Prolonged Intake of Coenzyme Q10 Impairs Cognitive Functions in Mice.

J Nutr. 2009 Aug 26.

Sumien N, Heinrich KR, Shetty RA, Sohal RS, Forster MJ.

Department of Pharmacology and Neuroscience, Institute for Aging and Alzheimer’s Disease Research, University of North Texas Health Science Center, Fort Worth, TX 76107.

Coenzyme Q(10) (CoQ(10)) is widely consumed as a dietary supplement to enhance bioenergetic capacity and to ameliorate the debilitative effects of the aging process or certain pathological conditions. Our main purpose in this study was to determine whether CoQ(10) intake does indeed attenuate the age-associated losses in motor, sensory, and cognitive functions or decrease the rate of mortality in mice. Mice were fed a control nonpurified diet or that diet containing 0.68 mg/g (low dosage) or 2.6 mg/g (high dosage) CoQ(10), starting at 4 mo of age, and were tested for sensory, motor, and cognitive function at 7, 15, and 25 mo of age. Amounts of the ubiquinols CoQ(9)H(2) and CoQ(10)H (2) measured in a parallel study were augmented in the cerebral cortex but not in any other region of the brain. Intake of the low-CoQ(10) diet did not affect age-associated decrements in muscle strength, balance, coordinated running, or learning/memory, whereas intake at the higher amount increased spontaneous activity, worsened the age- related losses in acuity to auditory and shock stimuli, and impaired the spatial learning/memory of old mice. The CoQ(10) diets did not affect survivorship of mice through 25 mo of age. Our results suggest that prolonged intake of CoQ(10) in low amounts has no discernable impact on cognitive and motor functions whereas intake at higher amounts exacerbates cognitive and sensory impairments encountered in old mice. These findings do not support the notion that CoQ(10) is a fitness-enhancing or an “antiaging” substance under normal physiological conditions.

Does this provide a case for CoQ10 supplementation? Not necessarily, but it certainly suggests that more research is definitely in order.

Personally, I take idebenone in lieu of CoQ10 because it is purported to serve an identical function, yet it is not susceptible to producing ROS under hypoxic conditions.

Coenzyme Q10 in the Human Retina.

Invest Ophthalmol Vis Sci. 2008 Dec 5; PMID: 19060288

Qu J, Kaufman Y, Washington I.

Department of Ophthalmology, Columbia University, NY, New York, United States; Ophthalmology, Peking University, Beijing, China.

Purpose: To determine the concentration of Coenzyme Q10 (CoQ10) in the human retina. Methods: Eye tissues were lyophilized and exhaustively extracted with heptane. The extracts were analyzed for Coenzyme Q10 by high-performance liquid chromatography (HPLC). Results: The average concentration of CoQ10 in the retina was 42+/-11 nmol/g dry retina for donors under 30 years of age and 24+/-13 nmol/g dry retina for donors above 80 years of age. The average concentrations of CoQ10 in the choroid was 27+/-16 nmol/g dry choroid for donors under 30 years of age and 18+/-11 nmol/g dry choroid for donors above 80 years of age. Conclusions: Coenzyme Q10 levels in the retina can decline by about 40 percent with age. This decline may have two consequences: a decrease in antioxidant ability and a decrease in the rate of ATP synthesis in the retina and, as such, this decline may be linked to the progression of macular degeneration.