Antioxidative efficacy of parallel and combined supplementation with coenzyme Q10 and d-alpha-tocopherol in mildly hypercholesterolemic subjects: a randomized placebo-controlled clinical study

Effects of Coenzyme Q10 Supplementation on Lipid Profiles in Adults: A Meta-analysis of Randomized Controlled Trials

CONTEXT

Previous meta-analyses have suggested that the effects of coenzyme Q10 (CoQ10) on lipid profiles remain debatable. Additionally, no meta-analysis has explored the optimal intake of CoQ10 for attenuating lipid profiles in adults.

OBJECTIVE

This study conducted a meta-analysis to determine the effects of CoQ10 on lipid profiles and assess their dose-response relationships in adults.

METHODS

Databases (Web of Science, PubMed/Medline, Embase, and the Cochrane Library) were systematically searched until August 10, 2022. The random effects model was used to calculate the mean differences (MDs) and 95% CI for changes in circulating lipid profiles. The novel single-stage restricted cubic spline regression model was applied to explore nonlinear dose-response relationships.

RESULTS

Fifty randomized controlled trials with a total of 2794 participants were included in the qualitative synthesis. The pooled analysis revealed that CoQ10 supplementation significantly reduced total cholesterol (TC) (MD -5.53 mg/dL; 95% CI -8.40, -2.66; I2 = 70%), low-density lipoprotein cholesterol (LDL-C) (MD -3.03 mg/dL; 95% CI -5.25, -0.81; I2 = 54%), and triglycerides (TGs) (MD -9.06 mg/dL; 95% CI -14.04, -4.08; I2 = 65%) and increased high-density lipoprotein cholesterol (HDL-C) (MD 0.83 mg/dL; 95% CI 0.01, 1.65; I2 = 82%). The dose-response analysis showed an inverse J-shaped nonlinear pattern between CoQ10 supplementation and TC in which 400-500 mg/day CoQ10 largely reduced TC (χ2 = 48.54, P < .01).

CONCLUSION

CoQ10 supplementation decreased the TC, LDL-C, and TG levels, and increased HDL-C levels in adults, and the dosage of 400 to 500 mg/day achieved the greatest effect on TC.

Coenzyme Q10 Supplementation and Oxidative Stress Parameters: An Updated Systematic Review and Meta-analysis of Randomized Controlled Clinical Trials

Background: Oxidative stress (OS) contributes to the development of some disorders, including malignancies, metabolic diseases, Alzheimer's disease, and Parkinson's disease. Objectives: The effects of coenzyme Q10 (CoQ10) supplementation on OS parameters have been assessed through an updated systematic review and meta-analysis. Methods: SCOPUS, PubMed, Cochrane Library, EMBASE, and Web of Sciences were used for article searching. Standardized mean difference (SMD) and its standard error were calculated using a random-effects DerSimonian and Laird model. All analyses were done using the STATA software version 16.0 (StataCorp, College Station, TX). Results: Based on twenty-five studies which remained to be incorporated in the meta-analysis, a statistically significant decrease in malondialdehyde (MDA) (SMD -2.74; 95% CI -3.89, -1.58; I2 = 96.9%) as well as nitric oxide (NO) (SMD -5.16; 95% CI -7.98, 2.34; I2 = 92.5%) was associated with CoQ10 supplementation, and a significant increase in total antioxidant capacity (TAC) (SMD 3.40; 95% CI 1.98, 4.83; I2 = 97.4%) and superoxide dismutase (SOD) activity (SMD 1.22; 95% CI 0.32, 2.12; I2 = 94.32%). Conclusions: The results showed no significant effect of CoQ10 supplementation on glutathione peroxidase (GPx), catalase (CAT) activities, and glutathione (GSH) levels. CoQ10 supplementation significantly reduced MDA and NO concentrations and increased TAC and SOD activity.

Coenzyme Q10 and Immune Function: An Overview

Coenzyme Q10 (CoQ10) has a number of important roles in the cell that are required for optimal functioning of the immune system. These include its essential role as an electron carrier in the mitochondrial respiratory chain, enabling the process of oxidative phosphorylation to occur with the concomitant production of ATP, together with its role as a potential lipid-soluble antioxidant, protecting the cell against free radical-induced oxidation. Furthermore, CoQ10 has also been reported to have an anti-inflammatory role via its ability to repress inflammatory gene expression. Recently, CoQ10 has also been reported to play an important function within the lysosome, an organelle central to the immune response. In view of the differing roles CoQ10 plays in the immune system, together with the reported ability of CoQ10 supplementation to improve the functioning of this system, the aim of this article is to review the current literature available on both the role of CoQ10 in human immune function and the effect of CoQ10 supplementation on this system.

