OTHER NAMES
• Ubiquinone • CoQ10 •
Coenzyme Q10 is a vitamin-like substance found in all cells. It is made by the body and is highly concentrated in the brain, heart, liver, kidneys, and pancreas. Coenzyme Q10 levels decrease with age and with certain disorders such as heart disease, Parkinson’s disease, cancer, and periodontal disease. Coenzyme Q10 is found in foods such as poultry, beef, and broccoli. Scientists can formulate coenzyme Q10 into pills in the laboratory through special processes combining beets, sugarcane, and yeast.
USES
There is some evidence that coenzyme Q10 may lower blood glucose slightly. Coenzyme Q10 is essential for cells to produce energy. Scientists theorize that, in diabetes, insulin-producing cells in the pancreas may not have the best possible coenzyme Q10 activity. In theory, taking coenzyme Q10 supplements may improve your body’s ability to produce insulin.
Coenzyme Q10 is better known for its potential cardiovascular benefits. Most people take coenzyme Q10 to help treat a variety of diseases such as heart disease, Parkinson’s, muscular dystrophy, and periodontal disease. Patients who take a class of cholesterol-lowering drugs called statins may take coenzyme Q10 supplements because statins are thought to lower coenzyme Q10 levels. However, the benefit of taking coenzyme Q10 for this purpose has not been consistently shown in rigorous, long-term studies.
DOSE
Doses of coenzyme Q10 have varied in different studies. In diabetes studies, the dose is 100–200 milligrams (mg) daily. For high blood pressure and other cardiovascular diseases, the dose has ranged from 100 to 225 mg daily, although up to 600 mg in divided doses has been used for various cardiovascular diseases.
STUDIES
Even though there is much enthusiasm for coenzyme Q10, and long-term studies have not shown harmful effects, further long-term studies are needed to determine its place in daily therapy.
Coenzyme Q10 has been evaluated most extensively as a treatment for heart disease, including high blood pressure and congestive heart failure. People with diabetes need to be extra careful about their risk of heart disease as two out of three people with diabetes die from heart disease and stroke.
However, many of the studies have used an open-label study design, where the participants know what treatment they are receiving, which may result in an unintentional bias in favor of coenzyme Q10. Other studies have not used a control group. In still other trials, study design has been inadequate (lacking randomization or blinding), or the end results for patients have been unsatisfactory. For example, blood pressure studies have had unacceptable end points (the target result or desired effect sought in a study). Although systolic and diastolic blood pressures decreased significantly, the pressures achieved at the end of the study were still much higher than would be recommended for people with diabetes.
• In a study of 109 patients with high blood pressure, coenzyme Q10 was added to existing treatment with high blood pressure medications. The average dose was 225 mg per day, and patients were followed for an average of 13 months. Systolic pressure decreased from 159 to 147 mmHg, and diastolic pressure decreased from 94 to 85 mmHg.
• In a separate study, 30 patients with high blood pressure received 60 mg coenzyme Q10 twice a day, and 30 patients received a vitamin B complex for 8 weeks. In patients treated with coenzyme Q10, blood pressure decreased significantly from 168 to 152 mmHg systolic and 106 to 97 mmHg diastolic. Meanwhile, in patients treated with vitamin B, systolic blood pressure decreased from only 166 to 164 mmHg and diastolic blood pressure decreased from only 105 to 103 mmHg. Although the scientists reported that patients did not have diabetes, patients were thought to have insulin resistance. Baseline glucose decreased in the coenzyme Q10 group from 141 to 95 milligram/deciliter (mg/dl) after 8 weeks. Decreases in blood glucose in the vitamin B complex—treated group were not significant. Fasting plasma insulin decreased from 465 to 257 picomoles/liter in the coenzyme Q10 group. This did not change significantly in the vitamin B group.
