Xi'an Lide Biochemical Engineering Co., Ltd.

Coenzyme Q₁₀, also known as ubiquinone, ubidecarenone, coenzyme Q, and abbreviated at times to CoQ₁₀/ko kju tn/, CoQ, or Q₁₀ is a coenzyme that is ubiquitous in the bodies of most animals. It is a 1,4-benzoquinone, where Q refers to the quinone chemical group and 10 refers to the number of isoprenyl chemical subunits in its tail.

This fat-soluble substance, which resembles a vitamin, is present in most eukaryotic cells, primarily in themitochondria. It is a component of the electron transport chain and participates in aerobic cellular respiration, which generates energy in the form of ATP. Ninety-five percent of the human bodys energy is generated this way.^[1][2] Therefore, those organs with the highest energy requirementssuch as the heart, liver, and kidneyhave the highest CoQ₁₀ concentrations.^[3][4][5]

There are three redox states of CoQ₁₀: fully oxidized (ubiquinone), semiquinone (ubisemiquinone), and fully reduced(ubiquinol). The capacity of this molecule to act as a 2 electron carrier (moving between the quinone and quinol form) and 1 electron carrier (moving between the semiquinone and one of these other forms) is central to its role in the electron transport chain, and as radical-scavenging antioxidant.

Deficiency and toxicity[edit]

There are two major factors that lead to deficiency of CoQ₁₀ in humans: reduced biosynthesis, and increased use by the body. Biosynthesis is the major source of CoQ₁₀. Biosynthesis requires at least 12 genes, and mutations in many of them cause CoQ deficiency. CoQ₁₀ levels also may be affected by other genetic defects (such as mutations of mitochondrial DNA, ETFDH, APTX, FXN, and BRAF, genes that are not directly related to the CoQ₁₀ biosynthetic process). The role of statins in deficiencies is controversial.^[6] Some chronic disease conditions (cancer, heart disease, etc.) also are thought to reduce the biosynthesis of and increase the demand for CoQ₁₀ in the body, but there are no definite data to support these claims.

Usually, toxicity is not observed with high doses of CoQ₁₀. A daily dosage up to 3600 mg was found to be tolerated by healthy as well as unhealthy persons.^[7]Some adverse effects, however, largely gastrointestinal, are reported with very high intakes. The observed safe level (OSL) risk assessment method indicated that the evidence of safety is strong at intakes up to 1200 mg/day, and this level is identified as the OSL.^[8]

Clinical assessment[edit]

Although CoQ₁₀ may be measured in plasma, these measurements reflect dietary intake rather than tissue status. Currently, most clinical centers measure CoQ₁₀levels in cultured skin fibroblasts, muscle biopsies, and blood mononuclear cells.^[6] Culture fibroblasts can be used also to evaluate the rate of endogenous CoQ₁₀ biosynthesis, by measuring the uptake of 14C-labelled p-hydroxybenzoate.^[9]

Inhibition by statins and beta blockers[edit]

CoQ₁₀ shares a biosynthetic pathway with cholesterol. The synthesis of an intermediary precursor of CoQ₁₀, mevalonate, is inhibited by some beta blockers, blood pressure-lowering medication,^[10] and statins, a class of cholesterol-lowering drugs.^[11] Statins can reduce serum levels of CoQ₁₀ by up to 40%.^[12]

Supplementation[edit]

CoQ₁₀ is not approved by the U.S. Food and Drug Administration (FDA) for the treatment of any medical condition.^[13] It is sold as a dietary supplement. In the U.S., supplements are not regulated as drugs, but as foods. How CoQ₁₀ is manufactured is not regulated and different batches and brands may vary significantly.^[13]

A 2004 laboratory analysis by ConsumerLab.com of CoQ₁₀ supplements on the market found that some did not contain the quantity identified on the product label. Amounts varied from "no detectable CoQ₁₀", to 75% of stated dose, and up to a 75% excess.^[14]

Generally, CoQ₁₀ is well tolerated. The most common side effects are gastrointestinal symptoms (nausea, vomiting, appetite suppression, and stomachache), rash, and headache.^[15]

Heart disease[edit]

A 2014 Cochrane Collaboration meta-analysis found "no convincing evidence to support or refute" the use of CoQ10 for the treatment of heart failure.^[16] Evidence with respect to preventing heart disease in those who are otherwise healthy is also poor.^[17]

Another 2014 study of 420 patients in 17 patient centers over 7 years found that it "improves symptoms, and reduces major adverse cardiovascular events" after 106 weeks.^[18]

A 2009 Cochrane review concluded that studies looking at the effects of CoQ₁₀ on blood pressure were unreliable, and therefore no conclusions could be made regarding its effectiveness in lowering blood pressure.^[19]

Huntington's disease[edit]

Available evidence suggests that "CoQ₁₀ is likely ineffective in moderately improving" the chorea associated with Huntington's disease.^[20]

Male infertility[edit]

While CoQ₁₀ can improve some measurements regarding sperm quality, there is no evidence that CoQ₁₀ increases live births or pregnancy rates.^[21]

Migraine headaches[edit]

Supplementation of CoQ₁₀ has been found to have a beneficial effect on the condition of some sufferers of migraine. This is based on the theory that migraines are a mitochondrial disorder,^[22] and that mitochondrial dysfunction can be improved with CoQ₁₀.^[23] The Canadian Headache Society guideline for migraine prophylaxis recommends, based on low-quality evidence, that 300 mg of CoQ₁₀ be offered as a choice for prophylaxis.^[24]

Statin myopathy[edit]

CoQ₁₀ has been routinely used to treat muscle breakdown associated as a side effect of use of statin medications. However, evidence from randomized controlled trials does not appear to support the idea that CoQ₁₀ is an effective treatment for statin myopathy.^[25]

Cancer[edit]

No large well-designed clinical trials of CoQ₁₀ in cancer treatment have been done.^[13] The National Cancer Institute identified issues with the few, small studies that have been done stating, "the way the studies were done and the amount of information reported made it unclear if benefits were caused by the CoQ₁₀or by something else".^[13] The American Cancer Society has concluded, "CoQ₁₀ may reduce the effectiveness of chemo and radiation therapy, so most oncologists would recommend avoiding it during cancer treatment."^[26]

Dental disease[edit]

A review study has shown that there is no clinical benefit to the use of CoQ₁₀ in the treatment of periodontal disease.^[27] Most of the studies suggesting otherwise were outdated, focused on in-vitro tests,^[28][29][30] had too few test subjects and/or erroneous statistical methodology and trial set-up,^[31][32] or were sponsored by a manufacturer of the product.^[33]

Parkinson's disease[edit]

A 2011 review by the Cochrane Collaboration suggesting CoQ₁₀ supplementation might benefit people with Parkinson's disease was subsequently withdrawn from publication following a review by independent editors.^[34]

Drug interactions[edit]

Coenzyme Q10 has potential to inhibit the effects of warfarin (Coumadin), a potent anticoagulant, by reducing the INR. The structure of coenzyme Q10 is very much similar to the structure of vitamin K, which competes with and counteracts warfarin's anticoagulation effects. Coenzyme Q10 should be avoided in patients currently taking warfarin due to the increased risk of clotting.^[15]