Effect of coenzyme Q10 in Europeans with chronic heart failure: A sub-group analysis of the Q-SYMBIO randomized double-blind trial

Evaluating the efficacy of ubiquinol in heart failure patients: a systematic review and meta-analysis

Aim: We aim to analyze past literature to evaluate the efficacy of coenzyme Q10 (CoQ-10) in the population with heart failure (HF). Methods: A systematic literature search was conducted through MEDLINE (via PubMed) and Cochrane Library. The outcomes analyzed were a reduction in HF-related mortality, an improvement in exercise capacity, and the left ventricular ejection fraction (LVEF). Results: Among 16 studies, CoQ-10 significantly reduced HF-related mortality by 40% and improved exercise capacity in patients with HF, but demonstrated no significant difference in LVEF however, the potential of its efficacy on LVEF could not be ruled out. Conclusion: CoQ-10 significantly enhances exercise capacity and reduces HF-related mortality; however, its impact on patients with reduced LVEF requires further investigation.

Comparison of Coenzyme Q10 (Ubiquinone) and Reduced Coenzyme Q10 (Ubiquinol) as Supplement to Prevent Cardiovascular Disease and Reduce Cardiovascular Mortality

PURPOSE OF REVIEW

According to the World Health Organization (WHO), cardiovascular disease is the leading cause of death worldwide. Heart failure has been defined as a global pandemic leading to millions of deaths. Recent research clearly approved the beneficial effect of Coenzyme Q10 supplementation in treatment and prevention of cardiovascular disease in patients with heart failure in clinical trials but did not distinguish between the oxidised form CoQ10 and reduced form CoQH2 of Coenzyme Q10. The aim of this study is to determine differences in medical application of CoQ10 and CoQH2 supplementation and evaluate the efficacy of CoQ10 and CoQH2 supplementation to prevent cardiovascular disease in patients with heart failure.

RECENT FINDINGS

A PubMed search for the terms "ubiquinone" and "ubiquinol" was conducted, and 28 clinical trials were included. Our findings go along with the biochemical description of CoQ10 and CoQH2, recording cardiovascular benefits for CoQ10 and antioxidative and anti-inflammatory properties for CoQH2. Our main outcomes are the following: (I) CoQ10 supplementation reduced cardiovascular death in patients with heart failure. This is not reported for CoQH2. (II) Test concentrations leading to cardiovascular benefits are much lower in CoQ10 studies than in CoQH2 studies. (III) Positive long-term effects reducing cardiovascular mortality are only observed in CoQ10 studies. Based on the existing literature, the authors recommend CoQ10 instead of CoQH2 to treat and prevent cardiovascular disease in patients with heart failure.

Pharmacological Targets in Chronic Heart Failure with Reduced Ejection Fraction

Heart failure management has been repeatedly reviewed over time. This strategy has resulted in improved quality of life, especially in patients with heart failure with reduced ejection fraction (HFrEF). It is for this reason that new mechanisms involved in the development and progression of heart failure, along with specific therapies, have been identified. This review focuses on the most recent guidelines of therapeutic interventions, trials that explore novel therapies, and also new molecules that could improve prognosis of different HFrEF phenotypes.

[Coenzyme Q-10 in the treatment of patients with chronic heart failure and reduced left ventricular ejection fraction: systematic review and meta-analysis]