Co-enzyme Q10 supplementation for the primary prevention of cardiovascular disease

BACKGROUND

Cardiovascular disease (CVD) remains the number one cause of death and disability worldwide and public health interventions focus on modifiable risk factors, such as diet. Coenzyme Q10 (CoQ10) is an antioxidant that is naturally synthesised by the body and can also be taken as a dietary supplement. Studies have shown that a CoQ10 deficiency is associated with cardiovascular disease.

OBJECTIVES

To determine the effects of coenzyme Q10 supplementation as a single ingredient for the primary prevention of CVD.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2013, Issue 11); MEDLINE (Ovid, 1946 to November week 3 2013); EMBASE (Ovid, 1947 to 27 November 2013) and other relevant resources on 2 December 2013. We applied no language restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) lasting at least three months involving healthy adults or those at high risk of CVD but without a diagnosis of CVD. Trials investigated the supplementation of CoQ10 alone as a single supplement. The comparison group was no intervention or placebo. The outcomes of interest were CVD clinical events and major CVD risk factors, adverse effects and costs. We excluded any trials involving multifactorial lifestyle interventions to avoid confounding.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials for inclusion, abstracted data and assessed the risk of bias.We contacted authors for additional information where necessary.

MAIN RESULTS

We identified six RCTs with a total of 218 participants randomised, one trial awaiting classification and five ongoing trials. All trials were conducted in participants at high risk of CVD, two trials examined CoQ10 supplementation alone and four examined CoQ10 supplementation in patients on statin therapy; we analysed these separately. All six trials were small-scale, recruiting between 20 and 52 participants; one trial was at high risk of bias for incomplete outcome data and one for selective reporting; all studies were unclear in the method of allocation and therefore for selection bias. The dose of CoQ10 varied between 100 mg/day and 200 mg/day and the duration of the interventions was similar at around three months.No studies reported mortality or non-fatal cardiovascular events. None of the included studies provided data on adverse events.Two trials examined the effect of CoQ10 on blood pressure. For systolic blood pressure we did not perform a meta-analysis due to significant heterogeneity. In one trial CoQ10 supplementation had no effect on systolic blood pressure (mean difference (MD) -1.90 mmHg, 95% confidence interval (CI) -13.17 to 9.37, 51 patients randomised). In the other trial there was a statistically significant reduction in systolic blood pressure (MD -15.00 mmHg, 95% CI -19.06 to -10.94, 20 patients randomised). For diastolic blood pressure we performed a random-effects meta-analysis, which showed no evidence of effect of CoQ10 supplementation when these two small trials were pooled (MD -1.62 mmHg, 95% CI -5.2 to 1.96).One trial (51 patients randomised) looked at the effect of CoQ10 on lipid levels. The trial showed no evidence of effect of CoQ10 supplementation on total cholesterol (MD 0.30 mmol/L, 95% CI -0.10 to 0.70), high-density lipoprotein (HDL)-cholesterol (MD 0.02 mmol/L, 95% CI -0.13 to 0.17) or triglycerides (MD 0.05 mmol/L, 95% CI -0.42 to 0.52).Of the four trials that investigated CoQ10 supplementation in patients on statin therapy, three of them showed that simultaneous administration of CoQ10 did not significantly influence lipid levels or systolic blood pressure levels between the two groups. The fourth trial showed a significant increase in the change in total and low-density lipoprotein (LDL)-cholesterol at three months across the four arms of the trial (α-tocopherol, CoQ10, CoQ10 + α-tocopherol and placebo), however the way in which the data were presented meant that we were unable to determine if there was any significant difference between the CoQ10 only and placebo arms. In contrast, there was no significant difference in the change in HDL-cholesterol and triglycerides after three months between the four arms of the trial.

AUTHORS' CONCLUSIONS

There are very few studies to date examining CoQ10 for the primary prevention of CVD. The results from the ongoing studies will add to the evidence base. Due to the small number of underpowered trials contributing to the analyses, the results presented should be treated with caution and further high quality trials with longer-term follow-up are needed to determine the effects on cardiovascular events.

