Coenzyme Q-10

Claims, Benefits: Prevents and treats heart disease, Parkinson’s disease, and many other disorders.

Bottom Line: This interesting antioxidant may be effective against heart failure and Parkinson’s. If you try it to treat a disease, get medical advice about doses and formulations—even though it’s just guesswork at this point—as well as about potential drug interactions. There’s no reason to take it if you are healthy. The long-term effects are unknown, and the price is high.

Full article, Wellness Letter, May 2003:

CoQ-10 Update

Coenzyme Q-10 (CoQ-10) has been the focus of scientific study for years and has become one of the most popular dietary supplements. This vitamin-like compound, it has been proposed, may help treat, or possibly even prevent, many disorders, including heart disease, hypertension, AIDS, asthma, Parkinson’s and Huntington’s disease, certain cancers, lung disease, gum disease, chronic fatigue syndrome, migraines, and allergies. It’s supposed to improve memory, boost immunity and energy, enhance exercise performance, and combat aging. Such sweeping claims should always arouse suspicion. Though in recent years scientists have learned a lot about CoQ-10, the clinical research is still in its infancy—and thus the marketing claims remain overblown.

Discovered in 1957, CoQ-10 is also called 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. It plays a crucial role in producing energy in cells. And it acts as a powerful antioxidant, meaning that it helps neutralize cell-damaging molecules called free radicals. Manufactured by all cells in the body, CoQ-10 is also found in small amounts in foods, notably meat and fish.

CoQ-10 is one of many substances in the body that tend to decline as people age or develop certain diseases (such as some cardiac conditions, Parkinson’s disease, and asthma). But that doesn’t mean that lower levels of CoQ-10 cause disease, or that supplemental CoQ-10 will combat disease or reverse the effects of aging. Some drugs, including certain cholesterol-lowering statins, beta-blockers, and antidepressants, can reduce CoQ-10 levels in the body, but there has been no evidence that this causes any adverse effects.

What the studies show

Interest in CoQ-10 grew in the early 1970s when researchers found that patients with congestive heart failure had much lower levels of it in their hearts and suggested that CoQ-10 supplements could help improve their heart function. Since then studies have yielded inconsistent results, and many have been poorly designed. However, three years ago two good studies on CoQ-10 and heart failure, one in Australia and one in Maryland, found no benefit. The research on CoQ-10 and hypertension remains sketchy, though one small study in 2001 did find it could significantly lower blood pressure in half of older people with hypertension. While not approved for any therapeutic use in the U.S., CoQ-10 is an accepted treatment for cardiovascular disease in Japan.

In a promising study on CoQ-10 and early-stage Parkinson’s disease published in October, researchers at the University of California, San Diego, found that very large doses of CoQ-10 (along with vitamin E) appeared to slow the progression of the disease. It reduced the decline in neurological function and improved daily life. The study was small, however, and the researchers said that its findings would have to be confirmed by a larger trial before they would recommend CoQ-10.

Research into other potential benefits of CoQ-10 supplements—for HIV, cancer, or other diseases—is more theoretical and/or preliminary. So far studies suggest that CoQ-10 does not improve exercise performance or fight gum disease.

Practical matters

• If you have heart disease or Parkinson’s, discuss CoQ-10 with your physician, preferably a specialist. If you’re already taking CoQ-10 on your own, make sure your doctor knows. If you have heart failure, there are effective drugs available. At best, CoQ-10 would be adjunct therapy.

• If you have other diseases, we can’t recommend CoQ-10 to treat them. Much more research is needed. Again, if you wish to take it, you should discuss it with your doctor. CoQ-10 can’t take the place of proven medical treatments.

• If you’re healthy, there’s no evidence CoQ-10 can help keep you healthy or prevent the effects of aging.

If you do take CoQ-10, or are considering it, keep these points in mind:

• The supplements seem to be safe. No serious side effects have been reported, though some users experience heartburn, nausea, abdominal pain, dizziness, and headache.

• CoQ-10 supplements may interact with medications, however, including some anti-clotting drugs and diabetes drugs.

• Also take vitamin E if you take CoQ-10. These two substances work together, at least in lab studies.

• No one knows how much CoQ-10 to take. Most studies have used doses of 50 to 200 milligrams a day. But the new study on Parkinson’s tested 300, 600, and 1,200 milligrams, with the largest dose having the greatest effect.

• It’s expensive—usually $15 to $45 a month. The larger doses some people recommend for heart patients cost $3 a day, and a 1,200-milligram dose could cost you $10 a day or more at the health-food store.

• Since CoQ-10 is fat-soluble, it’s probably best to take it with meals containing at least a little fat.

• CoQ-10 comes as soft-gel caps, wafers, tablets, and hard capsules containing powder. Despite the claims made by various CoQ-10 proponents and manufacturers, it is impossible to know which form is best absorbed and utilized. In addition, since dietary supplements are not regulated, you have no idea if brands of CoQ-10 contain the amounts listed on the labels or even if any of it is absorbed by your cells.

Remember this: There’s no reason to take CoQ-10 if you are healthy, "just to be safe." The long-term effects are unknown, and the price is high. If you try CoQ-10 to treat a disease, get medical advice about doses and formulations—even though it’s just guesswork at this point—as well as about potential drug interactions.

UC Berkeley Wellness Letter, May 2003