What Is The Best Form Of Coenzyme Q10?

  • Cristina PotterSport and Exercise Science - BSc, Loughborough University, England


About coenzyme Q10 

Coenzyme Q10, also referred to as CoQ10 or ubiquinone, is an antioxidant compound that the body produces naturally. An antioxidant is a molecule that neutralises free radicals in the body. Free radicals are unstable compounds that cause harm to the body's cells when in excess and have been linked to several illnesses, such as diabetes and cancer.1 Their unstable molecules allow them to react efficiently with other molecules, triggering significant chain chemical reactions in the body, specifically oxidation, which can be beneficial or harmful. One of the most vital antioxidants, coenzyme Q10, prevents the generation of free radicals and modification of the body's proteins and DNA. Coenzyme Q10 significantly improves energy, augments the immune system, and facilitates tissue and cell function.

To protect the body against oxidative stress, humans have evolved a sophisticated and complex antioxidant production system. Oxidative stress is an imbalance between the body's free radicals and antioxidant activity. When the balance between the two is maintained, free radicals help fight off pathogens. When free radicals are in excess of antioxidants, they begin to damage fatty tissue, proteins and DNA in the body, leading to various diseases. A 2011 study found that coenzyme Q10 supplementation, alone or combined with drug therapies and nutritional intervention, helped prevent or treat several conditions.2 These conditions include cardiovascular diseases, hypertension, cancer, radiation injuries, obesity, diabetes, acquired immune deficiency syndrome (AIDS), migraine, kidney failure and ageing. 

Coenzyme Q10 is vital for boosting the immune system and physical wellness. The body's cells and tissues are highly dependent on energy for respiration and thus require an adequate supply of coenzyme Q10 for optimal function.

Forms of coenzyme Q10

Coenzyme Q10 comes in two forms: ubiquinol and ubiquinone. The chemical structures are pictured below.3 The two forms are very similar. Yet, they differ in the number of hydrogen ions they have. Ubiquinone is the oxidised form of coenzyme Q10 because it has two fewer hydrogen ions, and ubiquinol is the reduced form of coenzyme Q10, with the addition of two hydrogen ions following a reduction reaction. 

Ubiquinol is the usable "active" form of coenzyme Q10 derived from ubiquinone. It is often recommended for supplementation because it does not require additional conversion processes to be used by the body's cells. 

In its reduced form, ubiquinol accounts for more than 80% of the total coenzyme Q10 in human plasma and protects biological membranes, proteins and lipids. The body's cellular and enzymatic reactions are susceptible to variations of total coenzyme Q10 and the ubiquinol/ubiquinone ratio. For example, the ubiquinol/ubiquinone ratio is widely considered a marker of oxidative stress in coronary heart disease, and the LDL (low-density lipoprotein or "bad" cholesterol)/coenzyme Q10 ratio has been suggested as an index of coronary risk factor.4

Health benefits of coenzyme 10 (Coq10)

Coenzyme Q10 plays a vital role in generating energy, positively enhancing the immune system and neutralising free radicals in the body. With age, the body begins to lose the ability to synthesise coenzyme Q10 from food, and deficiency begins to develop. Researchers have suggested that coenzyme Q10 supplementation alone or in combination with nutritional intervention can help maintain health and treat certain diseases. Decreased levels of coenzyme Q10 have been recorded in various animal diseases,5 and much evidence exists for its beneficial effects in treating several human health conditions.6

Cardiovascular disease

Coenzyme Q10 is predominant in cardiac muscles due to the high metabolic requirements of this cell type. Congestive heart failure has been strongly associated with low coenzyme Q10 in blood plasma and tissues. In addition, clinical studies were consistent in their findings; treatment of heart disease after the administration of coenzyme Q10 showed a significant improvement in heart muscle function.7


It has been suggested that coenzyme Q10 supplementation in humans can treat hypertension. Low levels of coenzyme Q10 in the blood have been found in those with hypertension. However, it is unknown if coenzyme Q10 deficiency causes high blood pressure.