Aim    The aim of the study was evaluation of the effect of the coenzyme Q10 (Q10) treatment on all-cause and cardiovascular mortality of patients with chronic heart failure (CHF). Q-10 increases the electron transfer in the mitochondrial respiratory chain and exerts anti-inflammatory and antioxidant effects. These effects improve the endothelial function and reduce afterload, which facilitates the heart pumping function. Patients with reduced left ventricular (LV) ejection fraction (EF) (CHFrEF) have low Q10.Material and methods    Criteria of inclusion in the meta-analysis: 1) placebo-controlled studies; 2) enrollment of at least 100 patients; 3) publications after 2010, which implies an optimal basic therapy for CHF; 4) duration of at least 6 months; 5) reported cardiovascular and/or all-cause mortality; 6) using sufficient doses of Q10 (>100 mg/day). The search was performed in CENTRAL, MEDLINE, Embase, Web of Science, E-library, and ClinicalTrials.gov databases. All-cause mortality was the primary efficacy endpoint in this systematic review and the meta-analysis. The secondary endpoint was cardiovascular mortality. Meta-analysis was performed according to the Mantel-Haenszel methods. The Cochrane criterion (I2) was used for evaluation of statistical heterogeneity. The random effects model was used at I2≥50 %, whereas the fixed effects model was used at I2<50.Results    Analysis of studies published from 01.01.2011 to 01.12.2021 identified 357 publications, 23 of which corresponded to the study topic, but only 6 (providing results of four randomized clinical trials, RCT) completely met the predefined criteria. The final analysis included results of managing 1139 patients (586 received Q10 and 553 received placebo). Risk of all-cause death was analyzed by data of four RCTs (1139 patients). The decrease in the risk associated with the Q10 treatment was 36 % (OR=0.64, 95 % CI 0.48-0.87, р=0.004). The heterogeneity of studies was low (Chi2=0.84; p=0.84; I2=0 %). Risk of cardiovascular mortality was analyzed by data of two RCTs (863 patients). The decrease in the risk associated with the Q10 treatment was significant, 55% (OR=0.45, 95 % CI: 0.32-0.64, р=0.00001). In this case, the data heterogeneity was also low (Chi2=0.41; p=0.52; I2=0 %).Conclusion    The meta-analysis confirmed the beneficial effect of coenzyme Q10 on the prognosis of patients with CHFrEF receiving the recommended basic therapy.

Heart Failure—Do We Need New Drugs or Have Them Already? A Case of Coenzyme Q10

Heart failure (HF) is a global epidemic that contributes to the deterioration of quality of life and its shortening in 1–3% of adult people in the world. Pharmacotherapy of HF should rely on highly effective drugs that improve prognosis and prolong life. Currently, the ESC guidelines from 2021 indicate that ACEI, ARNI, BB, and SGLT2 inhibitors are the first-line drugs in HF. It is also worth remembering that the use of coenzyme Q10 brought many benefits in patients with HF. Coenzyme Q10 is a very important compound that performs many functions in the human body. The most important function of coenzyme Q10 is participation in the production of energy in the mitochondria, which determines the proper functioning of all cells, tissues, and organs. The highest concentration of coenzyme Q10 is found in the tissue of the heart muscle. As the body ages, the concentration of coenzyme Q10 in the tissue of the heart muscle decreases, which makes it more susceptible to damage by free radicals. It has been shown that in patients with HF, the aggravation of disease symptoms is inversely related to the concentration of coenzyme Q10. Importantly, the concentration of coenzyme Q10 in patients with HF was an important predictor of the risk of death. Long-term coenzyme Q10 supplementation at a dose of 300 mg/day (Q-SYMBIO study) has been shown to significantly improve heart function and prognosis in patients with HF. This article summarizes the latest and most important data on CoQ10 in pathogenesis.

Levels of Plasma Coenzyme Q10 Are Associated with Physical Capacity and Cardiovascular Risk in the Elderly

Coenzyme Q₁₀ (CoQ₁₀) is an essential factor for mitochondrial activity and antioxidant protection of cells, tissues and plasma lipoproteins. Its deficiency has been associated with aging progression in animals and humans. To determine if CoQ₁₀ levels in plasma can be associated with frailty in elderly people (aged > 65), we studied the relationship of CoQ₁₀ levels in blood with other parameters in plasma and with the physical activity and capacity in aged people. Our results indicate that high CoQ₁₀ levels are directly associated with lower cardiovascular risk measured by the quotient total cholesterol/HDL cholesterol. Furthermore, high CoQ₁₀ levels were found in people showing higher physical activity, stronger muscle capacity. CoQ₁₀ also showed a strong inverse relationship with sedentarism and the up and go test, which is considered to be a frailty index. Interestingly, we found gender differences, indicating stronger correlations in women than in men. The importance of the maintenance of CoQ₁₀ levels in elderly people to avoid sarcopenia and frailty in elderly people is discussed.

