Coenzyme Q10 (CoQ10), also known as ubiquinone, is involved in cellular respiration and energy production. It is found in all human cells, with higher concentrations found in the liver, kidney, heart, and pancreas. It is also consumed as a dietary supplement for its antioxidant effects and is often promoted as a preventive agent for cardiovascular diseases, Parkinson’s disease, infertility, and cancer. Studies using murine models suggest antioxidant and neuroprotective effects ^(17) (18), and the potential to alleviate radiation-induced nephropathy ⁽³⁴⁾.

Data from some human studies suggest CoQ10 may benefit patients with coronary artery disease ⁽²⁾ and congestive heart failure ⁽²¹⁾, and reduce risk of cardiovascular mortality ⁽⁴⁶⁾. In a long-term trial, dietary supplementation with a combination of selenium and CoQ10 also improved cardiac function and significantly reduced mortality ^(43) (47). However, a systematic review concluded that current evidence does not support routine CoQ10 supplementation in patients with coronary heart disease ⁽⁴²⁾.

Observations that patients on statins have decreased CoQ10 concentrations in muscle cells ⁽²⁵⁾ resulted in efforts to evaluate CoQ10 for statin-induced myalgias, but data are inconclusive ^{(26) (27) (28) (45) (52)}. Short-term CoQ10 supplementation in diabetic hemodialysis patients improved markers of insulin metabolism, but not fasting glucose, HbA1c, or lipid profiles ⁽⁴⁸⁾. A meta-analysis concluded that evidence of benefit for diabetic kidney disease is limited and that additional study is needed ⁽⁴⁹⁾.

CoQ10 may be helpful in some cases for migraine prevention ⁽²²⁾. A small study found reduced migraine frequency following supplementation ⁽²³⁾, and other data suggest it may reduce number of migraine days and duration, but not number of attacks or severity ⁽⁵⁰⁾. A randomized trial of add-on supplementation in pediatric migraine failed to find benefit ⁽²⁴⁾.

In other studies, adjuvant CoQ10 improved depressive symptoms in patients with bipolar disorder ⁽⁴⁴⁾, but an antioxidant mixture including CoQ10, vitamins C and E, and lipoic acid was ineffective against Alzheimer’s disease ⁽²⁰⁾. Neuroprotective effects were reported in patients with progressive supranuclear palsy ⁽⁵⁾ and those with early ^(6) (33) but not mid-stage ⁽⁷⁾ Parkinson’s disease. Case reports also suggest CoQ10 supplementation improves postural hypotension, a hallmark of multiple-system atrophy ⁽³⁶⁾. However, a large multicenter trial found CoQ supplementation ineffective in slowing functional decline of Huntington’s disease ⁽⁵¹⁾.

Other data suggest CoQ10 supplementation may increase sperm motility in men ⁽⁸⁾, modulate expression of insulin, lipid, and inflammatory markers in women with polycystic ovary syndrome ⁽³⁵⁾, and reduce fatigue from physical exertion ⁽⁹⁾; affect reductions in oxidative stress markers ⁽⁵³⁾; as well as inflammatory markers in patients with chronic diseases ⁽⁵⁴⁾. In a study involving patients with sepsis, supplementation in early phase had a positive effect on clinical parameters and mitochondrial dysfunction ⁽⁵⁵⁾.

CoQ10 has also been investigated for anticancer effects. In patients with hepatocellular carcinoma, coenzyme Q10 levels were positively associated with antioxidant capacity and negatively correlated with inflammation markers post-surgery ⁽³⁷⁾. In breast cancer patients, a combination of CoQ10 and L-carnitine helped control cancer-related fatigue ⁽³⁸⁾; and in patients on tamoxifen therapy, CoQ10 was found effective in lowering inflammatory cytokine levels ⁽⁵⁶⁾. Older case reports suggest supplementation may be useful for treating the cancer ^(3) (4), although a randomized trial found no benefit against self-reported fatigue or quality of life ⁽²⁹⁾. Furthermore, antioxidant supplementation, including CoQ10, before and during treatment, was associated with an increased hazard of recurrence in breast cancer patients ⁽⁵⁷⁾. More research is needed ⁽³⁹⁾.

CoQ10 may interfere with the actions of warfarin ^(11) (12). Because of its antioxidant properties, it may also reduce effectiveness of chemotherapy and radiation therapy ⁽¹³⁾.