Changes in serum retinol, alpha-tocopherol, vitamin C, carotenoids, xinc and selenium after micronutrient supplementation during alcohol rehabilitation

Protection of Vitamin C on Oxidative Damage Caused by Long-Term Excess Iodine Exposure in Wistar Rats

Vitamin C was reported to be able to protect against oxidative damage due to its reducibility. 120 Wistar rats were randomly divided into 4 × 2 groups, including normal iodine (NI), high iodine (HI), low vitamin C (HI + LC), and high vitamin C (HI + HC); potassium iodide (KI) and potassium iodate (KIO₃) were commonly used as additives for iodized salt, so every group was also divided into KI and KIO₃ groups. After 6 months' feed, the activities of antioxidant enzymes and Lipid Peroxide (MDA) content in serum, liver, kidney, brain, thyroid and lens were determined. In serum, for males, long-term excess iodine intake caused oxidative damage; in the liver, male rats in the HI + LC group had the highest MDA content, which showed that low-dose vitamin C might promote oxidative damage; in kidneys, the MDA content in the HI and HI + LC groups of females was higher; in the brain, high-dose vitamin C could increase the activity of superoxide dismutase (SOD), which was decreased by high iodine intake, and it also decreased MDA content; in the thyroid, for KIO₃, the activity of SOD in the HI group was lower than NI and HI + LC; in the lens, the MDA content in females was lower than males. Long-term excess iodine exposure caused oxidative damage and showed sex difference, and vitamin C had a protective effect on it, especially for high-dose vitamin C.

Essential features for antioxidant capacity of ascorbic acid (vitamin C)

Vitamin C or ascorbic acid is an indispensable micronutrient for human health found principally on citrus species such as lemon and orange fruits and vegetables. It was involved in the production of proteins such as collagen. Its biochemical mechanism is related to its antioxidant capacity; however, its function at the cellular level is still unclear. Several theoretical studies about antioxidant and redox mechanisms for ascorbic acid were suggested; however, no derivative was proposed. Thereby, an electronic study of antioxidant capacity for ascorbic acid derivatives was performed using theoretical chemistry at the DFT/ B3LYP/6-311 +  + (2d,2p) level of theory. Simplified derivatives show that enol hydroxyls are more important than any other functional group. The vicinal enolic hydroxyl on β position is more important for antioxidant capacity of ascorbic than hydroxyl on α position. According to our molecular modifications, the keto-alkene compound showed the best values when compared to ascorbic acid in some molecular characteristics. No lactone derivatives have superior application potential as antioxidant when compared with ascorbic acid. Several structures are possible to be proposed and were related to spin density contributions and the increase of chemical stability. New promising structural derivatives related to ascorbic acid can be developed in the future.

Antioxidative role of dietary ascorbic acid against arsenic induced haematological, biochemical and histomorphological alterations in Cyprinus carpio

The current study investigated the antioxidant potential of ascorbic acid to counteract arsenic induced toxic response in Cyprinus carpio. The 96 h LC50 of 107.05 mg L-1 was recorded through acute toxicity test and 1/5th and 1/10th LC50 of arsenic were chosen as sublethal concentrations for assessing toxicity induced through arsenic exposure in fish for a period of 28 days. There were six experimental groups for sublethal toxicity testing viz. negative control (basal feed), positive control (basal feed + 1 g kg-1 diet ascorbic acid), 1/5th LC50 Arsenic, 1/10th LC50 Arsenic, 1/5th LC50 Arsenic with ascorbic acid supplement, 1/10th LC50 Arsenic with ascorbic acid supplement. Following exposure, blood indices, antioxidant enzyme activity and histomorphology of gills, liver and kidney were examined. The results showed decreased total erythrocyte count, haemoglobin, haematocrit and an increased total leukocyte count upon arsenic exposure in fish with an improvement observed in the blood indices in arsenic with ascorbic acid supplementation. The study also analysed the antioxidant enzyme activity of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase which was found to decline in response to arsenic exposure with an increase in their activity recorded in arsenic with ascorbic acid supplemented fish. Furthermore, uptake of arsenic was also found to decrease on ascorbic acid supplementation with improvement in the histoarchitecture of gills, liver and kidney of fish. Collectively, the findings of the present study suggest the effectiveness of ascorbic acid as an ameliorating agent against the deleterious effects of arsenic in fish.

