Roles of Q10

The two main functions of Q10 in the body


Coenzyme Q10 is found in all in bodily fluids and in allmost all the body's cells. The largest amounts are found in cardiac muscle, kidneys, liver, muscles and spleen.

In the body coenzyme Q10 exists in two active forms, an oxidized form called ubiquinone and a reduced form called ubiquinol. Q10 in its oxidized form, ubiquinone, acts as an electron-receiver, whereas the reduced form ubiquinol acts as an electron donor. The body's cells produce oxidized Q10 and the Q10 we get from the diet is on average about 50% oxidized and 50% reduced.


Ubiquinol – Antioxidant activity

Outside the body's cells the majority of the body's Q10 is the reduced ubiquinol, and this is thus the dominant form found in blood, plasma and lymph. This form functions as an effective antioxidant. Q10 is the only fat-soluble antioxidant that the body can produce and regenerate, and is the main factor in the protection of mtDNA from oxidative damage. The reason why Q10 is so effective as an antioxidant is that Q10 molecule is intended to give and receive electrons without being damaged as other antioxidants do when they neutralize free radicals in the body. As we get older the relative percentage of ubiquinol in the body will decrease a little bit - probably because elderly generally are eating less, getting more inflammation, getting reduced enzymatic activity and so on and thus needing more ubiquinol for antioxidant acivity.


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Ubiquinone – Energy production

Q10 is absolute essential for the body's energy production. Only 10% of the body's total energy production does not require Q10. It is this key feature of Q10 that has inspired many researchers to do scientific research with this substance. In this research, the predominant form of Q10 has been the oxidized ubiquinone form for the simple reason that it has been the only one available on the market. Only in 2006 did the reduced form ubiquinol become available, after which it was marketed as "active Q10."


The body's energy production takes place in some small micro bodies called mitochondria, found inside all cells of the body except the red blood cells. The more energy a cell type requires, the more mitochondria it contains and the more CoQ10 it needs.


To better understand how this works, let’s take a look at Q10 and cellular energy production. CoQ10 is found inside the mitochondria where it acts as an electron acceptor or donor in a chain of reactions ending up with production of the energy-rich molecule adenosine triphosphate, ATP.


When oxidized Q10 (ubiquinone) accepts electrons from another molecule in the chain, it becomes reduced (ubiquinol) and when reduced Q10 (ubiquinol) donates electrons, it becomes oxidized (ubiquinone).  In the inner membrane of the mitochondria Q10 takes up electrons who are transferred between enzyme complex I and III, or the complex II and III in the electron transport chain. Maintaining this state of equilibrium is how the body benefits from Q10.


Commercial Q10 products

Q10 in its reduced ubiquinol form is a very unstable molecule, which relatively quickly change to the oxidized form ubiquinone when upon contact with oxygen from the air. This characteristic has made it difficult for producers of ubiquinol supplements to produce ubiquinol preparations where the Q10 content remains in its reduced form right up until its expiration date. The fact that this is not always successful for producers to avoid their ubiquinol preparation oxidizing before the expiry date has been shown many times over the years since this type of Q10 hit the market.

In commercial products it is not hard to check if you whether you are dealing with ubiquinone or ubiquinol as the oxidized ubiquinone has a nice orange color and ubiquinol has a transparant, milky white color. Chemically, the difference between the two forms is only two protons and two electrons on the quinone head of the CoQ10 molecule.


Ubiquinol unstable

In the cells' mitochondria, the reduced ubiquinol molecule delivers two protons and electrons to the chain of proteins that ends up making ATP under the influence of oxygen. This converts ubiquinol to the oxidized form of Q10, ubiquinone. Subsequently, ubiquinone receives two protons and electrons, thereby converting back to ubiquinol, and the conversion of Q10 back and forth across the inner mitochondrial membrane occurs hundreds of times each second. With only a little oxygen required, the active Q10 in the form of ubiquinol converts to oxidized form ubiqinone. Ubiquinol is, in other words, an unstable molecule, but this it is also ubiquinol's strength. Since the reduced form of Q10 so easily delivers electrons to free radicals, it is an excellent antioxidant.


The real difference

There is a difference between ubiquinone and ubiquinol, between the oxidized form and the reduced form of Q10, but normally this difference disappears in our gut. It is claimed that ubiquinol is better absorbed from the intestines than ubiquinone, but this claim is not sufficiently documented. In reality, the only significant difference between ubiquinone and ubiquinol is the price. You will find more real differences in the quality and the bioavailability from various commercial products using the same form of Q10. In other words, not all ubiquinone products are equally good. But that's another issue.


A ubiquinone capsule and a ubiquinol capsule

Are you taking the right form of Q10?
Q10 exists in three slightly different forms in our body: ubiquinone, which is the fully oxidized form; semiquinone, which is a partially reduced form; and ubiquinol, which is the fully reduced form. All three forms of Q10 have important functions in the body and are, in this sense, equally important. However, only ubiquinone and ubiquinol are made as supplements, and there are some differences between these two forms of Q10 supplements that may be useful to know. 


Ubiquinone Q10

Ubiquinol QH
Has been used in all major scientific Q10 studies on safety, bioavailability, and efficacy  
Is biochemically stable as the substance does not oxidize further  
Is the less expensive form of Q10 when purchasing  
Contributes to the cellular energy production
Also approved as a drug  
Comes with documentation that it counteracts high blood pressure  
Comes with documentation that it counteracts chronic heart failure  
Replaces Q10 levels depleted by statins

Semiquinone, the third form of Q10

In actuality, Q10 exists in three forms as there is also an intermediate form called semiquinone (abbreviated SQ), which is a partially reduced form of Q10. However, this intermediate form is not relevant as a supplement.