Multivitamins and minerals modulate whole-body energy metabolism and cerebral blood-flow during cognitive task performance: a double-blind, randomised, placebo-controlled trial.

BACKGROUND: The brain is by far the most metabolically active organ in the body, with overall energy expenditure and local blood-supply closely related to neural activity. Both energy metabolism and cerebral vaso-dilation are dependent on adequate micronutrient status. This study investigated whether supplementation with ascending doses of multi-vitamin/minerals could modulate the metabolic and cerebral blood-flow consequences of performing cognitive tasks that varied in difficulty. METHODS: In this randomised, double-blind, placebo-controlled, parallel-groups study 97 healthy females (25-49 y), who were not selected on the basis of any nutritional parameters, received either placebo or one of two doses of multivitamins/minerals. Cerebral blood-flow (CBF) parameters in the frontal cortex, and total energy expenditure (TotalEnergy), carbohydrate and fat oxidation (CarbOxi/FatOxi), were measured during 5 tasks of graded cognitive difficulty and a control task (5 min per task) using Near-infrared spectroscopy (NIRS) and Indirect calorimetry of exhaled pulmonary gas (ICa) respectively. Assessments took place 60 min after the first dose and following eight weeks supplementation. RESULTS: During task performance supplementation with the first dose of micronutrients led to a dose-dependent increase in TotalEnergy and FatOxi throughout the post-dose assessment period following the higher dose, and increases in the total concentration of haemoglobin, a proxy measure for CBF, during task performance following the lower dose of vitamins/minerals (also containing coenzyme-Q10). Chronic supplementation over 8 weeks led to a dose-dependent increase in TotalEnergy during the task period. There were no interpretable effects on mood or cognitive performance. CONCLUSIONS: These results show that acute supplementation with micronutrients in healthy adults can modulate metabolic parameters and cerebral blood flow during cognitive task performance, and that the metabolic consequences are sustained during chronic supplementation. These findings suggest that both brain function and metabolism are amenable to micronutrient supplementation, even in adults who are assumed to have nutritional status typical of the population. TRIAL REGISTRATION: ClinicalTrials.gov - NCT02381964.

Vitamin C supplementation modulates gene expression in peripheral blood mononuclear cells specifically upon an inflammatory stimulus: a pilot study in healthy subjects.

In order to study the effects of vitamin C supplementation on gene expression and compare its action between physiological and inflammatory conditions, a pilot study was set up utilizing microarray and qPCR technologies. Five healthy volunteers were supplemented with 1 g vitamin C (Redoxon(®)) per day for five consecutive days. Peripheral blood mononuclear cells (PBMNC) were isolated before and just after the last supplementation, and RNA was isolated for the Affymetrix gene 1.0 ST chip analysis. PBMNC were also, ex vivo, treated with LPS, and gene expression was quantified by means of a "Human NFkB Signaling" qPCR array. Only a very moderate effect on the baseline gene expression modulation was associated with vitamin C supplementation. However, in spite of the limited number of subjects analyzed, vitamin C supplementation resulted in a markedly different modulation of gene expression upon the inflammatory stimulus, specifically at the level of the MyD88-dependent pathway and of the anti-inflammatory cytokine IL-10 synthesis. This study suggests that vitamin C supplementation in healthy subjects, not selected according to a specific genetic profile, consuming an adequate amount of vitamin C, and having a satisfactory vitamin C plasma concentration at the baseline, does not result in a significant modification of gene expression profile. Under this satisfactory micronutrient status, supplementation of vitamin C is "buffered" within a homeostatic physiological equilibrium. Differently, following a second "hit" constituted of an inflammatory stimulus such as LPS, able to trigger a critical burst to the normal physiological state, the higher availability of ascorbic acid emerges, and results in a significant modulation of cell response.

Synergistic chondroprotective effect of alpha-tocopherol, ascorbic acid, and selenium as well as glucosamine and chondroitin on oxidant induced cell death and inhibition of matrix metalloproteinase-3--studies in cultured chondrocytes.

