Coenzyme Q10: what are the contraindications?

Coenzyme Q10: definition and benefits

First discovered and isolated in the United States in 1957, coenzyme Q10 (often abbreviated to CoQ10) is structurally similar to vitamin K and is found throughout the body (1). Indeed it’s this ubiquity which gives it its other name of ubiquinone.

Coenzyme Q10 is involved in the mitochondrial respiratory chain where it ensures that nutrients are converted into energy directly usable by cells (2). Indeed, it is found at greater concentrations in energy-hungry organs such as the liver, kidneys and heart muscle (3).

Production of CoQ10 unfortunately tends to decline as a result of ageing, lifestyle, and taking certain medications (tricyclic antidepressants and statins, for example) (4-5). It has also been observed that people suffering from heart failure, poor gum health, metabolic abnormalities and muscle pain often have lower levels (6-7).

Coenzyme Q10 supplements (such as Coenzyme Q10, CoQ10+Tocotrienols and Ubiquinol) have thus been growing in popularity in recent years.

Coenzyme Q10: risks and contraindications

Though coenzyme Q10 supplementation is considered safe by the scientific community, it is contraindicated in certain, specific situations.

Pregnant women

Firstly, given the inadequate data available on safety, it is contraindicated for women who are pregnant or breastfeeding, as a precautionary measure.

CoQ10 and potential risks for diabetics

Those suffering from diabetes also need to exercise caution. While coenzyme Q10 is currently at the heart of promising studies on blood sugar regulation, it could, in some patients, cause hypoglycaemia, though this is the subject of much discussion in scientific journals (8-9). The literature also reports rare cases of auto-immune insulin syndrome in non-diabetics (10). While it is still possible to supplement under medical supervision, careful monitoring of blood sugar levels is essential.

Interactions between coenzyme Q10 and certain anticoagulants

Due to its chemical similarity to vitamin K, CoQ10 could also lower the efficacy of vitamin K antagonist-type anticoagulant drugs. Some studies have reported reduced sensitivity to warfarin, a treatment routinely prescribed in coordination with heparin for pulmonary embolisms or thrombophlebitis (11-12). As coenzyme Q10 appears to accelerate its metabolism, there is an increased risk of blood clots (13), although a crossover trial conducted on 24 subjects taking warfarin did not identify any sensitivity interactions (14). In view of the somewhat contradictory conclusions in this respect, it is again best to consult a health professional before starting supplementation.

Taking CoQ10 during treatment for cancer: is there a risk?

Finally, the issue of CoQ10 supplementation during cancer treatment is the subject of much debate. While a number of studies point to its potential protective effect against cardiotoxicity induced by certain chemotherapy drugs, it may, at the same time, reduce the efficacy of pro-oxidant therapeutic strategies such as radiotherapy and certain anti-cancer antibiotics – where the generation of free radicals plays a key role in killing cancer cells (15-16). Here again, it is crucial not to supplement without medical advice.

Coenzyme Q10: side-effects?

Coenzyme Q10 supplements are generally very well tolerated since the molecule is already naturally present in the body (17). Side-effects are therefore rare and mostly mild for healthy individuals, being mainly limited to minor gastrointestinal problems (nausea, diarrhoea).

CoQ10: which supplement to choose

Since production of coenzyme Q10 tends to decline from the age of 30 onwards, here are some tips for increasing your intake (18). While it is found in foods such as beef, chicken, oily fish and some oleaginous fruits, you can easily and significantly boost your intake by taking coenzyme Q10 supplements with high bioavailability (such as Coenzyme Q10, which comes in oil-based capsules for maximum absorption).

In some synergistic formulations, CoQ10 is combined with fat-soluble compounds like vitamin E (tocotrienols and tocopherols) which increases its uptake ten-fold and redirects its action towards the body’s ‘fattier’ organs such as the heart (the CoQ10+Tocotrienols combo is based on a patented blend of the full spectrum of tocotrienols plus alpha-tocopherol) (19).

For it to be mobilised by cells, ubiquinone must first be converted by enzymes into ubiquinol. It’s possible to supplement directly with this form of CoQ10 which is biologically-active and known to be the best absorbed (try Ubiquinol, which again, comes in the form of softgels) (20).