CoQ10 helps. It provides energy at a cellular level; it's good for your heart and helps with gum disease, too. To my knowledge there is no dose which is toxic. I've used 100mg once or twice a day.

Get the soft gel type as it is more easily absorbed.

This site has very useful info: http://www.vitacost.com/Healthnotes/...zyme-Q10.aspx.
[Vitacost sells supplements, but their 'Health Library' info includes references and I've found it helpful.] There is a link to find drug interactions,too.