Coenzyme Q10

Coenzyme Q10 (CoQ10) is nature’s biochemical spark plug. CoQ10 is an organic compound which is naturally produced by the body in small quantities and is used in cellular respiration and energy production in mammals. Produced commercially, CoQ10 is made by fermenting beets and sugar cane with yeast. It is consumed as a dietary supplement for its antioxidant properties, and is often promoted as a preventive agent for cardiovascular and neurological diseases, infertility, and cancer.


In oncology there is great interest in CoQ10. It is generally a safe supplement to take but it may be sensible to avoid taking CoQ10 during radiotherapy or chemotherapy as CoQ10 and other antioxidant vitamins might interfere with cancer treatment. This is because research in mice suggests that antioxidant supplements, including CoQ10 may antagonize the effect of radiation therapy.[1] As a result, Oncologists also guide against taking CoQ10 until a few weeks after chemotherapy as well. Due to ethical issues, human studies are lacking to support this evidence however a lab based study showed that CoQ10 did not affect the ability of doxorubicin chemotherapy to kill cancer cells.[2].

CoQ10 supplements may be helpful for some people with advanced cancer who are not on treatment. One study using a mixture of CoQ10, vitamin C, selenium, folic acid and beta carotene found advanced cancer patients lived more than 40% longer than the researchers predicted. The treatments also caused very few side effects.[3]. In addition, two early case reports describe efficacy for diagnosed breast cancer patients as the tumours regressed after taking CoQ10 supplements.[4,5] Since then a lab based study on breast cancer cells have shown that taking CoQ10 positively effects the molecules which effect are linked to cell invasion and metastasis.[6]

It is thought that low levels of circulating CoQ10 may be a useful predictor of cancer risk. In the multiethnic cohort study, scientists assessed the association of circulating CoQ10 levels with prostate cancer risk, using prediagnostic blood samples. The results show the possibility that moderate levels of circulating CoQ10 may be optimal for the reduction of prostate cancer risk.[7]

In melanoma however, CoQ10 plasma levels may be even more useful. A prospective study of patients with melanoma was conducted to assess the usefulness of CoQ10 plasma levels in predicting the risk of metastasis and the duration of the metastasis-free interval. Findings show that baseline plasma CoQ10 levels are a powerful and independent prognostic factor that can be used to estimate the risk for melanoma progression.[8] Baseline levels are also useful in estimating the risk for pancreatic cancer progression.[9] Like in melanoma and pancreatic cancer, low levels of circulating CoQ10 may also predict breast cancer risk in Chinese women, although in the population of women studied, they all had low levels. The risk of breast cancer may therefore only relate to chronically low levels.[10]

In a study of rats with induced hepatocellular carcinoma, CoQ10 in a dose of 0.4mg/kg/day given for 4 weeks reversed damage and prevented progression. It was concluded that CoQ10 may represent a potential therapeutic option for liver carcinogenesis.[11] The same effects are yet to be seen in human trials with liver cancer.


Studies in mice indicate CoQ10 has antioxidant and neuroprotective properties.[12,13] Small neuroprotective effects of CoQ10 have also been reported in a study of patients with progressive supranuclear palsy[14] as well as those with early Parkinson’s disease.[15] Those with midstage Parkinson’s disease do not derive benefit from taking CoQ10.[16] A mixture of antioxidants, including CoQ10, vitamins C, E, and lipoic acid appear to be ineffective against Alzheimer’s disease prevention.[17]


CoQ10 has been shown to confer benefits in patients with coronary artery disease[18] and may also be useful in patients with congestive heart failure.[19] Coenzyme Q10 has been shown to have effects on the endothelial function.[20] It is also known that coenzyme Q10 is a powerful anti-oxidant, mainly against lipid peroxidation.[21] Reports have shown that CoQ10 also reduces inflammatory responses[22] and also does this in those with diabetes.[23] It is reported that the endogenous production of coenzyme Q10 decreases after the age of 20, and the myocardial production is reduced to half at the age of 80.[24]


Female fecundity starts declining at age 32 and decreases more rapidly after age 37.[25] This decrease in the probability of conception occurs in spite of continuing ovulatory cycles.[26] Impaired mitochondrial performance created by suboptimal CoQ10 availability can drive age-associated oocyte deficits causing infertility, as shown by a study where women donated their eggs for experimentation.[27] In rats CoQ10 supplementation may protect ovarian reserve by counteracting both mitochondrial ovarian ageing and physiological programmed ovarian ageing.[28]

CoQ10 supplementation may increase sperm motility in asthenozoospermic men.[29] Dietary CoQ10 intake from foods alone may not be sufficient to optimise semen parameters.[30]


CoQ10 is structurally similar to vitamin K and therefore should be avoided by people taking warfarin as it can have an antagonistic action.[31,32]


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