Overproduction of reactive oxygen species and impaired antioxidant defence accompanied by chronic inflammatory processes may impair joint health. Pro-inflammatory cytokines such as interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) stimulate the expression of metalloproteinases which degrade the extracellular matrix. Little is known regarding the potential synergistic effects of natural compounds such as alpha-tocopherol (alpha-toc), ascorbic acid (AA) and selenium (Se) on oxidant induced cell death. Furthermore studies regarding the metalloproteinase-3 inhibitory activity of glucosamine sulfate (GS) and chondroitin sulfate (CS) are scarce. Therefore we have studied the effect of alpha-toc (0.1-2.5 micromol/L), AA (10-50 micromol/L) and Se (1-50 nmol/L) on t-butyl hydroperoxide (t-BHP, 100-500 micromol/L)-induced cell death in SW1353 chondrocytes. Furthermore we have determined the effect of GS and CS alone (100-500 micromol/L each) and in combination on MMP3 mRNA levels and MMP3 secretion in IL-1beta stimulated chondrocytes. A combination of alpha-toc, AA, and Se was more potent in counteracting t-BHP-induced cytotoxicity as compared to the single compounds. Similarly a combination of CS and GS was more effective in inhibiting MMP3 gene expression and secretion than the single components. The inhibition of MMP3 secretion due to GS plus CS was accompanied by a decrease in TNF-alpha production. Combining natural compounds such as alpha-toc, AA, and Se as well as GS and CS seems to be a promising strategy to combat oxidative stress and cytokine induced matrix degradation in chondrocytes.

The natural compound ascorbigen modulates NADPH-quinone oxidoreductase (NQO1) mRNA and enzyme activity levels in cultured liver cells and in laboratory rats.

Ascorbigen (ABG) is a natural compound that represents a breakdown product of the glucosinolates that are present in Brassica vegetables. It is postulated that ABG may have anticarcinogenic activity; however, the underlying molecular and cellular mechanisms are largely unknown. In the present study we investigated the effect of ABG on the mRNA and enzyme activity levels of NADPH-quinone oxidoreductase (NQO1), which is centrally involved in the detoxification of xenobiotics, in cultured liver cells and in rats. The mRNA levels of NQO1 showed an increase of up to 100% in cultured liver cells (HepG2) following incubation with different concentrations of ABG (3-100 micromol/l) compared to control cells. Furthermore, NQO1 activity was elevated (up to 20%) by ABG treatment. The in vitro results were confirmed in rats who received either 5 mg/day ABG or vehicle for 7 days. Significantly higher mRNA (a 90% increase) and enzyme activity levels (a 40% increase) of NQO1 were detected in the liver of ABG-treated rats as compared to control animals. Current data indicate that ABG is a moderate inducer of the phase II enzyme NQO1, both in cultured hepatocytes and in vivo.

Differential gene expression in skeletal muscle of rats with vitamin E deficiency.

Vitamin E (VE) deficiency is accompanied by myopathy in various animal species including man. Although gene expression profiles related to degenerative and regenerative processes in different kinds of myopathies have been studied, no global expression profile for skeletal muscle subject to VE deficiency has previously been reported. In the present study, Affymetrix GeneChip technology was used to obtain such a profile. Two groups of male rats were fed with either a diet deficient in VE or a control diet. Differential gene expression was monitored at five time-points over 430 days, with all animals individually profiled. Out of approximately 7000 genes represented on the Genechip, 56 were found to be up-regulated in response to VE deficiency in at least four consecutive time-points from as early as 91 days of deficiency. Up-regulated genes included muscle structure and extra cellular matrix genes, as well as anti-oxidative, anti-inflammatory and anti-fibrotic genes. Our data show that molecular transcription might provide a very early marker to detect oncoming degenerative conditions in VE deficiency. They provide further insight into possible molecular mechanisms underlying VE deficiency in skeletal muscle, and reveal the activation of an intensive protection program that can explain the long maintenance of muscle structure during deficiency.

Cortical gene expression in the vitamin E-deficient rat: possible mechanisms for the electrophysiological abnormalities of visual and neural function.

In mammals, severe and chronic deficiency of vitamin E (alpha-tocopherol) is associated with a characteristic neurological syndrome. Previously, we have shown that this syndrome is accompanied by electrophysiological abnormalities of neural and visual function. To investigate the molecular basis of the observed abnormalities, we used microarrays to monitor the expression of approximately 14,000 genes in the cerebral cortex from rats which had received diets containing 0, 1.25 and 5.0 mg/kg diet of all-rac-alpha-tocopheryl acetate for 14 months. Compared to the groups receiving 1.25 and 5.0 mg/kg alpha-tocopheryl acetate, a total of 11 genes were statistically significantly upregulated (> or =1.3-fold) and 34 downregulated (< or =1.3-fold) in the vitamin E-deficient group. Increased expression was observed for the genes encoding the antioxidant enzyme catalase and the axon guidance molecule tenascin-R, while decreased expression was detected for genes encoding protein components of myelin and determinants of neuronal signal propagation. Thus our observations suggest that vitamin E deficiency results in transcriptional alterations in the cerebral cortex of the rat which are consistent with the observed neurological and electrophysiological alterations.