Coenzyme Q10 to manage chronic heart failure with a reduced ejection fraction: a systematic review and economic evaluation

BACKGROUND

Chronic heart failure is a debilitating condition that accounts for an annual NHS spend of £2.3B. Low levels of endogenous coenzyme Q10 may exacerbate chronic heart failure. Coenzyme Q10 supplements might improve symptoms and slow progression. As statins are thought to block the production of coenzyme Q10, supplementation might be particularly beneficial for patients taking statins.

OBJECTIVES

To assess the clinical effectiveness and cost-effectiveness of coenzyme Q10 in managing chronic heart failure with a reduced ejection fraction.

METHODS

A systematic review that included randomised trials comparing coenzyme Q10 plus standard care with standard care alone in chronic heart failure. Trials restricted to chronic heart failure with a preserved ejection fraction were excluded. Databases including MEDLINE, EMBASE and CENTRAL were searched up to March 2020. Risk of bias was assessed using the Cochrane Risk of Bias tool (version 5.2). A planned individual participant data meta-analysis was not possible and meta-analyses were mostly based on aggregate data from publications. Potential effect modification was examined using meta-regression. A Markov model used treatment effects from the meta-analysis and baseline mortality and hospitalisation from an observational UK cohort. Costs were evaluated from an NHS and Personal Social Services perspective and expressed in Great British pounds at a 2019/20 price base. Outcomes were expressed in quality-adjusted life-years. Both costs and outcomes were discounted at a 3.5% annual rate.

RESULTS

A total of 26 trials, comprising 2250 participants, were included in the systematic review. Many trials were reported poorly and were rated as having a high or unclear risk of bias in at least one domain. Meta-analysis suggested a possible benefit of coenzyme Q10 on all-cause mortality (seven trials, 1371 participants; relative risk 0.68, 95% confidence interval 0.45 to 1.03). The results for short-term functional outcomes were more modest or unclear. There was no indication of increased adverse events with coenzyme Q10. Meta-regression found no evidence of treatment interaction with statins. The base-case cost-effectiveness analysis produced incremental costs of £4878, incremental quality-adjusted life-years of 1.34 and an incremental cost-effectiveness ratio of £3650. Probabilistic sensitivity analyses showed that at thresholds of £20,000 and £30,000 per quality-adjusted life-year coenzyme Q10 had a high probability (95.2% and 95.8%, respectively) of being more cost-effective than standard care alone. Scenario analyses in which the population and other model assumptions were varied all found coenzyme Q10 to be cost-effective. The expected value of perfect information suggested that a new trial could be valuable.

LIMITATIONS

For most outcomes, data were available from few trials and different trials contributed to different outcomes. There were concerns about risk of bias and whether or not the results from included trials were applicable to a typical UK population. A lack of individual participant data meant that planned detailed analyses of effect modifiers were not possible.

CONCLUSIONS

Available evidence suggested that, if prescribed, coenzyme Q10 has the potential to be clinically effective and cost-effective for heart failure with a reduced ejection fraction. However, given important concerns about risk of bias, plausibility of effect sizes and applicability of the evidence base, establishing whether or not coenzyme Q10 is genuinely effective in a typical UK population is important, particularly as coenzyme Q10 has not been subject to the scrutiny of drug-licensing processes. Stronger evidence is needed before considering its prescription in the NHS.