Magnesium, Calcium, Potassium, Sodium, Phosphorus, Selenium, Zinc, and Chromium Levels in Alcohol Use Disorder: A Review

Macronutrients and trace elements are important components of living tissues that have different metabolic properties and functions. Trace elements participate in the regulation of immunity through humoral and cellular mechanisms, nerve conduction, muscle spasms, membrane potential regulation as well as mitochondrial activity and enzymatic reactions. Excessive alcohol consumption disrupts the concentrations of crucial trace elements, also increasing the risk of enhanced oxidative stress and alcohol-related liver diseases. In this review, we present the status of selected macroelements and trace elements in the serum and plasma of people chronically consuming alcohol. Such knowledge helps to understand the mechanisms of chronic alcohol-use disorder and to progress and prevent withdrawal effects, also improving treatment strategies.

Cu-based metal–organic framework HKUST-1 as effective catalyst for highly sensitive determination of ascorbic acid

In this work, a Cu-based nanosheet metal–organic framework (MOF), HKUST-1, was synthesised using a solvent method at room temperature. Its morphology, structure and composition were characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman spectroscopy, nitrogen adsorption and desorption isotherms, energy dispersive X-ray spectroscopy (EDS) and elemental analysis (EA). This material was then loaded onto the surface of an indium tin oxide (ITO) electrode to catalyse the electrochemical oxidation of ascorbic acid (AA). An equal-electron-equal-proton reaction was deduced from the pH investigation, and a diffusion-controlled process was reinforced by the dynamics study. Under optimal conditions, the oxidation peak current at +0.02 V displayed a linear relationship with the concentration of AA within the ranges of 0.01–25 and 25–265 mM, respectively. The limit of detection (LOD) was 3 μM at S/N of 3. The superb response could be ascribed to the porous nanosheet structure of HKUST-1, which enhanced both the effective surface area and the electron transfer ability significantly. Moreover, the novel AA sensor demonstrated good reproducibility, favourable stability and high sensitivity towards glucose, uric acid (UA), dopamine (DA) and several amino acids. It was also successfully applied to the real sample testing of various AA-containing tablets.

In this work, a Cu-based nanosheet metal–organic framework (MOF), HKUST-1, was synthesised using a solvent method at room temperature and it demonstrated high capability and sensitivity towards the oxidation of ascorbic acid (AA).

On the Neurobiological Role of Oxidative Stress in Alcohol-Induced Impulsive, Aggressive and Suicidal Behavior

Objectives: Alcohol abuse is known to result in behavioral impairments (such as increased impulsivity, aggressive, and suicidal behavior), but the neurobiological basis for these behavioral impairments remains unknown. The objective of this review is to propose a neurobiological basis for alcohol-induced aggression, impulsivity, and suicidal behavior. Methods: Search was done by accessing PubMed/Medline, EBSCO, and PsycINFO databases. The search string used was "(Alcohol OR Alcoholism* OR Alcohol Abuse) AND (Behavior* OR Behavioral Impairment or Disorder) AND (Oxidative Stress OR Reactive Oxygen Species)." The electronic databases were searched for titles or abstracts containing these terms in all published articles between January 1, 1960, and May 31, 2019. The search was limited to studies published in English and other languages involving both animal and human subjects. Articles selected included randomized clinical trials (RCTs), observational studies, meta-analyses, and both systemic and narrative reviews, providing both quantitative and qualitative information with a measure of alcohol abuse or alcoholism as an outcome. Exclusion criteria were unpublished data of any form, including conference proceedings and dissertation. New key terms were identified (new term included: "Antioxidants, Neurotransmitters, Dopamine, Serotonin, GABA, Glutamate. Aggression, Impulsivity, Suicidal Behavior, hippocampus, prefrontal cortex, limbic system, psychiatric disorders, PTSD, Anxiety, Depression. These new terms were searched with Alcohol or Alcoholism or Alcohol Abuse and Oxidative Stress separately resulting in the identification of over 3000 articles. 196 were included in this article. Results: Multiple lines of evidence indicate that oxidative stress (OS) plays a critical underlying role in alcohol toxicity and behavioral impairments. Conclusions/Importance: People diagnosed with PTSD, anxiety disorder, depression, and those with a personality high in psychoticism as measured by the P Scale of the Eysenck Personality Questionnaire, with comorbid alcohol abuse or alcohol use disorder (AUD), may display increased impulsivity, aggression, and suicidal behavior because of the potentiating effect of alcohol-induced OS on their elevated brain oxidative status. Antioxidant therapy should be an integral part of acute alcohol intoxication and AUD treatment. Further research is necessary to fully understand the relationship between OS and alcohol-induced behavioral impairments.

