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Inositol for PCOS

Polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting 5-20% of women of reproductive age. It’s characterised by symptoms like ovulatory dysfunction, hyperandrogenism, and polycystic ovaries, often leading to infertility. Traditionally, metformin has been the go-to treatment for managing insulin resistance associated with PCOS, but its gastrointestinal side effects prompt the need for alternative treatments. A recent systematic review and meta-analysis (combines all the studies in this area) sheds light on the efficacy and safety of inositol as a potential alternative.

What is Inositol?

Inositol, a compound belonging to the vitamin B complex group, is naturally synthesized in the human body and comes in several forms, with myoinositol and D-chiro-inositol being the most significant. Known for their insulin-sensitizing properties, inositols have shown promise in regulating menstrual cycles, improving carbohydrate metabolism, and reducing symptoms of hyperandrogenism in women with PCOS.

Study Overview

The systematic review analysed 26 randomised controlled trials (RCTs) involving 1691 women with PCOS. The participants were divided into three groups: those receiving inositol, those receiving placebo, and those on metformin. The primary outcomes measured included cycle normalisation, body mass index (BMI), and parameters of carbohydrate metabolism and hyperandrogenism.

Key Findings

  1. Cycle Normalisation:

  • Inositol significantly improved menstrual cycle regularity compared to placebo. The likelihood of having a regular menstrual cycle was 1.79 times higher in the inositol group than in the placebo group.

  • When compared to metformin, inositol demonstrated non-inferiority, suggesting it is just as effective in normalising menstrual cycles.

  1. Body Mass Index (BMI):

  • Treatment with inositol resulted in a significant reduction in BMI compared to placebo, particularly with myoinositol.

  • Myoinositol showed a beneficial effect on weight loss, which is crucial since 60-70% of women with PCOS are overweight.

  1. Androgen Levels:

  • Inositol significantly reduced total testosterone and free testosterone levels, compared to placebo.

  • It also increased levels of sex-hormone binding globulin (SHBG), which helps lower free androgen levels in the body.

  1. Carbohydrate Metabolism:

  • Inositol improved glucose metabolism, reducing fasting plasma glucose and AUC insulin levels significantly compared to placebo.

  • It showed non-inferiority to metformin, indicating similar effectiveness in managing blood sugar levels.

  1. Safety and Side Effects:

  • Inositol had fewer side effects compared to metformin. The metformin group reported gastrointestinal issues such as nausea and bloating, while the inositol group did not report significant side effects.


Inositol has emerged as a promising alternative treatment for PCOS, providing comparable benefits to metformin in many aspects. Its effectiveness in normalising menstrual cycles, aiding weight loss, reducing androgen levels, and improving carbohydrate metabolism, combined with its safety profile, supports its inclusion in PCOS management guidelines. For women with PCOS seeking an alternative to metformin, inositol offers a viable and well-tolerated option.

Reference: Greff D, Juhász AE, Váncsa S, Váradi A, Sipos Z, Szinte J, Park S, Hegyi P, Nyirády P, Ács N, Várbíró S, Horváth EM. Inositol is an effective and safe treatment in polycystic ovary syndrome: a systematic review and meta-analysis of randomized controlled trials. Reprod Biol Endocrinol. 2023 Jan 26;21(1):10. doi: 10.1186/s12958-023-01055-z. PMID: 36703143; PMCID: PMC9878965.


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