FUTURE WORK

A new independent, well-designed clinical trial of coenzyme Q10 in a typical UK heart failure with a reduced ejection fraction population may be warranted.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42018106189.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 4. See the NIHR Journals Library website for further project information.

The Instability of the Lipid-Soluble Antioxidant Ubiquinol: Part 3-Misleading Marketing Claims

BACKGROUND

A lack of understanding of the processes involved in the absorption and transfer of the ubiquinol form of Coenzyme Q10 has led to a situation in which incorrect marketing claims are being made for the absorption of ubiquinol supplements, possibly misleading physicians and patients in the selection of a Coenzyme Q10 supplement for heart health benefits.In clinical trials, the ubiquinone form of Coenzyme Q10 has been associated with significantly improved symptoms and survival in patients with heart failure and significantly improved heart function and reduced cardiovascular mortality in community-living senior citizens. The ubiquinone form is the more stable and more extensively researched form. The ubiquinol form is unstable by virtue of being an electron donor that is easily oxidized to the ubiquinone form. Nevertheless, insufficiently documented marketing claims are being made for ubiquinol supplements.

METHODS

To investigate whether or not oral ubiquinol from supplements is absorbed in the ubiquinol form or ubiquinone form, our labs conducted 2 studies of the instability of ubiquinol supplements: a lab study of 13 ubiquinol products sold in the United States and an in vivo study of ubiquinol absorption in large dogs.

RESULTS

In the lab study, 76% to 84% of the oral ubiquinol in the nutritional supplements was oxidized to ubiquinone at body temperature in an 8.2 pH solution simulating small intestinal juice. That is to say, much of the oral ubiquinol had been converted to ubiquinone in the sort of pH environment that it would encounter prior to absorption. In a similar fashion, the percentage of ubiquinol converted to ubiquinone increased as the capsule contents passed through the stomach and small intestines of the study dogs.

CONCLUSIONS

Based on the data from the lab study and the large dog study, we concluded that ubiquinol in commercial nutritional supplements will most likely be oxidized to ubiquinone before it reaches the absorption cells and that the Coenzyme Q10 in the ubiquinol supplements will be absorbed predominantly in the ubiquinone state, transfer into the lymph nodes predominantly in the ubiquinone state and be reduced back to ubiquinol in the lymphatic system.

Coenzyme Q10 in the Treatment of Heart Failure with Preserved Ejection Fraction: A Prospective, Randomized, Double-Blind, Placebo-Controlled Trial

Background

Heart failure with preserved ejection fraction (HFpEF) is common in elderly people and is increasing in prevalence. No specific treatment for this condition exists. Coenzyme Q10 (CoQ10) is an essential cofactor for energy production, with reduced levels being noted in HF. Previous studies have suggested a possible role for CoQ10 in the treatment of HF. This study examined the effect of CoQ10 supplementation on diastolic function in HFpEF patients.

Methods

We conducted a prospective, randomized, double-blind, placebo-controlled trial including patients aged > 55 years presenting with New York Heart Association class II–IV heart failure symptoms and left ventricular ejection fraction > 50%, with impaired diastolic function. Echocardiography and levels of serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) were performed at baseline and following 4 months of CoQ10 or placebo supplementation.

Results

A total of 39 patients were enrolled—19 in the CoQ10 group and 20 in the placebo group. Baseline clinical characteristics were similar between groups, while compliance was high and also similar between the CoQ10 and placebo groups. There was no significant effect of treatment on indices of diastolic function (difference in the lateral E/e' ratio: −0.86 ± 6.57 in the CoQ10 group, +0.18 ± 3.76 in the placebo group; p = 0.561) or on serum NT-proBNP levels (− 72 pg/mL vs. − 42 pg/mL; p = 0.195).

Conclusions

In this pilot trial in elderly patients with HFpEF, treatment with CoQ10 did not significantly affect echocardiographic indices of diastolic function and serum NT-proBNP levels.

