A report from ConsumerLab.com, White Plains, NY, on CoQ10 supplements shows the vast majority of products contained the amount claimed on packaging, but large variations can make it difficult for consumers to choose the right dosage and form.

Among 39 products tested, the suggested daily servings ranged from 22 mg to 600 mg, and some products were “solubilized” formulas, which deliver more than twice as much CoQ10 into the blood as standard capsules of CoQ10 powder. ConsumerLab.com’s tests of the supplements showed that all but one contained the listed amount of the ingredient. (A product that made a cGMP claim provided only 87% of its claimed amount.)

CoQ10 is among the most popular and fastest growing supplements in the U.S. with $413 million sold in 2007, up more than 8% from the prior year, according to figures from Nutrition Business Journal. An “activated” chemical form of CoQ10 known as “ubiquinol” is also now widely sold.

CoQ10 may help treat congestive heart failure, prevent migraine headaches, and delay the progression of Parkinson’s disease. It may also help reverse side effects associated with cholesterol-lowering “statin” drugs and it has potential use in muscular dystrophy, AIDS, hypertension, mitochondrial encephalomyopathies, as well as other conditions. Although sometimes touted for enhancing athletic performance, this effect has not been well demonstrated. A small study in Japan of ubiquinol in elderly people suggested an improvement in self-assessed “vitality.” The ratio of ubiquinol to CoQ10 in the blood has been shown to decrease with age and in a variety of medical conditions, such as liver disease.

“An appropriate dose of CoQ10 or ubiquinol will depend on the condition for which it is being used and the type of formulation,” said Dr. Tod Cooperman. “One hundred milligrams of a ‘solubilized’ product may deliver more than twice the dose of a simple powder. People should not rely on products’ suggested serving sizes but on dosages proven useful in clinical trials or based on the recommendation of a health care provider.”

The ConsumerLab.com report includes information on the dosage used in various clinical studies and explains the differences in CoQ10 forms and product formulations, including which ones are more bioavailable.

The report provides results for 39 products, of which ConsumerLab.com selected 20. Nineteen were tested at the request of their manufacturers/distributors through CL’s Voluntary Certification Program and are included for having passed testing. Also identified is one product similar to one that passed but sold under a different brand name.

Brands included in the report are Andrew Lessman, Berkley & Jensen (BJ’s), Bio-Q-Sorb Active Q, Biosolv Quinogel, Carlson, CarniQNol Active Q, CoQfactor (Vital Basics), Doctor’s Best, Drinkables, Dr. Ronald Hoffman/Vitamin Shoppe, Enzymatic Therapy, Essentials (Gero Vita), FoodScience of Vermont, Good ‘N Natural, Healthy America, Healthy Origins, Life Extension, Member’s Mark (Sam’s Club), Nature Made, Nature’s Bounty, New Chapter, Origin (Target), Physician’s Health and Diet (Wellness International), Protocol for Life Balance, PureGels, Puritan’s Pride, Source Naturals, Swanson, Trace Minerals, Twinlab, USANA, VitaFusion, Vitamin World, Vitasmart, and Webber Naturals.