent in November, with the highest concentrations of total peroxides (680 +/- 458 microM H(2)O(2) equivalents vs December 47 +/- 58 microM H(2)O(2) equivalents and January 15 +/- 28 microM H(2)O(2) equivalents, P<0.001) and a concomitant decrease in oLAb titers with an antibody trough in December (439 +/- 150 mU/mL vs baseline 1036 +/- 328 mU/mL; P=0.003). In January, after recovery, they attained nearly pre-season levels of oxidative stress biomarkers. This study indicates midseason oxidative stress in top-level skiers, which was associated with the performance in these athletes.

Age-related change in the retinoid X receptor beta gene expression in peripheral blood mononuclear cells of healthy volunteers: effect of 13-cis retinoic acid supplementation.

The regulation of cell growth and differentiation and also expression of a number of genes by retinoids are mediated by nuclear retinoid receptors (RARs and/or RXRs). In this study we investigated age-related alteration in both RAR and RXR receptor subtypes gene expression and tissue transglutaminase (tTG) activity before and after supplementation with 13-cis retinoic acid (13cRA) in human peripheral blood mononuclear cells (PBMCs). Healthy men (40) were divided in two groups according to their age (young group: 26.1+/-4.1 years and old group: 65.4+/-3.8 years). Each volunteer received 13cRA (Curacné), 0.5mg/(kgday)) during a period of 4 weeks. We have shown that RXRbeta expression was decreased significantly (p=0.0108) in PBMCs of elderly men when compared to that of young volunteers. Distribution of retinoic acid receptor subtype expression in PBMCs was found in the order: RXRbeta>RARgamma>RXRalpha>RARalpha. The tTG activity in PBMCs reflected a trend to be enhanced after 13-cis retinoic acid supplementation. In conclusion, we demonstrate a significant decrease in the expression of RXRbeta subtype of rexinoid receptors in PBMCs of healthy elderly men. Our data suggest that in healthy elderly men reduction of RXRbeta expression in PBMCs might be a common feature of physiological senescence.

Effects of elderberry juice on fasting and postprandial serum lipids and low-density lipoprotein oxidation in healthy volunteers: a randomized, double-blind, placebo-controlled study.

BACKGROUND: In a recent pilot study, the intake of elderberry juice resulted in a significant decrease in serum cholesterol concentrations and an increase in low-density lipoprotein (LDL) stability. This study was designed to verify the preliminary results. OBJECTIVE: We investigated the impact of elderberry juice on cholesterol and triglyceride concentrations as well as antioxidant status in a cohort of young volunteers. DESIGN: Study A: The randomized, placebo-controlled trial for studying the effect of anthocyanes on lipid and antioxidant status, 34 subjects took capsules with 400 mg spray-dried powder containing 10% anthocyanes t.i.d. equivalent to 5 ml elderberry juice for 2 weeks. A subgroup of 14 subjects continued for an additional week to test for resistance to oxidation of LDL. Study B: To investigate the short-term effects on serum lipid concentrations, six subjects took a single dose of 50 ml of elderberry juice (equivalent to 10 capsules) along with a high-fat breakfast. RESULTS: In the placebo-controlled study, there was only a small, statistically not significant change in cholesterol concentrations in the elderberry group (from 199 to 190 mg/dl) compared to the placebo group (from 192 to 196 mg/dl). The resistance to copper-induced oxidation of LDL did not change within 3 weeks. In the single-dose experiment increases in postprandial triglyceride concentrations were not significantly different when the six subjects were investigated with and without elderberry juice. CONCLUSIONS: Elderberry spray-dried extract at a low dose exerts a minor effect on serum lipids and antioxidative capacity. Higher, but nutritionally relevant doses might significantly reduce postprandial serum lipids.

Lipid peroxidation and antioxidant status in professional American football players during competition.

BACKGROUND: Oxidative stress occurs during strenuous physical exercise, perhaps as a result of increased consumption of oxygen. MATERIALS AND METHODS: In this study, different markers of oxidative stress were determined in eight national league American football players. Before (March) and at three time-points during the competition season (May, June, July) serum total peroxide concentrations, auto-antibody titres against oxidized low-density lipoprotein (oLab), and lag time of reactive oxygen species-induced degradation of the fluorophore 1-palmitoyl-2-((2-(4-(6-phenyl-trans-1,3,5-hexatrienyl)phenyl)ethyl)- carbonyl)-sn-glycero-3-phosphocholine (DPHPC) were measured along with serum ascorbate, alpha- and gamma-tocopherol, and beta-carotene concentrations. RESULTS: Before the competition season, serum antioxidant concentrations were within the lower normal range; ascorbate concentrations increased significantly during the competition period (P < 0.05). Serum peroxide concentrations were within the normal range and increased significantly during the competition period (P < 0.05); in four of the eight subjects the increase was several times the baseline values, while four athletes did not show any increase. The oLab titres increased significantly at the mid-competition period time-point (P < 0.01), but levelled off thereafter. DISCUSSION: Given that it could not be predicted from the baseline oxidative stress and antioxidant status which subject would respond to strenuous exercise with an increase in oxidative stress status, it is concluded that oxidative stress should be monitored in all athletes.

