This review details the physiologic roles of two insulin sensitizers, myo-inositol (MI) and d-chiro-inositol (DCI). In the human ovary, MI is a second messenger of follicle-stimulating hormone (FSH) and DCI is an aromatase inhibitor. These activities allow a treatment for polycystic ovary syndrome (PCOS) to be defined based on the combined administration of MI and DCI, where the best MI:DCI ratio is 40:1. Moreover, MI enhances the effect of metformin and clomiphene on the fertility of PCOS women seeking pregnancy. As impaired intestinal transport may lead to unsuccessful inositol treatment, we also discuss new data on the use of alpha-lactalbumin to boost inositol absorption. Overall, the physiological activities of MI and DCI dictate the dosages and timing of inositol supplementation in the treatment of PCOS.
Keywords: alpha-lactalbumin; aromatase; clomiphene citrate; d-chiro-inositol; in vitro fertilization; insulin resistance; metformin; myo-inositol; polycystic ovary syndrome; testosterone.
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