• For congestive heart failure, the benefits of coenzyme Q10 are controversial. In general, coenzyme Q10 has improved the number of hospitalizations and certain clinical parameters of heart failure. In a well-designed, year-long study of 641 patients with heart failure, patients had fewer hospitalizations for heart failure and fewer episodes of pulmonary edema (excess fluid in the lungs) with coenzyme Q10. However, a recent study with excellent study design and well-defined parameters found no benefit with coenzyme Q10 in 55 patients with symptoms of serious heart failure. An ongoing long-term outcome trial with over 500 people with symptoms of heart failure who will be followed for over 2 years will hopefully better define the role of coenzyme Q10.
In studies of patients with type 1 or type 2 diabetes, coenzyme Q10 supplements have shown neutral to slightly improved effects on fasting glucose and A1C (a measure of blood glucose levels over 3 months).
• In a well-designed study, 34 patients with type 1 diabetes received 100 mg per day of coenzyme Q10 or a placebo (dummy pill) for 3 months. A1C decreased from 8.04 to 7.86% in the coenzyme Q10 group and from 8.02 to 7.84%in the placebo group. The decreases were not statistically significant in either group. Daily blood glucose decreased from 160 to 145 mg/dl in the coenzyme Q10 group and from 161 to 153 mg/dl in the placebo group. Again, the decreases were not significant in either group. There were no significant differences in systolic or diastolic blood pressures in either group.
• In a separate, well-designed study, 12 patients with type 2 diabetes were given 100 mg of coenzyme Q10 twice a day. Eleven patients received a placebo pill. All participants were also taking sulfonylureas, such as glyburide or glipizide. There was no improvement in diabetes control. A1C increased from 8.7 to 9.1% after 6 months in the coenzyme Q10 group and from 7.9 to 8.1% in the placebo group. Fasting glucose decreased from 211 to 198 mg/dl in the coenzyme Q10 group and from 203 to 191 mg/dl in the placebo group.
• Another study assessed the effect of coenzyme Q10 on blood glucose and blood pressure in 74 patients with type 2 diabetes and high cholesterol. Patients received either 100 mg of coenzyme Q10 twice daily, 200 mg fenofibrate daily, a combination of coenzyme Q10 and fenofibrate, or a placebo for 12 weeks. Blood glucose results were better for the combination of coenzyme Q10 and fenofibrate than either coenzyme Q10 alone or a placebo. The combination group may have benefited from the effect of fenofibrate on triglyceride lowering. The authors also reported that systolic pressure declined by 6.1 mmHg and diastolic pressure decreased by 2.9 mmHg with coenzyme Q10 supplementation.
SIDE EFFECTS AND DRUG INTERACTIONS
Adverse effects have been rare, even with long-term use of up to 6 years. In a few patients, gastrointestinal problems, including diarrhea, nausea, anorexia, and epigastric distress, have occurred. Although early reports stated there were abnormal increases in certain liver function tests, long-term administration of 600 mg per day has not changed liver function.
Coenzyme Q10 may interfere with the efficacy of certain medications such as the blood-thinning drug warfarin. However, a study of patients taking coenzyme Q10 and warfarin did not show that taking the two together interferes with blood thinning. Smoking also depletes the body’s coenzyme Q10 levels.
Treatment with statins may decrease levels of coenzyme Q10 that may contribute to statin-related muscle pain or aches, though this interaction is controversial. A study that used low doses of certain statins did not result in lower coenzyme Q10 levels, but another study using a low and high dose statin did find lower levels of coenzyme Q10. Decreased coenzyme Q10 concentrations with statin treatment have also been reported in people with diabetes.
People who take red-yeast rice should be aware that the supplement contains an ingredient that is essentially a statin and thus has statin-like effects. Red yeast may decrease the body’s natural supply of coenzyme Q10.
On the other hand, taking coenzyme Q10 with blood pressure or diabetes medications may increase the effectiveness of these drugs. A potentially beneficial drug interaction has occurred with a cancer medication called doxorubicin. Taking coenzyme Q10 may decrease some of doxorubicin’s harmful effects on the heart.
Some scientists say that coenzyme Q10 may have added benefit when combined with another supplement called L-carnitine to help provide anti-oxidant protection against certain toxins.