Coenzyme Q10 from food sources and from nutritional supplements does not cross the blood-brain barrier. Thus, human brain tissues are dependent upon endogenous bio-synthesis of Coenzyme Q10. The effectiveness of the blood-brain barrier in keeping out CoQ10 molecules is most likely a factor in the disappointing results seen in CoQ10 supplementation of patients with neurodegenerative disorders, e.g., Alzheimer’s disease and Parkinson’s disease [Mantle 2021].
In humans, the blood-brain barrier prevents the passage of CoQ10 molecules from the blood vessels in the brain to the brain tissues. Thus, oral supplements cannot augment the CoQ10 supply in the brain.
Mitochondrial dysfunction and oxidative stress play key roles in the development and progression of neurodegenerative disorders. Adequate supply of the vitamin-like substance Coenzyme Q10 is important for normal mitochondrial function and for effective antioxidant protection. However, the supply of Coenzyme Q10 from food and oral supplements cannot reach the brain [Mantle 2021].
As we grow older, mitochondrial dysfunction in brain tissue can have detrimental effects resulting in diminished cellular energy production and increased oxidative damage from harmful free radical species. With increased age comes the free radical-induced cellular damage that is seen in normal aging and in neurodegenerative disorders. Both aging and neurodegenerative disorders adversely affect cognitive function, i.e., information processing and memory in particular [Mantle 2021].
Coenzyme Q10 and the Blood-Brain Barrier
The blood-brain barrier is a tightly interconnected layer of protective cells that line the inner surfaces of the blood vessels within the brain. The blood-brain barrier serves as a filter and a gatekeeper for the brain. Its function is to keep harmful things from crossing from the blood circulation to the brain tissues [Cleveland Clinic 2023].
CoQ10 molecules – both in the oxidized form ubiquinone and in the reduced form ubiquinol – are too large to pass the blood-brain barrier via diffusion. Whether there exist transport carriers that could carry Coenzyme Q10 across the human blood-brain barrier needs further research. None have been identified. To date, there are no CoQ10 supplementation studies that show CoQ10 increases in brain tissue Coenzyme Q10 as a result [Mantle 2023].
Animal studies of neurodegenerative disorders have shown some promise of benefit following CoQ10 supplementation. This may indicate that there are important differences between the blood-brain barrier in humans and the blood-brain barrier in rodents. The latter may be less restrictive [Mantle 2021].
Statin Medications Inhibit Bio-Synthesis of Coenzyme Q10
In both its forms – ubiquinone and ubiquinol – Coenzyme Q10 is a vital component of the mitochondrial ATP energy generation process. Statin medications inhibit the bio-synthesis of Coenzyme Q10 in the same mevalonate biological pathway in which they inhibit the bio-synthesis of cholesterol. Thus, statins reduce endogenous CoQ10 synthesis and make ATP energy generation more difficult, especially in energy dependent cells such as heart muscle cells [Okuyama 2015].
Also in the brain cells, statins inhibit the synthesis of both cholesterol and Coenzyme Q10. It is not possible for oral CoQ10 supplementation to make up for the loss of Coenzyme Q10 in the brain. The Coenzyme Q10 in the supplement does not cross the blood-brain barrier.
Conclusion: Oral Coenzyme Q10 and the Blood-Brain Barrier
The CoQ10 molecule is too large to cross the blood-brain barrier in humans.
There are no studies showing increases in brain tissue Coenzyme Q10 as the result of oral supplementation. Not with ubiquinone and not with ubiquinol.
Statin medications inhibit the bio-synthesis of cholesterol and Coenzyme Q10 in the brain as well as in other body compartments.
The question is: how to replace the Coenzyme Q10 that is not generated in the brain cells of patients on statin medications?
Sources
Cleveland Clinic. Blood-brain barrier. 2023. Retrieved from https://my.clevelandclinic.org/health/body/24931-blood-brain-barrier-bbb
Mantle D, Heaton RA, Hargreaves IP. Coenzyme Q10, ageing and the nervous system: an overview. Antioxidants (Basel). 2021 Dec 21;11(1):2.
Mantle D, Lopez-Lluch G, Hargreaves IP. Coenzyme Q10 metabolism: a review of unresolved issues. Int J Mol Sci. 2023 Jan 30;24(3):2585.
Okuyama H, Langsjoen PH, Hamazaki T, Ogushi Y, Hama R, Kobayashi T, Uchino H. Statins stimulate atherosclerosis and heart failure: pharmacological mechanisms. Expert Rev Clin Pharmacol. 2015 Mar;8(2):189-99.
The information presented in this review article is not intended as medical advice. It should not be used as such.
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