Coenzyme Q10 may have potential anti-carcinogenic and immune-stimulating effects. When used alongside conventional treatment and other antioxidant nutrients, coenzyme Q10 showed an increased survival rate and regression of cancer incidence. Several studies have noted the incidence of coenzyme Q10 deficiency in various cancers, including breast, lung, prostate, pancreatic and colon cancer.8,9

Bronchial asthma

Coenzyme Q10 may be helpful in treating respiratory diseases, particularly asthma cases. A 2002 study observed significantly decreased levels of coenzyme Q10 in plasma and blood in patients with bronchial asthma compared to healthy subjects.10 Similarly, a 2005 study showed that patients with bronchial asthma have low plasma coenzyme Q10 concentration, which has the potential to cause antioxidant imbalance and oxidative stress.11


Research suggests that coenzyme Q10 supplementation can help lower blood sugar levels in those with diabetes. In those with type 2 diabetes, lower blood coenzyme Q10 levels have been recorded compared to healthy individuals. Similarly, a 1999 study concluded that coenzyme Q10 supplementation could be used in diabetic patients following a successful 6-month intervention.12 

Renal health

In 2000, 21 patients with chronic renal failure involved in a small pilot study were administered coenzyme Q10 capsules. At four weeks of the intervention, the number of patients on dialysis was lower in the treatment group (36.2%), while 90.0% of patients in the placebo group were on dialysis at the end of the study.13

Rheumatoid arthritis

Oxidative stress is a primary factor in pathogenic changes during rheumatoid arthritis; coenzyme Q10 treatment has been found to slow the progression of arthritis. In addition, soluble coenzyme Q10 intervention has alluded to cardio-protective effects in the model of adjuvant arthritis.14

Risks associated with coenzyme Q10

While coenzyme Q10 is typically well tolerated, some people experience mild side effects if taken in excess or at the wrong time. Many results of its use in treatment are inconclusive; hence, coenzyme Q10 supplementation is not a widely prescribed treatment for diseases. Some side effects include:

  • Mild insomnia has been reported as one of the most frequent side effects of oral coenzyme Q10 administration. However, most cases are due to overconsumption, incorrect dosages and product quality, as opposed to direct effects on the body.
  • Digestive issues and a loss of appetite.
  • Interaction with certain medications: coenzyme Q10 can impair the mechanisms of certain blood-thinning medications and has made hypoglycaemic treatments ineffective in those with diabetes.15
  • Nausea
  • Vomiting
  • Abdominal pain

Ubiquinol vs ubiquinone

Coenzyme Q10 has been demonstrated to be a front-line barrier against oxidative stress, mainly when the antioxidant is in its reduced form. Treatment with coenzyme Q10 that induces an increase in naturally-derived ubiquinol levels in plasma and lipoproteins has been shown to augment resistance to LDL peroxidation - a process involving the oxidative degradation of lipids (fats), whereby free radicals "steal" electrons from fats in the cells membranes, resulting in cell damage. In the case of ubiquinol, there is evidence to suggest that its supplementation helps prevent oxidative stress, obesity, metabolic syndromes such as diabetes, and insulin resistance, all of which are fundamental in the pathogenesis of lipid-related diseases like atherosclerosis and cardiovascular disease.16 In diabetic patients, cellular antioxidant defence is severely reduced, and coenzyme Q10 plasma levels are decreased, demonstrating the potential importance of supplementation to prevent diseases. The main chemical characteristic of coenzyme Q10 is its existence in three alternate redox states.


Ubiquinol is a reduced form of ubiquinone that traps free radicals and inhibits lipid peroxidation, protecting cell membranes against oxidative damage. It is as effective in preventing peroxidative damage to lipids as alpha-tocopherol, which is widely considered the best lipid-soluble antioxidant in humans. During gastrointestinal uptake, dietary coenzyme Q10 is reduced to the antioxidant-active ubiquinol form that enters the blood for uptake by the body's tissues. Alternatively, ubiquinol administration is widely recommended because it doesn't have to undergo chemical changes in the body - it is administered in its active form.


Ubiquinone is the fully oxidised state of coenzyme Q10. Often, when we talk about coenzyme Q10, we refer to it in its ubiquinone state. It acts as a redox component of transmembrane electron transport systems, such as the respiratory chain of mitochondria. 

The mechanisms of ubiquinone and ubiquinol remain highly similar, where the only difference lies in their chemical structure. The capacity of coenzyme Q10 to act as a two-electron carrier (moving between the quinone and quinol form) is central to its role in respiration, specifically in the electron transport chain, and as a free radical antioxidant.

Foods containing coenzyme Q10

Coenzyme Q10 in the diet contributes significantly to plasma coenzyme Q10 concentrations. It can be obtained through oral soft gel capsules or derived from natural food sources. Examples of foods that contain coenzyme Q10 include:

  • Meat and poultry: pork, beef and chicken have high concentrations of coenzyme Q10, as well as organ meats like pork heart, liver and kidney
  • Fatty fish: herring, trout and salmon
  • Vegetables: potatoes, tomatoes, carrots, and spinach, as well as cruciferous vegetables like cabbage Bak Choi, broccoli, cauliflower, kale and Brussel sprouts, are rich in plant-derived coenzyme Q10.
  • Fruit: oranges, apples, kiwis, and strawberries
  • Legumes: soybeans, lentils and chickpeas
  • Nuts and seeds: almonds, peanuts, pistachios and sesame seeds


Coenzyme Q10 is an essential antioxidant compound that the body uses to protect against oxidative stress, disease and illness, providing energy, supporting the immune system, and facilitating cell function. It comes in two forms: ubiquinol and ubiquinone. Ubiquinol is the usable form of coenzyme Q10 that can be directly used by the body's cells. Coenzyme Q10 serves many essential functions in physiological health. You can supplement coenzyme Q10 through nutritional intervention or over-the-counter soft gel capsules. It would be best if you spoke to a medical professional before starting any intervention practices to ensure you have the best treatment outcome while minimising potential side effects. 