Current experience in testing mitochondrial nutrients in disorders featuring oxidative stress and mitochondrial dysfunction: rational design of chemoprevention trials

An extensive number of pathologies are associated with mitochondrial dysfunction (MDF) and oxidative stress (OS). Thus, mitochondrial cofactors termed "mitochondrial nutrients" (MN), such as α-lipoic acid (ALA), Coenzyme Q10 (CoQ10), and l-carnitine (CARN) (or its derivatives) have been tested in a number of clinical trials, and this review is focused on the use of MN-based clinical trials. The papers reporting on MN-based clinical trials were retrieved in MedLine up to July 2014, and evaluated for the following endpoints: (a) treated diseases; (b) dosages, number of enrolled patients and duration of treatment; (c) trial success for each MN or MN combinations as reported by authors. The reports satisfying the above endpoints included total numbers of trials and frequencies of randomized, controlled studies, i.e., 81 trials testing ALA, 107 reports testing CoQ10, and 74 reports testing CARN, while only 7 reports were retrieved testing double MN associations, while no report was found testing a triple MN combination. A total of 28 reports tested MN associations with "classical" antioxidants, such as antioxidant nutrients or drugs. Combinations of MN showed better outcomes than individual MN, suggesting forthcoming clinical studies. The criteria in study design and monitoring MN-based clinical trials are discussed.

Coenzyme q10 abrogated the 28 days aluminium chloride induced oxidative changes in rat cerebral cortex

Objective:

The present study was designed to elucidate the impact of oral administration of aluminium chloride for 28 days with respect to oxidative stress in the cerebral cortex of female rats. Further, to investigate the potentials of Coenzyme (Co) Q10 (4, 8, and 12 mg/kg, i.p.) in mitigating the detrimental changes.

Materials and Methods:

Biochemical estimations of cerebral lipid peroxidation (LPO), reduced glutathione (GSH), vitamin E and activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were carried out after 28 days of aluminium chloride (AlCl₃) and Co Q10 exposures along with histopathological examination of cerebral cortex of the rats.

Results:

Subacute exposure to AlCl₃(5 mg/kg) led to significant decrease in levels of GSH, vitamin E and activities of SOD, CAT, GPx, and an increase in LPO of cerebral cortex. These aberrations were restored by Co Q10 (12 mg/kg, i.p.). This protection offered was comparable to that of L-deprenyl (1 mg/kg, i.p.) which served as a reference standard. Histopathological evaluations confirmed that the normal cerebral morphology was maintained by Co Q10.

Conclusion:

Thus, AlCl₃ exposure hampers the activities of various antioxidant enzymes and induces oxidative stress in cerebral cortex of female Wistar rats. Supplementation with intraperitoneal Co Q10 abrogated these deleterious effects of AlCl₃.

Nutritional countermeasures targeting reactive oxygen species in cancer: from mechanisms to biomarkers and clinical evidence

Reactive oxygen species (ROS) exert various biological effects and contribute to signaling events during physiological and pathological processes. Enhanced levels of ROS are highly associated with different tumors, a Western lifestyle, and a nutritional regime. The supplementation of food with traditional antioxidants was shown to be protective against cancer in a number of studies both in vitro and in vivo. However, recent large-scale human trials in well-nourished populations did not confirm the beneficial role of antioxidants in cancer, whereas there is a well-established connection between longevity of several human populations and increased amount of antioxidants in their diets. Although our knowledge about ROS generators, ROS scavengers, and ROS signaling has improved, the knowledge about the direct link between nutrition, ROS levels, and cancer is limited. These limitations are partly due to lack of standardized reliable ROS measurement methods, easily usable biomarkers, knowledge of ROS action in cellular compartments, and individual genetic predispositions. The current review summarizes ROS formation due to nutrition with respect to macronutrients and antioxidant micronutrients in the context of cancer and discusses signaling mechanisms, used biomarkers, and its limitations along with large-scale human trials.

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.

Effects of coenzyme Q10 on vascular endothelial function in humans: a meta-analysis of randomized controlled trials

OBJECTIVE

The purpose of this study was to quantify the effect of coenzyme Q10 on arterial endothelial function in patients with and without established cardiovascular disease.

BACKGROUND

Endothelial dysfunction has been implicated in the pathogenesis of atherosclerosis.

