The efficacy of coenzyme Q treatment in alleviating the symptoms of primary coenzyme Q deficiency: A systematic review.

Coenzyme Q (CoQ ) is necessary for mitochondrial electron transport. Mutations in CoQ biosynthetic genes cause primary CoQ deficiency (PCoQD) and manifest as mitochondrial disorders. It is often stated that PCoQD patients can be treated by oral CoQ supplementation. To test this, we compiled all studies describing PCoQD patients up to May 2022. We excluded studies with no data on CoQ treatment, or with insufficient description of effectiveness. Out of 303 PCoQD patients identified, we retained 89 cases, of which 24 reported improvements after CoQ treatment (27.0%). In five cases, the patient's condition was reported to deteriorate after halting of CoQ treatment. 12 cases reported improvement in the severity of ataxia and 5 cases in the severity of proteinuria. Only a subjective description of improvement was reported for 4 patients described as responding. All reported responses were partial improvements of only some symptoms. For PCoQD patients, CoQ supplementation is replacement therapy. Yet, there is only very weak evidence for the efficacy of the treatment. Our findings, thus, suggest a need for caution when seeking to justify the widespread use of CoQ for the treatment of any disease or as dietary supplement.