  1. Mathew BB, Tiwari A, Jatawa SK. Free radicals and antioxidants: A review. Journal of Pharmacy Research. 2011;4(12):4340-4343.
  2. Saini R. Coenzyme Q10: The essential nutrient. Journal of Pharmacy and Bioallied Sciences. 2011;3(3):466-667.
  3. Mgb Lifestyle. Ubiquinol vs. CoQ10 vs. Ubiquinone: The Difference & What To Use [Internet]. 2022. [updated 2022 Jun 16; cited 2022 Sep 14]. Available from: https://www.mindbodygreen.com/articles/ubiquinol-vs-coq10
  4. Kaikkonen J, Tuomainen TP, Nyyssönen K, Salonen JT. Coenzyme Q10: absorption, antioxidative properties, determinants, and plasma levels. Free radical research. 2002;36(4):389-397.
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  6. Folkers K, Osterborg A, Nylander M, Morita M, Mellstedt H. Activities of vitamin Q10 in animal models and a serious deficiency in patients with cancer. Biochemical and biophysical research communications. 1997;234(2):296-299.
  7. Gazdík F, Gvozdjáková A, Horváthová M, Weis- sová S, Kucharská J, Pijak M.R, Gazdíková K. Levels of coenzyme Q10 in asthmatics. Bratis- lavské lekárske listy. 2002;103: 353–356.
  8. Gvozdjáková A, Kucharská J, Bartkovjaková M, Gazdíková K, Gazdík F. Coenzyme Q10 sup- plementation reduces corticosteroid dosage in patients with bronchial asthma. In: Proceedings 4th Conference of the International Coenzyme Q10 Association, Los Angeles. 2005:108–109.
  9. Miyake Y, Shouzu A, Nishikawa M, Yonemoto T, Shimizu H, Omoto S, Hayakawa T, Inada M. Effect of treatment with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors on serum coenzyme Q10 in diabetic patients. Arzneimittelforschung. 1999;49(04):324-329.
  10. Singh RB, Khanna HK, Niaz MA. Randomized, double-blind placebo-controlled trial of coenzyme Q10 in chronic renal failure: discovery of a new role. Journal of nutritional & environmental medicine. 2000;10(4):281-288.
  11. Bauerova K, Bezek S. Role of reactive oxygen and nitrogen species in the etiopathogenesis of rheumatoid arthritis. General physiology and biophysics. 2000;18:15-20.
  12. Comstock GW, Burke AE, Hoffman SC, Helzlsouer KJ, Bendich A, Masi AT, Norkus EP, Malamet RL, Gershwin ME. Serum concentrations of α tocopherol, β carotene, and retinol preceding the diagnosis of rheumatoid arthritis and systemic lupus erythematosus. Annals of the rheumatic diseases. 1997;56(5):323-325.
  13. Stocker R, Bowry VW, Frei B. Ubiquinol-10 protects human low-density lipoprotein more efficiently against lipid peroxidation than does alpha-tocopherol. Proceedings of the National Academy of Sciences. 1991;88(5):1646-1650.
  14. Lakka HM, Laaksonen DE, Lakka TA, Niskanen LK, Kumpusalo E, Tuomilehto J, Salonen JT. The metabolic syndrome and total and cardiovascular disease mortality in middle-aged men. Jama. 2002;288(21):2709-2716.
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Cristina Potter

Sport and Exercise Science - BSc, Loughborough University, England

Cristina is highly motivated and an engaging life scientist, with a deep and abiding personal interest in clinical science, functional medicine, health, and medical affairs.
Committed to achieving and exceeding demanding targets and objectives, Cristina aims to optimise patient wellbeing through innovative medicine and extensive scientific research.
A well-rounded writer for Klarity, her knowledge extends from the evaluation of oncology drugs and interventions, to corticosteroid use and non-conventional, holistic approaches to disease.
Cristina aims to complete a Masters in Biomedical Science, with aspirations of working in Medical Affairs for leading Pharmaceutical Companies

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