Determination of plasma and leukocyte vitamin C concentrations in a randomized, double-blind, placebo-controlled trial with Ester-C(®)

Background

Rapid uptake of vitamin C into blood and retention in tissues are important indicators of the efficacy of vitamin C supplementation and its immune-supporting role. The objective of this study was to evaluate the bioavailability of vitamin C in plasma (reflective of recent intake) and leukocytes (reflective of tissue stores and influences on immune function) from a novel vitamin C formulation, Ester-C^®.

Methods

The study was a double-blind, placebo-controlled, crossover trial. Thirty-six subjects, 18–60 years of age, were randomized to receive placebo (PL, 0 mg vitamin C), ascorbic acid (AA, 1000 mg vitamin C), and Ester-C^® (EC, 1000 mg vitamin C). Plasma and leukocyte vitamin C were measured baseline and at 2, 4, 8 and 24 h postdose.

Results

The concentration and percent change from baseline in plasma were significantly higher with EC at all time points when compared to PL. No significant differences between EC and AA were observed in plasma concentration. Maximum plasma concentration was higher for EC compared to AA (P = 0.039) and PL (P < 0.001). Plasma area under the curve (AUC_0–24h) was higher for EC (P < 0.001) compared to PL. The concentration change from baseline in leukocyte vitamin C was increased with EC at 24 h post-dose (P = 0.036) while no significant within-group changes were observed in AA or PL at any time point. The percent change in leukocyte vitamin C concentration was higher for EC at 8 and 24 h compared to AA (P = 0.028 and P = 0.034, respectively) and PL (P = 0.042 and P = 0.036, respectively).

Conclusions

A single dose of EC resulted in favorable percent change in leukocyte vitamin C concentration compared to AA and PL, indicating EC is retained longer within leukocytes.

Trial registration ClinicalTrials.gov Identifier NCT01852903

Teaching and learning of medical biochemistry according to clinical realities: A case study

To foster medical students to become physicians who will be lifelong independent learners and critical thinkers with healthy skepticism and provide high-quality patient care guided by the best evidence, teaching of evidence-based medicine (EBM) has become an important component of medical education. Currently, the teaching and learning of biochemistry in medical schools incorporates its medical relevance and applications. However, to our knowledge there have been no reports on integrating EBM with teaching and learning medical biochemistry. Here, we present a case study to illustrate the significance of this approach. This case study was based on a biochemistry/nutrition question in a popular board review book about whether a homeless alcoholic man is at risk of developing a deficiency of vitamin E. The possible answers and explanation provided in the book raised a question about the correct answer, which provided us with an opportunity to adapt the philosophy and certain basic EBM principles to find evidence for the clinical applicability of a commonly taught biochemistry topic. The outcome of this case study not only taught us how to conduct an EBM exercise to answer a specific patient question, but also provided us with an opportunity for in-depth teaching and learning of the medical relevance of a specific biochemistry topic based on the best clinical evidence obtained from a systematic research of medical literature.

Choline and Fructooligosaccharide: Non-alcoholic Fatty Liver Disease, Cardiac Fat Deposition, and Oxidative Stress Markers

This study investigates the treatment of non-alcoholic fatty liver disease (NAFLD) in rats with choline and fructooligosaccharide (FOS). The healthy control group received standard diet. The other three groups consisted of animals with NAFLD. Group E_str received standard diet; group E_cho received standard diet plus choline (3 g/100 g diet); and group E_fos received standard diet plus FOS (10 g/100 g diet). Food intake, weight, urinary nitrogen, urinary ammonia, total cholesterol, serum triacylglyceride, liver and heart weights, tissue nitrogen, tissue fat, vitamin E, TBARS, and reduced glutathione (GSH) were measured in hepatic and heart tissue. Choline and FOS treatments resulted in total mean fat reduction in liver and heart tissue of 0.2 and 1.7 g, respectively. Both treatments were equally effective in reducing hepatic and cardiac steatosis. There were no differences in the TBARS level among experimental and control groups, indicating that the proposed treatments had no added protection against free radicals. While all experimental groups had increased vitamin E and GSH levels, choline treatment led to a significant increase compared to control.

