Coenzyme Q10: The Mitochondrial Energizer
Written by Trang Tran, Pharm.D. Candidate | Reviewed by Dr. Amy Knaperek, Pharm.D.
What is coenzyme Q10?
Coenzyme Q10, also known as CoQ10, ubiquinone, and ubidecarenone, is a fat-soluble compound that is produced inside the mitochondria of every cell and can be obtained from the diet. However, it is important to note that because humans and animals produce CoQ10 inside the body, CoQ10 is not considered a vitamin.
Even though coenzyme Q10 sounds like it is an enzyme (a protein that speeds up the rate at which chemical reactions take place in cells of the body), keep in mind that it is actually a cofactor, not an enzyme. As a cofactor, it assists an enzyme perform its job.
The highest amount of CoQ10 are found in the heart, brain, pancreas, liver, and kidneys.
What are the functions of coenzyme Q10?
The mitochondria is known as the powerhouse of the cell. Coenzyme Q10 is known to support mitochondrial function, thereby aiding in energy production. In other words, CoQ10 is needed to convert the energy from carbohydrates and fats to ATP (the form of energy used by cells).
Not only does CoQ10 play a vital role in energy production, but its reduced form (i.e., ubiquinol) also acts as an effective fat-soluble antioxidant that scavenges free radicals and prevents them from oxidizing LDL-cholesterol and causing cell damage. Besides neutralizing free radicals directly, the reduced form of CoQ10 also helps regenerate other antioxidants such as alpha-tocopherol (vitamin E) and ascorbate (vitamin C).
What are the potential health benefits of coenzyme Q10?
A randomized, double-blind, placebo-controlled, multicenter study found that CoQ10 was associated with less functional decline in patients with Parkinson’s disease, including activities of daily living.
Because CoQ10 is an antioxidant, it may confer therapeutic potential in the setting of diabetes by improving glycemic control through various mechanisms, including a decrease in oxidative stress which might be driving insulin resistance in fat and muscle tissues.
Since CoQ10 is highly concentrated in heart muscle and people with heart failure exhibited CoQ10 deficiency and mitochondrial dysfunction, a number of clinical trials investigating the effect of CoQ10 supplementation in the context of heart failure have been conducted. Several randomized controlled trials in a meta-analysis found that CoQ10 improved the clinical parameters related to congestive heart failure such as the frequency of heart failure hospitalization, difficulty breathing, fluid build-up, reduction in mortality, and improved exercise capacity.
Remarkably, one randomized controlled trial demonstrated that long-term CoQ10 supplementation is safe and led to improvement in symptoms as well as a reduction in major adverse cardiovascular events in a population with chronic heart failure. In fact, there is some evidence to suggest that CoQ10 supplementation may be a useful adjunct to conventional medical therapy for congestive heart failure and in patients undergoing coronary artery bypass graft surgery.
Based on a systematic review, CoQ10 used as an adjunct therapy resulted in a mean decrease in systolic and diastolic blood pressure of 16 and 10 mmHg, respectively. Thus, CoQ10 may play a role in the setting of high blood pressure.
Doxorubicin is a cancer drug that can cause toxicity to the heart, and remarkably, CoQ10 has been shown to provide protection from doxorubicin-induced cardiotoxicity.
What is the link between coenzyme Q10 and cholesterol-lowering drugs?
Statins (cholesterol-lowering drugs such as Zocor, Crestor, and Lipitor) can decrease circulating CoQ10 concentrations by inhibiting the enzyme called HMG-CoA reductase which in turn causes a decrease in the synthesis of an intermediate compound that serves as a precursor for the biosynthesis of CoQ10. However, since CoQ10 circulates with lipoproteins and statins reduce circulating lipids, the blood concentration of CoQ10 is potentially influenced by the concentration of circulating lipids.
It has been suggested that statin-induced muscle pain and weakness is related to a deficiency in CoQ10. A meta-analysis demonstrated that CoQ10 supplementation improved statin-associated muscle symptoms such as muscle pain, muscle weakness, muscle cramps, and muscle tiredness. This finding provided a potential complementary approach to statin-associated muscle symptoms.
What are the different forms of coenzyme Q10?
Although CoQ10 is synthesized in the body and is obtained from the diet, CoQ10 declines with age and with the use of cholesterol-lowering drugs. Therefore, supplementation may be necessary.
Coenzyme Q10 comes in two forms, namely, ubiquinone (the oxidized form) and ubiquinol (the reduced form). Ubiquinol is a potent lipophilic (fat-loving) antioxidant that protects the cells from free radical damage. Shortly after absorption, ubiquinone is reduced to its ubiquinol state. Compared to ubiquinone, ubiquinol has been shown to have better bioavailability or a greater extent of absorption.
However, solubilized forms of ubiquinone or ubiquinol have been shown to offer better absorption/bioavailability than non-solubilized powder-based CoQ10 products (compressed tablets, chewable tablets, powder-filled capsules, and softgels containing a suspension in oil).
Additionally, the absorption efficiency is also dose-dependent. That is, the efficiency of absorption decreases as the dose increases. Therefore, split dosing is superior to single dosing with pharmacologic doses of CoQ10.
Because CoQ10 is fat-soluble, it is best absorbed when taken with a meal. In general, doses higher than 100 mg/day are divided into two or three doses throughout the day.
What dosage forms are available for coenzyme Q10?
Coenzyme Q10 supplement is available as powder-based compressed tablets, chewable tablets, powder-filled hard-shell capsules, softgels containing an oil suspension, and liquids. In general, oil-based preparations of CoQ10 are better absorbed than dry formulations because CoQ10 is lipophilic.
What are the food sources of coenzyme Q10?
Foods rich in coenzyme Q10 include primarily meat, poultry, and fish. Moderate sources of coenzyme Q10 can be found in fruit, vegetables, eggs, and dairy products.
What are the safety concerns of coenzyme Q10?
Evidence of safety is strong with doses up to 1,200 mg/day. However, side effects such as nausea, diarrhea, appetite suppression, heartburn, and abdominal discomfort may occur especially with daily doses 200 mg or greater. Dividing daily doses greater than 100 mg into two or three daily doses may help minimize these side effects.