Coenzyme Q10 (CoQ10), also known as ubiquinone, is an increasingly popular ingredient in dietary supplements. Its growing popularity is not only due to its role in cellular energy production but also because of its strong antioxidant properties. As a result, it is often used as a support in the treatment of diseases related to oxidative stress, such as heart disease, diabetes, cancer, and neurodegenerative diseases.
First, let’s focus on what coenzyme Q10 is and its role in our body. Coenzyme Q10 is a naturally occurring compound in the human body, essential for the proper functioning of cells. Its chemical structure makes it highly soluble in fats, enabling it to rapidly penetrate cell membranes. CoQ10 is an essential building block of mitochondria – the organelles responsible for energy production in cells.
In a biochemical context, Coenzyme Q10 serves many functions. One of the most important is its role in the production of adenosine triphosphate (ATP), which is the body’s primary energy carrier. Therefore, CoQ10 is found in higher concentrations in tissues with high energy demands, such as the heart, liver, kidneys, and muscles.
In addition to its role in energy production, CoQ10 is a potent antioxidant. Its reduced form, called ubiquinol, has the ability to neutralize free radicals, helping to protect cells from oxidative stress. By regenerating other antioxidants, such as vitamin E, CoQ10 becomes an important element in protection against oxidative damage.
One of the key areas where coenzyme Q10 has been used is in cardiology. Its deficiency has been linked to many health problems, including congestive heart failure. Heart diseases are one of the most common causes of death worldwide, so finding effective therapies is a priority. For this reason, researchers from the University of Japan conducted a study in 2020 to investigate whether ubiquinol supplementation could contribute to improving endothelial function in patients with heart failure with reduced ejection fraction (HFrEF). The study involved 20 patients with stabilized heart failure. One month after enrollment, which was the period needed to exclude the influence of previously used treatment methods, the patients started alternative treatment lasting for 3 months. Randomly assigned groups of patients received ubiquinol at a dose of 400mg per day (200mg twice a day) or were given a placebo. The endothelial function was assessed using the Reactive Hyperemia Index (RHI), which is a measure of vascular reactivity and is used to evaluate endothelial function. Endothelial function plays a crucial role in processes such as the release of nitric oxide (NO), which is responsible for blood vessel dilation, regulation of vascular permeability, and modulation of inflammatory and blood clotting responses. The low value of RHI indicates impaired endothelial function, which is associated with many cardiovascular diseases, including heart failure. Using the logarithmic version of the index (LnRHI) allows for a better capture of subtle differences in low values, providing a more stable and statistically consistent assessment of changes in endothelial function. In the presented study, the analysis of LnRHI showed a tendency for improvement in vascular health. Additionally, a significant change in RHI values before and after ubiquinol treatment was demonstrated, with a change from 1.57 to 1.74, while there were no significant changes in the placebo group. However, there was no significant impact on kidney function, lipid profile, fasting glucose, or level of type natriuretic peptide. Nevertheless, this is the first study to show that CoQ10 significantly improved endothelial function as assessed by RHI. The LnRHI level increased from 0.45 to 0.55 as a result of supplementation. According to a recently published meta-analysis, a 0.1 increase in LnRHI corresponds to a 21% decrease in the risk of cardiovascular events. However, initial LnRHI levels (after the first month) did not show significant differences between groups, suggesting a small impact of ubiquinol on improving endothelial function. This could be due to a short washout period, which may have influenced the lack of complete reversibility of the effects. Other limitations of the study included a small number of patients and a lack of assessment of endothelial function and oxidative stress markers. Despite these limitations, the study results suggest that CoQ10 may support the treatment of cardiovascular diseases. However, further larger studies are needed to confirm these observations and to more precisely investigate the mechanisms behind the action of this supplement.
Although the mechanisms of CoQ10’s action on endothelial function remain unclear, its significant impact on improving energy metabolism and preventing oxidative stress in cardiac muscle cells can be confirmed. Therefore, endothelial function can serve not only as a diagnostic and prognostic marker, but also as a therapeutic target, even in advanced conditions such as heart failure.
Based on the article by Kawashima C, Matsuzawa Y, Konishi M, Akiyama E, Suzuki H, Sato R, Nakahashi H, Kikuchi S, Kimura Y, Maejima N, Iwahashi N, Hibi K, Kosuge M, Ebina T, Tamura K, Kimura K. “Ubiquinol Improves Endothelial Function in Patients with Heart Failure with Reduced Ejection Fraction: A Single-Center, Randomized Double-Blind Placebo-Controlled Crossover Pilot Study.” Am J Cardiovasc Drugs. 2020 Aug;20(4):363-372. doi: 10.1007/s40256-019-00384-y. PMID: 31713723.
