Coenzyme Q10 (CoQ10) is a molecule produced in the body. It aids mitochondria during energy production and is a part of the endogenous antioxidant system. It is similar to other pseudovitamin compounds because it is vital for survival, but does not necessarily need to be taken as a supplement. However, there is a potential for deficiency due to suffering a heart attack, taking statins, various disease states, and aging.
It is found in various foods; mainly meat and fish.
Some research suggests minor improvements in the function of blood vessels, leading to reduce blood pressure and improved blood flow. However, more studies are needed to confirm this. The proposed mechanism is related to nitric oxide preservation, as seen with grape seed extract, pycnogenol, and resveratrol.
It seems to be strongly effective for reducing the symptoms of fibromyalgia, but this is based on a handful of small studies, and much more research is needed to confirm this.
It seems to be safe but more research is needed to evaluate its safety in the long-term. In animals, a massive dose of 350 mg per kg of body weight has been observed to exacerbate the effects of aging, but human studies don't suggest any convincing adverse effects from normal doses.
The standard dose for CoQ10 is generally 90 mg for a low dose and 200 mg for the higher dose, taken once daily with a meal due to its reliance on food for absorption. Dose-dependence is not commonly observed with CoQ10 supplementation and 90 mg tends to be the best cost-effective dose.
There generally isn't too much of a therapeutic effect of CoQ10 supplementation (mostly taken with the 'just in case' mentality that pervades multivitamin supplementation), although for people who have previously experience a heart attack or damage to cardiac tissue as well as for people on statin therapy supplementation becomes much more important.
CoQ10 supplements can be either the oxidized form (ubiquinone) or reduced form (ubiquinol) as both forms seem pretty equally potent in increasing circulating levels of total CoQ10 in the body. "Total CoQ10" refers to the sum of both forms, since CoQ10 can readily swap between forms as it acts in the body.