Vitamin E kinetics in smokers and nonsmokers.

Does cigarette smoking increase vitamin E utilization in vivo? A trial was carried out in 6 smokers and 5 nonsmokers of comparable ages and serum lipids. Subjects consumed 75 mg each d(3)-RRR and d(6)-all rac-alpha-tocopheryl acetates (natural and synthetic vitamin E, respectively) daily for 7 d with a standardized breakfast. Fasting blood samples were drawn on days -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 9, 14, 21 (negative days indicate supplementation). In both groups, plasma d(3)-alpha-tocopherol concentrations were approximately double of d(6)-alpha-tocopherol. At day 0, the %d(3) alpha-tocopherols (d(3)-alpha-tocopherol/total-alpha-tocopherol x 100) were similar in both smokers and nonsmokers. Subsequently, there was a trend toward a faster exponential disappearance of the plasma %d(3) alpha-tocopherol in smokers compared with nonsmokers (0.30 +/- 0.04 compared with 0.24 +/- 0.05, p =.0565). The calculated %d(3) half-lives were 55.6 +/- 7.4 h in smokers and 72.1 +/- 17.3 h in nonsmokers (p =.0630). By day 21, the %d(3) in smokers had decreased to 1.4% +/- 0.3% while it was 2.2% +/- 0.7% (p =.0418) in the nonsmokers. These data suggest that smoking increases plasma vitamin E disappearance, but further studies are needed to confirm this finding and to assess its cause.

Ex vivo low-density lipoprotein oxidizability and in vivo lipid peroxidation in patients on CAPD.

BACKGROUND: Chronic renal failure is associated with accelerated atherosclerosis and a high incidence of cardiovascular disease. Oxidative modification of low-density lipoprotein (LDL) is considered a key event in atherogenesis. METHODS: We studied the ex vivo oxidizability of LDL exposed to Cu2+ ions (lag time, rate of propagation, maximum conjugated diene formation) and its relationship with LDL density, fatty acids, and antioxidants, along with plasma malondialdehyde (MDA) and autoantibodies against Cu2+-, MDA-, and hypochlorous acid-modified LDL and plasma antioxidants in 17 continuous ambulatory peritoneal dialysis (CAPD) patients and 21 healthy control subjects. RESULTS: LDL alpha- and gamma-tocopherol and total polyunsaturated fatty acid (PUFA) concentrations were significantly higher in the CAPD patients. LDL density was shifted to small, dense LDL. LDL oxidizability was comparable to that of healthy subjects. Lag time correlated positively with LDL alpha-tocopherol and inversely with both total PUFA concentrations and density; the rate of oxidation and LDL density correlated positively with total PUFA and total fatty acid concentrations, respectively. Ratios of autoantibody titers against oxidized to native LDL did not differ between the two groups. While plasma alpha- and gamma-tocopherol concentrations and tocopherol to cholesterol ratios were significantly higher, vitamin C concentrations were very low in the CAPD patients. MDA concentrations were 1.7 times higher than in healthy subjects. CONCLUSIONS: (1) Ex vivo LDL oxidizability is normal in CAPD patients as a result of efficient protection by LDL-associated lipophilic antioxidants, although the LDL composition is altered toward high oxidizability; and (2) the plasma antioxidant screen is insufficient due to impaired vitamin C status.

Vitamin A, vitamin E and carotenoid status and metabolism during ageing: functional and nutritional consequences (VITAGE PROJECT).

Among the nutritional factors contributing to maintain health during ageing, fat-soluble vitamins (FSV) are crucial to protect against free radical-generated degenerative processes or impaired efficiency of the immune system. However, no sound scientific evidence is able to confirm specific dietary needs in vitamin A, vitamin E and carotenoids for the healthy elderly. VITAGE project aims at providing such evidence by undertaking studies on male volunteers from 3 European countries, aged between 20-75 years. Biomarkers and variables related to status, metabolism and functions will be measured either in steady-state conditions, or during dietary depletion and repletion in FSV. Original, yet already developed, methodologies will provide clear information about the physiological characteristics of vitamin A, vitamin E and carotenoids. Simultaneously, marketing opportunities for FSV-enriched dietetic foods, specifically designed for the elderly will be determined. The scientific and economical evidence obtained in this project will provide the basis to implement a EU nutritional policy towards the elderly and to develop a new sector of dietetic food products.

