How strong is the evidence for Coenzyme Q10?

Meta-analyses spanning from 1997 through a 2014 Cochrane review find CoQ10 supplementation can modestly improve symptoms and some outcomes in heart failure, though a 2022 health-technology assessment concluded the evidence is not yet strong enough to firmly establish cost-effective clinical benefit for reduced-ejection-fraction heart failure specifically. That evidence is currently rated moderate (58/100), built on 8 published studies, including 8 meta-analyses -- a reasonable base, but not yet enough for full certainty.