Today’s medical biochemistry note is about Coenzyme Q10 and idiopathic male infertility.

Worldwide 15% of reproductive-age couples suffer from infertility, and male infertility contributes to almost half of infertility cases [1-3]. Male infertility can be attributed to multifactorial heterogeneous conditions, including varicocele, cryptorchidism, hypogonadism, infection, systemic diseases, testicular cancer, genetic abnormalities, and oxidative stress-induced male infertility. In approximately 30% to 40% of cases, no known etiology is identified, and this condition has been termed as idiopathic male infertility [1,3-5].

The effect of reactive oxygen species (ROS) and free radical-mediated injury to spermatozoa has been identified as an important mediator of male infertility by causing damage to the sperm membrane and decreasing sperm motility. Studies have reported suppressed antioxidant capacity and increase levels of ROS in the seminal fluid of infertile men in comparison to their controls [1, 2, 6-7].

Coenzyme Q10 (CoQ10) is fat-soluble ubiquinone with bioenergetic and the antioxidant role. It is a crucial component of the mitochondrial respiratory chain and is present in well-measurable levels in seminal fluid, where it probably exerts an essential function in energy metabolism and antioxidant properties [1, 8] Concentration in seminal fluid of CoQ10 is correlated with sperm count and motility and alterations of CoQ10 content are associated with male infertility, such as asthenozoospermia and varicocele [9, 10] Furthermore, the damage of oxidative stress on seminal fluid is considered responsible for 30% to 80% of male subfertility cases [11].

CoQ10 is a non-enzymatic antioxidant and free radical scavenging found in human mitochondria. Approximately half of the body’s CoQ10 is endogenously synthesized via the cholesterol metabolic pathway, and the remainder is obtained through diet in organic meats, beef, soy oil, sardines, and peanut [1, 2, 8, 9, 12]. Supplementation with CoQ10 enhances sperm parameters in infertile men such as motility, morphology, and concentration according to several clinical trials and a meta-analysis published by Lafuente et al. [13-15]. However, whether these improvements in sperm parameters translate to higher rates of conception or live birth is still unclear.

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