Coenzyme Q10

What is Coenzyme Q10?

Coenzyme Q10 (CoQ10), also known as ubiquinone and ubidecarenone, is often described as a vitamin or at least a vitamin-like substance. However, it is not strictly a vitamin, as it can be synthesised in the liver. CoQ10 is synthesised from the amino acid tyrosine (this synthesis in turn requires other vitamins and minerals) but is also absorbed from a wide variety of foods.

There has been a proliferation of research results showing possible causes of deficiency.¹ It is possible to evaluate these to try to identify indications for supplementation in health and disease. Evidence of benefit from supplementation is harder to find.

As with other vitamins and dietary supplements the strongest case for use can be made in conditions where deficiency is associated with disease and where supplementation corrects or prevents the disease. It is more difficult to establish benefit in health maintenance and disease prevention. In common with other naturally occurring antioxidant compounds, many claims are made for benefit through antioxidant activity.

Contexte²

In common with other coenzymes, it is a cofactor upon which other enzymes depend for their function. It appears to be a coenzyme for a number of cell enzymes, including enzymes within the mitochondrial oxidative phosphorylation pathway which produces adenosine triphosphate (ATP). This is fundamental to energy production within cells. It may also have a role as an antioxidant and it undoubtedly has antioxidant activity.³ It was discovered in the USA and England in 1957 and by the 1970s, could be produced in large enough quantities to allow more research to be done.

Indications²

Since the 1980s it has been possible to measure normal blood and tissue levels of CoQ10, although the latter procedure is not always easily reproducible. It has thus been possible to define deficiency of CoQ10 and possible associated disease. Deficiency can arise through:

• Reduced biosynthesis.

• Increased utilisation.

• Reduced dietary intake.

• A combination of these factors (probably most often the cause).

There are a number of interesting therapeutic possibilities but there is no clear evidence of benefit in any of these to date.

Some examples of possible indications and interesting research findings include the following.

Use with statins

Administration of HMG-CoA reductase inhibitors ('statins') has been associated with a reduction in CoQ10 levels (due to inhibition of mevalonate synthesis). There has been speculation that this reduction may be associated with statin-induced myopathy. However, the reduction may just reflect reduction in the lipoprotein carriers of CoQ10 and may not be statin-specific.

There are mixed reports on the benefits of CoQ10 in helping statin-associated myalgia; it appears to help symptoms but there is no associated decrease in CK levels⁴ ) but routine CoQ10 supplementation is not currently recommended.⁵ There is a lack of evidence to support routine CoQ10 supplementation and even though there are few safety concerns more research is needed to support such a recommendation. The National Institute for Health and Care Excellence (NICE) does not recommend prescribing it to increase statin adherence.⁵

la maladie de Parkinson

There is evidence that impairment of mitochondrial function and oxidative damage contribute to the pathophysiology of Parkinson's disease (PD). Changes in levels of CoQ10 in the cerebrospinal fluid of patients with PD have been found but the clinical significance is unclear. CoQ10 supplementation appears to benefit animal models of PD better than people.⁶

Maladies cardiaques

There are good theoretical reasons for expecting benefit from CoQ10 supplementation in heart disease. There is concern that therapies (such as statins) that may lower CoQ10 levels may also precipitate worsening of heart failure. . A 2021 Cochrane review concluded that there was moderate-quality evidence that coenzyme Q10 probably reduces all-cause mortality and hospitalisation for heart failure.⁷ There is low-quality evidence of inconclusive results as to whether coenzyme Q10 has an effect on the risk of myocardial infarction, or stroke.

Other findings

The role and benefits of CoQ10 have been investigated in a number of conditions but thus far there have been no recommendations for the supplementation. This includes the following conditions:

• Asthme.

• Hypertension.

• Maladie de la thyroïde.

• Subfertility.⁸

• Syndrome de fatigue chronique.

• Pre-eclampsia.

• Mitochondrial disorders.

The British National Formulary for Children (BNFC) does list the unlicensed used of CoQ10 for mitochondrial disorders.⁹

Non-prescription CoQ10

CoQ10 is widely available and patients may initiate therapy themselves. CoQ10 supplementation appears safe without major adverse effects. It has not been tested in pregnancy. A possible interaction with coumarin anticoagulants has been reported at high doses.