Trial Registration

This trial was registered in the US National Institutes of Health Clinical Trials Registry (ClinicalTrials.gov identifier: NCT02779634).

Role of Coenzyme Q10 in Health and Disease: An Update on the Last 10 Years (2010-2020)

The present review focuses on preclinical and clinical studies conducted in the last decade that contribute to increasing knowledge on Coenzyme Q₁₀'s role in health and disease. Classical antioxidant and bioenergetic functions of the coenzyme have been taken into consideration, as well as novel mechanisms of action involving the redox-regulated activation of molecular pathways associated with anti-inflammatory activities. Cardiovascular research and fertility remain major fields of application of Coenzyme Q₁₀, although novel applications, in particular in relation to topical application, are gaining considerable interest. In this respect, bioavailability represents a major challenge and the innovation in formulation aspects is gaining critical importance.

Mitochondrial Dysfunction in Atrial Fibrillation-Mechanisms and Pharmacological Interventions

Despite the enormous progress in the treatment of atrial fibrillation, mainly with the use of invasive techniques, many questions remain unanswered regarding the pathomechanism of the arrhythmia and its prevention methods. The development of atrial fibrillation requires functional changes in the myocardium that result from disturbed ionic fluxes and altered electrophysiology of the cardiomyocyte. Electrical instability and electrical remodeling underlying the arrhythmia may result from a cellular energy deficit and oxidative stress, which are caused by mitochondrial dysfunction. The significance of mitochondrial dysfunction in the pathogenesis of atrial fibrillation remains not fully elucidated; however, it is emphasized by the reduction of atrial fibrillation burden after therapeutic interventions improving the mitochondrial welfare. This review summarizes the mechanisms of mitochondrial dysfunction related to atrial fibrillation and current pharmacological treatment options targeting mitochondria to prevent or improve the outcome of atrial fibrillation.

Coenzyme Q10: Clinical Applications beyond Cardiovascular Diseases

Coenzyme Q₁₀ (CoQ₁₀) is an essential cofactor in oxidative phosphorylation (OXPHOS), present in mitochondria and cell membranes in reduced and oxidized forms. Acting as an energy transfer molecule, it occurs in particularly high levels in the liver, heart, and kidneys. CoQ₁₀ is also an anti-inflammatory and antioxidant agent able to prevent the damage induced by free radicals and the activation of inflammatory signaling pathways. In this context, several studies have shown the possible inverse correlation between the blood levels of CoQ₁₀ and some disease conditions. Interestingly, beyond cardiovascular diseases, CoQ₁₀ is involved also in neuronal and muscular degenerative diseases, in migraine and in cancer; therefore, the supplementation with CoQ₁₀ could represent a viable option to prevent these and in some cases might be used as an adjuvant to conventional treatments. This review is aimed to summarize the clinical applications regarding the use of CoQ₁₀ in migraine, neurodegenerative diseases (including Parkinson and Alzheimer diseases), cancer, or degenerative muscle disorders (such as multiple sclerosis and chronic fatigue syndrome), analyzing its effect on patients’ health and quality of life.

The Use of Coenzyme Q10 in Cardiovascular Diseases

CoQ10 is an endogenous antioxidant produced in all cells that plays an essential role in energy metabolism and antioxidant protection. CoQ10 distribution is not uniform among different organs, and the highest concentration is observed in the heart, though its levels decrease with age. Advanced age is the major risk factor for cardiovascular disease and endothelial dysfunction triggered by oxidative stress that impairs mitochondrial bioenergetic and reduces NO bioavailability, thus affecting vasodilatation. The rationale of the use of CoQ10 in cardiovascular diseases is that the loss of contractile function due to an energy depletion status in the mitochondria and reduced levels of NO for vasodilatation has been associated with low endogenous CoQ10 levels. Clinical evidence shows that CoQ10 supplementation for prolonged periods is safe, well-tolerated and significantly increases the concentration of CoQ10 in plasma up to 3–5 µg/mL. CoQ10 supplementation reduces oxidative stress and mortality from cardiovascular causes and improves clinical outcome in patients undergoing coronary artery bypass graft surgery, prevents the accumulation of oxLDL in arteries, decreases vascular stiffness and hypertension, improves endothelial dysfunction by reducing the source of ROS in the vascular system and increases the NO levels for vasodilation.

