View source for Coenzyme Q10

{{DISPLAYTITLE:Coenzyme Q<sub>10</sub>}}
{{chembox
| verifiedrevid = 310148203
|   ImageFile = Ubiquinone.png
|   IUPACName = 2-[(2''E'',6''E'',10''E'',14''E'',18''E'',22''E'',26''E'',30''E'',34''E'')-3,7,11,15,19,23,27,31,35,39-decamethyltetraconta-2,6,10,14,18,22,26,30,34,38-decaenyl]-5,
6-dimethoxy-3-methylcyclohexa-2,5-diene-1,4-dione
| Section1 = {{Chembox Identifiers
|   CASNo_Ref = {{cascite}}
| CASNo = 303-98-0
|   PubChem = 5281915
|   SMILES = CC1=C(C(=O)C(=C(C1=O)OC)OC)C/C=C(\C)/CC/C=C(\C)/CC/C=C(\C)/CC/C=C(\C)/
CC/C=C(\C)/CC/C=C(\C)/CC/C=C(\C)/CC/C=C(\C)/CC/C=C(\C)/CCC=C(C)C
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| Section2 = {{Chembox Properties
|   C=59 | H = 90 | O=4
|   Appearance = 
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| Section7 = {{Chembox Hazards
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| Section8 = {{Chembox Related
|   OtherCpds = [[1,4-Benzoquinone]]<br>[[Quinone]]<br>[[Plastoquinone]] 
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}}

'''Coenzyme Q<sub>10</sub>''' (also known as '''ubiquinone''', '''ubidecarenone''', '''coenzyme Q''', and abbreviated at times to '''CoQ<sub>10</sub>''' (pronounced "ko-cue-ten"), '''CoQ''', '''Q10''', or '''Q''') is a [[1,4-benzoquinone]], where '''Q''' refers to the [[quinone]] chemical group, and '''10''' refers to the number of [[isoprene|isoprenyl]] chemical subunits in its tail. 

This oil-soluble, vitamin-like, substance is present in most [[Eukaryote|eukaryotic]] cells, primarily in the [[mitochondria]]. It is a component of the [[electron transport chain]] and participates in [[Cellular respiration#Aerobic respiration|aerobic cellular respiration]], generating energy in the form of [[Adenosine triphosphate|ATP]].  Ninety-five percent of the human body’s energy is generated this way.<ref>Ernster L, Dallner G: Biochemical, physiological and medical aspects of ubiquinone function. Biochim  Biophys Acta 1271: 195-204, 1995</ref><ref>Dutton PL, Ohnishi T, Darrouzet E, Leonard, MA, Sharp RE, Cibney BR, Daldal F and Moser CC. 4 Coenzyme Q oxidation reduction reactions in mitochondrial electron transport (pp 65-82) in Coenzyme Q: Molecular mechanisms in health and disease edited by Kagan VE and Quinn PJ, CRC Press (2000), Boca Raton</ref> Therefore, those organs with the highest energy requirements&mdash;such as the heart, liver and kidney &mdash;have the highest CoQ<sub>10</sub> concentrations.<ref>Okamoto, T.et al. (1989) Interna.J.Vit.Nutr.Res.,59,288-292</ref><ref>Aberg,F.et al. (1992)Archives of Biochemistry and Biophysics, 295, 230-234</ref><ref>Shindo, Y., Witt, E., Han, D., Epstein, W., and Packer, L., Enzymic and non-enzymic antioxidants in epidermis and dermis of human skin, Invest. Dermatol., 102 (1994) 122-124.</ref> There are three redox states of Coenzyme Q10: fully oxidized (ubiquinone), semiquinone (ubisemiquinone), and fully reduced ([[ubiquinol]]).


==Discovery==
Coenzyme Q<sub>10</sub> was first discovered by Professor Fredrick L. Crane and colleagues at the [[University of Wisconsin–Madison]] Enzyme Institute in [[1957]].<ref>{{cite journal |author=Crane F, Hatefi Y, Lester R, Widmer C |title=Isolation of a quinone from beef heart mitochondria |journal=Biochim Biophys Acta |volume=25 |issue=1 |pages=220–1 |year=1957 |pmid=13445756 |doi=10.1016/0006-3002(57)90457-2}}</ref><ref name="washington">Peter H. Langsjoen, "[http://faculty.washington.edu/~ely/coenzq10.html Introduction of Coezyme Q10]"</ref> In [[1958]], its chemical structure was reported by Dr. [[Karl Folkers]] and coworkers at [[Merck and Company|Merck]]; in 1968, Folkers became a Professor in the Chemistry Department at the [[University of Texas at Austin]].<ref name="washington" /><ref>Wolf DE, Hoffman CH, Trenner NR, Arison BH, Shunk CH, Linn BD, McPherson JF, and Folkers K.
Structure studies on the coenzyme Q group. J Am Chem Soc 1958: 80:4752.</ref>

==Chemical properties==
The oxidized structure of CoQ<sub>10</sub> is shown on the top right. The various kinds of Coenzyme Q can be distinguished by the number of [[isoprene|isoprenoid]] [[side-chain]]s they have. The most common Coenzyme Q in human [[mitochondria]] is CoQ<sub>10</sub>. The 10 refers to the number of isoprene repeats. The image below has three [[isoprene|isoprenoid]] units and would be called Q<sub>3</sub>. [[Image:Ubiquinone3.png|center|300px]]