Effect of Vitamin E on Cytochrome P450 mRNA Levels in Cultured Hepatocytes (HepG2) and in Rat Liver.

Vitamin E has been described in the literature as a regulator of gene expression. The gene-regulatory activity of vitamin E with regard to genes encoding cytochrome P450 (CYP) enzymes, which play a pivotal role both in the metabolism of xenobiotics and vitamin E, has not been conclusively characterised. The objective of the current study was, therefore, to elucidate the short- and long-term effects of natural and synthetic vitamin E on CYP gene expression using Affymetrix GeneChip® technology. To this end, HepG2 cells were incubated with 0, 10, 30, 80 and 300 µM RRR-α-tocopheryl acetate (natural vitamin E) or all rac-α-tocopheryl acetate (synthetic vitamin E) for 7 days and the mRNA of CYP genes was quantified. The expression of only one (CYP20A1) of 14 CYP genes with detectable mRNA levels was dose-dependently up-regulated. No differences in gene-regulatory activity were observed between RRR- and all rac-α-tocopheryl acetate. To study the role of vitamin E in CYP gene expression in vivo, Fisher 344 rats were randomly assigned to either a vitamin E-enriched (60 mg/kg RRR-α-tocopheryl acetate) or - deficient (1.7 mg/kg RRR-α-tocopheryl acetate) diet for 290 days. Neither in the vitamin E-enriched, nor in the vitamin E-deficient rats, were significant changes in the liver CYP, mRNA levels observed. In conclusion, our data indicated that vitamin E does not appear to modulate cytochrome P450 mRNA expression in HepG2 cells or in rats.

Comparative quantification of pharmacodynamic parameters of chiral compounds (RRR- vs. all-rac-alpha tocopherol) by global gene expression profiling.

Pharmacologically active compounds (e.g. from the groups of pharmaceutical drugs, cofactors or vitamins) often consist of two or more stereoisomers (enantiomers or diastereoisomers) which may differ in their pharmacodynamic/kinetic, toxicological and biological properties. A well-known example is vitamin E which is predominantly administered as two different forms, one derived from natural sources (mainly soybeans), and one from production by chemical total-synthesis. While vitamin E from natural sources occurs as a single stereoisomer (RRR-alpha-tocopherol), synthetic vitamin E (all-rac-alpha-tocopherol) is an equimolar mixture of eight stereoisomers. Based on a number of animal studies it has been suggested that the biological potency of natural-source vitamin E is 1.36 greater compared to its counterpart produced by chemical synthesis. In this study, we have used the Affymetrix GeneChip technology to evaluate the feasibility of a new bio-assay where the gene regulatory activities of RRR-alpha-tocopherol and all-rac-alpha-tocopherol were quantified and compared on the genome-wide level. For this purpose, HepG2 cells were supplemented with increasing amounts of RRR- or all-rac-alpha-tocopherol for 7 days. Genes showing a dose-related induction/repression were identified by global gene expression profiling. Our findings show that RRR- and all-rac-alpha-tocopherol share an identical transcriptional activity, i.e. induce/repress the expression of the same set of genes. Based on the transcriptional dose-response data, EC50 and IC50 values were determined for each of these genes. The feasibility of calculating a "transcriptional potency factor" of RRR- vs. all-rac-e-tocopherol was evaluated by dividing the EC50/IC50 of RRR-alpha-tocopherol by the corresponding EC50/IC50 of all-rac-alpha-tocopherol for every of the vitamin E responsive genes. Using this approach we have calculated 215 single biopotency ratios. Subsequently, the mean of all potency ratios was found to be 1.05. In the present work we propose a new assay for the analysis and comparison of the biological activity and potency of chiral compounds in vivo.

Dietary vitamin E modulates differential gene expression in the rat hippocampus: potential implications for its neuroprotective properties.

