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There is a lot of buzz about CoQ10 (coenzyme Q10). It is all over the Internet, but much of the surrounding science is not well-founded. Still, there is some good science around this supplement. We will talk about that in this post. Also, we’ll discuss the differences between the 2 types of CoQ10.

What is coenzyme Q10 (CoQ10)?

CoQ10 (short for coenzyme Q10) is ubiquitous (found everywhere) in animal tissue. Hence, we got the “ubiquinone” and “ubiquinol” names for the 2 forms of CoQ10 (we’ll discuss these 2 forms later). However, you won’t see much CoQ10 floating free in the bloodstream as it’s often bound to LDL.

CoQ10 is a powerful, fat-soluble antioxidant. It is a coenzyme (a non-protein element that’s needed by an enzyme to function). CoQ10 is critical to ATP production inside our mitochondria. ATP is short for adenosine triphosphate, the molecule our body uses to store and transfer energy in cells.

Mitochondrion Diagram

CoQ10 is also the third-largest selling supplement in the US. It’s an expensive supplement, so it would be nice to know if CoQ10 works and which CoQ10 form is better.

What is CoQ10 good for? 

We’ve cleared that CoQ10 is ubiquitous, exists in oxidized and reduced forms, an antioxidant, part of the mitochondrial process, and a safe yet expensive supplement. What’s not clear, though, is whether an increase in CoQ10 levels improves things like athletic performance or disease states. There’s evidence that CoQ10 improves cardiovascular inflammation, heart failure, stroke, diabetes, and athletic performance. But there are also pieces of scientific literature which indicate it doesn’t. 

Let’s look at some studies to see if taking CoQ10 is beneficial. 

Study #1: CoQ10 and athletic performance

In the study titled “Ubiquinol Supplementation Enhances Peak Power Production in Trained Athletes: A Double-Blind, Placebo Controlled Study,” daily supplementation of 300 mg ubiquinol for 6 weeks lead to good CoQ10 levels in the blood and significantly improved physical performance of athlete subjects. Verdict: good.

Study #2: CoQ10 and coronary artery disease

Another study was done on coronary artery disease (CAD). It’s titled “Effects of Coenzyme Q10 Supplementation (300 Mg/Day) on Antioxidation and Anti-Inflammation in Coronary Artery Disease Patients During Statin Therapy: A Randomized, Placebo-Controlled Trial.” Here, the patients improved when they were given oral CoQ10, significantly improving antioxidant enzyme activities and lowering inflammation during statin therapy. Verdict: good. 

Study #3: CoQ10 and heart failure

If there’s one place you’d expect to see CoQ10 depletion, it would be in the heart tissue. The heart is in constant use and burns energy more than any other organ in the body. Here is an excellent study that looked at CoQ10’s impact on heart failure patients. The title: “Coenzyme Q10 for the treatment of heart failure: a review of the literature.” In this study, researchers gave patients CoQ10 and saw an improvement in functional parameters, like ejection fraction, stroke volume, and cardiac output, with minimal side effects. Verdict: good.

Study #4: CoQ10 and exercise performance

So far, so good, right? Then you go to other studies. This one, “Impact of Oral Ubiquinol on Blood Oxidative Stress and Exercise Performance,” looked at the exercise performance of adults (not athletes like in study #1). Researchers saw good blood levels of CoQ10, but they didn’t see any significant change in terms of exercise performance. Verdict: mixed.

Study #5: CoQ10 and sepsis

In very sick patients who were hospitalized with sepsis (life-threatening infections), their CoQ10 levels were decreased. In the study “Ubiquinol (reduced Coenzyme Q10) in patients with severe sepsis or septic shock: a randomized, double-blind, placebo-controlled, pilot trial,” when researchers gave these patients CoQ10, they saw an increase in CoQ10 levels. However, they didn’t see any difference in terms of clinical outcomes. Verdict: mixed.

Study #6: CoQ10 and stroke

This one, “Coenzyme Q10 supplementation improves acute outcomes of stroke in rats pretreated with atorvastatin,” is on CoQ10’s outcome on strokes but done on lab animals. There was a decrease in future strokes in groups with CoQ10. However, animals dosed with a higher quantity of statin showed worse results. This shows that statins do affect CoQ10 presence (which we’ll discuss in study #8.) Again, it’s a confusing picture. Verdict: mixed. 

Study #7: CoQ10 and cardiovascular inflammation

This one is on one of my favorite topics—cardiovascular (CV) inflammation. This good study is titled “Effects of Coenzyme Q10 on Markers of Inflammation: A Systematic Review and Meta-Analysis.” The results were mixed. There was a sign that CoQ10 could improve CV inflammation as supplementation significantly decreased TNF-α (an inflammatory marker). But there were also holes in the data, like there’s no significant difference between CoQ10 and placebo concerning CRP (also an inflammatory marker). Verdict: mixed.

