Coenzyme Q10 supplementation raises plasma levels without improving mitochondrial function in older adults

Mitochondrial function is important to healthy aging, as it influences energy metabolism, oxidative stress, and physical performance. With age, mitochondrial function and biosynthesis of coenzyme Q10 (CoQ10) may change. CoQ10 serves as a key antioxidant and component of the electron transport system. Supplementation with CoQ10 may help preserve mitochondrial function and support healthy aging. Forty older community-dwelling adults (74 ± 4 years) received either daily oral CoQ10 supplementation (400 mg daily) or a placebo in a 12-week double-blinded, randomized, placebo-controlled design. Before and after the supplementation period, muscle biopsies were obtained. Subsequently, oral glucose tolerance tests (OGTT) and VO₂max tests were conducted. Mitochondrial respiratory capacity (MRC), mitochondrial H₂O₂ emission, and mitochondrial content were assessed in both isolated mitochondria and permeabilized muscle fibers. Levels and redox status of CoQ10 were measured in plasma, muscle tissue, and isolated skeletal muscle mitochondria. Additionally, resting metabolic rate, cognitive function, and body composition were investigated. Plasma levels of CoQ10 increased significantly without changes in redox status after the intervention. No changes between groups or time were observed in muscle and isolated mitochondria regarding MRC, H₂O₂ emission, mitochondrial content, and levels of CoQ10. Glucose homeostasis, VO₂max, and body composition were also unchanged. Twelve weeks of supplementation led to increased plasma levels of CoQ10, with unchanged levels in muscle tissue and isolated mitochondria. No differences in mitochondrial function, glucose homeostasis, and physical performance were found in a cohort of robust older adults.