Best Myo-Inositol Supplement (2026): Label Servings, the 40:1 Ratio & Research
A 2024 meta-analysis reviewed the published inositol trials (Fitz 2024, PMID: 38163998). See the myo-inositol research summary.
Studies used the 40:1 ratio (myo-inositol : D-chiro-inositol). Follow the serving on the label, and talk to your doctor before starting.
Best value: Micro Ingredients Myo + D-Chiro powder (40:1). Studied formulation: Ovasitol.
What it has been studied for
Myo-inositol is a sugar-like molecule central to insulin signaling, which is why researchers have studied it. Small human trials have measured insulin and other lab markers (Fitz 2024, PMID: 38163998). It is not a treatment for any condition; talk to your doctor.
The 40:1 ratio (why it's on the label)
Some products pair myo-inositol with a small amount of D-chiro-inositol in a 40:1 ratio — the proportion found naturally in the body and used in key trials (including the Ovasitol formulation). Studies used 40:1 rather than a high-D-chiro blend.
Servings and safety
Follow the serving on the label. Studies used the 40:1 ratio over weeks to months. Studies report it is generally well tolerated; high doses occasionally cause mild GI upset. Talk to your doctor before starting.
Best myo-inositol, ranked
| Product | Ratio | Servings | Price | Cost/Day | Pick | Buy |
|---|---|---|---|---|---|---|
| Micro Ingredients Myo & D-Chiro Inositol Powder 40:1 | Myo-inositol | 221 | $34.95 | $0.31 | Best Value | Buy |
| Ovasitol by Theralogix 90-day supply | Myo + D-chiro (40:1) | 180 | $86.68 | $0.96 | Quality Pick | Buy |
| Wholesome Story Myo-Inositol & D-Chiro Inositol 40:1 | Myo + D-chiro (40:1) | 30 | $27.95 | $1.87 | Buy |
Price check · Myo-Inositol
What Myo-Inositol actually costs across the brands we track
What you pay. The 3 Myo-Inositol products here run $0.31 to $1.87 a day across 3 brands, a 6.0× gap. Some of these state a certification on the listing itself. That is a weaker claim than a certifier confirming it: a listing repeats what the brand says, and a registry entry shows what a certifier has checked.
Method: the 3 Myo-Inositol products in our catalogue, each priced at its own labelled serving rather than by pack size, across 3 brands. How we price.
Frequently asked questions
What has myo-inositol been studied for?
It has been studied in small human trials, and results vary by study. It is not a treatment for any condition; talk to your doctor.
What's the 40:1 ratio?
Myo-inositol to D-chiro-inositol in the body's natural proportion, used in studies (e.g., Ovasitol). Studies used 40:1.
How do I take it?
Follow the serving on the label. Studies used the 40:1 ratio. Talk to your doctor before starting.
Are there side effects?
Studies report it is generally well tolerated, with mild GI upset at most. Talk to your doctor before using it.
Related guides
Sources
- Fitz V, et al. "Inositol for Polycystic Ovary Syndrome: A Systematic Review and Meta-analysis to Inform the 2023 Update of the International Evidence-Based PCOS Guidelines." J Clin Endocrinol Metab. 2024;109(6):1630-1655. PMID: 38163998
- NIH / international PCOS guideline evidence on inositol.