Coenzyme Q10: Role, Sources and What the Research Shows

What is coenzyme Q10?

What exactly is Q10?

Coenzyme Q10 (CoQ10) – also called ubiquinone – is a naturally occurring molecule present in almost all cells of the human body. Its name comes from the Latin ubique, “everywhere”. Unlike a vitamin, we do not need to get it from food: our cells make it continuously themselves^[1]. It is most abundant in the most energy-hungry organs – heart, kidneys, liver and muscles^[2].

What does it do in the body?

It plays two well-described roles. First, it plays a crucial role in cellular energy production: as an electron carrier in the mitochondrial electron transport chain (the respiratory chain), it helps the mitochondria of cells – the cell’s tiny power plants – generate energy in the form of ATP, through oxidative phosphorylation^[1][2]. Second, it acts as a naturally occurring antioxidant: thanks to its antioxidant properties it helps protect cells from free radicals and oxidative stress – the oxidative damage caused by these unstable molecules, including lipid peroxidation of membranes. Q10 is even described as the only antioxidant of this kind that the body can make on its own^[1].

Ubiquinone or ubiquinol: what is the difference?

It is the same molecule in two states. Ubiquinone is the oxidised form, ubiquinol the reduced form. In the body, Q10 constantly switches between the two – and it is precisely this back-and-forth that allows it to carry energy and neutralise free radicals^[1]. Both forms exist as supplements, where Q10 is usually obtained through a yeast fermentation process; we return below to the widespread but flimsy idea that ubiquinol is “better absorbed”.

How does the body make its coenzyme Q10?

The body assembles almost all of its coenzyme Q10 itself, cell by cell^[1]. It is a small internal chemistry factory: a sequence of steps, run by around fifteen genes, that builds the molecule piece by piece^[20]. Understanding this “synthesis pathway” sheds light on two things most articles leave out: why statins lower Q10, and why some deficiencies are genetic.

A molecule in two parts

Coenzyme Q10 is made of an active “head” and a long “tail”. The head carries electrons and neutralises free radicals^[1]; the tail, a chain of small units called isoprenoids, anchors it in cell membranes. In humans this tail has ten of these units – that “10” is what gives the molecule its name. And it is precisely this tail that links it to a well-known production line.

The same assembly line as cholesterol

The Q10 tail is built by the mevalonate pathway – the very same sequence of reactions the body uses to make cholesterol^[19][2]. The two molecules therefore start from the same point. This detail is crucial, because it explains a well-known side effect of cholesterol-lowering drugs.

This factory runs continuously, without our having to think about it. But it remains a delicate assembly: when a faulty gene, a medicine or age slows one of its steps, Q10 levels can fall. That is exactly what we look at next.

Why do coenzyme Q10 levels fall?

Does Q10 decline with age?

Yes, this is one of the best-established points. Foundational work measured the amount of Q10 in human organs at different ages: it peaks around age 20, then declines steadily^[3]. In the heart, for example, the level in an older person is markedly lower than in a young adult^[3]. This decline is a natural part of ageing – not, in itself, a disease or a deficiency to be corrected urgently.

Do statins lower coenzyme Q10?

Yes. Statins, widely prescribed against cholesterol, block a production step that the body uses both for cholesterol and for Q10; reduce one and you reduce the other. An analysis pooling several clinical trials confirmed it: statin therapy lowers blood Q10 levels, whatever the statin^[4]. What this decline actually means for health, however, remains debated – more on that under muscle pain.

Coenzyme Q10 deficiency: genetic or “secondary”?

“Q10 deficiency” is a phrase to use with care. The gradual age-related decline is not a deficiency in the medical sense: it is a natural, silent phenomenon that defines no disease^[3]. True coenzyme Q10 deficiency is something else entirely – and specialists distinguish two broad families^[22].

Primary (genetic) deficiency

Primary deficiency is a rare genetic disorder. It occurs when one of the genes of the synthesis pathway is faulty: the “assembly line” described above stalls, and the body can no longer make enough Q10^[20]. These forms most often appear in childhood and can affect the brain, the muscles or the kidneys^[23]. They have nothing to do with ordinary ageing and call for a specialist medical diagnosis – the measurement is usually made on a small muscle sample^[23]. One important point: these deficiencies often respond to high-dose supplementation, which makes early detection valuable^[20].

Secondary (acquired) deficiency

Secondary deficiency is far more common, and its causes are varied^[22]. It does not come from a faulty production gene, but from other factors: taking statins, oxidative stress, certain diseases, or genetic defects with no direct link to the synthesis pathway^[22]. Notably, several researchers now place ageing itself among the forms of secondary deficiency^[24] – which gives the age-related decline a framework, without making it a disease.

Food sources: how much do they count, and supplements?

Which foods contain the most Q10?

