Dr. William V. Judy, founder and president of SIBR Research Institute, has done studies showing that oral ubiquinol is converted to ubiquinone prior to its absorption in the small intestines. In the lymph, it is converted back to the ubiquinol form. It makes sense that the CoQ10 is primarily in the ubiquinol form in the lymph and blood because, there, the need for Coenzyme Q10’s antioxidant properties is greater than the need for the bio-energetics function of the ubiquinone form.

A well-formulated ubiquinone Coenzyme Q10 supplement was absorbed significantly better than a well-formulated ubiquinol supplement, so not all Coenzyme Q10 supplements are the same. This is one of the take-home messages from a recent carefully designed Spanish university study [Lopez-Lluch 2018].

Remember: Ubiquinol supplements are notoriously difficult to work with.  As an antioxidant posed to give up its two extra electrons, ubiquinol is by its very nature unstable.  Often, the ubiquinol is oxidized (gives up its electrons) while still in the soft-gel capsule.

If the contents of the ubiquinol capsule look yellow or orange, then the ubiquinol in the capsule has changed to the ubiquinone form.  The ubiquinol should be milky white inside the capsule.

Dr. Judy’s lab and dog studies of ubiquinol

The following progression of oral ubiquinol from supplements has been shown in Dr. William Judy’s lab studies and large dog studies:

  • The ubiquinol is almost completely converted to the ubiquinone form of Coenzyme Q10 when it is exposed to the gastric juices in the stomach and the duodenum.
  • The Coenzyme Q10 from the ubiquinol supplement is absorbed in the jejunum while still in the ubiquinone form.
  • The ubiquinone Coenzyme Q10 is then converted back to the ubiquinol form as the CoQ10 passes into the lymph and makes its way to the blood circulation.

Note: The dogs used in the studies were not anesthetized, were not harmed, and were not sacrificed.

Begs the question: why ubiquinol?

Dr. Judy’s lab studies and dog studies raise the question: why buy a ubiquinol product?  A well-formulated ubiquinone CoQ10 preparation will raise the concentration of the antioxidant form of CoQ10, the ubiquinol form, in the blood significantly.

Ubiquinone CoQ10 supplementation and increases in ubiquinol concentrations

Dr. Roland Stocker and his colleagues were the first to show, already in the early 1990’s, that the administration of ubiquinone CoQ10 raises the levels of ubiquinol (the reduced form of CoQ10) in the plasma and in the lipoproteins [Mohr 1992].

People who want the antioxidant protection of the ubiquinol form of CoQ10 can rest assured that taking a well-formulated ubiquinone CoQ10 supplement will give them that protection.

Different forms and different formulations of CoQ10

Fact: CoQ10 supplements differ as to form:

  • ubiquinone form: the stable, much tested form
  • ubiquinol form: the unstable, much less tested form

Fact: CoQ10 supplements differ as to composition and formulation.

The recently completed Spanish university study compared not only different forms of CoQ10 supplements – ubiquinone and ubiquinol – but also variously formulated ubiquinone CoQ10 supplements.

The ubiquinone CoQ10 supplements that were tested for absorption differed in the composition of the oils used to dissolve the CoQ10 raw material and in the extent to which the oils containing the CoQ10 were pre-heated prior to being filled into capsules.

The best ubiquinone CoQ10 formulation

The best ubiquinone CoQ10 formulation, the one that was absorbed nearly twice as well as the ubiquinol formulation, also out-performed five other ubiquinone CoQ10 supplements [Lopez-Lluch 2018].

The best formulated ubiquinone CoQ10 supplement gave an absorption that was about three times better than the absorption of any of the other ubiquinone CoQ10 supplements tested [Lopez-Lluch 2018].

Formulation of CoQ10 preparations even more important than form?

It should be noted that the ubiquinol supplement also out-performed the five ubiquinone CoQ10 supplements.

Given this outcome, it is fair to conclude that the composition and the formulation of the CoQ10 supplement is even more important for absorption than the form of the CoQ10.

Health effects of CoQ10 supplementation most important

Okay, we test the absorption of Coenzyme Q10 because consumers want to know that the substance is not just eliminated.

But, we know that the reason consumers take CoQ10 supplements is for the health benefits:

  • Improved symptoms and survival for heart failure patients [Mortensen 2014]
  • Better heart health for elderly citizens [Alehagen 2013, 2018]
  • Increased physical function for Gulf War Illness patients [Golomb 2013]
  • Protection against adverse effects of statin medications [Okuyama 2015]
  • Lower blood pressure [Rosenfeldt 2007]
  • Reduced migraine frequency and intensity [Sandor 2005]

Same ubiquinone CoQ10 product used

The best-absorbed ubiquinone Coenzyme Q10 supplement in the Spanish university study is the same ubiquinone formulation that showed significant health effects in randomized controlled studies:


Alehagen, U., Aaseth, J., Alexander, J., & Johansson, P. (2018). Still reduced cardiovascular mortality 12 years after supplementation with selenium and coenzyme Q10 for four years: A validation of previous 10-year follow-up results of a prospective randomized double-blind placebo-controlled trial in elderly. Plos One, 13(4), e0193120. doi:10.1371/journal.pone.0193120

Alehagen, U., Johansson, P., Björnstedt, M., Rosén, A., & Dahlström, U. (2013). Cardiovascular mortality and N-terminal-proBNP reduced after combined selenium and coenzyme Q10 supplementation: a 5-year prospective randomized double-blind placebo-controlled trial among elderly Swedish citizens. International Journal of Cardiology, 167(5), 1860-1866.

Golomb, B.  CoQ10 and gulf war illness.  Neural Computation 2014 Nov; Vol. 26 (11), pp. 2594-651

López-Lluch, G., Del Pozo-Cruz, J., Sánchez-Cuesta, A., Cortés-Rodríguez, A. B., & Navas, P. (2019). Bioavailability of coenzyme Q10 supplements depends on carrier lipids and solubilization. Nutrition, 57, 133–140.

Mohr, D., Bowry, V. W., & Stocker, R. (1992). Dietary supplementation with coenzyme Q10 results in increased levels of ubiquinol-10 within circulating lipoproteins and increased resistance of human low-density lipoprotein to the initiation of lipid peroxidation. Biochimica et Biophysica Acta, 1126(3), 247-254.

Mortensen, S. A., Rosenfeldt, F., Kumar, A., Dolliner, P., Filipiak, K. J., Pella, D., & Littarru, G. P. (2014). The effect of coenzyme Q10 on morbidity and mortality in chronic heart failure: results from Q-SYMBIO: a randomized double-blind trial. JACC. Heart Failure, 2(6), 641-649.

Okuyama, H., Langsjoen, P. H., Hamazaki, T., Ogushi, Y., Hama, R., Kobayashi, T., & Uchino, H. (2015). Statins stimulate atherosclerosis and heart failure: pharmacological mechanisms. Expert Review of Clinical Pharmacology, 8(2), 189-199.

Rosenfeldt, FL et al. Coenzyme Q10 in the treatment of hypertension: a meta-analysis of the clinical trials. Journal of Human Hypertension, 2007, 21: 297-306.

Sándor, P. S., Di Clemente, L., Coppola, G., Saenger, U., Fumal, A., Magis, D., & Schoenen, J. (2005). Efficacy of Coenzyme Q10 in migraine prophylaxis: a randomized controlled trial. Neurology, 64(4), 713-715.

Disclaimer: The information contained in this review article is not intended as medical advice and should not be construed in that way.