The 40:1 myo-inositol/D-chiro-inositol plasma ratio is able to restore ovulation in PCOS patients: comparison with other ratios

Eur Rev Med Pharmacol Sci. 2019 Jun;23(12):5512-5521. doi: 10.26355/eurrev_201906_18223.


Objective: The aim of this clinical trial was to evaluate the efficacy of seven different ratios between two inositols stereoisomers, myo-inositol (MI) and D-chiro-inositol (DCI), in the therapy of polycystic ovary syndrome (PCOS).

Patients and methods: fifty-six PCOS patients (8 for each group) were treated by oral route using the following formulations: DCI alone, and 1:3.5; 2.5:1; 5:1; 20:1; 40:1, 80:1 MI/DCI ratio. They received 2 g of inositols twice a day for 3 months. The primary outcome was ovulation, the secondary outcome included the improvement of FSH, LH, Sex Hormone Binding Globulin (SHBG), 17-beta-Estradiol (E2), free testosterone, basal and postprandial insulin levels, as well as HOMA index, BMI and menses.

Results: We found that the 40:1 MI/DCI ratio is the best for PCOS therapy aimed at restoring ovulation and normalizing important parameters in these patients. The other formulations were less effective. In particular, a decreased activity was observed when the 40:1 ratio was modified in favour of DCI.

Conclusions: Our data demonstrated that DCI activity is beneficial mainly at a specific ratio with MI, whereas the increase of DCI causes the loss of the beneficial effects at reproductive level. These results in humans validate a previous preclinical study with different MI/DCI ratios carried out in an experimental model of PCOS mice.

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Animals
  • Drug Administration Schedule
  • Drug Combinations
  • Estradiol / blood
  • Female
  • Follicle Stimulating Hormone / blood
  • Humans
  • Inositol / administration & dosage*
  • Inositol / blood
  • Inositol / chemistry
  • Insulin / blood
  • Luteinizing Hormone / blood
  • Mice
  • Middle Aged
  • Ovulation / drug effects*
  • Polycystic Ovary Syndrome / blood
  • Polycystic Ovary Syndrome / drug therapy*
  • Sex Hormone-Binding Globulin / analysis
  • Stereoisomerism
  • Testosterone / blood
  • Treatment Outcome
  • Young Adult


  • Drug Combinations
  • Insulin
  • Sex Hormone-Binding Globulin
  • Testosterone
  • Inositol
  • Estradiol
  • Luteinizing Hormone
  • Follicle Stimulating Hormone