What does it do? People often take CoQ10 to offset a decline in natural levels which occurs with the use of statin (cholesterol-lowering) medication. Some take it to feel more energized or for a variety of other purposes. It may also modestly help with elevated cholesterol levels, migraine, and other conditions. The evidence supporting these uses remains preliminary, although it does benefit people with congestive heart failure (see What It Does).

After being absorbed into the body, more than 90% of CoQ10 is converted to its active form, known as ubiquinol (CoQH2-10), which is also available as a supplement and appears to have greater bioavailability (i.e., it raises blood levels more) (see What It Is).

• How much to take? CoQ10 and ubiquinol are typically taken at a dose of 50 to 200 mg per day, although higher doses have been used (see Dosage).
• What did CL’s tests show? In laboratory testing, one product was Not Approved, as it contained nearly twice its listed amount of CoQ10. Cost comparisons showed you could spend as little as 7 cents to over $2 for an equivalent amount of CoQ10, and from 34 cents to over $1 for ubiquinol (See What CL Found).
• Best choice? Among 23 CL Approved products, CL selected several Top Picks for providing high quality CoQ10 or ubiquinol at very good value.
• How to take it? Gastrointestinal side-effects may occur but can be minimized by breaking up the dose throughout the day, although it may interfere with sleep if taken before bed. CoQ10 and ubiquinol are best absorbed when taken with or shortly after a fatty meal, although certain forms can be taken without fats (see Absorption and Bioavailability Enhancers).
• Cautions: At typical doses, CoQ10 and ubiquinol appear to be generally safe, but there are possible interactions with blood thinners and diabetes medications (see Concerns and Cautions).