Antioxidant vitamins and brain dysfunction in alcoholics

AIMS

Alcohol induces cytokine secretion by Kupffer cells, which may exert also deleterious effects on distant organs, mediated in part by cytokine-derived increased production of reactive oxygen species (ROS). It is therefore important to assess antioxidant levels. The objective of this study is to analyse the relation of antioxidant vitamins with brain atrophy and cognitive dysfunction.

METHODS

In 77 alcoholic patients admitted for withdrawal syndrome, subjected to brain computed tomography (CT), and 19 controls, we determined antioxidant vitamin levels and analysed their relationships with data of brain atrophy and dysfunction. Searching for causes of altered vitamin levels, we also assessed liver function, nutritional status, eating habits, alcohol intake, proinflammatory cytokine (TNF-α, IL-6, IL-8) levels and malondialdehyde (MDA) levels.

RESULTS

Both retinol (vitamin A) and tocopherol (vitamin E) levels were decreased in alcoholics, the former in relation with liver failure, and the latter in relation with triglyceride levels and fat mass. Both were related to data of brain atrophy and cerebellar shrinkage (to which also IL-6 was significantly related).

CONCLUSION

Among alcoholics, liver function impairment leads to altered serum vitamin A levels, which are related to brain alterations. Vitamin E levels are also decreased, but although in relation with liver function impairment, its decrease seems to be more dependent on nutritional status and irregular eating habits. Both vitamins are lower in patients with cerebellar atrophy and other features related to brain atrophy.

An evidence-based systematic review of vitamin A by the natural standard research collaboration

An evidence-based systematic review of vitamin A by the Natural Standard Research Collaboration consolidates the safety and efficacy data available in the scientific literature using a validated and reproducible grading rationale. This paper includes written and statistical analysis of clinical trials, plus a compilation of expert opinion, folkloric precedent, history, pharmacology, kinetics/dynamics, interactions, adverse effects, toxicology, and dosing.

Additive effect of alpha-tocopherol and ascorbic acid in combating ethanol-induced hepatic fibrosis

OBJECTIVE

To investigate the efficacy of combined administration of alpha-tocopherol (AT) and ascorbic acid (AA) in reducing ethanol-induced hepatotoxicity.

METHODS

Rats were maintained for 90 days and grouped as follows: I-control rats, II-ethanol, III-alpha-tocopherol, IV-ethanol+alpha-tocopherol, V-AA, VI-ethanol+ascorbic acid, VII-alpha-tocopherol+ascorbic acid, VIII-ethanol+alpha-tocopherol+ascorbic acid. At the end of the experimental period, markers of hepatic function, oxidative stress, and the expression of markers of inflammation and fibrosis were assayed.

RESULTS

The markers of hepatic function, lipid peroxidation products, protein carbonyls, and the expression of nuclear factor kappa B, tumor necrosis factor alpha, transforming growth factor beta 1, cytochrome P4502E1, and collagen Type I were elevated after ethanol administration. All these parameters were reduced in the ethanol group administered AT and AA in combination. The activities of antioxidant enzymes which were reduced by ethanol administration were enhanced on combined administration of AT and AA. The reduction in hepatic fibrosis was almost 20% more in AT and AA co-administered group compared with AT and AA alone treated groups.

DISCUSSION

Combined administration of fat soluble AT and water soluble AA was beneficial against ethanol-induced hepatotoxicity. This may be due to their different subcellular localizations.

Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases

BACKGROUND

Our systematic review has demonstrated that antioxidant supplements may increase mortality. We have now updated this review.

OBJECTIVES

To assess the beneficial and harmful effects of antioxidant supplements for prevention of mortality in adults.

SEARCH METHODS

We searched The Cochrane Library, MEDLINE, EMBASE, LILACS, the Science Citation Index Expanded, and Conference Proceedings Citation Index-Science to February 2011. We scanned bibliographies of relevant publications and asked pharmaceutical companies for additional trials.

SELECTION CRITERIA

We included all primary and secondary prevention randomised clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention.

