Myo-Inositol Guide (2026): Research, the 40:1 Ratio & Label Servings
Myo-inositol has been studied in randomized trials, including trials in PCOS. Some of the trials that combined it with D-chiro-inositol used a 40:1 myo-to-D-chiro ratio, a detail worth checking on the label. Below: the research, the ratio, and how to read labels. This page makes no claim that it treats any condition; talk to your doctor.
40:1 inositol picks, priced at the 4.1 g comparison amount
The 90-day canister holds 180 scoops. Two scoops supply 4,000 mg myo-inositol plus 100 mg D-chiro-inositol, a 40:1 ratio.
Four capsules provide 2.05 g of the 40:1 blend; the 4.1 g comparison amount requires two label servings, or eight capsules.
One scoop provides 2.05 g of the 40:1 blend; use two scoops to match the 4.1 g comparison dose.
As an Amazon Associate we earn from qualifying purchases. Costs use the price at our last check and the number of label servings required to reach 4,000 mg myo-inositol plus 100 mg D-chiro-inositol. Compare the complete catalog at myo-inositol products.
On this page
How Long Did the Myo-Inositol Trials Run?
See the best myo-inositol picks, ranked by ratio and cost per day →
Timeline by Goal
Only outcomes with a stated trial timeline are listed below.
| Goal | What the Evidence Shows | Source-Trial Duration |
|---|---|---|
| Insulin and hormone lab markers | Changes in insulin sensitivity and hormone levels were reported | Reported by about 12 weeks |
| Cycle records | Changes in cycle regularity were reported in the cited trials | Reported around the 3-month mark in the trials |
Sources: Unfer V, et al. Endocr Connect. 2017. PMID 29042448; Pundir J, et al. BJOG. 2018. PMID 28544572; Genazzani AD, et al. Gynecol Endocrinol. 2008. PMID 18335328; Costantino D, et al. Eur Rev Med Pharmacol Sci. 2009. PMID 19499845 — all cited on our myo-inositol research page.
Product Options
Studied formulation Ovasitol by Theralogix 90-day supply $0.96/day
The 40:1 myo-to-D-chiro-inositol ratio used in the studies.
Check price →Best value Micro Ingredients Myo & D-Chiro Inositol Powder 40:1 $0.31/day
Same 40:1 ratio as loose powder, at the lowest cost per day we track.
Check price →What Changes the Timeline
- Which outcome you're tracking. Insulin and hormone levels were reported around 12 weeks. Cycle changes were reported slightly later, around 3 months.
- Dose consistency. The trials dosed daily. Lower or inconsistent dosing wasn't tested for a faster or slower timeline.
- The 40:1 ratio. The trial that directly compared the 40:1 myo-to-D-chiro-inositol combination against myo-inositol alone reported better hormone and insulin numbers with the combination (Nordio 2012, PMID 22774396) — but that trial didn't report the combination working faster, only better by the same endpoint.
When to Reassess
The cited trials ran about 3 months. There is no established timeline for any individual, so talk to your doctor about what to expect.
More myo inositol guides
Dosage Guide (2 g ×2, the 40:1 ratio)
Best Myo-Inositol Supplement
Testing Registry Check: Inositol (what registries show)
Compare Myo-Inositol Products by Cost per Dose
About our data
Every comparison uses clinical evidence from PubMed systematic reviews, product label data from the NIH Dietary Supplement Label Database, and third-party certifications (USP, NSF). Products are ranked by cost per day. See our methodology and editorial standards.
Verification check · Myo-Inositol
What we could and could not verify about Myo-Inositol
2 of the 3 are confirmed in NSF/ANSI 173: Ovasitol by Theralogix 90-day supply and Wholesome Story Myo-Inositol & D-Chiro Inositol 40:1. The other product we track is not listed in any registry we checked. That means nobody independent has confirmed it; it is not evidence against it.
Method: our Myo-Inositol roster matched against the full public registries of third-party-certified supplements in the US, NSF/ANSI 173, USP Verified and Informed Sport, 5,317 listings, retrieved 2026-08-25. Absence means nobody independent has checked that Myo-Inositol product, not that it failed. Full method and limitations.
Frequently asked questions
How long did the myo-inositol trials run?
Roughly 12 weeks (3 months) in the trials we reviewed.
Does myo-inositol have a stated timeline for gestational diabetes research?
No. The gestational-diabetes-prevention evidence (a 2023 Cochrane review) doesn't give a timeline on this hub. For ovulation and cycle outcomes, the evidence does not support a proven timeline, regardless of how long you take it.
Sources
- Unfer V, et al. "Myo-inositol effects in women with PCOS: a meta-analysis of randomized trials." Endocr Connect. 2017;6(8):647-658. PMID: 29042448
- Pundir J, et al. "Inositol treatment of anovulation in women with polycystic ovary syndrome: a meta-analysis of randomised trials." BJOG. 2018;125(3):299-308. PMID: 28544572
- Genazzani AD, et al. "Myo-inositol administration positively affects hyperinsulinemia and hormonal parameters in overweight patients with polycystic ovary syndrome." Gynecol Endocrinol. 2008;24(3):139-44. PMID: 18335328
- Costantino D, et al. "Metabolic and hormonal effects of myo-inositol in women with polycystic ovary syndrome." Eur Rev Med Pharmacol Sci. 2009;13(2):105-10. PMID: 19499845
- Nordio M, Proietti E. "The combined therapy with myo-inositol and D-chiro-inositol reduces the risk of metabolic disease in PCOS overweight patients compared to myo-inositol supplementation alone." Eur Rev Med Pharmacol Sci. 2012;16(5):575-81. PMID: 22774396