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Coenzyme Q10 (CoQ10), also known as ubiquinone, is a powerful antioxidant discovered by researchers at the University of Wisconsin in 1957. 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 food.
Japanese scientists first discovered the therapeutic properties of CoQ10 in the 1960s. Today, it is widely prescribed in Europe, Israel, and Japan for heart conditions. CoQ10 appears to 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. Ongoing 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 side effects of certain prescription medications.
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Sources
Every cell in your body needs CoQ10, but no U.S. Dietary Reference Intake (formerly known as the Recommended Dietary Allowance) has been established for this important substance because the body can manufacture CoQ10 from scratch.
Because CoQ10 is found in all animal and plant cells, we obtain small amounts of this nutrient from our diet. However, it would be hard to get a therapeutic dosage from food.
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Therapeutic Dosages
The typical recommended dosage of CoQ10 is 30 to 300 mg daily, often divided into 2 or 3 doses; 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.1
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Therapeutic Uses
Although not all studies have been positive, the best-documented use of CoQ10 is for treating congestive heart failure.33-36, 51-52 Keep in mind that it is taken along with conventional medications, not instead of them.
Weaker evidence suggests that this supplement may be useful for cardiomyopathy and other forms of heart disease.5,6,7CoQ10 may also be helpful for hypertension,8–11,58 kidney failure,49diabetes,40,58 and for preventing the heart damage caused by certain types of cancer chemotherapy.59-61
Note: People with severe illnesses such as heart disease, cancer and kidney failure should not use CoQ10 except under physician supervision.
Promising, but far from definitive new evidence suggests that CoQ10 may slow the progression of Parkinson’s disease.57
CoQ10 is 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.12
Highly preliminary studies suggest CoQ10 might be helpful for amyotrophic lateral sclerosis.13,14
CoQ10 has been tried but not found effective for the treatment of Huntington's disease.48
Some evidence indicates that CoQ10 supplements may offer benefit for people taking medications that interfere with the body's production of CoQ10, or partially block its action. It has been suggested (but not proven) that these effects on CoQ10 may play a role in the known side effects of these treatments, and that taking CoQ10 supplements might help. The best evidence is for the cholesterol-lowering drugs in the statin family, such as lovastatin (Mevacor), simvastatin (Zocor), and pravastatin (Pravachol).22–25 For several other categories of drugs, the evidence that they interfere with CoQ10 is provocative but less than solid. 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.26–31
CoQ10 has additionally been proposed as a treatment for a wide variety of other conditions, including AIDS, angina, cancer, male infertility, muscular dystrophy, and obesity, but there is, as yet, no evidence that it is effective. It has also been used as a performance enhancer for athletes.
Although one double-blind study of 25 highly trained cross-country skiers found some benefit,15 most studies evaluating potential sports supplement uses of CoQ10 have returned negative rather than positive results.16–21
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What Is the Scientific Evidence for Coenzyme Q10 (CoQ10)?
Congestive Heart Failure
Most, but not all, studies tell us 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 healthy people.32 This fact alone does not prove that CoQ10 supplements will help CHF; however, it prompted medical researchers to try using CoQ10 as a treatment for heart failure.
In the largest study, 641 people with moderate to severecongestive heart failure were monitored for 1 year.33 Half were given 2 mg per kilogram body weight of CoQ10 daily; the rest were given 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 over 250 participants.34,35, 53
However, two recent and very well-designed double-blind studies enrolling a total of about 85 people with congestive heart failure failed to find any evidence of benefit 36, 54 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.37,38,39
Hypertension
An 8-week, double-blind, placebo-controlled study of 59 men already taking medications for high blood pressure found that 120 mg daily of CoQ10 reduced blood pressure by about 9% as compared to placebo.40
A 12 week, double-blind, placebo-controlled study of 83 people with isolated systolic hypertension (a type of high blood pressure in which only the "top" number is high) found that use of CoQ10 at a dose of 60 mg daily improved blood pressure measurements to a similar extent. 50
Similarly, in a 12 week, double-blind, placebo-controlled trial of 74 people with diabetes, use of CoQ10 at a dose of 100 mg twice daily significantly reduced blood pressure as compared to placebo.58
Anti-hypertensive effects were also seen in previous smaller trials, most of which were not double-blind.41,42,43
Parkinson’s Disease
CoQ10 has shown some promise for slowing the progression of Parkinson’s disease. In a 16-month, double-blind, placebo-controlled trial, 80 people with Parkinson’s disease were given either CoQ10 or placebo.57 Participants in this trial had early stages of the disease, and did not yet need medication.
The results suggest that in participants taking CoQ10, symptoms of disease developed more slowly. However, from a statistical point of view, the results were less than conclusive. Further trials will be necessary to confirm (or deny) these encouraging results.