==Biochemical role==
[[Image:ETC.PNG|thumb|300px|[[Electron transport chain]] ("UQ" visible in green near center.)]]
CoQ<sub>10</sub> is found in the [[biological membrane|membranes]] of many [[organelles]].  Since its primary function in cells is in generating energy, the highest concentration is found on the inner [[biological membrane|membrane]] of the [[mitochondrion]].  Some other organelles that contain CoQ<sub>10</sub> include [[endoplasmic reticulum]], [[peroxisome]]s, [[lysosome]]s, and [[vesicle (biology)|vesicle]]s. In its reduced form ([[ubiquinol]]), Coenzyme Q10 acts as an important antioxidant in the body.

==Biosynthesis==
The biosynthesis is a multistage process requiring at least eight vitamins and several trace elements. The [[1,4-Benzoquinone|benzoquinone]] portion of coenzyme Q<sub>10</sub> is synthesized from [[tyrosine]], whereas the [[isoprene]] sidechain is synthesized from [[acetyl-CoA]] through the [[mevalonate pathway]]. The mevalonate pathway is also used for the first steps of cholesterol biosynthesis.

==Absorption and metabolism==
===Absorption===
CoQ<sub>10</sub> is a crystalline powder that is insoluble in water because of its low polarity. It has a relatively high molecular weight (863 g/mol), and its solubility in lipids is also limited, so it is very poorly absorbed in the gastrointestinal tract.<ref name="Zmitek" /><sup>,</sup><ref name="K. Chopra, Mitochondrion 2007">H. N. Bhagavan and R. K. Chopra, Mitochondrion, 7: S78-S88 (2007).</ref> Absorption follows the same process as that of lipids and the uptake mechanism appears to be similar to that of [[vitamin E]], another lipid-soluble nutrient. Emulsification and [[micelle]] formation is required for the absorption of fats. For CoQ<sub>10</sub>, this process is facilitated chiefly by secretions from the [[pancreas]] and [[bile salts]] in the small intestine.<ref name="Bhagavan">H. N. Bhagavan and R. K. Chopra, Free Radic. Res., 40: 445-453 (2006).</ref> A general rule is that the higher the dose orally administered the lower the percent of the dose absorbed.<ref name="Bhagavan" />

===Metabolism===
Data on the metabolism of CoQ<sub>10</sub> in animals and humans are limited.<ref name="Zmitek" /> A study with [[carbon-14|<sup>14</sup>C-labeled]] CoQ<sub>10</sub> in [[rat]]s showed most of the radioactivity in the liver 2 hours after oral administration when the peak plasma radioactivity was observed, but it should be noted that CoQ<sub>9</sub> is the predominant form of coenzyme Q in rats.<ref>H. Kishi, N. Kanamori, S. Nisii, E. Hiraoka, T. Okamoto and T. Kishi, Metabolism and Exogenous Coenzyme Q10 in vivo and Bioavailability of Coenzyme Q10 Preparations in Japan. In Biomedical and Clinical Aspects of Coenzyme Q. pp. 131-142, Elsevier, Amsterdam 1964.</ref> It appears that CoQ<sub>10</sub> is metabolised in all tissues, while a major route for its elimination is biliary and fecal excretion. After the withdrawal of CoQ<sub>10</sub> supplementation, the levels return to their normal levels within a few days, irrespective of the type of formulation used.<ref name="Ozawa"/>

=== Factors affecting CoQ<sub>10</sub> levels ===
Various factors reduce the concentration of CoQ<sub>10</sub> in different organs; the following are known:
<li>Use of statins reduce CoQ<sub>10</sub> levels — see below.</li>
<li>Aging, in individuals older than 20 years, reduces CoQ<sub>10</sub> levels in internal organs.<ref>{{cite doi|10.1007/BF02535072}}</ref><ref>{{cite doi|10.1111/j.1471-4159.1990.tb01889.x}}</ref></li>
<li>UV exposure reduces CoQ<sub>10</sub> levels in the skin.<ref>{{cite pmid|8151122}}</ref></li>