DATA COLLECTION AND ANALYSIS

Three authors extracted data. Random-effects and fixed-effect model meta-analyses were conducted. Risk of bias was considered in order to minimise the risk of systematic errors. Trial sequential analyses were conducted to minimise the risk of random errors. Random-effects model meta-regression analyses were performed to assess sources of intertrial heterogeneity.

MAIN RESULTS

Seventy-eight randomised trials with 296,707 participants were included. Fifty-six trials including 244,056 participants had low risk of bias. Twenty-six trials included 215,900 healthy participants. Fifty-two trials included 80,807 participants with various diseases in a stable phase. The mean age was 63 years (range 18 to 103 years). The mean proportion of women was 46%. Of the 78 trials, 46 used the parallel-group design, 30 the factorial design, and 2 the cross-over design. All antioxidants were administered orally, either alone or in combination with vitamins, minerals, or other interventions. The duration of supplementation varied from 28 days to 12 years (mean duration 3 years; median duration 2 years). Overall, the antioxidant supplements had no significant effect on mortality in a random-effects model meta-analysis (21,484 dead/183,749 (11.7%) versus 11,479 dead/112,958 (10.2%); 78 trials, relative risk (RR) 1.02, 95% confidence interval (CI) 0.98 to 1.05) but significantly increased mortality in a fixed-effect model (RR 1.03, 95% CI 1.01 to 1.05). Heterogeneity was low with an I(2)- of 12%. In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertrial heterogeneity. Meta-regression analysis did not find a significant difference in the estimated intervention effect in the primary prevention and the secondary prevention trials. In the 56 trials with a low risk of bias, the antioxidant supplements significantly increased mortality (18,833 dead/146,320 (12.9%) versus 10,320 dead/97,736 (10.6%); RR 1.04, 95% CI 1.01 to 1.07). This effect was confirmed by trial sequential analysis. Excluding factorial trials with potential confounding showed that 38 trials with low risk of bias demonstrated a significant increase in mortality (2822 dead/26,903 (10.5%) versus 2473 dead/26,052 (9.5%); RR 1.10, 95% CI 1.05 to 1.15). In trials with low risk of bias, beta-carotene (13,202 dead/96,003 (13.8%) versus 8556 dead/77,003 (11.1%); 26 trials, RR 1.05, 95% CI 1.01 to 1.09) and vitamin E (11,689 dead/97,523 (12.0%) versus 7561 dead/73,721 (10.3%); 46 trials, RR 1.03, 95% CI 1.00 to 1.05) significantly increased mortality, whereas vitamin A (3444 dead/24,596 (14.0%) versus 2249 dead/16,548 (13.6%); 12 trials, RR 1.07, 95% CI 0.97 to 1.18), vitamin C (3637 dead/36,659 (9.9%) versus 2717 dead/29,283 (9.3%); 29 trials, RR 1.02, 95% CI 0.98 to 1.07), and selenium (2670 dead/39,779 (6.7%) versus 1468 dead/22,961 (6.4%); 17 trials, RR 0.97, 95% CI 0.91 to 1.03) did not significantly affect mortality. In univariate meta-regression analysis, the dose of vitamin A was significantly associated with increased mortality (RR 1.0006, 95% CI 1.0002 to 1.001, P = 0.002).

AUTHORS' CONCLUSIONS

We found no evidence to support antioxidant supplements for primary or secondary prevention. Beta-carotene and vitamin E seem to increase mortality, and so may higher doses of vitamin A. Antioxidant supplements need to be considered as medicinal products and should undergo sufficient evaluation before marketing.

Selenium levels in men with liver disease in Hungary

PROJECT

We studied the relationship between selenium (Se) levels and chronic liver disease (CLD) severity and the association between socioeconomic and lifestyle factors and serum Se levels.

PROCEDURE

We performed a case-control study in Hungarian men, examining 281 patients with CLD and 778 controls. Liver function was evaluated using biochemical markers, and liver disease was verified with physical examination and blood tests. Linear regression analysis was performed to study the association of serum Se level with biochemical markers in cases and controls. In control participants we examined the relationship between Se levels and age, financial status, education, alcohol consumption, cigarette smoking, type of fat used for cooking and body mass index.

