Coenzyme Q10 as a therapeutic supplement

DEFINITION: Natural substance of the human body used as a supplement to treat specific health conditions.

• PRINCIPAL PROPOSED USES: Cardiomyopathy, congestive heart failure, heart attack recovery, hypertension, nutrient depletion/interference caused by various medications
• OTHER PROPOSED USES: Amyotrophic lateral sclerosis (Lou Gehrig’s disease), asthma, diabetes, kidney failure, migraine headaches, Parkinson’s disease, periodontal disease, preeclampsia and pregnancy-induced hypertension, sports performance enhancement, tinnitus

Overview

Coenzyme Q₁₀ (CoQ₁₀), also known as ubiquinone, is a major part of the body’s mechanism for producing energy. The name of this supplement comes from the word “ubiquitous,” which means “found everywhere.” Indeed, CoQ₁₀ is found in every cell in the body. It plays a fundamental role in the mitochondria, the parts of the cell that produce energy from glucose and fatty acids.

Japanese scientists first reported therapeutic properties of CoQ₁₀ in the 1960s. Some evidence suggests that CoQ₁₀ might assist the heart during times of stress on the heart muscle, perhaps by helping it use energy more efficiently.

CoQ₁₀’s best-established use is for congestive heart failure, but the evidence that it works is not entirely consistent. Some research suggests that it may also be useful for other types of heart problems, Parkinson’s disease, and several additional illnesses. It is generally used in addition to, rather than instead of, standard therapies. CoQ₁₀ supplementation might also be of value for counteracting the side effects of certain prescription medications.

Requirements and Sources

Every cell in the human body needs CoQ₁₀, but there is no dietary requirement because the body can manufacture CoQ₁₀ itself. For additional CoQ₁₀, some food sources include oily fish, organ meat, broccoli, soy products, nuts, seeds, meat, and spinach.

Therapeutic Dosages

The typical recommended dosage of CoQ₁₀ is 30 to 300 milligrams (mg) daily; higher daily intakes have been used in some studies. CoQ₁₀ is fat-soluble and may be better absorbed when taken in an oil-based soft gel form rather than in a dry form, such as tablets and capsules. Dividing the total daily dosage up into two or more separate doses may produce higher blood levels. A finely ground-up (nanoparticular) form of the supplement appears to be much better absorbed than standard CoQ₁₀ products.

Therapeutic Uses

Although not all studies have been positive, some evidence supports the use of CoQ₁₀ for treating congestive heart failure. CoQ₁₀ is taken with conventional medications, not as a replacement for them.

Some evidence suggests that this supplement may be useful for heart attack recovery, cardiomyopathy, hypertension, diabetes, strengthening the heart before heart surgery, and migraine headaches. Although CoQ₁₀ has been widely advertised as effective for treating Parkinson’s disease, in fact, there is only minimal evidence that it works and some evidence that it does not work.

CoQ₁₀ has shown the potential to prevent heart damage and other side effects caused by certain types of cancer chemotherapy, like adriamycin. This evidence is weak, however, and it cannot be stated with any certainty that CoQ₁₀ is actually helpful.

CoQ₁₀ has shown some promise as an aid to the treatment of kidney failure. People with severe illnesses, such as heart disease, cancer, or kidney failure, should not use CoQ₁₀ or any supplement, except under a physician’s supervision.

Preliminary studies suggest CoQ₁₀ might be helpful for amyotrophic lateral sclerosis. CoQ₁₀ has been tried, but not found effective, for the treatment of Huntington’s disease. Certain medications may interfere with the body’s production of CoQ₁₀ or partially block its function. The best evidence regards cholesterol-lowering drugs in the statin family, such as lovastatin (Mevacor), simvastatin (Zocor), and pravastatin (Pravachol), along with the supplement red yeast rice (which contains naturally occurring statins). These medications impair CoQ₁₀ synthesis as an inevitable side effect of their mechanism of action. Since these drugs are used to protect the heart and since CoQ₁₀ deficiency could, in theory, impair heart function, it has been suggested that this side effect may work against the intended purpose of taking statins. Furthermore, one might naturally guess that some of the side effects of statins could be caused by this induced CoQ₁₀ deficiency. However, studies designed to determine whether the use of CoQ₁₀ supplements actually offers any benefit to people taking statins have returned inconsistent results at best.

For several other categories of drugs, the evidence that they interfere with CoQ₁₀ is provocative but even less reliable. These include oral diabetes drugs (especially glyburide, phenformin, and tolazamide), beta-blockers (specifically propranolol, metoprolol, and alprenolol), antipsychotic drugs in the phenothiazine family, tricyclic antidepressants, methyldopa, hydrochlorothiazide, clonidine, and hydralazine. Again, while in theory CoQ₁₀ supplementation might be helpful for people using these medications, there is no direct evidence to support this hypothesis.