==== Inhibition by statins and beta blockers ====
Coenzyme Q<sub>10</sub> shares a common biosynthetic pathway with [[cholesterol]]. The synthesis of an intermediary precursor of coenzyme Q<sub>10</sub>, [[mevalonate]], is inhibited by some [[beta blocker]]s, blood pressure-lowering medication,<ref>{{cite journal |author=Kishi T, Watanabe T, Folkers K |title=Bioenergetics in clinical medicine XV. Inhibition of coenzyme Q10-enzymes by clinically used adrenergic blockers of beta-receptors |journal=Res Commun Chem Pathol Pharmacol |volume=17 |issue=1 |pages=157–64 |year=1977 |pmid=17892}}</ref> and [[statins]], a class of cholesterol-lowering drugs.<ref>[http://www.cholesterol-and-health.com/Synthesis-Of-Cholesterol.html The Synthesis of Cholesterol<!-- Bot generated title -->]</ref><ref>{{cite journal | last = Mortensen | first = S.A. | coauthors = ''et al.'' | title = Dose-Related Decrease of Coenzyme Q10 During Treatment with HMG-CoA Reductase Inhibitors | journal = Molecular Aspects of Medicine | volume = 18 Suppl. | year = 1997 | pages = 137–144 | pmid = 9266515 | accessdate = 2009-11-29 }}</ref>  Statins can reduce serum levels of coenzyme Q<sub>10</sub> by up to 40%.<ref>{{cite journal |author=Ghirlanda G, Oradei A, Manto A, Lippa S, Uccioli L, Caputo S, Greco A, Littarru G |title=Evidence of plasma CoQ10-lowering effect by HMG-CoA reductase inhibitors: a double-blind, placebo-controlled study |journal=J Clin Pharmacol |volume=33 |issue=3 |pages=226–9 |year=1993 |pmid=8463436}}</ref> Some research suggests the logical option of supplementation with coenzyme Q<sub>10</sub> as a routine adjunct to any treatment that may reduce [[endogenous]] production of coenzyme Q<sub>10</sub>, based on a balance of likely benefit against very small risk.<ref>{{cite journal |author=Sarter B |title=Coenzyme Q10 and cardiovascular disease: a review |journal=J Cardiovasc Nurs |volume=16 |issue=4 |pages=9–20 |year=2002 |pmid=12597259 }}</ref><ref>{{cite journal |author=Thibault A, Samid D, Tompkins A, Figg W, Cooper M, Hohl R, Trepel J, Liang B, Patronas N, Venzon D, Reed E, Myers C |title=Phase I study of lovastatin, an inhibitor of the mevalonate pathway, in patients with cancer |journal=Clin Cancer Res |volume=2 |issue=3 |pages=483–91 |year=1996 |pmid=9816194}}</ref>

==Pharmacokinetics==
Some reports have been published on the pharmacokinetics of CoQ<sub>10</sub>. The plasma peak can be observed 2–6 hours after oral administration, mainly depending on the design of the study. In some studies, a second plasma peak was also observed at about 24 hours after administration, probably due to both enterohepatic recycling and redistribution from the liver to circulation.<ref>H. N. Bhagavan and R. K. Chopra, Free Radic. Res., 40: 445-453 (2006)</ref> Tomono et al. used deuterium-labelled crystalline CoQ10 to investigate pharmacokinetics in human and determined an elimination half-time of 33 hours.<ref>Y. Tomono, J. Hasegawa, T. Seki, K. Motegi and N. Morishita, Int. J. Clin. Pharmacol. Ther., 24: 536-541 (1986).</ref>

==Improving the bioavailability of CoQ<sub>10</sub>==
The importance of how drugs are formulated for bioavailability is well known. In order to find a principle to boost the bioavailability of CoQ<sub>10</sub> after oral administration, several new approaches have been taken and different formulations, and forms have been developed and tested on animals or humans<ref name="Zmitek">Zmitek et al. (2008) Agro Food Ind. Hi Tec. 19, 4, 9. - [http://www.teknoscienze.com/leafpdf/schema/index.html?folder=144&pagina=10 Improving the bioavailability of CoQ<sub>10</sub>]</ref>, such as Nano CoQ-10.[http://www.thecatalog.com/sol-1823.html]  

===Reduction of particle size===
The obvious strategy is reduction of the particle size to as low as the micro- and nano-scale. Nanoparticles have been explored as a delivery system for various drugs and an improvement of the oral bioavailability of drugs with poor absorption characteristics has been reported;<ref>E. Mathiowitz, J. S. Jacob, Y. S. Jong, G. P. Carino, D. E. Chickering, P. Chaturvedi, C. A. Santos, K. Vijayaraghavan, S. Montgomery, M. Bassett and C. Morrell, Nature, 386: 410-414 (1997).</ref> the pathways of absorption and the efficiency were affected by reduction of particle size. This protocol has so far not proved to be very successful with CoQ<sub>10</sub>, although reports have differed widely.<ref>C. H. Hsu, Z. Cui, R. J. Mumper and M. Jay, AAPS PharmSciTech., 4: E32 (2003).</ref><sup>,</sup><ref>S. S. Joshi, S. V. Sawant, A. Shedge and A. D. Halpner, Int. J. Clin. Pharmacol. Ther., 41: 42-48 (2003).</ref> The use of the aqueous suspension of finely powdered CoQ<sub>10</sub> in pure water has also only revealed a minor effect.<ref name="Ozawa">Y. Ozawa, Y. Mizushima, I. Koyama, M. Akimoto, Y. Yamagata, H. Hayashi and H. Murayama, Drug Res., 36-1: 689-690 (1986).</ref>

===Soft-gel capsules with CoQ<sub>10</sub> in oil suspension===
A successful approach was to use the emulsion system to facilitate absorption from the gastrointestinal tract and to improve bioavailability. Emulsions of soybean oil (lipid microspheres) could be stabilised very effectively by lecithin and were utilised in the preparation of soft gelatine capsules. In one of the first such attempts, Ozawa et al. performed a pharmacokinetic study on beagle dogs in which the emulsion of CoQ<sub>10</sub> in soybean oil was investigated; about two times higher plasma CoQ<sub>10</sub> level than that of the control tablet preparation was determined during administration of a lipid microsphere.<ref name="Ozawa" /> Although an almost negligible improvement of bioavailability was observed by Kommuru et al. with oil-based soft-gel capsules in a later study on dogs,<ref>T. R. Kommuru, M. Ashraf, M. A. Khan and I. K. Reddy, Chemical & Pharmaceutical Bulletin, 47: 1024-1028 (1999).</ref> the significantly increased bioavailability of CoQ<sub>10</sub> was confirmed for several oil-based formulations in most other studies.<ref name="K. Chopra, Mitochondrion 2007"/> 

