CoQ10: How Reliable Is It?

By Jane Farrell

Editor’s Note: CoQ10 is a popular supplement that’s said to be effective in fighting everything from congestive heart failure to gum disease. But is it safe, and is there reliable evidence to support these claims? Before you reach for a bottle of CoQ10 on your next trip to the drugstore, read this information from the National Center for Complementary and Alternative Medicine, a division of the federal National Institutes of Health:

Coenzyme Q10 (CoQ10), an antioxidant that is necessary for cells to function properly, is found most frequently in vital organs such as the heart, liver, kidneys and pancreas. (Fish, meat and grains have small amounts, but not enough to supply adequate levels to humans.) According to the NCCAM, CoQ10 levels decrease as you age. Some illnesses have been associated with low levels of the substance.

The NCCAM says that reliable evidence shows that CoQ10 can help some people who have cardiovascular “disorders.” However, the agency experts, caution, the evidence is limited and inconclusive when it comes to muscle weakness, cancer and reproductive disorders.

Here are some specifics:

According to the NCCAM, research reviews published in 2007 and 2009 showed that for heart-failure patients, taking CoQ10 was linked to improved heart function and feeling better. A 2013 meta-analysis (a study of other studies) also found an association between taking CoQ10 and improved heart function.

And a randomized controlled trial of 117 patients in 2011, the NCCAM says, showed that if it was taken with a combination of nutrients, CoQ10 was linked with quicker recovery after bypass and heart valve surgeries.

But the findings are more ambivalent when it comes to blood-pressure control. According to the NCCAM, some studies have indicated that CoQ10 might be linked with blood-pressure control, but a 2009 review of the research said that the findings are limited.

The agency also says that a small trial in 2012 showed that CoQ10 doesn’t reduce high blood pressure or heart rate in patients with metabolic syndrome.

Claims have been made that CoQ10 cab help ease muscle weakness (myopathy) that can be linked to taking statins. But a 2010 review wasn’t definite, the NCCAM says. And a clinical trial in 2012 showed that for patients with muscle weakness, CoQ10 was no better than a placebo.

The NCCAM says that according to a 2010 review, there’s evidence that CoQ10 may improve semen quality and sperm count in infertile men. But, the agency adds, it’s not clear whether this means that conception is likelier.

As for cancer, there’s no evidence that CoQ10 prevents or treats it. But there are two large studies, the NCCAM says, that found that women who developed breast cancer were likely to have abnormal CoQ10 levels, either very low or high.

CoQ10 has also been examined for possible effects on amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig’s disease), Down syndrome, diabetes, Huntington’s disease, migraines, Parkinson’s disease, neuromuscular diseases, and age-related cellular changes. Because the research on these issues is so limited, the NCCAM says, experts can’t draw any conclusions.

The NCCAM reports that the most common side effects of CoQ10 include insomnia, headaches, fatigue and increased liver enzymes. The agency also emphasizes that CoQ10 should not be used by women who are pregnant or breastfeeding. And warfarin, a blood thinner, may be made less effective by taking CoQ10.

(There is some ongoing research: The NIH is currently sponsoring studies investigating the effects of CoQ10 on mild-to-moderate muscle pain in people who take statins, fertility in older women, and breast cancer treatments.)

Overall, the NCCAM cautions consumers not to use CoQ10 supplements in place of a healthy diet or conventional medical care.

Before using any dietary supplement, consult reliable sources. Then talk to your doctor: He or she can advise you whether a supplement is safe, given the other medications you’re taking. If you are already taking another dietary supplement, mention that as well. Your physician needs to have a complete picture.

For reliable information about complementary and alternative approaches to health, visit the NCCAM’s website.