CoQ₁₀ has also been suggested as a performance enhancer for athletes. However, while one double-blind study of twenty-five highly trained cross-country skiers found some benefit, most studies evaluating potential sports supplement uses of CoQ₁₀ have returned negative rather than positive results.

CoQ₁₀ is also sometimes claimed to be an effective treatment for periodontal disease. However, the studies on which this idea is based are too flawed to be taken as meaningful. Even weaker evidence, far too weak to rely upon, hints that CoQ₁₀ might be useful in some cases of tinnitus (ringing in the ear).

One preliminary study of CoQ₁₀ for people undergoing treatment for human immunodeficiency virus (HIV) infection found conflicting results; the supplement appeared to improve general well-being, but it did not protect mitochondria (as the researchers had hoped it would) and actually seemed to worsen symptoms of nerve-related pain (peripheral neuropathy).

Other evidence, though weak, suggests that CoQ₁₀ might be helpful for asthma, as well as reducing the side effects (specifically, cardiac toxicity) of the cancer chemotherapy drug doxorubicin. CoQ₁₀ has additionally been proposed as a treatment for a wide variety of other conditions, including angina, cancer, male infertility, muscular dystrophy, and obesity, but there is little evidence that it is effective. There is also some evidence that CoQ₁₀ may reduce the risk of pre-eclampsia (high blood pressure during pregnancy) in women who are at risk for this condition.

Scientific Evidence

Congestive heart failure. Most but not all studies suggest that CoQ₁₀ can be helpful for people with congestive heart failure (CHF). In this serious condition, the heart muscles become weakened, resulting in poor circulation and shortness of breath.

People with CHF have significantly lower levels of CoQ₁₀ in heart muscle cells than do healthy people. This fact alone does not prove that the supplements will help CHF; however, it prompted medical researchers to try using CoQ₁₀ as a treatment for heart failure.

The largest study was a one-year, double-blind, placebo-controlled trial of 641 people with moderate to severe congestive heart failure. Half were given two mg per kilogram body weight of CoQ₁₀ daily; the rest were given a placebo. Standard therapy was continued in both groups. The participants treated with CoQ₁₀ experienced a significant reduction in the severity of their symptoms. No such improvement was seen in the placebo group. The people who took CoQ₁₀ also had significantly fewer hospitalizations for heart failure.

Similarly, positive results were also seen in other double-blind studies involving a total of more than 270 participants. One double-blind study found that in people with heart failure so severe they were waiting for a heart transplant, use of CoQ₁₀ improved subjective symptoms. However, several very well-designed double-blind studies enrolling approximately one hundred people with congestive heart failure failed to find any evidence of benefit. The reason for this discrepancy is not clear.

Cardiomyopathy. Cardiomyopathy is the general name given to conditions in which the heart muscle gradually becomes diseased. Several small studies suggest that CoQ₁₀ supplements are helpful for some forms of cardiomyopathy.

Hypertension. An eight-week double-blind, placebo-controlled study of fifty-nine men already taking medications for high blood pressure found that 120 mg daily of CoQ₁₀ reduced blood pressure by about 9 percent, compared with a placebo.

A twelve-week double-blind, placebo-controlled study of eighty-three people with isolated systolic hypertension (a type of high blood pressure in which only the “top” number is high) found that the use of CoQ₁₀ at a dose of 60 mg daily improved blood pressure measurements to a similar extent.

Similarly, in a twelve-week double-blind, placebo-controlled trial of seventy-four people with diabetes, the use of CoQ₁₀ at a dose of 100 mg twice daily significantly reduced blood pressure compared with a placebo. Antihypertensive effects were also seen in previous smaller trials, most of which were not double-blind.

CoQ₁₀ may also be beneficial in reducing the risk of high blood pressure during pregnancy (preeclampsia). In one study, 235 pregnant women at risk for preeclampsia were randomized to receive CoQ₁₀ (200 mg daily) or a placebo for twenty weeks until they delivered their babies. The women in the treatment group had fewer cases of preeclampsia compared with those who took the placebo.

Heart attack recovery. In a double-blind trial, 144 people who had recently experienced a heart attack were given either a placebo or 120 mg of CoQ₁₀ daily for one year, along with conventional treatment. The results showed that participants receiving CoQ₁₀ experienced significantly fewer heart-related problems, such as episodes of angina pectoris, arrhythmia, or recurrent heart attacks.

A double-blind study of forty-nine people who had suffered a full cardiac arrest requiring cardiopulmonary resuscitation (CPR) found that use of CoQ₁₀ along with mild hypothermia (chilling of the body) was more effective than mild hypothermia plus a placebo. Individuals recovering from a heart attack should not take any herbs or supplements except under the supervision of a physician.

