Many claims are made for Coenzyme Q10 (CoQ10) is also known as ubiquinone because it belongs to a class of compounds called quinones, and because it’s ubiquitous in living organisms, especially in the heart, liver and kidneys.
This vitamin-like compound, discovered in 1957, plays a crucial role in producing energy in cells. It also acts as a powerful antioxidant, meaning that it helps neutralize cell-damaging free radicals. Manufactured by all cells in the body, CoQ10 is also found in small amounts in some foods, notably meat and fish.
Sold as a dietary supplement, CoQ10 is purported to help treat, or possibly prevent, heart disease, hypertension, Parkinson’s disease, certain cancers, migraines, HIV/AIDS, infertility, gum disease, allergies and so on. It’s also said to boost immunity, enhance athletic performance, aid memory and slow aging.
Like many substances in the body, CoQ10 levels decline with age and are lower in people with certain medical conditions, such as Parkinson’s, some cardiac disorders and asthma. But that doesn’t mean that CoQ10 “deficiency” causes disease or that supplements will treat disease or reverse the effects of aging.
Some cholesterol-lowering statin drugs, as well as certain beta-blockers and antidepressants, can reduce blood levels of CoQ10, but there’s no evidence that this leads to any health problems.
Putting CoQ10 to the test
According to the Natural Standard, which evaluates complementary and alternative therapies, there is “unclear scientific evidence” for most uses of CoQ10, and “fair scientific evidence” against its use for diabetes and Huntington’s disease. Much of the encouraging research has been in the lab, while human studies have tended to yield inconsistent results. Here are some uses that look more promising:
Hypertension. An analysis of 12 studies of people with hypertension, in the Journal of Human Hypertension in 2007, found that CoQ10 lowered systolic blood pressure (the top number in a blood pressure reading) 11 to 17 points, and diastolic (the bottom number) 8 to 10 points. This may be due to CoQ10’s ability to dilate blood vessels. The Natural Standard gives CoQ10 a “B” for hypertension, citing “good” evidence for this use but also the need for more studies.
Heart conditions. People with cardiac disease often have low levels of CoQ10, and cells of the heart are sensitive to reductions in CoQ10. According to a 2010 review in Nutrition, heart failure patients with low CoQ10 have higher death rates. CoQ10 has shown a range of heart benefits, including a reduction in arrhythmias after bypass surgery and improvements in cardiac function indicators in people with heart failure. CoQ10 may benefit the cardiovascular system through its antioxidant and anti-inflammatory effects and by improving blood vessel function.
But there is not enough evidence to recommend it for people with coronary heart disease. Research on CoQ10 as a treatment for heart failure has been inconsistent. A large clinical trial in 2013 found that it can reduce mortality rates from heart failure; a 2013 Cochrane review concluded that it does not. CoQ10 is prescribed for certain heart ailments in Japan and several European countries.
Parkinson’s disease. A study from the University of California, San Diego, published in the Archives of Neurology in 2002, found that very large doses of CoQ10 appeared to slow the progression of early Parkinson’s disease and improved daily life. Though a 2007 study in the same journal did not find a benefit of CoQ10, it included people with more advanced disease and used lower doses for a shorter time. Better-designed studies are needed.
CoQ10 and statin users
A side effect of statin drugs is muscle problems. Statins work by inhibiting an enzyme that's integral to cholesterol production in the body. This enzyme is also involved in the production of CoQ10, so statins reduce blood levels of it as well. It's not known if statins' effect on CoQ10 contributes to their adverse effects. So far, research on the effects of CoQ10 supplements in statin users has had mixed results. A major study on people with confirmed statin-related musicle problems is now underway and may clarify matters.
Side effects: No serious side effects have been reported, though some CoQ10 users experience heartburn, nausea, abdominal pain, dizziness and headaches. Supplements may interact with some medications, however, including the blood thinner warfarin (Coumadin) and some diabetes drugs.
Bottom line: The claims for CoQ10 are overblown, and there’s no reason to take the supplement, especially if you are healthy. No one knows how much to take or which formulation, if any, is best.
If you have heart disease, high blood pressure, or Parkinson’s disease and are considering CoQ10, discuss it with your doctor first. If you have heart failure, there are effective drugs; at best, CoQ10 would be an adjunct therapy.
Originally published April 2011. Updated January 2014.