Written by Helen Cooke and the CAM-Cancer Consortium.
Updated April 29, 2014

Co-enzyme Q10

Does it work?

This summary is currently (April 2016) being updated. The version published here was assessed as up to date in April 2014.

Does CoQ10 work as an anti-cancer agent?

Controlled clinical studies

A trial involving 210 women undergoing tamoxifen treatment for breast cancer reported reduced levels of angiogenesis markers and lipid levels (p<0.05) in the group treated with CoQ10 (100mg) alongside tamoxifen19. Tamoxifen can cause hypertriglyceridemia, increasing the risk of cardiovascular disease, so reducing lipid levels may be beneficial. The women were split into 4 groups; One group were left untreated, one group were treated for more than a year with tamoxifen, one group were followed up for 45 days after they were given instruction to take CoQ10 100mg, another group were followed up for 90 days after they were given instruction to take CoQ10 100mg, Results were compared to 42 disease-free women who acted as a control group. Methodological limitations include lack of randomisation, blinding, inappropriate control groups and questionable patient compliance issues; patients self-administered both tamoxifen and CoQ10.

Researchers who conducted a three year (non-randomised) study with a sample of melanoma patients (n=81) found that the group treated with CoQ10 (400mg) alongside interferon reported improved quality of life (favourable mood effects, reduction in physical weakness and in the severity of tinnitus) compared to the control group who received interferon only. The patients with stage II melanoma in this group also appeared to have a lower rate of metatatic recurrence at 5 year follow-up (approximately 10 times lower). A survival study could not be understaken due to the small patient sample and relatively short duration of follow-up20. Methodological limitations include the use of subjective measures and lack of blinding, which leads to a potential for bias.

Pre-clinical data

There is some preliminary evidence from laboratory and animal studies that chemicals very similar to CoQ10 (analogues of CoQ10) have anti-cancer effects6,43. One study involving mice who had been inoculated with small cell lung cancer and then given CoQ10 and single dose radiation therapy showed less inhibition of tumour growth than the mice in the control group. It was proposed the results may have been due to CoQ10’s antioxidant properties. Radiation leads to the production of free radicals, which antioxidants protect against30.

Overall there is no good quality evidence to support CoQ10 working as an anti-cancer agent. The above controlled trials19,20 were not randomised or high quality clinical trials.

Does CoQ10 work as a protector against adverse effects of chemotherapeutic agents?


A Cochrane systematic review (updated in 2011) reported that no definite conclusions can be made about the efficacy of different cardioprotective agents for cancer patients receiving anthracyclines23. It only included one small (n=20) randomised controlled trial on CoQ10, which did not show cardioprotective effect.

A systematic review by Roffe et al. (2004)24 states that there is some evidence of a protective benefit from CoQ10, however, the authors conclude that the studies reviewed are all methodologically flawed and the results not conclusive. The article reviewed six studies, three randomised and three non-randomised. The numbers of people included in the clinical studies were small, so the results need to be interpreted with caution. The review stated that many unanswered questions remain about the use of CoQ10 alongside anthracycline. Little is known about how long these effects can last for or the best way to administer CoQ10 (what levels should be taken/should it be administered with food etc).

Bryant et al. (2007) conducted a systematic review to evaluate technologies to reduce anthracycline-induced cardiotoxicity in children. The review presented the results of one study that reported a protective effective of CoQ10 on cardiac function 25. The review concluded it was difficult to draw conclusions because related studies were lacking, both in terms of quality and quantity.

Controlled clinical trials

All controlled clinical trials investigating whether CoQ10 protects against chemotherapy induced cardiotoxicity were included in the above systematic reviews.

Pre-clinical data

Animal evidence supporting the cardioprotective effects of CoQ10 has been seen on the heart muscles of mice, rats and rabbits given the chemotherapy drug Doxorubicin (Adriamycin)27,28. However, the same positive benefit was not found in another study with Adriamycin29 and also radiotherapy30. A further mice study concluded that CoQ10 ameliorated acute cisplatin nephrotoxicity31.

It therefore appears that although there is some evidence that CoQ10 works as a protector against adverse effects of several chemotherapeutic drugs, further higher quality trials are still needed to confirm this.

Does CoQ10 work as a protector against chronic fatigue?

CoQ10 supports the release of energy in cells; therefore, it is theorised that chronic fatigue may sometimes be caused by a deficiency in CoQ10. Supporters of this theory suggest that supplementing the diet with CoQ10 may counteract cancer-related chronic fatigue cancer16, but no trials are available.


Helen Cooke, CAM-Cancer Consortium. Co-enzyme Q10 [online document]. http://www.cam-cancer.org/The-Summaries/Dietary-approaches/Co-enzyme-Q10. April 29, 2014.

Document history

Assessed as up to date in April 2014 by Barbara Wider.
Revised and updated in December 2012 by Helen Cooke.
Fully revised and updated in September 2011 by Helen Cooke.
Fully revised and updated in August 2009 by Helen Cooke.
First published in 2005, authored by Helen Seers and Helen Cooke.


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