Cystic fibrosis: nutritional status and micronutrients.

Recent studies have focused on the current dietary intake of cystic fibrosis patients, the impact of nutritional support on both the nutritional status and clinical outcome variables, and the effects on the nutritional status of antibiotic therapy and surgical treatment of meconium ileus. In addition to weight and height, skinfold measurements, bioelectrical impedance analysis and dual energy X-ray absorptiometry have been employed for the determination of nutritional status. A proton pump inhibitor has been used successfully along with pancreatic enzymes for the improvement of fat absorption. Attention has been paid to resting energy expenditure during pulmonary exacerbations, to vitamin K function in bone mineralization and to risk factors for low bone mineral density in cystic fibrosis. The relationships between glutathione and nutritional status have been studied, along with possible interactions with albumin, a potent antioxidant. Finally, a beneficial effect of docosahexaenoic acid on cystic fibrosis pathology has been suggested, but this requires further critical evaluation.

Low density lipoprotein immunoapheresis does not increase plasma lipid peroxidation products in vivo.

Extracorporeal elimination of low density lipoprotein (LDL) is frequently used in drug-resistant hypercholesterolemia. LDL-immunoapheresis selectively removes LDL and lipoprotein(a) [Lp(a)] from plasma. Lipid peroxidation is one unwanted side effect, that occurs during extracorporeal plasma treatment. The purpose of this study was to investigate the effect of LDL immunoapheresis on lipid peroxidation. Before and after a single LDL-immunoapheresis treatment, plasma concentrations of lipid hydroperoxides, determined with two different spectophotometric assays, thiobarbituric acid-reacting substances (TBARS), determined spectrophotometrically and malondialdehyde (MDA), determined by an MDA-TBA/HPLC method, were measured in 13 hypercholesterolemic patients. In addition MDA was also determined in the eluate of the apheresis column. Before treatment, plasma cholesterol and LDL cholesterol concentrations were significantly higher in patients than in healthy control subjects, as were the lipid peroxidation products. LDL-immunoapheresis treatment of the patients led to significant decreases in total cholesterol (69+/-8%), LDL-cholesterol (79+/-7%), HDL-cholesterol (35+/-17%), triglycerides (38+/-21%), apolipoprotein-B (77+/-6%), apolipoprotein-A1 (25+/-5%) and Lp(a) concentrations (76+/-10%). Changes in plasma lipid peroxide concentrations (17+/-8 nmol/l before vs. 14+/-5 nmol/l after treatment) were not significant, neither were those in TBARS (3. 0+/-2.6 micromol/l vs. 2.3+/-1.3 micromol/l) or MDA concentrations (1.03+/-0.17 micromol/l vs. 1.0+/-0.20 micromol/l). Patients with high baseline values showed a decrease, whereas others did not. MDA was present (0.57+/-0.13 micromol/l) in the eluate of the apheresis column, suggesting that, along with LDL, lipid peroxidation products are also removed. From these results we conclude that a single LDL-immunoapheresis treatment effectively reduces LDL and Lp(a) in the absence of increases in plasma lipid peroxidation products.

The effect of idebenone, a coenzyme Q analogue, on hydrophobic bile acid toxicity to isolated rat hepatocytes and hepatic mitochondria.

Oxidant stress induced by hydrophobic bile acids has been implicated in the pathogenesis of liver injury in cholestatic liver disorders. We evaluated the effect of idebenone, a coenzyme Q analogue, on taurochenodeoxycholic acid (TCDC)-induced cell injury and oxidant stress in isolated rat hepatocytes and on glycochenodeoxycholic acid (GCDC)-induced generation of hydroperoxides in fresh hepatic mitochondria. Isolated rat hepatocytes in suspension under 9% oxygen atmosphere were preincubated with 0, 50, and 100 micromol/l idebenone for 30 min and then exposed to 1000 micromol/l TCDC for 4 h. LDH release (cell injury) and thiobarbituric acid reactive substances (measure of lipid peroxidation) increased after TCDC exposure but were markedly suppressed by idebenone pretreatment. In a second set of experiments, the addition of 100 micromol/l idebenone up to 3 h after hepatocytes were exposed to 1000 micromol/l TCDC resulted in abrogation of subsequent cell injury and markedly reduced oxidant damage to hepatocytes. Chenodeoxycholic acid concentrations increased to 5.15 nmol/10(6) cells after 2 h and to 7.05 after 4 h of incubation of hepatocytes with 1000 micromol/l TCDC, and did not differ in the presence of idebenone. In freshly isolated rat hepatic mitochondria, when respiration was stimulated by succinate, 10 micromol/l idebenone abrogated the generation of hydroperoxides during a 90-minute exposure to 400 micromol/l GCDC. These data demonstrate that idebenone functions as a potent protective hepatocyte antioxidant during hydrophobic bile acid toxicity, perhaps by reducing generation of oxygen free radicals in mitochondria.

