How a small molecule participates in the creation of energy that our cells use every second.

Every muscle movement, heartbeat, transmission of a nerve impulse, and a large part of cell renewal processes require energy. However, the human body does not use this energy directly from food. Energy from carbohydrates and fats must first be converted into a form that cells can use.

That form is called ATP – adenosine triphosphate.

A large part of ATP is produced within the mitochondria, structures found in almost all of our cells. And at the very center of this process is a molecule that is discussed much less than vitamins and minerals:

coenzyme Q10, or CoQ10.

Mitochondria: where food becomes cellular energy

Mitochondria are often described as the "powerhouses of the cell." Basically, this is true, but the process that takes place within them is considerably more sophisticated.

After the breakdown of nutrients, molecules like NADH and FADH₂ are formed, which carry high-energy electrons.

These electrons enter a system of proteins embedded in the inner mitochondrial membrane, known as the electron transport chain.

The chain consists of several protein complexes.

Electrons do not move from one end of the system to the other on their own. Molecules are needed that can accept, transport, and pass them on again.

One of the most important is precisely CoQ10. [1,2]

Where does CoQ10 fit in?

CoQ10 is a lipophilic molecule naturally present in our cells, especially in the inner mitochondrial membrane.

In the electron transport chain, it acts as a kind of mobile electron carrier.

It accepts electrons primarily from mitochondrial complexes I and II and transfers them toward complex III. [1,3]

A seemingly small step, but without it, the entire energy production system cannot function normally.

As electrons pass through the respiratory chain, their energy is used to move protons across the inner mitochondrial membrane.

This creates a difference in proton concentration between the two sides of the membrane – a proton gradient.

We can think of it as stored energy.

The cell then allows the protons to flow back through an enzyme called ATP synthase.

It is precisely this energy that drives the creation of ATP.

Nutrients → electrons → respiratory chain → proton gradient → ATP

CoQ10 is located almost at the very center of this energy system. [1,2]

Why is ATP so important?

ATP is not just "energy for exercise."

It is the universal energy currency of the cell.

Cells use ATP for muscle contraction, maintaining ion gradients, protein synthesis, signal transmission, active transport across membranes, and numerous other processes necessary to maintain life.

At the same time, the organism does not have huge reserves of ATP that it is simply waiting to spend.

ATP is constantly produced and reused.

Therefore, the efficiency of mitochondria is not just a matter of feeling energetic. It is an integral part of almost all basic cell functions.

Why does the heart contain a lot of CoQ10?

Not all tissues are equally energy-demanding.

The heart, for example, must work without stopping – day, night, and throughout one's entire life. The liver and kidneys also have very high metabolic demands.

These are precisely among the tissues in which relatively high concentrations of CoQ10 are found. [4]

This makes biological sense.

The more a cell depends on continuous ATP production, the more important a functional mitochondrial system is.

But CoQ10 does not only participate in energy production.

CoQ10 has two main forms

CoQ10 can switch between an oxidized and a reduced form:

ubiquinone → ubiquinol

The ability to reversibly accept and donate electrons is the reason it can function within the respiratory chain.

But the same characteristic also enables it to perform another important function.

In its reduced form, ubiquinol, CoQ10 can participate in the antioxidant protection of lipid membranes. [2,5]

This is especially important precisely in the mitochondria.

Energy has its chemical price

The mitochondrial respiratory chain is extremely efficient, but it is not perfect.

A small portion of electrons can react with oxygen during the process and create reactive oxygen species – ROS.

ROS are not enemies in themselves. In controlled amounts, they participate in normal cellular signaling.

The problem arises when their creation outpaces the cell's ability to maintain redox balance.

That is when we speak of oxidative stress.

Mitochondria are therefore in an interesting position: they are simultaneously one of the main sources of cellular energy and one of the sites where oxidative load can be generated.

CoQ10 links precisely these two processes – bioenergetics and redox balance. [2,5]

What happens to CoQ10 as we age?

One can often find the claim that "after a certain age, CoQ10 production drops sharply."

The real science is more nuanced.

Research shows that CoQ10 levels can decrease with age in certain human tissues, but that decline is not identical in every organ, nor can it be easily converted into a single universal figure. [6]

For example, an analysis of the human retina found approximately 40% lower CoQ10 concentrations in donors over 80 years old compared to donors younger than 30. [7]

A large study of 860 European adults also showed that the relationship between serum CoQ10 and age is not a simple linear curve. Concentrations showed an inverted U-shaped pattern, with a decrease in older subjects and a simultaneous change in redox status toward a greater proportion of oxidized CoQ10. [8]

That is why it is more accurate to say:

aging is associated with changes in CoQ10 status and its decrease in some tissues, but the magnitude of the change depends on the tissue and the individual.

Why might levels change?

CoQ10 is not a vitamin that the human body must obtain entirely from food.

Our cells can synthesize it themselves through a complex biosynthetic process involving a large number of proteins. [9]

With age, a series of processes important for mitochondrial function change simultaneously: the quality of mitochondrial proteins, the ability to control oxidative stress, mitochondrial dynamics, and the efficiency of energy metabolism.

Therefore, the relationship between CoQ10 and aging is likely not a simple one-way story.

It is not yet completely clear whether the reduced amount of CoQ10 in certain tissues is a cause, a consequence, or a combination of changes that accompany aging. [6]

That distinction is important.