The Role of Antioxidants Supplementation in Clinical Practice: Focus on Cardiovascular Risk Factors

Oxidative stress may be defined as an imbalance between reactive oxygen species (ROS) and the antioxidant system to counteract or detoxify these potentially damaging molecules. This phenomenon is a common feature of many human disorders, such as cardiovascular disease. Many of the risk factors, including smoking, hypertension, hypercholesterolemia, diabetes, and obesity, are associated with an increased risk of developing cardiovascular disease, involving an elevated oxidative stress burden (either due to enhanced ROS production or decreased antioxidant protection). There are many therapeutic options to treat oxidative stress-associated cardiovascular diseases. Numerous studies have focused on the utility of antioxidant supplementation. However, whether antioxidant supplementation has any preventive and/or therapeutic value in cardiovascular pathology is still a matter of debate. In this review, we provide a detailed description of oxidative stress biomarkers in several cardiovascular risk factors. We also discuss the clinical implications of the supplementation with several classes of antioxidants, and their potential role for protecting against cardiovascular risk factors.

Mitochondria as a therapeutic target for cardiac ischemia‑reperfusion injury (Review)

Acute myocardial infarction is the leading cause of cardiovascular-related mortality and chronic heart failure worldwide. As regards treatment, the reperfusion of ischemic tissue generates irreversible damage to the myocardium, which is termed 'cardiac ischemia-reperfusion (IR) injury'. Due to the large number of mitochondria in cardiomyocytes, an increasing number of studies have focused on the roles of mitochondria in IR injury. The primary causes of IR injury are reduced oxidative phosphorylation during hypoxia and the increased production of reactive oxygen species (ROS), together with the insufficient elimination of these oxidative species following reperfusion. IR injury includes the oxidation of DNA, incorrect modifications of proteins, the disruption of the mitochondrial membrane and respiratory chain, the loss of mitochondrial membrane potential (∆Ψm), Ca²⁺ over-load, mitochondrial permeability transition pore formation, swelling of the mitochondria, and ultimately, cardiomyocyte necrosis. The present review article discusses the molecular mechanisms of IR injury, and summarizes the metabolic and dynamic changes occurring in the mitochondria in response to IR stress. The mitochondria are strongly recommended as a target for the development of therapeutic agents; however, the appropriate use of agents remains a challenge.

Statin Treatment in Specific Patient Groups: Role for Improved Cardiovascular Risk Markers

Ample evidence supports the use of statin therapy for secondary prevention in patients with a history of atherosclerotic cardiovascular disease (ASCVD), but evidence is wanting in the case of primary prevention, low-risk individuals, and elderly adults 65+. Statins are effective in lowering low-density lipoprotein (LDL), which has long been a target for treatment decisions. We discuss the weakening dependence between cholesterol levels and mortality as a function of age and highlight recent findings on lipoprotein subfractions and other superior markers of ASCVD risk. The efficacy of statins is compared for distinct subsets of patients based on age, diabetes, ASCVD, and coronary artery calcium (CAC) status. Most cardiovascular risk calculators heavily weight age and overestimate one's absolute risk of ASCVD, particularly in very old adults. Improvements in risk assessment enable the identification of specific patient populations that benefit most from statin treatment. Derisking is particularly important for adults over 75, in whom treatment benefits are reduced and adverse musculoskeletal effects are amplified. The CAC score stratifies the benefit effect size obtainable with statins, and forms of coenzyme Q are discussed for improving patient outcomes. Robust risk estimator tools and personalized, evidence-based approaches are needed to optimally reduce cardiovascular events and mortality rates through administration of cholesterol-lowering medications.