METHODS AND RESULTS

The search included MEDLINE, Cochrane Library, Scopus, and EMBASE to identify studies up to 1 July 2011. Eligible studies were randomized controlled trials on the effects of coenzyme Q10 compared with placebo on endothelial function. Two reviewers extracted data on study characteristics, methods, and outcomes. Five eligible trials enrolled a total of 194 patients. Meta-analysis using random-effects model showed treatment with coenzyme Q10 significantly improvement in endothelial function assessed peripherally by flow-mediated dilatation (SMD 1.70, 95% CI: 1.00-2.4, p<0.0001). However, the endothelial function assessed peripherally by nitrate-mediated arterial dilatation was not significantly improved by using fix-effects model (SMD -0.19, 95% CI: -1.75 to 1.38, p = 0.81).

CONCLUSION

Coenzyme Q10 supplementation is associated with significant improvement in endothelial function. The current study supports a role for CoQ10 supplementation in patients with endothelial dysfunction.

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.

Specific and rapid analysis of ubiquinones using Craven's reaction and HPLC with postcolumn derivatization

A new method for the analysis of ubiquinones in various samples was developed using an HPLC system with postcolumn derivatization. Craven's reaction, a specific color reaction for the analysis of ubiquinones, was used in the system. Because the reaction progressed in organic solvents that contained ubiquinones and ethylcyanoacetate under an alkaline condition, the selectivity for ubiquinone detection was higher than that for ubiquinone detection using the nonderivatized ultraviolet detection system at 275 nm, a system widely used for the analysis of ubiquinones. The new detection system can avoid the adverse effects of impurities. Furthermore, it can confirm specificity by stopping the color reaction under a neutral condition. The detection limit for ubiquinone-10 was 1 ng (1.2 pmol). A good linearity for the calibration curve was observed in the range of 11.7 pmol to 11.7 nmol. To investigate the possible application of this method, various samples, such as soybean capsules used as a dietary supplement and biological materials (rice as well as bovine plasma and liver samples), were applied to the system and their ubiquinone contents were quantified. This method is thought to be widely and conveniently applicable for determining the level of ubiquinones because of its high selectivity for ubiquinone detection.

Synergistic effects of phenolics and carotenoids on human low-density lipoprotein oxidation

Low-density lipoprotein oxidation is believed to play an important role in the development of atherosclerosis and therefore a high resistance of LDL against oxidation may prevent atherogenesis and accompanying disorders. Several secondary plant metabolites have been tested for their ability to prevent oxidation of LDL and many phenolics as well as carotenoids have been shown to enhance LDL oxidation resistance. We showed that the quercetingylcoside rutin is able to inhibit copper-induced formation of conjugated dienes and loss of tryptophan fluorescence in LDL. However, enrichment of LDL with the carotenoids lutein or lycopene did not result in an alleviation of LDL oxidation. Since there is an agreement that not one antioxidant alone can lead to health benefits but the combination, as found for example in fruits and vegetables, is the active principle, we tested whether the combination of a phenolic compound (i. e. rutin) and carotenoids (i.e. lutein or lycopene) leads to synergistic effects. Both combinations were shown to exert supra-additive protection of LDL towards oxidation, which is most likely due to different allocation of the antioxidants in the LDL-particle and to different mechanisms of antioxidant action.

Plasma coenzyme Q10 response to oral ingestion of coenzyme Q10 formulations

Plasma coenzyme Q10 (CoQ10) response to oral ingestion of various CoQ10 formulations was examined. Both total plasma CoQ10 and net increase over baseline CoQ10 concentrations show a gradual increase with increasing doses of CoQ10. Plasma CoQ10 concentrations plateau at a dose of 2400 mg using one specific chewable tablet formulation. The efficiency of absorption decreases as the dose increases. About 95% of circulating CoQ10 occurs as ubiquinol, with no appreciable change in the ratio following CoQ10 ingestion. Higher plasma CoQ10 concentrations are necessary to facilitate uptake by peripheral tissues and also the brain. Solubilized formulations of CoQ10 (both ubiquinone and ubiquinol) have superior bioavailability as evidenced by their enhanced plasma CoQ10 responses.