===Novel forms of CoQ<sub>10</sub> with increased water-solubility===
Facilitating drug absorption by increasing its solubility in water is a common pharmaceutical strategy and has also been shown to be successful for Coenzyme Q<sub>10</sub>. Various approaches have been developed to achieve this goal, with many of them producing significantly better results over oil-based soft-gel capsules in spite of the many attempts to optimize their composition.<ref name="Zmitek" /> Examples of such approaches are use of the aqueous dispersion of solid CoQ<sub>10</sub> with [[tyloxapol]] [[polymer]],<ref>K. Westesen and B. Siekmann. Particles with modified physicochemical properties, their preparation and uses. US6197349. 2001.</ref> formulations based on various solubilising agents, i.e., hydrogenated [[lecithin]], <ref>H. Ohashi, T. Takami, N. Koyama, Y. Kogure and K. Ida. Aqueous solution containing [[ubidecarenone]]. US4483873. 1984</ref> and complexation with [[cyclodextrins]]; among the latter, complex with [[β-cyclodextrin]] has been found to have highly increased bioavailability.<ref>Zmitek, J. et all (2008) Relative bioavailability of two forms of a novel water soluble CoQ10 [http://content.karger.com/ProdukteDB/produkte.asp?Doi=129661 Ann. Nutri. Metab. 52:281-287 (2008)]</ref><sup>,</sup><ref>D. Madhavi, and D. Kagan.  (2010) "A Study of the Bioavailability of a Sustained-release CoEnzyme Q10-β-cyclodextrin Complex" 9(1):20-25. </ref> and is also used in pharmaceutical and food industry for CoQ<sub>10</sub>-fortification.<ref name="Zmitek" />
Also some other novel carrier systems like liposomes, nanoparticles, dendrimers etc can be used to increase the bioavailability of Coenzyme Q<sub>10</sub>.

===Ubiquinol form===
Since the ubiquinol form has two additional hydrogens, it results in the conversion of two ketone groups into hydroxyl groups on the active portion of the molecule. This causes an increase in the polarity of the CoQ<sub>10</sub> molecule and maybe a significant factor behind the observed enhanced bioavailability of ubiquinol. Orally, ubiquinol exhibits greater bioavailability than ubiquinone: one study showed subjects ingesting 150 mg per day ubiquinol supplementation displayed peak values within 28 days of 3.84 mcg/ml of plasma.<ref>Hosoe K, et al. Study On Safety And bioavailability of ubiquinol (Kaneka QH™) after single and 4-week multiple oral administration to healthy volunteers. Regulatory Toxicology and Pharmacology. 2007, 47: 19-28</ref>  Additionally, research in an animal model investigating the neuroprotective effects of both forms of CoQ10 showed greater blood levels and improved efficacy by ubiquinol in comparison to ubiquinone.<ref>Cleren, C, et al. Therapeutic effects of coenzyme Q10 (CoQ10) and reduced CoQ10 in the MPTP model of Parkinsonism. Journal of Neurochemistry. 2008, 104: 1613-1621</ref>


==Supplementation benefits==

Coenzyme Q10 is the 3rd most sold dietary ingredient in the United States after omega-3 and multivitamins.
 
According to the Mayo Clinic<ref name= "Mayo">Mayo Clinic [http://www.mayoclinic.com/health/coenzyme-q10/NS_patient-coenzymeq10 Drugs and Supplements: Coenzyme Q10] (accessed 13 November 2008)</ref> "CoQ10 has been used, recommended, or studied for numerous conditions, but remains controversial as a treatment in many areas."  Further clinical results are needed to determine whether supplementation with coenzyme Q<sub>10</sub> is beneficial for healthy people.

===Mitochondrial disorders===
Supplementation of coenzyme Q<sub>10</sub> is a treatment for some of the very rare and serious [[mitochondrial disease|mitochondrial disorder]]s and other [[metabolic disorder]]s, where patients are not capable of producing enough coenzyme Q<sub>10</sub> because of their disorder.<ref>{{cite journal | last = Genova | first = M.L. | coauthors = ''et al.'' | title = Mitochondrial Production of Oxygen Radical Species and the Role of Coenzyme Q as an Antioxidant | journal = Experimental Biology and Medicine | volume = 228 | issue = 5 | year = 2003 | month = May | pages = 506–513 | pmid = 12709577 | accessdate = 2009-11-29 }} [http://www.ebmonline.org/cgi/content/full/228/5/506]</ref> Coenzyme Q<sub>10</sub> is then prescribed by a physician.<ref>{{cite journal | last = Berbel-Garcia | first = A. | coauthors = ''et al.'' | title = Coenzyme Q 10 improves lactic acidosis, strokelike episodes, and epilepsy in a patient with MELAS | journal = Clinical Neuropharmacology | volume = 27 | year = 2004 | month = July | pages = 187–191 | pmid = 15319706 | accessdate = 2006-12-01 | doi = 10.1097/01.wnf.0000137862.67131.bf | issue = 4 }}</ref>