A wide range of cell culture, animal and human epidemiological studies are suggestive of a role of vitamin E (VE) in brain function and in the prevention of neurodegeneration. However, the underlying molecular mechanisms remain largely unknown. In the current investigation Affymetrix gene chip technology was utilised to establish the impact of chronic VE deficiency on hippocampal genes expression. Male albino rats were fed either a VE deficient or standard diet (60 mg/kg feed) for a period of 9 months. Rats were sacrificed, the hippocampus removed and genes expression established in individual animals. VE deficiency showed to have a strong impact on genes expression in the hippocampus. An important number of genes found to be regulated by VE was associated with hormones and hormone metabolism, nerve growth factor, apoptosis, dopaminergic neurotransmission, and clearance of amyloid-beta and advanced glycated endproducts. In particular, VE strongly affected the expression of an array of genes encoding for proteins directly or indirectly involved in the clearance of amyloid beta, changes which are consistent with a protective effect of VE on Alzheimer's disease progression.

Dietary alpha-tocopherol affects differential gene expression in rat testes.

Gene-chip technology was employed to study the effect of dietary vitamin E (VE) on gene expression in rat testes. Male albino rats were fed with either a diet deficient in VE or a standard diet containing VE. Differential gene expression was monitored at five individual time-points over a period of 14 months with all animals individually profiled. Low VE intake resulted in the consistent up-regulation of 7-dehydrocholesterol reductase and GATA binding protein 4, both involved in testosterone synthesis. Cyclin D3, important in cell cycle progression and Wilms tumor 1, related to cancer development, were also up-regulated in the vitamin E deficient animals. This study demonstrates that low dietary VE intake has long-term effects on gene expression in the testes. Our data provides insights into the possible molecular mechanisms underlying the beneficial effects of vitamin E on the male reproductive organ.

Identification of hepatic molecular mechanisms of action of alpha-tocopherol using global gene expression profile analysis in rats.

The recent discovery that vitamin E (VE) regulates gene activity at the transcriptional level indicates that VE may exert part of its biological effects by mechanisms which may be independent of its well-recognised antioxidant function. The objective of this study was the identification of hepatic vitamin E-sensitive genes and examination of the effects of VE on their corresponding biological endpoints. Two groups of male rats were randomly assigned to either a VE-sufficient diet or to a control diet deficient in VE for 290 days. High-density oligonucleotide microarrays comprising over 7000 genes were used to assess the transcriptional response of the liver. Differential gene expression was monitored over a period of 9 months, at four different time-points, and rats were individually profiled. This experimental strategy identified several VE-sensitive genes, which were chronically altered by dietary VE. VE supplementation down-regulated scavenger receptor CD36, coagulation factor IX and 5-alpha-steroid reductase type 1 mRNA levels while hepatic gamma glutamyl-cysteinyl synthetase was significantly up-regulated. Measurement of the corresponding biological endpoints such as activated partial thromboplastin time, plasma dihydrotestosterone and hepatic glutathione substantiated the gene chip data which indicated that dietary VE plays an important role in a range of metabolic processes within the liver.

Lycopene and vitamin E interfere with autocrine/paracrine loops in the Dunning prostate cancer model.

Epidemiological studies have consistently associated high intakes of lycopene or vitamin E with a reduced prostate cancer risk. Both compounds were tested in the MatLyLu Dunning prostate cancer model to gain insight into the in vivo action of lycopene and vitamin E. Supplementation for 4 weeks with 200 ppm lycopene, 540 ppm vitamin E, or both led to plasma levels comparable with those in humans. Both compounds also accumulated in tumor tissue. Macroscopic evaluation of the tumors by magnetic resonance imaging showed a significant increase in necrotic area in the vitamin E and the lycopene treatment groups. Microarray analysis of tumor tissues revealed that both compounds regulated local gene expression. Vitamin E reduced androgen signaling without affecting androgen metabolism. Lycopene interfered with local testosterone activation by down-regulating 5-alpha-reductase and consequently reduced steroid target genes expression (cystatin-related protein 1 and 2, prostatic spermine binding protein, prostatic steroid binding protein C1, C2 and C3 chain, probasin). In addition, lycopene down-regulated prostatic IGF-I and IL-6 expression. Based on these findings, we suggest that lycopene and vitamin E contribute to the reduction of prostate cancer by interfering with internal autocrine or paracrine loops of sex steroid hormone and growth factor activation/synthesis and signaling in the prostate.

Modulation of hepatic gene expression by alpha-tocopherol in cultured cells and in vivo.