Diabetes
In the 12 week, double-blind, placebo-controlled trial of 74 people with diabetes mentioned above, use of CoQ10 at a dose of 100 mg twice daily significantly improved blood sugar control as compared to placebo.58 Similar benefits were seen in the n 8-week, double-blind, placebo-controlled study of 59 men also described above.40 However, a third study failed to find any effect on blood sugar control.62
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Safety Issues
CoQ10 appears to be extremely safe. No significant side effects have been found, even in studies that lasted a year.44 However, people with severe heart disease should not take CoQ10 (or any other supplement) except under a doctor's supervision.
As noted above, two studies suggest that CoQ10 might reduce blood sugar levels in people with diabetes.45 While this could potentially be helpful for treatment of diabetes, it might present a risk as well; diabetics using CoQ10 might inadvertently push their blood sugar levels dangerously low. However, another trial in people with diabetes found no effect on blood sugar control.46,58 The bottom line: If you have diabetes, make sure to track your blood sugar closely if you 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.47,55 However, a small, double-blind study found no interaction between CoQ10 and warfarin.56 Nonetheless, in view of warfarin’s low margin of safety, prudence indicates physician supervision before combining CoQ10 with warfarin.
The maximum safe dosages of CoQ10 for young children, pregnant or nursing women, or those with severe liver or kidney disease have not been determined.
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Interactions You Should Know About
If you are taking:
Cholesterol-lowering drugs in the statin family, red yeast rice (which contains natural statin drugs), beta-blockers (specifically propranolol, metoprolol, and alprenolol), antipsychotic drugs in the phenothiazine family, tricyclic antidepressants, methyldopa, hydrochlorothiazide, clonidine, or hydralazine: You may need more coenzyme Q10.
Coumadin (warfarin) : You should not take CoQ10 except on a physician's advice.
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References
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2. Morisco C, Trimarco B, Condorelli M. Effect of coenzyme Q10 therapy in patients with congestive heart failure: a long-term multicenter randomized study. Clin Investig. 1993;71(8 suppl):S134–S136.
3. Hashiba K, Kuramoto K, Ishimi Z, et al. Heart. 1972;4:1579–1589. Cited by: Werbach MR. Nutritional Influences on Illness [book on CD-ROM]. Tarzana, Calif: Third Line Press; 1998.
4. Hofman-Bang C, Rehnquist N, Swedberg K, et al. Coenzyme Q10 as an adjunctive treatment of congestive heart failure. J Am Coll Cardiol. 1992;19:216A.
5. Langsjoen H, Langsjoen P, Langsjoen P, et al. Usefulness of coenzyme Q10 in clinical cardiology: a long-term study. Mol Aspects Med. 1994;15(suppl):S165–S175.
6. Langsjoen PH, Vadhanavikit S, Folkers K. Response of patients in classes III and IV of cardiomyopathy to therapy in a blind and crossover trial with coenzyme Q10. Proc Natl Acad Sci U S A. 1985;82:4240–4244.
7. Pogessi L, Galanti G, Comeglio M, et al. Effect of coenzyme Q10 on left ventricular function in patients with dilative cardiomyopathy. Curr Ther Res. 1991;49:878–886.
8. Digiesi V, Cantini F, Brodbeck B. Effect of coenzyme Q10 on essential arterial hypertension. Curr Ther Res. 1990;47:841–845.
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32. Werbach MR. Nutritional Influences on Illness [book on CD-ROM]. Tarzana, Calif: Third Line Press; 1998.
33. Morisco C, Trimarco B, Condorelli M. Effect of coenzyme Q10 therapy in patients with congestive heart failure: a long-term multicenter randomized study. Clin Investig. 1993;71(8 suppl):S134–S136.
34. Hashiba K, Kuramoto K, Ishimi Z, et al. Heart. 1972;4:1579–1589. Cited by: Werbach MR. Nutritional Influences on Illness [book on CD-ROM]. Tarzana, Calif: Third Line Press; 1998.
35. Hofman-Bang C, Rehnquist N, Swedberg K, et al. Coenzyme Q10 as an adjunctive treatment of congestive heart failure. J Am Coll Cardiol. 1992;19:216A.
36. Khatta M, Alexander BS, Krichten CM, et al. The effect of coenzyme Q10 in patients with congestive heart failure. Ann Intern Med. 2000;132:636-640.
37. Langsjoen H, Langsjoen P, Langsjoen P, et al. Usefulness of coenzyme Q10 in clinical cardiology: a long-term study. Mol Aspects Med. 1994;15(suppl):S165–S175.
38. Langsjoen PH, Vadhanavikit S, Folkers K. Response of patients in classes III and IV of cardiomyopathy to therapy in a blind and crossover trial with coenzyme Q10. Proc Natl Acad Sci U S A. 1985;82:4240–4244.
39. Pogessi L, Galanti G, Comeglio M, et al. Effect of coenzyme Q10 on left ventricular function in patients with dilative cardiomyopathy. Curr Ther Res. 1991;49:878–886.