The effect of essential oils of dietary wormwood (Artemisia princeps), with and without added vitamin E, on oxidative stress and some genes involved in cholesterol metabolism

Wormwood (Artemisia princeps) due to the abundance of antioxidant in its essential oils (EO), has been used as a traditional drug and health food in Korea. Oxidative stress plays an important role in the etiology of atherosclerosis thus antioxidative chemicals improves hepatic lipid metabolism partly by reducing oxysterol formation. The antioxidant activity was assessed using two methods, human low-density lipoprotein (LDL) oxidation and the anti-DPPH free radical assays. It was found that the antioxidant activity of EO with vitamin E higher than EO alone. To study mechanisms accounting for the antiatherosclerotic properties of this wormwood EO, we examined the expression of key genes in cholesterol metabolism such as the LDL receptor, the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and sterol regulatory element binding proteins. The induction was increased up to twofold at 0.05 mg/mL of EO treatment in HepG2 cells for 24h. When EO (0.2 mg/mL) was co-incubated with vitamin E, interestingly, the LDL receptor was dramatically induced by 5-6-folds. HMG-CoA reductase did not change. However, treatment with the higher concentration resulted in cytotoxicity. Our data suggest that wormwood EO with vitamin E may be anti-atherogenic due to their inhibition of LDL oxidation and upregulation of the LDL receptor.

Treatment of essential hypertension and non-insulin dependent diabetes mellitus with vitamin C

Inappropriate response of the carotid body region to encroachment of its perfusion results in essential hypertension (EH) and/or non-insulin dependent diabetes mellitus (NIDDM). This encroachment is caused by atherosclerosis. The carotid body perceives the encroachment on the lumen as a reduction in the availability of oxygen and glucose for the brain. Raising the perfusion pressure (thus, resulting in EH) and/ or inducing insulin resistance (causing NIDDM) are seen as compensatory mechanisms in response to the primary pathology, ie the encroachment of the lumen by atherosclerosis. Therefore, the reduction or reversal of the atherosclerosis process will help improve perfusion to the carotid bodies, which will in turn reduce or reverse the pathophysiological compensatory adjustments described above. A supplemental therapy, in addition to the standard treatment, with vitamin C is suggested here. The argument in favour of this suggestion is the basis of this paper. Vitamin C is a very important antioxidant. It is suggested to be used without any interference with the usual therapy prescribed for these two chronic diseases. It is recommended to be administered in small, frequent doses of 100mg every 2h, except during sleep. There is no need for compensation for the occasional missed dose. The safety of larger doses of vitamin C than the current recommendations, represents the beauty and is reassuring in recommending this approach.

Dietary antioxidants in preventing atherogenesis

Several naturally occurring constituents have received considerable attention because of their potential antioxidant activity. Consuming a diet rich in natural antioxidants has been associated with prevention from and/or treatment of atherosclerosis. Bioactive components of food, which are of special interest, include the Vitamins E and C, polyphenols, carotenoids-mainly lycopene and beta-carotene, and coenzyme Q10, featured by antioxidant properties. Antioxidant therapy is supposed to be effective in the early stages of atherosclerosis by preventing LDL oxidation and the oxidative lesion of endothelium. This review focuses on the effect of dietary antioxidants pertained to LDL oxidation and to the vascular endothelial dysfunction. Now that the human genome has been completely sequenced, genetic factors involved in oxidation may open new horizons to identify persons at risk for cardiovascular disease, allowing effective dietary intervention strategies to recover normal homeostasis and to prevent diet-related implications. On this basis, current studies on the action of selected antioxidant nutraceuticals on the activity of transcription factors, such as final targets in the signal transduction cascade and gene regulation, may emerge into new treatment concepts.

Selenium and antioxidant vitamin status of elderly German women

OBJECTIVE

Low antioxidant intake and status have been shown to be associated with an elevated risk for various diseases. Data on the status of antioxidant vitamins, selenium and coenzyme Q10 of younger female seniors are scarce. The aim of this study was to assess the status of these antioxidants, as well as influencing factors such as dietary intake, anthropometric data and educational level in female seniors (60-70 years) in Germany.

DESIGN

Dietary intake of alpha-tocopherol, beta-carotene and ascorbic acid was determined by a 3-day diet record. Serum concentrations of alpha-tocopherol, beta-carotene, ascorbic acid, selenium and coenzyme Q10 were measured. Anthropometric measures, socioeconomic and educational status were assessed.

SETTING

In total, 178 elderly women without severe diseases in the region of Hannover, Germany, were included in the study. The mean (+/- s.d.) age and BMI of the women was 63.2 (2.73) years and 25.6 (3.77) kg/m2, respectively. The study participants were generally better educated than the overall German female population.

