PCOS and Inositols – Advances and Lessons We are Learning. A Narrative Review

Introduction: This Expert Opinion covers recent updates in the use of Inositol in polycystic ovary syndrome (PCOS), highlighting the specific effects triggered upon ovarian steroidogenesis. Areas Covered: An impressive body of evidence, obtained from molecular, animal and clinical studies, demonstrated the striking association between PCOS and the metabolism of myo-Inositol (myo-Ins) and its isomer D-Chiro-Inositol (DCI). Early investigations focused primarily on the metabolic consequences of inositol in modulating insulin transduction. However, recent advances disclosed that Inositols trigger direct effects on steroidogenesis. High DCI levels exacerbate androgen synthesis, and downregulate aromatase expression. Myo-Ins modulates insulin effects too, but exerts opposite actions on steroidogenesis, by increasing aromatase and FSH receptor expression. Clinical studies demonstrated myo-Ins efficacy, suggesting that an appropriate ratio in between myo-Ins/DCI (40:1) improves the reproductive function in PCOS women, even in absence of insulin resistance. Expert Opinion: Inositol-based treatments in PCOS are gaining momentum, demonstrating safety and efficacy greater than those obtained with other pharmacological agents. The efficacy depends not only on the modulation of insulin sensitivity but also on the direct, steroidogenic effects upon the ovaries. Adequate adsorption of Inositol is a critical issue, and the association of α-Lactalbumin can significantly overcome this problem. However, if a treatment based on inositol could be equally effective on different phenotypes of PCOS needs a specific assessment.