RESULTS

Serum Se levels were lower in cases (median 0.87 μmol/L (IQR: 0.77-1.03)) than in controls (median 1.08 μmol/L (IQR: 0.97-1.19)). In controls, increases in bilirubin and glutamic-oxaloacetic transaminase (GOT) were associated with decreases in Se levels. In patients with CLD, a statistically significant relationship was found between serum Se and the GOT/GPT ratio, albumin and bilirubin. Younger, better-educated controls had significantly higher, and regular smokers and heavy drinkers had significantly lower Se levels. The use of vegetable oil/fat was also associated with higher Se levels. Se level was associated with the severity of liver injury in people even in patients who did not exhibit signs and symptoms of CLD.

CONCLUSIONS

Serum Se level is strongly associated with the severity of liver damage in people with CLD from the early stage on.

Experimental induction of steatosis in different tissues after the ingestion of a carbohydrate-rich diet: effect on the liver, on the heart and on indicators of oxidation

CONTEXT

The western dietary pattern is characterized by a high calorie intake with a high proportion of simple sugars. This diet is associated with comorbidities such as hepatic fat deposition and is possibly related to non-alcoholic fatty liver disease.

OBJECTIVE

To evaluate the capacity of a hyperglucidic diet to induce steatosis in adult male Wistar rats. After the administration of a carbohydrate-rich diet, we also evaluated the presence of hepatic and cardiac steatosis and the levels of intrinsic antioxidants in the liver.

METHODS

Forty-six eutrophic adult male Wistar rats were used and 10 of them were chosen, at random, to serve as controls, while the remaining ones formed the experimental group. Control animals received the standard ration offered by the animal house and the experimental group received the hyperglucidic diet. The diets were offered for 21 days and, at the end of this period, tissue samples were collected for analysis of indicators of oxidative stress (malondialdehyde, and reduced glutathione) and of vitamin E. The animals were then sacrificed by decapitation and their viscera were removed for analysis of liver and heart fat.

RESULTS

The hyperglucidic diet used induced hepatic fat deposition, with lipid vacuoles being detected in 83% of the livers analyzed by histology. No lipid vacuoles were observed in the heart. Malondialdehyde and reduced glutathione levels remained unchanged when the animals were submitted to the hyperglucidic diet, probably because there was no liver development of fibrosis or inflammation. In contrast, the levels of vitamin E (antioxidant) were reduced, as confirmed in the literature for steatotic animals.

CONCLUSION

The hyperglucidic diet induced hepatic steatosis. In the heart there was an increase in fat content, although no histological changes were observed. These alterations cannot be explained by the presence of malondialdehyde or reduced glutathione (indicators of oxidation), since the values were similar in the groups studied. However, a significant reduction of vitamin E was observed in the experimental group.

Influence of selenium and/or magnesium on alleviation alcohol induced oxidative stress in rats, normalization function of liver and changes in serum lipid parameters

The aim of this study was to evaluate the attenuating effect of given selenium and/or magnesium on ethanol-induced oxidative stress, disturbances of liver function and cholesterol metabolism. Forty male rats were divided into five groups: C – control, Et – intoxicated with alcohol (15% solution in drinking water), Et + Mg, Et + Se, Et + Mg + Se – intoxicated with alcohol and supplemented with selenium (0.4 mg Se/l water), magnesium (100 mg Mg/l water) and combination of Se and Mg, respectively. The experiment was carried out over the 3 months. The results show that the chronic ingestion of alcohol induces lipid peroxidation and histopathological changes in liver. Supplementation with magnesium only partially alleviates oxidative stress and damages in this tissue. The both selenium alone and combination of magnesium and selenium significantly elevated total antioxidant status (TAS) in serum, activity of glutathione peroxidase and ratio of reduced glutathione to oxidized glutathione (GSH/GSSG) in liver and retarded oxidative stress and histopathological changes in this tissue. Chronic administration of ethanol (alone and with magnesium) resulted in significant decrease in the serum total cholesterol and retardation in the body weight gain in comparison with the control group. In the groups supplemented with selenium and selenium and magnesium simultaneously, concentration of total cholesterol in serum and body gains was similar to the control group. Supplementation of Se or selenium and magnesium simultaneously significantly enhances antioxidant defence and is more effective against alcohol-induced oxidative stress, disturbance of liver function and cholesterol metabolism than the separate use of magnesium.