To obtain a comprehensive understanding of the molecular mechanisms of action of vitamin E (VE), global gene expression profiles using DNA arrays in rat liver and hepatocellular liver carcinoma cells (HepG2) were obtained. For the analysis of short-term (49 days) and long-term (290 days) VE deficiency, rats were fed semisynthetic diets either supplemented with or deficient in VE. In addition, HepG2 cells were treated with VE concentrations comparable to those that were achieved in the in vivo experiment. Differential gene expression in rat liver and that in HepG2 cells were measured by DNA arrays comprising up to 7,000 genes. Dietary VE deficiency over a 7-week period did not induce any significant changes in the expression profile among the genes evaluated. However, long-term VE deficiency upregulated coagulation factor IX (FIX), 5-alpha-steroid reductase type 1, and CD36 mRNA levels. Furthermore, VE deficiency resulted in a significant downregulation of hepatic gamma-glutamyl-cysteinyl synthetase, the rate-limiting enzyme of glutathione synthesis. According to the rat experiment, VE supplementation changed coagulation factor IX and CD36 expression in HepG2 cells; thus, in vivo data could be partly confirmed with the in vitro model. Overall, the current studies reveal that dietary VE has important long-term effects on liver gene expression with potential downstream effects on extrahepatic tissues.

Alpha-tocopherol affects androgen metabolism in male rat.

The Alpha-Tocopherol Beta-Carotene Cancer Prevention Study has provided the first evidence implicating vitamin E in hormone synthesis. The effect of vitamin E on stereoidogenesis in testes and adrenal glands was assessed in growing rats using Affymetrix gene-chip technology. Dietary supplementation of rats with vitamin E (60 mg/kg feed) for a period of 429 days caused a significant repression of genes encoding for proteins centrally involved in the uptake (low-density lipoprotein receptor) and de novo synthesis (for example, 7-dehydrocholesterol reductase, 3-hydroxy-3-methylglutaryl coenzyme A synthase, 3-hydroxy-3-methylglutaryl-coenzyme A reductase, isopentenyl-diphosphate delta-isomerase, and farnesyl pyrophosphate synthetase) of cholesterol, the precursor of all steroid hormones. The present investigation indicates that dietary vitamin E may induce changes in stereoidogenesis by affecting cholesterol homeostasis.

Sterol-regulatory element-binding protein (SREBP)-2 contributes to polygenic hypercholesterolaemia.

Sterol-regulatory element-binding protein (SREBP)-2 is a key regulator of cholesterol. When cells are deprived of cholesterol, proteolytic cleavage releases the NH(2)-terminal domain of SREBP-2 that binds and activates the promoters of SREBP-2-regulated genes including the genes encoding the low-density lipoprotein (LDL) receptor, 3-hydroxymethyl-3-glutaryl-(HMG-)CoA-synthase, and HMG-CoA-reductase. Thus, SREPB-2 gene activation leads to enhanced cholesterol uptake and biosynthesis. A novel protein polymorphism (SREBP-2-595A/G) discovered in the regulatory domain of human SREBP-2 was investigated regarding its impact on cholesterol homeostasis. In human embryonic kidney (HEK)-293-cells, the cleavage-rate of the SREBP-2-595A-isoform was slightly decreased compared to that of the SREBP-2-595G-isoform. Since cleavage of SREBP-2 activates the LDL receptor-mediated uptake of plasma cholesterol, we hypothesized the LDL receptor-mediated uptake to be decreased in homozygous SREBP-2-595A-carriers and thus, plasma total cholesterol (TC) to be higher than in SREBP-2-595G-carriers. Multiple linear regression analysis of population samples from Switzerland (N=1334) and Israel (N=923) demonstrated a significant positive, gene dose-dependent association of the SREBP-2-595A-isoform with higher plasma TC (P=0.001). This cholesterol-modulating effect was present in hypercholesterolaemic (DeltaTC=1.05 mmol/l, 14.4%; P=0.002; N=477), but absent in normocholesterolaemic subjects (DeltaTC=0.06 mmol/l, 1.4%; P=0.334; N=1780). In summary, a slightly but constantly decreased cleavage-rate of the SREBP-2-595A-isoform compared to that of the SREBP-2-595G-isoform may lead to a reduced transcriptional activation of the LDL receptor-gene weakening the SREBP-mediated compensation mechanisms, and may, therefore, be a critical factor in the development of polygenic hypercholesterolaemia.