Q10 is found mainly in animal-source foods and a few vegetable oils: organ meats (heart, liver) first, then meats (beef, pork, chicken), oily fish (sardines, mackerel, herring), oils from soya and rapeseed and, in smaller amounts, nuts (peanuts, pistachios) and some green vegetables.

Is food enough?

Most of our Q10 comes from our own production, not from the plate^[1]. The 3 to 5 mg provided each day by food^[5] are in any case little compared with the 100 to 300 mg a day used in supplement studies. In other words: you cannot “make up” a supplement through cooking, and a normal diet does not saturate the body with Q10. The two are not in the same league.

Q10 supplements: what the research really shows

Here is the heart of the matter – and the part where honesty counts most. Coenzyme Q10 is a dietary supplement: it does not treat, prevent or cure any disease. The studies below explore some leads; they do not turn Q10 into a remedy, and their results are often cautious or split.

Does Q10 “give” energy when you are healthy?

This is the most common marketing argument – and the weakest. Q10’s role in cellular energy production is real^[1], but one must not confuse biochemistry with a felt boost. In a person who is already healthy and well nourished, nothing solidly shows that a Q10 supplement increases energy, reduces everyday tiredness or improves physical performance. That is precisely why no claim of this kind is authorised for Q10 in Europe or Switzerland.

What do the studies show, area by area?

The table below summarises the main areas studied and, above all, the level of evidence for each. It shows that the most-discussed signals concern diseases, studied in medically supervised patients – not the “comfort” use of a healthy person.

Heart, blood pressure, muscles, migraine: why such cautious answers?

Because the studies often contradict each other. On the heart, the most striking signal comes from a trial in patients with congestive heart failure: Q10 added to their usual treatment was associated with fewer serious complications and lower cardiovascular mortality over two years^[6], with improved left ventricular ejection fraction in the European subgroup^[7]. On blood pressure, older analyses announced large reductions^[8], but a Cochrane review in primary hypertension found no clinically clear effect^[9]; recent, larger analyses observe only a modest fall in systolic pressure^[10][11]. On muscle pain under statins, one meta-analysis concludes there is a benefit^[12], another finds none compared to placebo^[13]. On migraine, one meta-analysis sees fewer attacks^[14], another judges the effect uncertain^[15]. On male fertility, Q10 improves some sperm parameters, but with no proof of an effect on pregnancies^[16].

Coenzyme Q10 and skin: what do the studies say?

Skin is a favourite focus of Q10 marketing – it appears in countless “anti-ageing” creams. How much is this lead really worth? The starting point is real: skin contains coenzyme Q10, and this reserve declines with age and under external stressors such as the sun^[27]. But from a biological observation to a proven benefit is a step – one the research takes only in small steps.

Does swallowed Q10 act on the skin?

A few small trials suggest so, without firmly establishing it. In a controlled trial in about thirty people, taking Q10 by mouth for twelve weeks reduced the depth of some wrinkles and improved skin smoothness, compared with a placebo^[25]. On the other hand, hydration and skin thickness did not change, and no protection against sunburn was observed^[25]. Another trial, in women aged 40 to 65, found similar results – but there Q10 was combined with collagen, which makes it impossible to attribute the effect to Q10 alone^[26].

And Q10 creams?

Applied to the skin, Q10 penetrates it and strengthens its antioxidant defences, according to laboratory work^[27]. The mechanism is plausible, but these studies mainly concern parameters measured in the laboratory, not a visible and lasting rejuvenation – and several were run by cosmetics manufacturers, which calls for caution.

How to take coenzyme Q10, and what precautions?

Should it be taken with a meal?

Yes – this is the most useful practical point. Q10 is fat-soluble: it needs fat to pass well into the body. Taking it during a meal containing a little fat (and not on an empty stomach), swallowed with a little water, improves absorption. No time of day has proven superior: morning or evening, what matters is regularity and the meal.

Ubiquinone or ubiquinol: should you pay more?

It is often said that ubiquinol is absorbed markedly better. The reality is more nuanced. A small study did measure a higher blood level after ubiquinol than after ubiquinone^[17] – but it involved only about a dozen people and was run by a Q10-manufacturing laboratory, which calls for caution. Above all, a higher blood level does not prove a better health outcome. To date, neither form has shown a clear clinical superiority.

Is it safe?

Q10 is generally well tolerated. A safety assessment estimated an intake level with no observed adverse effect of up to 1’200 mg a day, far above the usual supplement doses^[18]. The most common reported side effects are mild and infrequent – mainly minor digestive upsets such as nausea^[18]. Some situations nonetheless call for medical advice before starting supplementation:

• !On blood thinners (such as warfarin): an interaction is possible – as a precaution, ask your doctor before taking it.
• !Pregnancy and breastfeeding: insufficient data – best avoided unless advised by a doctor.
• !Before surgery: report any supplement use to the care team.
• !On a statin or any other treatment, or with pre-existing health conditions: possible interactions, so consult a healthcare professional before adding anything.

Frequently asked questions