The number of individuals who take Coenzyme Q10 (CoQ10) supplements has been steadily increasing. CoQ10 has been suggested for treatment of a variety of disorders, in particular high blood pressure and statin-induced muscle pain. In this article I would like to discuss the available literature about CoQ10 with a view to answering the question, “Do we have enough evidence that CoQ10 works and that the benefits of taking this supplement justify its significant cost?”
CoQ10 is a potent antioxidant, a membrane stabilizer, and an essential cofactor in the mitochondrial respiratory system, helping to generate adenosine triphosphate (ATP), the main energy source for cells. It is found in all human cells, with the highest concentrations in the heart, liver, kidney, and pancreas. CoQ10 was first isolated from beef heart mitochondria by Frederick Crane of Wisconsin, USA, in 1957. CoQ10 is almost always measured by high performance liquid chromatography (HPLC). CoQ10 is fat soluble and transported in lipoprotein particles in the circulatory system. It has been positively correlated with plasma total cholesterol and Low Density Lipoprotein-cholesterol (LDL-C).
Research studies have shown that plasma CoQ10 is reduced by statins (cholesterol-reducing medication). Both CoQ10 and statins are synthesized by the mevalonate pathway. According to some reports, following statin therapy, the reduction can be up to 54% in plasma/serum CoQ10 concentrations.
The adult reference interval for plasma/serum CoQ10 is approximately 0.5 – 1.7 ?mol/L. Because the plasma CoQ10 level is strongly correlated with lipid level concentration, it has been suggested that the ratio of CoQ10 to total or LDL-cholesterol should be reported.
Different CoQ10 Supplements
Different brands of CoQ10 supplements are currently available on the market; however, due to a lack of standardization, the formulation of these supplements can be significantly different. The variability of supplements and their bioavailability is based on whether they are dry powder capsules or dispersed in oil. Furthermore, significant variability has been seen in the absorption of CoQ10 between individuals. 
CoQ10 from Food
CoQ10 is synthesized in the body, and it is also obtained from the diet. Fish (tuna, salmon, sardines, and mackerel), meat, and vegetable oils are good sources of CoQ10 in food. Meat products are the largest source of CoQ10 in the normal diet.
Cholesterol-lowering Medications and CoQ10
Cholesterol-lowering medications, specifically the so-called “statins”, are effective and safe  drugs that reduce the risk of cardiovascular disease events (heart attacks and strokes). However, statin therapy carries risks ranging from muscle pain and weakness to rhabdomyolysis (breakdown of muscle fibers). Myopathy–muscle pain or weakness with blood creatine kinase levels more than ten times the upper limit of the normal range–typically occurs in fewer than one in 10,000 patients on standard statin doses. However, this risk varies between statins, and increases with use of higher doses and interacting drugs. Rhabdomyolysis is rarer; however, with the release of myoglobin into the circulation, it carries a risk of kidney failure. The etiology behind the muscle pain and discomfort in those taking statins is unclear.
A very small double-blind study of 32 patients published in 2007 has suggested that CoQ10 supplementation may relieve the muscle pain associated with starting statin therapy. However, another study, also published in 2007 and randomizing 44 patients, did not find any improvement in muscle pain and discomfort with CoQ10 supplementation, despite the fact that the patients in this study took a higher dosage of CoQ10 than those in the earlier research.
Some individuals have reported diarrhea, nausea, suppressed appetite, heart burn, and abdominal discomfort. There have not been any meaningful studies on pregnant or breast-feeding women.
Simultaneous use of this supplement with warfarin could result in a decrease in the anticoagulant effect of warfarin.
Oral supplementation of CoQ10 increases plasma, lipoprotein, and blood vessel levels, but it is unclear whether tissue CoQ10 levels are increased, especially in healthy individuals.
Some studies have suggested that cholesterol-lowering medications–the so-called statins–can reduce the synthesis of CoQ10, resulting in decreased plasma concentration . Other studies have not confirmed these findings . Many patients ask whether we have enough convincing and reliable reasons for using CoQ10 for the treatment or prevention of potential statin-related muscle pain. I have to say “No.” Convincing and reliable data is very scarce–almost non-existent. However, I must mention that, if taking this supplement can help a patient who is at risk for more serious heart and vascular complications to remain on statins, a trial of three to four weeks at a dose of 200 mg daily may be worthwhile. Otherwise, longer-term treatment with CoQ10 to treat statin-induced muscle pain or weakness cannot be recommended at this time.
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