Protective Properties of Coenzyme Q10
Effects of Coenzyme Q10 Supplementation on Biomarkers of Oxidative Stress in Adults
A GRADE-Assessed Systematic Review and Updated Meta-Analysis of Randomized Controlled Trials
Oxidative stress, specifically referring to the imbalance between oxidation processes and antioxidant defenses, seems to play a relevant role in the pathogenesis of many age-associated chronic diseases, and aging or age-associated chronic diseases could also increase the level of oxidative stress. The reactive oxygen and nitrogen species (RONS) are highly reactive and toxic molecules continuously produced from the oxidation process. Malondialdehyde (MDA) is the typical product of lipid peroxidation, in which process free radicals attack lipids containing carbon-carbon double bond(s), such as polyunsaturated fatty acids.
The body's antioxidant defenses contain the enzymatic scavenger of RONS by superoxide dismutase (SOD), which can convert superoxide (O2•−) into oxygen and hydrogen peroxide. Total antioxidant capacity (TAC), also named nonenzymatic antioxidant capacity, is usually evaluated as the moles of oxidants neutralized by one liter of body fluids. Under the oxidative stress status, the excessive oxidation products suppress the antioxidant defense system of cells, with MDA, being overproduced and the levels of SOD decreasing. Emerging evidence from long-term prospective studies has suggested that antioxidant supplementation may be effective in attenuating the outcomes of age-associated chronic diseases.
Coenzyme Q10 (CoQ10) is a lipid-soluble antioxidant mainly biosynthesized by the body itself. In vivo, CoQ10 is present in the inner membrane of mitochondria as an electron carrier which contributes to oxidative phosphorylation by transporting electrons from complex I and II to complex III. Apart from this, CoQ10 also obtains much attention for its capability of neutralizing free radicals in lipid structures.
Although CoQ10 can be endogenously biosynthesized, the production of CoQ10 declines with aging, especially for people with age-associated chronic diseases. In light of the fact that only a minor proportion of CoQ10 is obtained from our diet, the administration of CoQ10 supplements warrants more consideration.
Prior systematic reviews of randomized clinical trials (RCTs) have focused on the effects of CoQ10 supplementation on oxidative stress status, but there were fewer studies extended to the general population. The number of studies included for the same oxidative stress biomarkers was inconsistent, although the search deadlines were very close. Furthermore, less information on evidence quality and evidence certainty was made to ascertain potential clinical translatability and effective dose of CoQ10 supplementation targeting oxidative stress. In this context, a comprehensive systematic review and meta-analysis including more RCTs based on the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) method are needed to evaluate the efficacy and optimal dose of CoQ10 supplementation in improving oxidative stress status.
Therefore, we employed this updated systematic review and meta-analysis with the objective to evaluate the role and effective dose of CoQ10 supplements on oxidative stress biomarkers such as TAC, SOD, and MDA in the general population. Furthermore, we assessed the evidence certainty of the antioxidant effect of CoQ10 based on the GRADE approach.
In conclusion, the present systematic review and meta-analysis of 34 RCTs indicate that CoQ10 supplementation may be effective to attenuate oxidative stress status in the general population, especially in people with CAD or T2D. The supplementation of 100–150 mg/day CoQ10 is recommended for ameliorating the oxidative stress status. Further investigations using a larger sample size, a broad age range of elderly people, and a longer supplementation period are required to research the effects of different doses of CoQ10 supplements as well as the circulating CoQ10 levels on people with age-associated chronic diseases.
Dai, S.; Tian, Z.; Zhao, D.; Liang, Y.; Liu, M.; Liu, Z.; Hou, S.; Yang, Y. Effects of Coenzyme Q10 Supplementation on Biomarkers of Oxidative Stress in Adults: A GRADE-Assessed Systematic Review and Updated Meta-Analysis of Randomized Controlled Trials. Antioxidants 2022, 11, 1360. https://doi.org/10.3390/antiox11071360
Published: 13 July 2022