Low coenzyme Q10 levels in patients with acute cardiovascular disease are associated with long-term mortality

Coenzyme Q10 (CoQ10) plays a potential role in the prevention and treatment of cardiovascular disease through improved cellular bioenergetics. Critical illness in the intensive care unit has been reported to be associated with decreased circulating CoQ10 levels, and we previously demonstrated the association of low CoQ10 levels with in-hospital mortality. However, the association of CoQ10 with the acute phase of cardiovascular disease and long-term mortality remains unclear. We enrolled 242 consecutive patients with cardiovascular disease admitted to the coronary care unit of Juntendo University Hospital to investigate the association between long-term mortality and serum CoQ10 levels. During a mean follow-up of 3.2 years, 58 patients died. The mean serum CoQ10 levels were significantly lower in the non-survivors than in the survivors (0.48 ± 0.27 vs. 0.58 ± 0.38 mg/L; p = 0.035). Compared with the patients with above-median CoQ10 levels (0.46 mg/L), the cumulative incidence of all-cause mortality was significantly higher in those with lower CoQ10 levels (p = 0.025). Multivariate Cox regression analysis further demonstrated that lower CoQ10 levels were associated with poor prognosis. Low serum CoQ10 levels during the acute phase of cardiovascular diseases were associated with long-term mortality in patients, suggesting the utility of low serum CoQ10 levels as a predictor and potential therapeutic target.

Disorders of Human Coenzyme Q10 Metabolism: An Overview

Coenzyme Q10 (CoQ10) has a number of vital functions in all cells, both mitochondrial and extramitochondrial. In addition to its key role in mitochondrial oxidative phosphorylation, CoQ10 serves as a lipid soluble antioxidant, plays an important role in fatty acid, pyrimidine and lysosomal metabolism, as well as directly mediating the expression of a number of genes, including those involved in inflammation. In view of the central role of CoQ10 in cellular metabolism, it is unsurprising that a CoQ10 deficiency is linked to the pathogenesis of a range of disorders. CoQ10 deficiency is broadly classified into primary or secondary deficiencies. Primary deficiencies result from genetic defects in the multi-step biochemical pathway of CoQ10 synthesis, whereas secondary deficiencies can occur as result of other diseases or certain pharmacotherapies. In this article we have reviewed the clinical consequences of primary and secondary CoQ10 deficiencies, as well as providing some examples of the successful use of CoQ10 supplementation in the treatment of disease.

The Effect of Cellular Coenzyme Q10 Deficiency on Lysosomal Acidification

Coenzyme Q₁₀ (CoQ₁₀) deficiency currently represents the only treatable mitochondrial disorder, however, little is known about how it may affect other organelles. The lysosome has been found to have a large concentration of CoQ₁₀ localised at its membrane; additionally, it has been suggested that it plays a role in the normal acidification of the lysosomal lumen. As a result, in this study we assessed the effect of CoQ₁₀ deficiency on lysosomal acidification. In order to investigate this, a neuronal cell model of CoQ₁₀ deficiency was established via the treatment of SH-SY5Y cells with para-aminobenzoic acid (PABA). This method works through the competitive inhibition of the CoQ₁₀ biosynthetic pathway enzyme, CoQ₂. A single 1 mM (5 days) treatment with PABA resulted in a decrease of up to 58% in cellular CoQ₁₀ (p < 0.05). It was found that this resulted in a significant decrease in fluorescence of both the LysoSensor (23%) and LysoTracker (35%) probes used to measure lysosomal pH (p < 0.05). It was found that subsequent treatment with CoQ₁₀ (5 µM, 3 days) was able to restore cellular CoQ₁₀ concentration (p < 0.005), which was associated with an increase in fluorescence from both probes to around 90% of controls (p < 0.05), suggesting a restoration of lysosomal pH. This study provides insights into the association between lysosomal pH and cellular CoQ₁₀ status and the possibility that a deficit in the status of this isoprenoid may result in an impairment of lysosomal acidification.