RESULTS

Dietary intake of the ascorbic acid and alpha-tocopherol was below RDA in six and 75% of the women, respectively. In comparison to estimated desirable serum concentrations of alpha-tocopherol, ascorbic acid, beta-carotene and selenium, lower concentrations were found in 23, 1, 6, and 39% of the women, respectively. Ascorbic acid (r = 0.205, P = 0.009) and beta-carotene (r = 0.173, P = 0.025) intake were significantly associated with serum concentrations. Beta-carotene concentrations were influenced by the type of diet, BMI, and school education (R2 = 0.128, P < 0.001). Serum selenium was positively associated with alcohol intake (r = 0.229, P = 0.003). Neither employment nor vocational training was predictive for the serum concentrations of antioxidant vitamins, selenium or coenzyme Q10.

CONCLUSIONS

Poor status of selenium and alpha-tocopherol is highly prevalent even among younger, well-educated female seniors, whereas ascorbic acid and beta-carotene status seems sufficient in most women.

Influence of coenzyme Q(10) and cerivastatin on the flow-mediated vasodilation of the brachial artery: results of the ENDOTACT study

AIM

Endothelial dysfunction (ED) is the functional prestep in atherosclerosis. Aim of the present study was to evaluate the effects of a potent antioxidant (coenzyme Q(10), CoQ(10)) and of cerivastatin on ED of the brachial artery.

METHODS AND RESULTS

Twenty-five male patients with manifest ED (flow-mediated vasodilation [FMD%]<4.5%) were included in this prospective, randomized, cross-over study. ED of the brachial artery was assessed by the use of high-resolution ultrasound. Each patient had to pass through three treatment phases ((1) single therapy with cerivastatin (C), (2) single therapy with CoQ(10), (3) combination therapy). FMD% significantly improved throughout all treatment phases ((1) 3.50+/-4.05% vs. 8.80+/-6.39%, p=0.009; (2) -0.25+/-4.0% vs. 7.06%+/-4.39%, p=0.004; (3) 3.14+/-3.54% vs. 8.82+/-5.78%, p=0.011). C led to a significant decrease of CoQ(10) plasma levels (1.23+/-0.34 vs. 0.87+/-0.39 microg/ml, p=0.004).

CONCLUSION

Our results indicate a positive influence of CoQ(10) supplementation on human ED, which appears to be independent of lipid lowering. Although large-scale studies evaluating other antioxidants failed to demonstrate a positive prognostic effect, Q(10) has never been evaluated in larger trials. Experimental as well as clinical results indicate that CoQ(10) warrants further attention in atherosclerosis research.

The monoterpene terpinolene from the oil of Pinus mugo L. in concert with alpha-tocopherol and beta-carotene effectively prevents oxidation of LDL

Antioxidants from several nutrients, e.g. vitamin E, beta-carotene, or flavonoids, inhibit the oxidative modification of low-density lipoproteins. This protective effect could possibly retard atherogenesis and in consequence avoid coronary heart diseases. Some studies have shown a positive effect of those antioxidants on cardiovascular disease. Another class of naturally occurring antioxidants are terpenoids, which are found in essential oils. The essential oil of Pinus mugo and the contained monoterpene terpinolene effectively prevent low-density lipoprotein (LDL)-oxidation. In order to test the mechanism by which terpinolene protects LDL from oxidation, LDL from human blood plasma enriched in terpinolene was isolated. In this preparation not only the lipid part of LDL is protected against copper-induced oxidation--as proven by following the formation of conjugated dienes, but also the oxidation of the protein part is inhibited, since loss of tryptophan fluorescence is strongly delayed. This inhibition is due to a retarded oxidation of intrinsic carotenoids of LDL, and not, as in the case of some flavonoids, attributable to a protection of intrinsic alpha-tocopherol. These results are in agreement with our previous results, which showed the same effects for a monoterpene from lemon oil, i.e. gamma-terpinene.

Effect of supplemental vitamin E for the prevention and treatment of cardiovascular disease

OBJECTIVE

To evaluate and synthesize the evidence on the effect of supplements of vitamin E on the prevention and treatment of cardiovascular disease.

DESIGN

Systematic review of placebo-controlled randomized controlled trials; meta-analysis where justified.