Study #8: CoQ10 and statins

CoQ10 is depleted by statins. How? Look at the metabolic pathway below. The process starts with Acetyl-CoA (acetyl coenzyme A, a molecule that’s part of many metabolic processes), HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A), then mevalonic acid (a precursor for making both cholesterol and CoQ10). Statins are HMG-CoA reductase inhibitors; meaning, they stop the production of mevalonic acid as well as the production of cholesterol and CoQ10. 

Role of hydroxyl-methylglutaryl coenzyme A reductase inhibitors on coenzyme Q10 synthesis

Role of hydroxyl-methylglutaryl coenzyme A reductase inhibitors on coenzyme Q10 synthesis. Deichmann R, Lavie C, Andrews S. Coenzyme q10 and statin-induced mitochondrial dysfunction. Ochsner J. 2010;10(1):16-21.

Here is a summary of other studies done on CoQ10 found in the Ochsner Journal, titled “Coenzyme Q10 and statin-induced mitochondrial dysfunction.” It touched on the association of CoQ10 problems and statins. Note that this article was published in the spring of 2010, and there has been a lot of data since then. The article also listed studies showing CoQ10 deficiency in muscle tissue as one mechanism for statin-induced myopathies. However, CoQ10 supplements have not been shown to improve muscle function consistently. Verdict: mixed.

Why are there inconsistencies?

First problem: statins decrease CoQ10 levels. Some studies we covered above involve administering statins along with CoQ10. That’s one problem why there are inconsistencies in the CoQ10 studies

Second problem: we’re looking at a microscopic, biochemical process (the work of CoQ10 in the mitochondria), but we’re coming up with huge assumptions to get us over to the endpoint. While we can document increases in CoQ10 levels, we still focused on documenting outcomes like improvement in performance. Take study #1, for instance. In measuring athletic performance,  the usual indicator is VO2 max (maximal oxygen uptake). Sometimes we see improvements; sometimes we don’t. Same with disease states. Sometimes we see improvement; sometimes we don’t.

Ubiquinone vs. ubiquinol: The 2 types of CoQ10

What are the differences between ubiquinone and ubiquinol?

  • Ubiquinone and ubiquinol are redox pairs of CoQ10. Remember the concept of redox in chemistry? Redox (reduction-oxidation) is a chemical reaction that involves the transfer of electrons between two molecular forms. If a molecule loses an electron, loses a hydrogen atom, or gains an oxygen atom, that molecule is oxidized. Ubiquinone is the oxidized form of CoQ10. Conversely, if the molecule gains an electron, gains a hydrogen atom, or loses an oxygen atom, that molecule is reduced. Ubiquinol is the reduced form of CoQ10. 
  • CoQ10 shifts between oxidized and reduced forms, depending on the environment. Inside the mitochondria, CoQ10 supports cellular metabolism, so it must be in the oxidized form. To serve as an antioxidant, CoQ10 is in the reduced form in the blood and lymph, since ubiquinol has a propensity for taking electrons. 
  • In the 8 studies that we covered above, some are on ubiquinol, while others just say CoQ10. While CoQ10 generally refers to all forms of CoQ10, when people talk about CoQ10, it’s likely they are referring to ubiquinone. Sometimes, you’ll see some write-ups indicating ubiquinol as “CoQH2” due to the extra hydrogen atoms in its structure or just to differentiate ubiquinol from ubiquinone. The images below illustrate the 2 CoQ10 forms.
Ubiquinone Structure

Ubiquinone structure.


Ubiquinol Structure

Ubiquinol structure. Triples in LA / CC BY-SA (

  • Ubiquinone is yellowish; ubiquinol is milky white. If you bought the more expensive ubiquinol, but what you get is a yellowish supplement, it may be possible that ubiquinol already oxidized and turned into ubiquinone. 
  • Ubiquinone was the first to be discovered, in 1957. Ubiquinol later surfaced in 2006. Ubiquinol is then claimed as the superior CoQ10, as it’s said to be absorbed more easily than ubiquinone. There is even a claim that only 4% of ubiquinone makes it to the bloodstream, which is said to be especially true for people aged 60 years or older.  

Ubiquinone vs. ubiquinol: Which is better?

There’s enough evidence to show that ubiquinol is worthwhile, though I think the evidence is inconclusive. While there are studies (like “Ubiquinol is superior to ubiquinone to enhance Coenzyme Q10 status in older men”) specifying ubiquinol to be better, I still think there are lots of conflicts in the data now. There’s something that we’re missing that is causing a lot of red herrings in the findings on these studies, especially in the sepsis trial (study #7). I take ubiquinol when I can find it and ubiquinone when I can’t. Also, I recommend CoQ10 to my patients, have them tested, and make adjustments based on their CoQ10 levels. 

My name is Ford Brewer. I’m a co-founder of PrevMed. We do heart attack, stroke, cancer & disability prevention. I’m licensed in over 40 states. We travel to states to see patients, and we provide telemedicine. Here at PrevMed, we can’t make you do high-Intensity intervals and resistance training or manage an appropriate BMI. But we can help you by telling you what you need to do, why, and how to organize around it, and provide recommendations to support you in staying healthy. If you’re interested in how we can help you, check out our services page.

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