Antioxidant supplements for liver diseases

BACKGROUND

Several liver diseases have been associated with oxidative stress. Accordingly, antioxidants have been suggested as potential therapeutics for various liver diseases. The evidence supporting these suggestions is equivocal.

OBJECTIVES

To assess the benefits and harms of antioxidant supplements for patients with liver diseases.

SEARCH STRATEGY

We searched The Cochrane Library, MEDLINE, EMBASE, LILACS, the Science Citation Index Expanded, and Conference Proceedings Citation Index-Science to January 2011. We scanned bibliographies of relevant publications and asked experts and pharmaceutical companies for additional trials.

SELECTION CRITERIA

We considered for inclusion randomised trials that compared antioxidant supplements (beta-carotene, vitamin A, C, E, and selenium) versus placebo or no intervention for autoimmune liver diseases, viral hepatitis, alcoholic liver disease, and cirrhosis (any aetiology).

DATA COLLECTION AND ANALYSIS

Four authors independently selected trials for inclusion and extracted data. Outcome measures were all-cause mortality, liver-related mortality, liver-related morbidity, biochemical indices at maximum follow-up in the individual trials as well as adverse events, quality-of-life measures, and cost-effectiveness. For patients with hepatitis B or C we also considered end of treatment and sustained virological response. We conducted random-effects and fixed-effect meta-analyses. Results were presented as relative risks (RR) or mean differences (MD), both with 95% confidence intervals (CI).

MAIN RESULTS

Twenty randomised trials with 1225 participants were included. The trials assessed beta-carotene (3 trials), vitamin A (2 trials), vitamin C (9 trials), vitamin E (15 trials), and selenium (8 trials). The majority of the trials had high risk of bias and showed heterogeneity. Overall, the assessed antioxidant supplements had no significant effect on all-cause mortality (relative risk [RR] 0.84, 95% confidence interval [CI] 0.60 to 1.19, I(2) = 0%), or liver-related mortality (RR 0.89, 95% CI 0.39 to 2.05, I(2) = 37%). Stratification according to the type of liver disease did not affect noticeably the results. Antioxidant supplements significantly increased activity of gamma glutamyl transpeptidase (MD 24.21 IU/l, 95% CI 6.67 to 41.75, I(2) = 0%).

AUTHORS' CONCLUSIONS

We found no evidence to support or refute antioxidant supplements in patients with liver disease. Antioxidant supplements may increase liver enzyme activity.

Meta-analysis: antioxidant supplements for liver diseases - the Cochrane Hepato-Biliary Group

BACKGROUND

Several liver diseases have been associated with oxidative stress. Accordingly, antioxidants have been suggested as potential therapeutics for various liver diseases. The evidence supporting these suggestions is equivocal.

AIM

To assess the benefits and harms of antioxidant supplements for patients with liver diseases.

METHODS

We identified trials through electronic and manual searches until August 2009. We included randomized trials comparing antioxidant supplements (beta-carotene, vitamin A, C, E and selenium) vs. placebo or no intervention for autoimmune liver diseases, viral hepatitis, alcoholic liver disease and cirrhosis (any aetiology). Random-effects and fixed-effect meta-analyses were conducted. Results were presented as relative risks (RR), or mean difference (MD), both with 95% confidence intervals (CI).

RESULTS

Twenty randomized trials with 1225 participants were included. The trials assessed beta-carotene (3 trials), vitamin A (2 trials), vitamin C (9 trials), vitamin E (15 trials) and selenium (8 trials). The majority of the trials had high risk of bias and showed heterogeneity. Overall, the assessed antioxidant supplements had no significant effect on all-cause mortality [relative risk (RR) 0.84, 95% confidence interval (CI) 0.60-1.19, I(2) = 0%] or liver-related mortality (RR 0.89, 95% CI 0.39-2.05, I(2) = 37%). Stratification according to the type of liver disease assessed did not affect the conclusions. Antioxidant supplements significantly increased the activity of gamma glutamyl transpeptidase (MD 24.21 IU/L, 95% CI 6.67-41.75, I(2) = 0%).

CONCLUSIONS

We found no evidence to support or refute antioxidant supplements in patients with liver disease. Antioxidant supplements may increase liver enzymes.

Vitamin C metabolites, independent of smoking status, significantly enhance leukocyte, but not plasma ascorbate concentrations

INTRODUCTION

The objective of this study was to test the effects of acute doses of vitamin C alone, calcium ascorbate with vitamin C metabolites, and placebo, on total plasma and leukocyte vitamin C concentrations over 24 hours.