===Heart failure===
There is some clinical evidence<ref name="Langsjoen">Peter H. Langsjoen, University of Washington, [http://faculty.washington.edu/ely/coenzq10.html INTRODUCTION TO COENZYME Q10] (accessed 13 November 2008)</ref> that supplementation with coenzyme Q<sub>10</sub> is beneficial in treatment of patients with congestive heart failure. However, The American College of Cardiology published in 2005 an expert consensus document concluding that the value of coenzyme Q<sub>10</sub> in cardiovascular disease has not been clearly established.<ref>ROBERT ALAN BONAKDAR  and ERMINIA GUARNERI,  [http://www.aafp.org/afp/20050915/1065.html American Family Physician page on CoEnzyme Q10]  (Sept 2005, accessed 13 November 2008)</ref>  The Mayo clinic says that there is not enough scientific evidence to recommend for or against the use of CoQ<sub>10</sub> in patients with coronary heart disease.<ref name= "Mayo" />

===Migraine headaches===
Supplementation of coenzyme Q<sub>10</sub> has been found to have a beneficial effect on the condition of some sufferers of [[migraine]] headaches. So far, three studies have been done, of which two were small, did not have a placebo group, were not randomized, and were [[open-label trial|open-label]],<ref>{{cite journal |author=Rozen T, Oshinsky M, Gebeline C, Bradley K, Young W, Shechter A, Silberstein S |title=Open label trial of coenzyme Q10 as a migraine preventive |journal=Cephalalgia |volume=22 |issue=2 |pages=137–41 |year=2002 |pmid=11972582 |url = http://www.blackwell-synergy.com/doi/full/10.1046/j.1468-2982.2002.00335.x |doi=10.1046/j.1468-2982.2002.00335.x}}</ref> and one was a double-blind, randomized, placebo-controlled trial, which found statistically significant results despite its small sample size of 42 patients.<ref>{{cite journal |author=Sándor PS, et al.|title=Efficacy of coenzyme Q10 in migraine prophylaxis: A randomized controlled trial |journal=Neurology |volume=64 |pages=713–715 |year=2005 |url = http://www.neurology.org/cgi/content/abstract/64/4/713|pmid=15728298|doi=10.1212/01.WNL.0000151975.03598.ED |issue=4 |doi_brokendate=2010-04-28}}</ref> Dosages were 150 to 300&nbsp;mg/day.

===Cancer===
CoQ<sub>10</sub> is also being investigated as a treatment for [[cancer]], and as relief from cancer treatment side-effects.<ref>{{cite journal |url=http://www.ncbi.nlm.nih.gov/pubmed/17250435 |author=Katsuhisa Sakano, Mami Takahashi, Mitsuaki Kitano, Takashi Sugimura, Keiji Wakabayashi |title=Suppression of Azoxymethane-induced Colonic Premalignant Lesion Formation by Coenzyme Q10 in Rats. |publication=Asian Pacific J Cancer Prev, |volume=7, |pages=599-603, |year=2006 }}</ref>
<ref>http://www.cancer.gov/cancertopics/pdq/cam/coenzymeQ10/Patient/page2 Coenzyme Q10. NCI</ref>
<ref>http://clinicaltrials.gov/ct2/show/NCT00976131 Study of CoQ10 During One Cycle of Doxorubicin Treatment for Breast Cancer</ref>
<ref>http://clinicaltrials.gov/ct2/show/NCT00096356 Coenzyme Q10 in Relieving Treatment-Related Fatigue in Women With Breast Cancer </ref>

===Cardiac arrest===
Another recent study shows a survival benefit after cardiac arrest if coenzyme Q<sub>10</sub> is administered in addition to commencing active cooling of the body to 90&ndash;93 degrees Fahrenheit (32&ndash;34 degrees Celsius).<ref>
{{cite journal | last = Damian | first = M. S. | coauthors = ''et al.'' | title = Coenzyme Q10 Combined With Mild Hypothermia After Cardiac Arrest | journal = Circulation, American Heart Foundation | volume = 110 | year = 2004 | month = July | pages = 3011–3016 | url = http://www.circ.ahajournals.org/cgi/content/abstract/110/19/3011 | accessdate = 2006-12-01 | pmid = 15520321 | doi = 10.1161/01.CIR.0000146894.45533.C2 | issue = 19 }}
</ref>

