You may have heard the terms ubiquinone and ubiquinol when referring to CoQ10. They sound the same, but are they? This guide will outline the differences between the two and discuss which is the best CoQ10 supplement for fertility.


By Dr. Kenosha Gleaton

Coenzyme Q10, also known as CoQ10, is a popular antioxidant recommended for a variety of conditions from infertility to heart conditions to migraines. Fun fact: CoQ10 is not a vitamin! It’s a nutrient that exists in almost every cell of the human body. In your body, CoQ10 shifts back and forth between two states in a continuous cycle: ubiquinone and ubiquinol. CoQ10 supplements on the market will be one of these two forms.

What’s the difference between ubiquinol and ubiquinone?

Both ubiquinol and ubiquinone are true forms of CoQ10, and the terms are often used interchangeably. From a chemistry standpoint, ubiquinol is the reduced form of CoQ10, whereas ubiquinone is the oxidized form. 

Remember that CoQ10 occurs naturally in the body, where it shifts between its ubiquinone and ubiquinol form in a continuous cycle. When you take a ubiquinone supplement, your body converts it to ubiquinol and back again. So regardless of what form of CoQ10 you take, your body will convert it to the other form as needed. 

Image retrieved from Oregon State University

Ubiquinone was the only version of CoQ10 on the market until 2007, when the developer of the patented technology for producing the active form of CoQ10 commercialized (and trademarked) ubiquinol. Because of this, ubiquinol is more expensive. Some people assume that because it’s more expensive, it is better. But there’s no compelling data to support that claim. 

Ubiquinol and ubiquinone: is one better than the other?

Research has not proven one form of CoQ10 is better than the other, and given the body naturally converts between the two forms, it is unlikely that there is a big difference between them.

It is important to note that ubiquinone has been on the market longer and has been used in the vast majority of clinical trials of CoQ10 (including those studying the benefits of CoQ10 for fertility). 

Both forms of CoQ10—ubiquinol and ubiquinone—are considered safe, with few side effects.

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Which form of CoQ10 is more bioavailable?

The bioavailability of a supplement is the proportion which reaches systemic circulation and can be used by the body. Both ubiquinone and ubiquinol have high bioavailability.

One study found no significant difference in the absorption of various CoQ10 formulations and that CoQ10 appeared in the blood as ubiquinol, even if it was consumed as ubiquinone. Another study of seven different supplement formulations found large differences in the bioavailability of formulations, with the best absorbable formulations being soft-gel capsules containing either ubiquinone or ubiquinol.

CoQ10 for fertility

Female fertility

Female fertility typically declines after the age of 35. This decline is primarily due to an age-related decrease in egg quality that typically occurs in many women. In the aging process, CoQ10 concentration in parts of the body (including female eggs) declines. Therefore, some fertility doctors recommend CoQ10 supplementation for women over 35 to make up for the natural decline that may contribute to decreased egg quality. 

The data on CoQ10 is emerging, and there haven't been randomized double-blind clinical trials focusing on female fertility yet. Studies that have been conducted so far suggest that, in women over 35, supplementing with CoQ10 may lead to improved egg quality, improved embryo quality, and improved reproductive health and pregnancy outcomes. Another 2017 study concluded that high CoQ10 levels in follicular fluid (fluid that surrounds the ovum in the ovary) is associated with higher pregnancy rates.

Male fertility

Prenatal vitamins and other supplements are not only for a woman's reproductive health. In addition to considering taking prenatal vitamins for men, taking CoQ10 may support male fertility parameters, specifically by improving sperm motility. Poor sperm motility means that the sperm do not swim properly and may not be able to reach the egg. Sperm is extremely susceptible to oxidative stress, which can cause sperm damage. Antioxidants combat oxidative stress. As a potent antioxidant, CoQ10 has been shown in clinical trials to improve male fertility parameters like sperm motility.

In a meta-analysis published in 2018, researchers concluded that CoQ10 supplementation resulted in better sperm motility along with improved sperm concentrations and sperm count. Check out our Guide to Male Fertility for more nutrition and lifestyle guidance for men trying to conceive.

The benefits of CoQ10 supplements are for both egg and sperm health. However, deciding which supplement is best can depend on a few factors, but both forms are considered safe, with few side effects.




  • CoQ10 is a natural antioxidant, and both forms of CoQ10—ubiquinol and ubiquinone —are considered safe with few side effects.
  • More clinical trials have been conducted with ubiquinone than ubiquinol.
  • Ubiquinone and ubiquinol shift from one form to the other inside the body.
  • In terms of absorption and bioavailability, there is no clear cut difference between ubiquinone and ubiquinol.
  • Ubiquinol is trademarked, patented, and produced by one private company, and costs more to manufacture than ubiquinone.
  • Any supplement routine should be discussed with your physician who can give further guidance on what is best for you.

Learn more about the antioxidant fertility supplement, CoQ10 here.