Parkinson’s disease. An early twenty-first-century study raised hopes that CoQ₁₀ might help slow the progression of Parkinson’s disease. In this sixteen-month double-blind, placebo-controlled trial, eighty people with Parkinson’s disease were given either CoQ₁₀ (at a dose of 300 mg, 600 mg, or 1,200 mg daily) or a placebo. Participants in this trial had early stages of the disease and did not yet need medication. The results appeared to suggest that CoQ₁₀, especially at the highest dose, might have slowed disease progression. However, for a variety of statistical reasons, the results were, in fact, quite inconclusive.

A subsequent double-blind, placebo-controlled study of 28 people with Parkinson’s disease, which was well controlled by medications, indicated that 360 mg of CoQ₁₀ daily could produce a mild improvement in some symptoms. Based on these results, a more substantial study was undertaken, enrolling 131 people with Parkinson’s disease (again, well controlled by medications). This repeat trial used an especially finely ground form of CoQ₁₀ that, though taken at a dose of only 300 mg daily, produced blood levels of the supplement equivalent to those produced by 1,200 mg daily of ordinary CoQ₁₀; it did not work. While benefits were seen in both the placebo and the CoQ₁₀ group, CoQ₁₀ failed to prove more effective than placebo. Further trials will be necessary to confirm (or deny) these results.

Diabetes. In the twelve-week double-blind, placebo-controlled trial of people with diabetes mentioned above, the use of CoQ₁₀ at a dose of 100 mg twice daily significantly improved blood sugar control compared with a placebo. Similar benefits were seen in the eight-week double-blind, placebo-controlled study of fifty-nine men also described above. However, other studies have failed to find any effect on blood sugar control. In a 2024 meta-analysis, researchers concluded that CoQ₁₀ supplementation lowered insulin resistance and positively impacted cardiovascular function in individuals with diabetes. Blood pressure levels, lipid profiles, and glycemic index recordings were all noted to improve using the supplement.

Safety Issues

In general, CoQ₁₀ appears to be extremely safe. No significant side effects have been found, even in year-long studies. However, people with severe heart disease should not take CoQ₁₀ (or any other supplement) except under a doctor’s supervision.

Several studies suggest that CoQ₁₀ might reduce blood sugar levels in people with diabetes. While this may be helpful for the treatment of diabetes, it might present a risk as well. People with diabetes who use CoQ₁₀ might inadvertently push their blood sugar levels dangerously low. However, one trial in people with diabetes found no effect on blood sugar control. Persons with diabetes should track their blood sugar closely if they start taking CoQ₁₀ (or, indeed, any herb or supplement).

CoQ₁₀ chemically resembles vitamin K. Since vitamin K counters the anticoagulant effects of warfarin (Coumadin), it has been suggested that CoQ₁₀ may have the same effect. However, a small, double-blind study found no interaction between CoQ₁₀ and warfarin. Nonetheless, in view of warfarin’s low margin of safety, prudence indicates physician supervision before combining CoQ₁₀ with warfarin.

CoQ₁₀ might also interact with reverse transcriptase inhibitors used for treatment of HIV (for example, lamivudine and zidovudine). These medications can cause damage to the mitochondria, the energy-producing subunits of cells, leading to a variety of side effects, including lactic acidosis (a dangerous metabolic derangement), peripheral neuropathy (injury to nerves in the extremities), and lipodystrophy (cosmetically undesirable rearrangement of fat in the body). The supplement CoQ₁₀ has been tried to minimize these side effects, but unexpected results occurred. In a double-blind, placebo-controlled study, use of CoQ₁₀ improved the general sense of well-being in people with HIV infection using reverse transcriptase inhibitors. For reasons that are unclear, it actually worsened symptoms of peripheral neuropathy. For this reason, people with HIV who have peripheral neuropathy symptoms should use CoQ₁₀ only with caution.

The maximum safe dosage of CoQ₁₀ for young children, pregnant or nursing women, or those with severe liver or kidney disease has not been determined.

Important Interactions

Individuals taking cholesterol-lowering drugs in the statin family, red yeast rice, beta-blockers (specifically propranolol and metoprolol), antipsychotic drugs in the phenothiazine family, tricyclic antidepressants, methyldopa, hydrochlorothiazide, clonidine, hydralazine, and oral diabetes drugs (especially glyburide, phenformin, and tolazamide) may need more CoQ₁₀. People taking Coumadin (warfarin) and other blood-thinning medicines should not take CoQ₁₀ except on a physician’s advice. In those taking reverse-transcriptase inhibitors (for HIV infection), CoQ₁₀ might improve their general sense of well-being but worsen peripheral neuropathy symptoms.

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