Coenzyme Q10 (CoQ10), also known as ubiquinone, is a lipoidal vitamin-like substance similar in structure to vitamin K. CoQ10 resembles a vitamin but is unique in that it is not only present in many human foods, but also can be biosynthesized within mammalian tissue. Two other vitamins having similar properties, including the ability to be synthesized within mammalian tissue, are nicotinamide and vitamin C.

CoQ6 through CoQ10 are the most common forms of this coenzyme and occur in a wide range of microorganisms. However, CoQ10 is found only in mammals. Studies have shown that, although other CoQ ‘homologues’ are found in human tissue, only CoQ10 is functional. The homologues occur in such trace amounts as to be functionally insignificant.

Coenzyme Q10 has captured the imagination of medical scientists since it was discovered in 1957 and isolated in 1960. Thereafter, researchers found it to be essential in cell respiration, electron transfer and the control of oxidation reactions (redox reactions). What this may mean therapeutically will be discussed later.

Coenzyme Q10 can be found human heart tissue. Its importance to humans is illustrated by the fact the heart may cease to function as coenzyme Q10 levels fall.

Coenzyme Q10—method of action

Dr. F. L. Crane and colleagues first isolated and extracted Coenzyme Q10 from mammalian tissue in 1957. Their initial research concluded CoQ10 was able to add or remove oxygen from a biologically active molecule. The importance of this becomes clear when it is realized that a lack of oxygen can produce a decline in cellular energy, while an overabundance will result in the formation of toxic substances.

CoQ10 is found in the myocardium and is particularly concentrated in the inner membranes of the mitochondria and of the Golgi apparatus. Mitochondria manufacture adenosine triphosphate (ATP).

CoQ10 plays a critical role in pumping protons across the mitochondrial membrane, hence providing the body with enough energy to stay alive. It serves the same function as the cylinders in an automobile engine where the gasoline is ignited and explodes to drive the piston. Without CoQ10 the cell is like a dead engine; there is no spark or ignition. CoQ10 also appears to exert regulatory effects on mitochondrial enzymes. CoQ10 functions in redox reactions in Golgi membranes. The role of CoQ10 as a redox carrier in the respiratory chain is well established based on the evidence of reconstitution data and kinetic evidence.

Research on CoQ10-depleted or replenished submitochondrial particles demonstrates that this coenzyme is essential to the redox component between NADH and succinate dehydrogenase and cytochrome. It also has regulatory effects on the succinate dehydrogenase and NADH dehydrogenase and cyctochrome b-C1 complex.

These findings are important therapeutically, for they provide insight as to how CoQ10 can benefit those with congestive heart failure, for example, where correction of deficiencies and improved bioenergetics occur following treatment with CoQ10.

Oral administration elevates plasma CoQ10 levels. CoQ10 passes quickly from plasma into the tissue, reaching levels higher in tissue than would occur solely due to equilibration. CoQ10 is absorbed mainly into the liver and to a lesser degree into other tissues.

A carefully designed study compared CoQ10-containing vesicles with beta-carotene containing vesicles. The study raised the possibility that the observed CoQ10 antioxidant effect could be to scavenge singlet oxygen and to affect the structure of the lipid bilayer so as to inhibit the decomposition of hydrogen peroxide and the release of harmful free radicals.