===Blood pressure===
There are several reports concerning the effect of CoQ<sub>10</sub> on blood pressure in human studies.<ref> Cupp MJ and Tracy TS. Chapter 4: Coenzyme Q10 (Ubiquinone, Ubidecarenone), pp 53-85 in Dietary Supplements edited by Cupp MJ and Tracy TS Humana press, Totowa, New Jersey (2003) </ref>
A recent (2007) meta-analysis of the clinical trials of CoQ<sub>10</sub> for hypertension reviewed all published trials of coenzyme Q<sub>10</sub> for [[hypertension]], and assessed overall efficacy, consistency of therapeutic action, and side-effect incidence. Meta-analysis was performed in 12 clinical trials (362 patients) comprising three randomized controlled trials, one crossover study, and eight open-label studies. The meta-analysis concluded that coenzyme Q<sub>10</sub> has the potential in hypertensive patients to lower [[systolic blood pressure]] by up to 17&nbsp;mm Hg and [[diastolic blood pressure]] by up to 10&nbsp;mm Hg without significant side-effects.<ref>{{cite journal |url=http://www.ncbi.nlm.nih.gov/pubmed/17287847 |author=Rosenfeldt FL, Haas SJ, Krum H, Hadj A, Ng K, Leong J-Y, Watts GF. |title=Coenzyme Q<sub>10</sub> in the treatment of hypertension: a meta-analysis of the clinical trials. |publication=J Human Hypertension |volume=21 |pages=297-306 |year=2007 }}</ref>

=== Periodontal disease===
Studies have shown that diseased gum tissue is deficient in CoQ<sub>10</sub> compared to healthy gum tissue.<ref>{{cite journal |author=Littarru GP, Nakamura R, Ho L, Folkers K, Kuzell WC |title= Deficiency of coenzyme Q10 in gingival tissue from patients with periodontal disease |journal= Proc Natl Acad Sci U S A |volume=68 |issue=10 |pages=2332–2335 |year=1971 |pmid=5289867 |doi=10.1073/pnas.68.10.2332 |pmc=389415}}</ref><sup>,</sup><ref>{{cite journal |author= Nakamura R, Littarru GP, Folkers K, Wilkinson EG |title= Study of CoQ10-enzymes in gingiva from patients with periodontal disease and evidence for a deficiency of coenzyme Q10 |journal= Proc Natl Acad Sci U S A |volume=71 |issue=4 |pages=1456–60 |year=1974 |pmid= 4151519 |doi= 10.1073/pnas.71.4.1456 |pmc= 388248}}</ref>  Human clinical trials have suggested a link between oral administration of CoQ10 and improved gingival health,<ref>{{cite journal |author= McRee JT, Hanioka T, Shizukuishi S, Folkers K |title= Therapy with coenzyme Q10 for patients with periodontal disease |journal= J Dent Health |volume=43 |pages=659–666 |year=1993}}</ref> immune response in gum tissues,<ref>{{cite journal |author= Folkers K, Hanioka T, Xia LJ, McRee JT, Langsjoen P |title= Coenzyme Q10 increases T4/T8 ratios of lymphocytes in ordinary subjects and relevance to patients having the AIDS related complex |journal= Biochem Biophys Res Commun. |volume=176 |issue=2 |pages=786–91 |year=1991 |pmid=1673841 |doi= 10.1016/S0006-291X(05)80254-2}}</ref> and a reversal of the diseased gum conditions.<ref>{{cite journal |author= Wilkinson EG, Arnold RM, Folkers K |title= Bioenergetics in clinical medicine. VI. adjunctive treatment of periodontal disease with coenzyme Q10 |journal= Res Commun Chem Pathol Pharmacol. |volume=14 |issue=4 |pages=715–719 |year=1976 |pmid=785563}}</ref>  In addition to oral supplementation, topical application of CoQ10 on gum tissues has been shown to improve [[periodontitis]] and [[gingivitis]] conditions.<ref>{{cite journal |author= Hanioka T, Tanaka M, Ojima M, Shizukuishi S, Folkers K |title= Effect of topical application of coenzyme Q10 on adult periodontitis |journal= Mol Aspects Med. |volume=15 |issue=Suppl:s |pages=241–248 |year=1994 |pmid=7752836 |doi= 10.1016/0098-2997(94)90034-5}}</ref>

