myo Inositol · supplement
Evidence tier: moderate
A nutrient with strong evidence for PCOS, anxiety with obsessive thinking, and fertility support.
Myo inositol is a sugar like molecule that acts as a second messenger inside the cell for insulin signalling. Supplying it is thought to improve the ovary's response to insulin, which in turn lowers androgen output and allows normal follicle development and ovulation to resume. In women without PCOS the ovarian myo inositol to D-chiro-inositol ratio is about 100 to 1, while in women with PCOS it is reported at about 0.2 to 1, and correcting that imbalance is the leading explanation for the effect. This is a coherent and well supported account, not a proven one.
Moderate, and only for polycystic ovary syndrome. This is the strongest ingredient in its batch and the grade is earned rather than granted: the PCOS literature is large, replicated and consistent in direction. A 2026 umbrella review of meta analyses found inositol significantly raised ovulation rates against placebo or folic acid (RR 2.75) and improved insulin resistance measured by HOMA-IR (MD -1.14), both rated moderate quality, and called inositol a promising therapy. The honest counterweight has to be stated in the same breath: the systematic review and meta analysis commissioned to inform the 2023 International Evidence based PCOS Guidelines, covering thirty trials and 2,230 participants, concluded that the evidence supporting the use of inositol in the management of PCOS is limited and inconclusive, with most outcomes rated low to very low certainty under GRADE (PMID 38163998). The same umbrella review found no high quality evidence anywhere in its 85 outcome measures. So the direction of effect is believable and repeatedly observed, the magnitude and the certainty are not settled, and the guideline writing body itself declines to endorse it. Against metformin, inositol performs comparably on reproductive outcomes with fewer gastrointestinal side effects. Everything outside PCOS is a different and much weaker story: a meta analysis of inositol in psychiatry found no statistically significant effects on depressive, anxiety or obsessive compulsive symptoms (Mukai 2014), which directly refutes the mood claims made for this ingredient.
4 g of myo inositol daily, usually split as 2 g twice daily, frequently combined with 400 micrograms of folic acid. Trials increasingly use a myo inositol to D-chiro-inositol ratio of 40 to 1, which is the ratio reported to restore ovulation most reliably when ratios were compared head to head.
2 to 4 g twice daily for PCOS or anxiety; combined with D-chiro inositol 40:1 ratio for fertility.
Onset: ~84 days
Very safe. May lower blood sugar, caution with antidiabetic medications.
Pregnancy: caution
Breastfeeding: caution
Active compounds: myo-inositol, D-chiro-inositol
Remedies using Inositol · Browse by body system · Check it against what you take
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.