coQ10 is pretty unnoticeable unless you have too little, then about everything can go wrong, often starting with the heart.
Importantly, statin drugs, given for high cholesterol, also inhibit the natural production of coQ10. So if you are taking a statin drug, like Lipitor, Vytorin, Crestor and Zocor, it is important that you also take a coQ10 supplement. This is more important the older you are, because natural coQ10 production decreases with age.
http://www.spacedoc.net/statins_CoQ10.htm
bookmark