METHODS

A double-blind, placebo-controlled, four-way crossover study was performed consisting of four separate phases lasting 24 hours each and utilizing one of four oral 1000-mg preparations within each phase (one of vitamin C alone, two separate vitamin C formulations of calcium ascorbate with vitamin C metabolites, and placebo). There was a 7-day washout between phases, and blood draws at seven time points within each phase of the study for a total of 28 serologic measurements per subject and 420 total measurements for the entire clinical trial. Vitamin C concentration in plasma and leukocytes were measured by high-performance liquid chromatography at baseline and at six sequential time periods over 24 hours.

RESULTS

Fifteen healthy males were enrolled, aged 18-39 years; nine were had never smoked and six were chronic smokers. No significant difference in plasma vitamin C levels was observed when comparing the different preparations. However, at 24 hours, calcium ascorbate with metabolites resulted in significantly higher concentrations of vitamin C in leukocytes (P<0.0001) compared with vitamin C alone. These results were similar for both metabolite formulations, and independent of smoking status.

CONCLUSION

Regardless of smoking status, vitamin C metabolites may enhance leukocyte utilization of vitamin C itself, despite no consistent difference in plasma levels among the different preparations. A larger clinical investigation is warranted to confirm these preliminary findings, and to determine the clinical relevance of this impact on overall immune function.

Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases

BACKGROUND

Animal and physiological research as well as observational studies suggest that antioxidant supplements may improve survival.

OBJECTIVES

To assess the effect of antioxidant supplements on mortality in primary or secondary prevention randomised clinical trials.

SEARCH STRATEGY

We searched The Cochrane Library (Issue 3, 2005), MEDLINE (1966 to October 2005), EMBASE (1985 to October 2005), and the Science Citation Index Expanded (1945 to October 2005). We scanned bibliographies of relevant publications and wrote to pharmaceutical companies for additional trials.

SELECTION CRITERIA

We included all primary and secondary prevention randomised clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention. Included participants were either healthy (primary prevention trials) or had any disease (secondary prevention trials).

DATA COLLECTION AND ANALYSIS

Three authors extracted data. Trials with adequate randomisation, blinding, and follow-up were classified as having a low risk of bias. Random-effects and fixed-effect meta-analyses were performed. Random-effects meta-regression analyses were performed to assess sources of intertrial heterogeneity.

MAIN RESULTS

Sixty-seven randomised trials with 232,550 participants were included. Forty-seven trials including 180,938 participants had low risk of bias. Twenty-one trials included 164,439 healthy participants. Forty-six trials included 68111 participants with various diseases (gastrointestinal, cardiovascular, neurological, ocular, dermatological, rheumatoid, renal, endocrinological, or unspecified). Overall, the antioxidant supplements had no significant effect on mortality in a random-effects meta-analysis (relative risk [RR] 1.02, 95% confidence interval [CI] 0.99 to 1.06), but significantly increased mortality in a fixed-effect model (RR 1.04, 95% CI 1.02 to 1.06). In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertrial heterogeneity. In the trials with a low risk of bias, the antioxidant supplements significantly increased mortality (RR 1.05, 95% CI 1.02 to 1.08). When the different antioxidants were assessed separately, analyses including trials with a low risk of bias and excluding selenium trials found significantly increased mortality by vitamin A (RR 1.16, 95% CI 1.10 to 1.24), beta-carotene (RR 1.07, 95% CI 1.02 to 1.11), and vitamin E (RR 1.04, 95% CI 1.01 to 1.07), but no significant detrimental effect of vitamin C (RR 1.06, 95% CI 0.94 to 1.20). Low-bias risk trials on selenium found no significant effect on mortality (RR 0.91, 95% CI 0.76 to 1.09).

AUTHORS' CONCLUSIONS

We found no evidence to support antioxidant supplements for primary or secondary prevention. Vitamin A, beta-carotene, and vitamin E may increase mortality. Future randomised trials could evaluate the potential effects of vitamin C and selenium for primary and secondary prevention. Such trials should be closely monitored for potential harmful effects. Antioxidant supplements need to be considered medicinal products and should undergo sufficient evaluation before marketing.