MEASUREMENTS AND MAIN RESULTS

Eighty-four eligible trials were identified. For the outcomes of all-cause mortality, cardiovascular mortality, fatal or nonfatal myocardial infarction, and blood lipids, neither supplements of vitamin E alone nor vitamin E given with other agents yielded a statistically significant beneficial or adverse pooled relative risk (for example, pooled relative risk of vitamin E alone = 0.96 [95% confidence interval (CI), 0.84 to 1.10]; 0.97 [95% CI, 0.80 to 1.90]; and 0.72 [95% CI, 0.51 to 1.02] for all-cause mortality, cardiovascular mortality, and nonfatal myocardial infarction, respectively.

CONCLUSIONS

There is good evidence that vitamin E supplementation does not beneficially or adversely affect cardiovascular outcomes.

Measurement of reduced and oxidized coenzyme Q9 and coenzyme Q10 levels in mouse tissues by HPLC with coulometric detection

BACKGROUND

Ubiquinone-responsive multiple respiratory chain dysfunction due to coenzyme Q(10) (CoQ(10)) deficiency has been previously identified in muscle biopsies. However, previous methods are unreliable for estimating CoQ(10) redox status in tissue. We developed an accurate method for measuring tissue concentrations of reduced and oxidized coenzyme Q (CoQ).

METHODS

Mouse tissues were weighed in the frozen state and homogenized with cold 1-propanol on ice. After solvent extraction, centrifugation and filtration, the filtrate was subsequently analyzed by reversed-phase HPLC with coulometric detection.

RESULTS

Reference calibration curves were used to determine reduced and oxidized coenzyme Q(9) (CoQ(9)) and CoQ(10) concentrations in tissues. The method is sensitive ( approximately 15 microg/l), reproducible (6% CV) for CoQ(9) and CoQ(10), and linear up to 20 mg/l for CoQ(9) and CoQ(10). Analytical recoveries were 90-104%. In mouse tissues the amounts of total CoQ (TQ) ranged from 261 to 1737 nmol/g of protein. Total CoQ(9) levels are comparable with the values of those previously reported. CoQ is found to be mostly in the reduced form in mouse liver ( approximately 87%), heart ( approximately 60%), and muscle tissues ( approximately 58%); in the brain, most of the CoQ is in the oxidized state ( approximately 65%).

CONCLUSION

This procedure provides a precise, sensitive, and direct assay method for the determination of reduced and oxidized CoQ(9) and CoQ(10) in mouse hindleg muscle, heart, brain, and liver tissues.

The degree of unsaturation of dietary fatty acids and the development of atherosclerosis (review)

Atherosclerosis is the principal contributor to the pathogenesis of myocardial and cerebral infarction, gangrene and loss of function in the extremities. It results from an excessive inflammatory-fibroproliferative response to various forms of insult to the endothelium and smooth muscle of the artery wall. Atherosclerotic lesions develop fundamentally in three stages: dysfunction of the vascular endothelium, fatty streak formation and fibrous cap formation. Each stage is regulated by the action of vasoactive molecules, growth factors and cytokines. This multifactorial etiology can be modulated through the diet. The degree of unsaturation of dietary fatty acids affects lipoprotein composition as well as the expression of adhesion molecules and other pro-inflammatory factors, and the thrombogenicity associated with atherosclerosis development. Thus, the preventive effects of a monounsaturated-fatty acid-rich diet on atherosclerosis may be explained by the enhancement of high-density lipoprotein-cholesterol levels and the impairment of low-density lipoprotein-cholesterol levels, the low-density lipoprotein susceptibility to oxidation, cellular oxidative stress, thrombogenicity and atheroma plaque formation. On the other hand, the increase of high-density lipoprotein cholesterol levels and the reduction of thrombogenicity, atheroma plaque formation and vascular smooth muscle cell proliferation may account for the beneficial effects of polyunsaturated fatty acid on the prevention of atherosclerosis. Thus, the advantages of the Mediterranean diet rich in olive oil and fish on atherosclerosis may be due to the modulation of the cellular oxidative stress/antioxidant status, the modification of lipoproteins and the down-regulation of inflammatory mediators.