Bioavailability of Coenzyme Q10: An Overview of the Absorption Process and Subsequent Metabolism

A lack of understanding of the processes determining the absorption and subsequent metabolism of coenzyme Q₁₀ (CoQ₁₀) has resulted in some manufacturers’ making incorrect claims regarding the bioavailability of their CoQ₁₀ supplements, with potential consequences for the use of such products in clinical trials. The purpose of the present review article is, therefore, to describe the various stages of exogenous CoQ₁₀ metabolism, from its first ingestion, stomach transit, absorption from the small intestine into the lymphatic system, transport in blood, and access into cells. In particular, the importance of CoQ₁₀ crystal dispersion in the initial formulation is emphasised, the absence of which reduces bioavailability by 75%. In addition, evidence comparing the relative bioavailability and efficacy of ubiquinone and ubiquinol forms of CoQ₁₀ has been reviewed.

Clinical Evidence for Q10 Coenzyme Supplementation in Heart Failure: From Energetics to Functional Improvement

Oxidative stress and mitochondrial dysfunction are hallmarks of heart failure (HF). Coenzyme Q10 (CoQ10) is a vitamin-like organic compound widely expressed in humans as ubiquinol (reduced form) and ubiquinone (oxidized form). CoQ10 plays a key role in electron transport in oxidative phosphorylation of mitochondria. CoQ10 acts as a potent antioxidant, membrane stabilizer and cofactor in the production of adenosine triphosphate by oxidative phosphorylation, inhibiting the oxidation of proteins and DNA. Patients with HF showed CoQ10 deficiency; therefore, a number of clinical trials investigating the effects of CoQ10 supplementation in HF have been conducted. CoQ10 supplementation may confer potential prognostic advantages in HF patients with no adverse hemodynamic profile or safety issues. The latest evidence on the clinical effects of CoQ10 supplementation in HF was reviewed.

Comparative Bioavailability of Different Coenzyme Q10 Formulations in Healthy Elderly Individuals

Coenzyme Q10 (CoQ10) plays a central role in mitochondrial oxidative phosphorylation. Several studies have shown the beneficial effects of dietary CoQ10 supplementation, particularly in relation to cardiovascular health. CoQ10 biosynthesis decreases in the elderly, and consequently, the beneficial effects of dietary supplementation in this population are of greater significance. However, most pharmacokinetic studies have been conducted on younger populations. The aim of this study was to investigate the single-dose bioavailability of different formulations of CoQ10 in a healthy geriatric population. A randomized, three-period, crossover bioavailability study was conducted on 21 healthy older adults (aged 65–74). The treatment was a single dose with a one-week washout period. Three different formulations containing the equivalent of 100 mg of CoQ10 were used: Q10Vital^® water-soluble CoQ10 syrup (the investigational product—IP); ubiquinol capsules (the comparative product—CP); and ubiquinone capsules (the standard product—SP). Ubiquinone/ubiquinol was followed in the plasma for 48 h. An analysis of the ratio of the area under the baseline-corrected concentration curve (ΔAUC₄₈) for total CoQ10 and a comparison to SP yielded the following: The bioavailability of CoQ10 in the IP was 2.4-fold higher (95% CI: 1.3–4.5; p = 0.002), while the bioavailability of ubiquinol (CP) was not significantly increased (1.7-fold; 95% CI: 0.9–3.1, p = 0.129). No differences in the redox status of the absorbed coenzyme Q10 were observed between formulations, showing that CoQ10 appeared in the blood mostly as ubiquinol, even if consumed as ubiquinone.

The Important Role of CoQ10 in Aging

Coenzyme Q₁₀ (CoQ₁₀) is an essential lipid present in all cell membranes[...].