40. Singh RB, Niaz MA, Rastogi SS, et al. Effect of hydrosoluble coenzyme Q10 on blood pressures and insulin resistance in hypertensive patients with coronary artery disease. J Human Hypertens. 1999;13:203–208.
41. Digiesi V, Cantini F, Brodbeck B. Effect of coenzyme Q10 on essential arterial hypertension. Curr Ther Res. 1990;47:841–845.
42. Langsjoen P, Langsjoen P, Willis R, et al. Treatment of essential hypertension with coenzyme Q10. Mol Aspects Med. 1994;15(suppl):S265–S272.
43. Digiesi V, Cantini F, Oradei A, et al. Coenzyme Q10 in essential hypertension. Mol Aspects Med. 1994;15(suppl):S257–S263.
44. Lampertico M, Comis S. Italian multicenter study on the efficacy and safety of coenzyme Q10 as adjuvant therapy in heart failure. Clin Investig. 1993;71(8 suppl):S129–S133.
45. Singh RB, Niaz MA, Rastogi SS, et al. Effect of hydrosoluble coenzyme Q10 on blood pressures and insulin resistance in hypertensive patients with coronary artery disease. J Human Hypertens. 1999;13:203–208.
46. Eriksson JG, Forsen TJ, Mortensen SA, et al. The effect of coenzyme Q10 administration on metabolic control in patients with type 2 diabetes mellitus. Biofactors. 1999;9:315–318.
47. Spigset O. Reduced effect of warfarin caused by ubidecarenone [letter]. Lancet. 1994;344:1372–1373.
48. Huntington Study Group. A randomized, placebo-controlled trial of coenzyme Q10 and remacemide in Huntington's disease. Neurology. 2001;57:397–404.
49. Singh RB, Khanna HK, Niaz MA. Randomized, double-blind placebo-controlled trial of coenzyme Q10 in chronic renal failure: discovery of a new role. J Nutr Environ Med. 2000;10:281-288.
50. Burke BE, Neuenschwander R, Olson RD. Randomized, double-blind, placebo-controlled trial of coenzyme Q10 in isolated systolic hypertension. South Med J. 2001;94:1112–1117.
51. Munkholm H, Hansen HH, Rasmussen K. Coenzyme Q10 treatment in serious heart failure. Biofactors. 1999;9:285-289.
52. Watson PS, Scalia GM, Galbraith A, et al. Lack of effect of coenzyme Q on left ventricular function in patients with congestive heart failure. J Am Coll Cardiol. 1999;33:1549-1552.
53. Munkholm H, Hansen HH, Rasmussen K. Coenzyme Q10 treatment in serious heart failure. Biofactors. 1999;9:285-289.
54. Watson PS, Scalia GM, Galbraith A, et al. Lack of effect of coenzyme Q on left ventricular function in patients with congestive heart failure. J Am Coll Cardiol. 1999;33:1549-1552.
55. Combs AB, Porter TH, Folkers K. Anticoagulant activity of a naphtoquinone analog of vitamin K and an inhibitor of coenzyme Q10-enzyme systems. Res Commun Chem Pathol Pharmacol. 1976;13:109–114.
56. Engelsen J, Nielsen JD, Winther K. Effect of coenzyme Q10 and Ginkgo biloba on warfarin dosage in stable, long-term warfarin-treated outpatients. A randomised, double-blind, placebo-crossover trial. Thromb Haemost. 2002;87:1075-1076.
57. Shults CW, Oakes D, Kieburtz K, et al. Effects of coenzyme q10 in early Parkinson disease: evidence of slowing of the functional decline. Arch Neurol. 2002;59:1541-1550.
58. Hodgson JM, Watts GF, Playford DA, et al. Coenzyme Q(10) improves blood pressure and glycaemic control: a controlled trial in subjects with type 2 diabetes. Eur J Clin Nutr. 2002;56:1137-1142.
59. Combs AB, Choe JY, Truong DH, et al. Reduction by coenzyme Q10 of the acute toxicity of adriamycin in mice. Res Commun Chem Pathol Pharmacol. 1977;18:565-568.
60. Judy WV, Hall JH, Dugan W, et al. Coenzyme Q10 reduction of Adriamycin cardiotoxicity. Biomed Clin Aspects Coenzyme Q. 1984;4:231-241.
61. Sugiyama S, Yamada K, Hayakawa M, et al. Approaches that mitigate doxorubicin-induced delayed adverse effects on mitochondrial functions in rat hearts; Liposome-encapsulated doxorubican or combination therapy with antioxidant. Biochem Mol Biol Int. 1995;36:1001-1007.
62. Eriksson JG, Forsen TJ, Mortensen SA, et al. The effect of coenzyme Q10 administration on metabolic control in patients with type 2 diabetes mellitus. Biofactors. 1999;9:315–318.
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