Serum coenzyme Q10 concentrations in healthy men supplemented with 30 mg or 100 mg coenzyme Q10 for two months in a randomised controlled study

Serum coenzyme Q10 (Q10) concentrations were evaluated in healthy male volunteers supplemented with 30 mg or 100 mg Q10 or placebo as a single daily dose for two months in a randomised, double-blind, placebo-controlled study. Median baseline serum Q10 concentration in 99 men was 1.26 mg/l (10%, 90% fractiles: 0.82, 1.83). Baseline serum Q10 concentration did not depend on age, while borderline significant positive associations were found for body weight and smoking 1-10 cigarettes/d. Supplementation with 30 mg or 100 mg Q10 resulted in median increases in serum Q10 concentration of 0.55 mg/l and 1.36 mg/l, respectively, compared with a median decrease of 0.23 mg/l with placebo. The changes in the Q10 groups were significantly different from that in the placebo group, and the increase in the 100 mg Q10 group was significantly greater than that in the 30 mg Q10 group. The change in serum Q10 concentration in the Q10 groups did not depend on baseline serum Q10 concentration, age, or body weight.

Alpha-tocopherol supplementation in healthy individuals reduces low-density lipoprotein oxidation but not atherosclerosis: the Vitamin E Atherosclerosis Prevention Study (VEAPS)

BACKGROUND

Epidemiological studies have demonstrated an inverse relationship between vitamin E intake and cardiovascular disease (CVD) risk. In contrast, randomized controlled trials have reported conflicting results as to whether vitamin E supplementation reduces atherosclerosis progression and CVD events.

METHODS AND RESULTS

The study population consisted of men and women > or =40 years old with an LDL cholesterol level > or =3.37 mmol/L (130 mg/dL) and no clinical signs or symptoms of CVD. Eligible participants were randomized to DL-alpha-tocopherol 400 IU per day or placebo and followed every 3 months for an average of 3 years. The primary trial end point was the rate of change in the common carotid artery far-wall intima-media thickness (IMT) assessed by computer image-processed B-mode ultrasonograms. A mixed effects model using all determinations of IMT was used to test the hypothesis of treatment differences in IMT change rates. Compared with placebo, alpha-tocopherol supplementation significantly raised plasma vitamin E levels (P<0.0001), reduced circulating oxidized LDL (P=0.03), and reduced LDL oxidative susceptibility (P<0.01). However, vitamin E supplementation did not reduce the progression of IMT over a 3-year period compared with subjects randomized to placebo.

CONCLUSIONS

The results are consistent with previous randomized controlled trials and extend the null results of vitamin E supplementation to the progression of IMT in healthy men and women at low risk for CVD.

Antioxidant vitamins in the prevention of cardiovascular disease: a systematic review

Do antioxidant vitamins, in regular food or as food supplements, protect against myocardial infarction and stroke? In this systematic literature review on the effects of antioxidant vitamins in the primary prevention of cardiovascular disorders, studies with ischaemic heart disease, stroke or combined cardiovascular events as end-points have been included. Studies on the effects of antioxidant vitamins on intermediary end-points (such as blood lipids and blood pressure) and as secondary prevention in patients with manifest cardiovascular disease are reviewed in a conventional manner. In observational studies (case-control or cohort design), people with high intake of antioxidant vitamins by regular diet or as food supplements generally have a lower risk of myocardial infarction and stroke than people who are low-consumers of antioxidant vitamins. The associations in observation studies have been shown for carotene, ascorbic acid as well as tocopherol. In randomized controlled trials, however, antioxidant vitamins as food supplements have no beneficial effects in the primary prevention of myocardial infarction and stroke. Serious adverse events have been reported. After an initial enthusiasm for antioxidants in the secondary prevention of cardiovascular disease, recent reports from of several large randomized trials have failed to show any beneficial effects. Thus, the apparent beneficial results of high intake of antioxidant vitamins reported in observational studies have not been confirmed in large randomized trials. The discrepancy between different types of studies is probably explained by the fact that supplement use is a component in a cluster of healthy behaviour. Antioxidant vitamins as food supplements cannot be recommended in the primary or secondary prevention against cardiovascular disease.

Did the antioxidant trials fail to validate the oxidation hypothesis?

Most clinical trials on antioxidants using vitamin E or beta-carotene have failed to note any significant change in cardiovascular endpoints. The results of these studies have been interpreted as a setback for the oxidation hypothesis. An analysis of the hypothesis and the trials, however, points out major misconceptions about the hypothesis and unjustified outcome expectations. Wrong selection of patient population, endpoints that are incompatible with the hypothesis, poor choice of antioxidants, and lack of inclusion of biochemical markers of oxidative stress and markers of vascular response are some of the contributors to the "failure" of these trials.