Co Enzyme Q10

Where to Find It CoQ10 is found primarily in fish and meat, but the amounts in food are far less than what can be obtained from supplements.

Possible Deficiencies
Deficiency is poorly understood, but it may be caused by synthesis problems in the body rather than an insufficiency in the diet. Low blood levels have been reported in people with heart failure, cardiomyopathy, gingivitis (inflammation of the gums), morbid obesity, hypertension, muscular dystrophy, diabetes, AIDS, and in some people on kidney dialysis. People with phenylketonuria (PKU) may be deficient in CoQ10 because of dietary restrictions.81 CoQ10 levels are also generally lower in older people. The test used to assess CoQ10 status is not routinely available from medical laboratories.Best Form to Take Some,82 but not all,83 research suggests that a fat-soluble form of CoQ10 is absorbed better than CoQ10 in granular (powder) form.84

How to Use It
Adult levels of supplementation are usually 30–90 mg per day, although people with specific health conditions may supplement with higher levels (with the involvement of a physician). Most of the research on heart conditions has used 90–150 mg of CoQ10 per day. People with cancer who consider taking much higher amounts should discuss this issue with a doctor before supplementing. There are several anecdotal reports of large amounts of CoQ10 resulting in improvements in certain types of cancer. However, controlled trials are needed to confirm these preliminary observations. Most doctors recommend that CoQ10 be taken with meals to improve absorption.

Source
http://www.evitamins.com/encyclopedia/assets/nutritional-supplement/coenzyme-q10/how-it-works