===Lifespan===
One study demonstrated that low dosages of coenzyme Q<sub>10</sub> reduce [[oxidation]] and [[DNA]] double-strand breaks, and a combination of a diet rich in [[polyunsaturated fatty acids]] and coenzyme Q<sub>10</sub> supplementation leads to a longer lifespan in rats.<ref name=pmid_15036411>{{cite journal |author=Quiles JL, Ochoa JJ, Huertas JR, Mataix J |title=Coenzyme Q supplementation protects from age-related DNA double-strand breaks and increases lifespan in rats fed on a PUFA-rich diet. |journal=Exp Gerontol. |volume=39 |issue=2 |pages=189–94 |year=2004 |pmid=15036411|doi=10.1016/j.exger.2003.10.002}}</ref>  Coles and Harris demonstrated an extension in the lifespan of rats when they were given coenzyme Q<sub>10</sub> supplementation.<ref name=coles_harris_coq10>{{cite journal |author=Coles L, Harris S |title=Coenzyme Q-10 and Lifespan Extension. |journal=Advances in Anti-Aging Medicine. |volume=1 |issue=1 |pages=205–215 |year=1996}}</ref>  But multiple studies have since found no increase in lifespan or decrease in aging in mice and rats supplemented with coenzyme Q<sub>10</sub>. <ref name=pmid_9584986>{{cite journal |author=Lonnrot K, Holm P, Lagerstedt A, Huhtala H, Alho H |title=The effects of lifelong ubiquinone Q10 supplementation on the Q9 and Q10 tissue concentrations and life span of male rats and mice.|journal=Biochem Mol Biol Int.. |volume=44 |pages=727–37 |year=1998 |pmid=9584986 |issue=4}}</ref>  <ref name=pmid_15059645>{{cite journal |author=Lee C-K, Pugh TD, Klopp RG, Edwards J, Allison DB, Weindruch R,Prolla TA. |title=The impact of alpha-lipoic acid, coenzyme Q10 and caloric restriction on life span and gene expression patterns in mice. |journal=Free Radic Biol Med. |volume=36 |pages=1043–57 |year=2004 |pmid=15059645 |doi=10.1016/j.freeradbiomed.2004.01.015 |issue=8}}</ref> <ref name=pmid_19710165>{{cite journal |author=Sohal RS, Kamzalov S, Sumien N, Ferguson M, Rebrin I, Heinrich KR,Forster MJ. |title=The impact of alpha-lipoic acid, coenzyme Q10 and caloric restriction on life span and gene expression patterns in mice. |journal=Free Radic Biol Med. |volume=40 |pages=480–7 |year=2006 |pmid=16443163 |issue=3 |doi=10.1016/j.freeradbiomed.2005.08.037 |pmc=2834650}}</ref> <ref name=pmid_16443163>{{cite journal |author=Nathalie Sumien,Kevin R. Heinrich, Ritu A. Shetty, Rajindar S. Sohal, and Michael J. Forster. |title=Prolonged Intake of Coenzyme Q10 Impairs Cognitive Functions in Mice |journal=J. Nutr. |volume=139 |pages=1926–1932 |year=2009 |pmid=19710165 |doi=10.3945/jn.109.110437 |issue=10 |pmc=2744613}}</ref> Another study demonstrated that coenzyme Q<sub>10</sub> extends the lifespan of ''C. elegans'' (nematode).<ref name=pmid_14706236>{{cite journal |author=Ishii N, Senoo-Matsuda N, Miyake K, Yasuda K, Ishii T, Hartman PS, Furukawa S |title=Coenzyme Q10 can prolong C. elegans lifespan by lowering oxidative stress. |journal=Mech Ageing Dev. |volume=125 |issue=1 |pages=41–6 |year=2004 |pmid=14706236 |doi=10.1016/j.mad.2003.10.002}}</ref>

===Radiation injury===
A 2002 study reported that, in [[laboratory rat|rat]] experiments,  coenzyme Q<sub>10</sub> taken as dietary supplement reduced radiation damage to the animals' blood.<ref>{{cite journal |title= Effect of Ubiquinone-10 on the Blood System in Rats Exposed to Radiation
|journal=Bulletin of Experimental Biology and Medicine|issn=0007-4888|issue= 6|month=June|year= 2002
|doi=10.1023/A:1020225623808|pages=562–564
|author=A. S. Koryagin, E. V. Krylova, and L. D. Luk'yanova |volume= 133 |pmid= 12447465}}. Abstract: "The use of synthetic ubiquinone-10 (2 and 10 mg/kg) as a therapeutic food additive normalized the counts of erythrocytes, reticulocytes, and leukocytes and the content of hemoglobin in the blood and inhibited lipid peroxidation in erythrocytes in irradiated rats (3 Gy)."</ref>

===Parkinson's disease===
A 2002 study in 80 [[Parkinson's disease]] patients found 1200mg/day reduced the progression by 44%.<ref>{{cite web|url=http://www.ninds.nih.gov/news_and_events/press_releases/pressrelease_parkinsons_coenzymeq10_101402.htm |title=Study Suggests Coenzyme Q<sub>10</sub> Slows Functional Decline in Parkinson's Disease |year=2002}}</ref>
<ref>{{cite journal |author=Shults et al. |title="Effects of coenzyme Q10 in early Parkinson disease: evidence of slowing of the functional decline." |journal=Archives of Neurology, |date=October 2002, |volume=59, No. 10, pp. 1541-1550 }}</ref> and a phase III trial of 1200mg/d and 2400mg/d should run until 2011.<ref>http://clinicaltrials.gov/ct2/show/NCT00740714 Effects of Coenzyme Q10 (CoQ) in Parkinson Disease (QE3) </ref>

==Coenzyme Q<sub>10</sub> concentrations in foods and dietary intake==

Detailed reviews on occurrence of CoQ<sub>10</sub> and dietary intake were published recently.<ref name="Pravst">Pravst et al. (2010) [http://www.informaworld.com/smpp/content~db=all~content=a919984573 Coenzyme Q10 Contents in Foods and Fortification Strategies] ''Critical Reviews in Food Science and Nutrition'', '''50''' (4) 269-280</ref> Besides endogenous synthesis, CoQ<sub>10</sub> is also supplied to the organism by various foods. However, despite the scientific community’s great interest in this compound, a very limited number of studies have been performed to determine the contents of CoQ<sub>10</sub> in dietary components. The first reports on this issue were published in 1959, but the sensitivity and selectivity of the analytical methods at that time did not allow reliable analyses, especially for products with low concentrations. <ref name="Pravst" />  Developments in analytical chemistry have since enabled a more reliable determination of CoQ<sub>10</sub> concentrations in various foods (Table below).