Effects of pancreatic enzyme preparations on erythrocyte glutathione peroxidase activities and plasma selenium concentrations in cystic fibrosis.

To substitute for exocrine pancreatic insufficiency, patients with cystic fibrosis (CF) take pancreatic enzymes (PE) originating from porcine pancreas. Five different pancreatic enzyme preparations used by our patients contained 0.5-1.4 microg selenium per g tablet. In patients taking PE in doses that were gradually increased to improve fat absorption during a 48-month period, the effects of PE dose on erythrocyte selenium-dependent glutathione peroxidase (SeGSH-Px) activities and plasma selenium concentrations were studied. At baseline, erythrocyte SeGSH-Px activities were significantly lower in patients (p=.01), while plasma selenium concentrations did not differ between patients and healthy subjects. When PE dose and, consequently, selenium intake from PE was increased, erythrocyte SeGSH-Px activities (p < .001) and plasma selenium concentrations (p=.02) increased. Changes in SeGSH-Px activities during the initial 8 months correlated with those in selenium intake from PE (r=0.67, p < .001). Plasma selenium concentrations plateaued at 12 months and erythrocyte SeGSH-Px activities did so at 36 months, when patients had reached SeGSH-Px activities similar to those of healthy subjects. At 48 months, patients took an average lipase dose of 17400 U x kg(-1) x d(-1) and selenium dose from PE of 0.53 microg x kg(-1) x d(-1). We conclude that selenium content of PE preparations has a significant effect on SeGSH-Px activity in patients with CF. This form of selenium supply needs to be taken into account when selenium supplements are given to patients with CF.

Plasma vitamin C concentrations in patients with cystic fibrosis: evidence of associations with lung inflammation.

Vitamin C status and possible associations with the disease process in cystic fibrosis (CF) patients were investigated. Plasma vitamin C concentrations in patients from two different mid-European populations (Swiss, n = 62; Austrian, n = 60) taking no or low-dose vitamin C from multivitamin supplements did not differ from each other or from control subjects (n = 34). Vitamin C concentrations decreased with age (5.05 mumol.L-1, y-1). When followed up for 12 mo, patients had the highest plasma vitamin C concentrations in February and the lowest in May and August (P < 0.01); the decrease in vitamin C was accompanied by increases in plasma malondialdehyde (P < 0.001) and tumor necrosis factor alpha concentrations (P < 0.01). During supplementation with vitamin E for 2 mo or beta-carotene for 12 mo vitamin C concentrations did not change. They correlated inversely with white blood cell count (r = -0.36, P = 0.008), bands (r = -0.36, P = 0.02), alpha 1-acid glycoprotein (r = -0.45, P = 0.002), interleukin 6 (r = -0.46, P = 0.0006), and neutrophil elastase/alpha 1-proteinase inhibitor complexes (r = -0.34, P = 0.02). In patients with vitamin C concentrations < 40 mumol/L, all indexes of inflammation were relatively high, whereas those with concentrations > 80 mumol/L (upper quartile of control subjects) showed clearly lower values. These results are consistent with the hypothesis that by scavenging oxygen free radicals vitamin C interacts with an inflammation-amplifying cycle of activation of alveolar macrophages and neutrophils, release of proinflammatory cytokines and oxygen free radicals, and inactivation of antiproteases.

Reference values for plasma concentrations of vitamin E and A and carotenoids in a Swiss population from infancy to adulthood, adjusted for seasonal influences.

In a cross-sectional survey, plasma concentrations of alpha- and gamma-tocopherol, alpha- and beta-carotene (cis and trans isomers), lycopene, and retinol were determined by reversed-phase HPLC, and ratios of plasma alpha-tocopherol to cholesterol were calculated in 208 Swiss individuals ages 0.4-38.7 years. The influence of age, sex, and season of sampling was studied. Age was a significant predictor of all plasma concentrations except alpha-carotene. No sex-related differences were observed. Season of sampling affected alpha-tocopherol and retinol (higher in winter) and gamma-tocopherol and cholesterol concentrations (higher in winter and spring than in the other seasons). After correction for seasonal influences, age differences were 0.24 micromol/L per year for alpha-tocopherol, 0.04 micromol/L per year for retinol, and 0.04 micromol/L per year for cholesterol concentrations; ratios of plasma alpha-tocopherol to cholesterol were not affected by age. We constructed age-specific reference intervals from the regression line and a multiple of the standard deviation. Separate regression equations are presented for seasons with low and high values.