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⁾. Other studies using a combination of selenium and CoQ10 also suggest improved cardiac function and reduced mortality risk ^{(43) (47) (58)}. However, a systematic review concluded that current evidence does not support routine CoQ10 supplementation in patients with coronary heart disease ⁽⁴²⁾. According to the American Heart Association, large-scale randomized trials are needed to definitively determine the value of supplementation in managing heart failure ⁽⁶¹⁾.

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⁾. Supplementation may also reduce pain in those with diabetic neuropathy ⁽⁶²⁾. A meta-analysis concluded that evidence of benefit in diabetic kidney disease is limited and additional study is needed ⁽⁴⁹⁾. Also, supplementation did not improve work efficiency in patients with chronic kidney disease ⁽⁶³⁾.

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⁾.

Although neuroprotective effects have been reported in small trials ^{(5) (6) (33)}, larger well-designed trials have not shown benefit with CoQ10 supplementation in Parkinson’s ^(7) (59) or Huntington’s disease ⁽⁵¹⁾. 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 alpha-lipoic acid was ineffective against Alzheimer’s disease ⁽²⁰⁾.

Some 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 ^(9) (64). It may also help reduce reduce some measures of oxidative stress ^(53) (60), and inflammatory markers in general population ⁽⁶⁵⁾ and in patients with chronic diseases ⁽⁵⁴⁾. In patients with sepsis, supplementation in the early phase improved clinical parameters and mitochondrial dysfunction ⁽⁵⁵⁾.

CoQ10 has also been investigated in cancer patients. Preliminary studies on whether it can help control cancer-related fatigue are mixed ^(29) (38). In patients on tamoxifen therapy, CoQ10 appeared to lower inflammatory cytokine levels ⁽⁵⁶⁾. CoQ10 levels have been positively associated with antioxidant capacity and negatively correlated with inflammation markers post-surgery in patients with hepatocellular carcinoma ⁽³⁷⁾. However, 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⁾.