{| border="1"
|+ '''Table:''' CoQ<sub>10</sub> levels in selected foods <ref name="Pravst" />
! Food !! Coenzyme Q<sub>10</sub> concentration [mg/kg]
|-
!Meat
|-
| - beef
|-
|    -- heart	|| 113
|-
|    -- liver	||39-50
|-
|    -- muscle	||26-40
|-
| - pork        
|-
|    -- heart      ||11.8-128.2
|-
|    -- liver      ||22.7-54.0
|-
|    -- muscle     ||13.8-45.0
|-
| - chicken
|-
|   -- heart      ||116.2-132.2
|-	
!Fish	
|-
| - sardine	||5-64
|-
| - mackerel	
|-
| --  red flesh	||43-67
|-
| --  white flesh	||11-16
|-
| - salmon	||4-8
|-
| - tuna	||5
|-
|
|-	
!Oils	
|-
| - soybean	||54-280
|-
| - olive	||4-160
|-
| - grapeseed	||64-73
|-
| - sunflower 	||4-15
|-
| - rice bran	||/
|-
| - coconut	||/
|-
|
|-
!Nuts	
|-
| - peanuts	||27
|-
| - walnuts	||19
|-
| - sesame seeds	||18-23
|-
| - pistachio nuts	||20
|-
| - hazelnuts	||17
|-
| - almond	||5-14
|-
|
|-	
!Vegetables	
|-
| - parsley	||8-26
|-
| - broccoli	||6-9
|-
| - cauliflower	||2-7
|-
| - spinach	||up to 10
|-
| - grape	||6-7
|-
| - Chinese cabbage	||2-5
|-
|
|-	
!Fruit	
|-
| - avocado	||10
|-
| - blackcurrant	||3
|-
| - strawberry	||1
|-
| - orange	||1-2
|-
| - grapefruit	||1
|-
| - apple	||1
|-
|}

Meat and fish are the richest source of dietary CoQ<sub>10</sub> and levels over 50 mg/kg can be found in beef, pork and chicken heart and chicken liver. Dairy products are much poorer sources of CoQ<sub>10</sub> compared to animal tissues. Vegetable oils are also quite rich in CoQ<sub>10</sub>. Within vegetables, parsley, and perilla are the richest CoQ<sub>10</sub> sources, but significant differences in their CoQ<sub>10</sub> levels can be found in the literature. Broccoli, grape, and cauliflower are modest sources of CoQ<sub>10</sub>. Most fruit and berries represent a poor to very poor source of CoQ<sub>10</sub>, with the exception of avocado, with a relatively high CoQ<sub>10</sub> content.<ref name="Pravst" /> 

===Intake===
In the developed world, the estimated daily intake of CoQ<sub>10</sub> has been determined at 3-6 mg per day, derived primarily from meat.<ref name="Pravst" />

===Effect of heat and processing===
Cooking by frying reduces CoQ<sub>10</sub> content by 14-32%.<ref>[http://www.ncbi.nlm.nih.gov/pubmed/9129255 The coenzyme Q10 content of the average Danish die...[Int J Vitam Nutr Res. 1997&#93; - PubMed Result<!-- Bot generated title -->]</ref>

==See also==
*[[Idebenone]] - synthetic analog with reduced oxidant generating properties
*[[Ubiquinol]]

==References==
{{Reflist|2}}

==External links==
* [http://www.grg.org/movies/CoQ10Mice03.mov A video showing the effects of Coenzyme Q<sub>10</sub> on the aging and activity of mice]
* [http://www.stanford.edu/group/hopes/treatmts/antiox/ceq1.html Coenzyme Q10: An Antioxidant Drug] - from the [[Huntington's Disease Outreach Project for Education at Stanford]]
* [http://www.usp.org/USPVerified/ingredients/ingredients.html  List of USP Verified CoQ<sub>10</sub> Ingredients]
* [http://www.cancer.gov/cancer_information/doc.aspx?viewid=0E5B4097-610C-4A49-844F-D935F1D7BB07 National Cancer Institute page on Coenzyme Q<sub>10</sub>]
* Robert Alan Bonakdar and Erminia Guarneri,  [http://www.aafp.org/afp/20050915/1065.html American Family Physician page on Coenzyme Q<sub>10</sub>]
* [http://faculty.washington.edu/ely/coenzq10.html An Introduction to Coenzyme Q<sub>10</sub>] at [[University of Washington]]
* [http://lpi.oregonstate.edu/f-w02/coenzymeq10.html  Possible Health Benefits of Coenzyme Q<sub>10</sub>] at [[Oregon State University]]
* [http://www.ninds.nih.gov/news_and_events/press_releases/pressrelease_parkinsons_coenzymeq10_101402.htm Study Suggests Coenzyme Q<sub>10</sub> Slows Functional Decline in Parkinson's Disease] at [[National Institute of Neurological Disorders and Stroke]]

{{Electron transport chain}}
{{Enzyme cofactors}}
{{Antioxidants}}

[[Category:Cellular respiration]]
[[Category:Glycolysis]]
[[Category:Antioxidants]]
[[Category:Dietary antioxidants]]
[[Category:Coenzymes]]
[[Category:Benzoquinones]]
[[Category:Phenol ethers]]

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