The fact that a molecule decreases with age does not automatically mean that its additional intake will "stop aging."

Does more CoQ10 automatically mean more energy?

No.

This is one of the most important differences between biochemistry and marketing.

We know that CoQ10 is necessary for normal mitochondrial energy production. Severe genetic disorders of CoQ10 biosynthesis can lead to an actual CoQ10 deficiency and impaired mitochondrial function. [9]

But it does not follow from this that a person with normal CoQ10 status will necessarily produce proportionally more ATP or feel more energy by taking increasing amounts.

Mitochondrial metabolism is regulated by a large number of interconnected systems.

CoQ10 is a key part of the machine, but it is not the only part of the machine.

Therefore, the results of supplementation research must be viewed in the context of the population, health status, dose, duration of administration, and formulation.

And the formulation is especially important

CoQ10 is an extremely lipophilic molecule – it dissolves better in fats than in water.

This creates a problem with oral intake.

It is not enough to just know how many milligrams of CoQ10 a capsule contains. It is also important how much of that CoQ10 the digestive system can make available for absorption.

Reviews of clinical research are precisely why they cite bioavailability as one of the key challenges of CoQ10 formulation. [5,10]

Absorption can be affected by the physical form of CoQ10, the carrier, the method of formulation, and taking it with food.

This is the same principle that applies to numerous bioactive compounds:

The amount on the label tells how much of the substance was ingested. Bioavailability tells how much of that the organism can actually make available.

CoQ10 is more than an "antioxidant"

CoQ10 is often presented simply as an antioxidant.

That is not incorrect, but it misses its perhaps even more fundamental role.

Above all, CoQ10 is part of mitochondrial bioenergetics.

It connects the reactions by which we obtain electrons from food with the respiratory chain that allows the creation of a proton gradient, and subsequently ATP.

At the same time, it can participate in maintaining the redox balance of membranes.

Newer research shows that the CoQ system is also linked to a series of other metabolic pathways – including fatty acid and amino acid metabolism and other mitochondrial enzymatic processes. [1]

That is why it is perhaps more accurate to view CoQ10 as one of the key nodes between metabolism, energy, and cellular redox balance.

Energy begins at the cellular level

When we talk about energy, we often think about whether we are tired or how much we can train.

At the biological level, the story begins much earlier.

In the inner membrane of an almost microscopically small mitochondrion, billions of electrons continuously pass through a precisely organized system of molecules.

Their movement creates a gradient.

The gradient drives ATP synthase.

ATP is formed.

And between several key points of that system, electrons are transported by CoQ10.

That is why CoQ10 is not just another ingredient associated with "energy."

It is part of the very biochemistry by which the cell produces energy.

Literature and sources

[1] Alcázar-Fabra M, Navas P, Brea-Calvo G. Coenzyme Q10 and Metabolic Targets in Mitochondria. Antioxidants. 2021;10(4):520. Review of the role of CoQ10 in the respiratory chain and other mitochondrial metabolic processes. PubMed Central (PMC)

[2] Crane FL. Biochemical functions of coenzyme Q10. Journal of the American College of Nutrition. 2001. Review of oxidative phosphorylation, electron transport, and the antioxidant role of CoQ10. PubMed

[3] CoQ10 transfers electrons from complex I and II to complex III and thereby participates in the creation of the proton gradient necessary for ATP synthesis. Review of the physiological role of CoQ10. PubMed Central (PMC)

[4] Hernández-Camacho JD et al. Coenzyme Q10: From bench to clinic in aging diseases, a translational review. Critical Reviews in Food Science and Nutrition. Review of the distribution, biological function, and connection of CoQ10 with highly metabolically active tissues. PubMed

[5] Cirilli I et al. Role of Coenzyme Q10 in Health and Disease: An Update on the Last 10 Years (2010–2020). Antioxidants. 2021. Review of bioenergetic, antioxidant, and clinically researched functions of CoQ10 and the problems of its bioavailability. PubMed Central (PMC)

[6] Varela-López A et al. CoQ10 and Aging. Biology. 2019. The authors state that CoQ10 levels can decrease with age in humans, but that the change is not equal in all tissues, nor is it clear whether it represents a cause or a consequence of the aging process. PubMed

[7] Qu J et al. Coenzyme Q10 in the human retina. Investigative Ophthalmology & Visual Science. 2009. In a study of human tissues, the average CoQ10 concentration in the retina was about 40% lower in donors over 80 years old than in the group younger than 30. PubMed

[8] Niklowitz P et al. Coenzyme Q10 serum concentration and redox status in European adults: influence of age, sex, and lipoprotein concentration. Journal of Clinical Biochemistry and Nutrition. 2016. Study of 860 adults aged 18 to 82. PubMed

[9] González-García P et al. Biosynthesis, Deficiency, and Supplementation of Coenzyme Q. 2023. Review of CoQ biosynthesis, genetic and secondary deficiencies, and factors affecting CoQ10 concentration in human tissues. PubMed

[10] Gutierrez-Mariscal FM et al. Coenzyme Q10 supplementation – In ageing and disease. Frontiers in Physiology / literature review. 2021. The authors emphasize the differences in the bioavailability of formulations and the need for higher-quality clinical research.