Myo-Inositol
Also known as: inositol, myo-inositol, cis-1,2,3,5-trans-4,6-cyclohexanehexol, vitamin B8 (obsolete), meso-inositol
Myo-inositol is a sugar alcohol the body makes from glucose and the most abundant inositol isomer in cells, where it forms the backbone of phosphatidylinositol signaling lipids and the second messengers that relay insulin and hormone signals. It is not a true vitamin, but it is sold alongside B vitamins. Its main use is in women's hormone and metabolic formulas: meta-analyses of randomized trials in polycystic ovary syndrome support 2 to 4 g per day, often in a 40:1 ratio with D-chiro-inositol. It is a sweet, water-soluble powder that dissolves easily in drink mixes.
Research summary
Precursor of phosphatidylinositol and inositol phosphoglycan second messengers that mediate insulin signaling, FSH signaling in the ovary, and serotonin receptor function.
Dosage
Daily amounts, of compound.
| Lowest studied | Typical range | Highest studied | Upper limit |
|---|---|---|---|
| 2 g | 2–4 g | 4 g | — |
Doses are grams of myo-inositol. Meta-analyses of randomized PCOS trials pool studies that mostly used 2 to 4 g/day (Unfer 2017, Fatima 2023); a ratio study gave 2 g of inositols twice daily, 4 g/day total, with the 40:1 myo- to D-chiro ratio (about 3.9 g myo-inositol plus 100 mg D-chiro) restoring ovulation best (Nordio 2019). Usually split morning and evening, with or without food. Mild GI upset is the main tolerability issue at high intake. No UL. Higher gram-level doses have been used in psychiatric research and are not reflected here.
Standardization: ≥98% myo-inositol
Source material: corn or rice bran phytate hydrolysis
Forms of Inositol
| Form | Typical dose | Element % | Formats | Price |
|---|---|---|---|---|
| Myo-Inositol | 2–4 g | — | Powder, Capsule, Tablet | low |
| D-Chiro-Inositol | 100–600 mg | — | Capsule, Powder, Tablet | high |
Format suitability
- Capsule
- Powder
- Tablet
- Softgel
- Gummy
- Liquid
Gram doses make capsule counts high (about 4 to 8 capsules for 2 to 4 g); powder is the natural format. Mildly sweet and freely soluble.
Formulation notes
Commonly combined with D-chiro-inositol (40:1), folate, and chromium in PCOS and fertility formulas. Corn-derived grades are typically gluten-free but confirm source.
Sources
- Myo-inositol effects in women with PCOS: a meta-analysis of randomized controlled trials. (Unfer V, 2017)PubMed
- Effects of myo-inositol vs. metformin on hormonal and metabolic parameters in women with PCOS: a meta-analysis. (Fatima K, 2023)PubMed
- The 40:1 myo-inositol/D-chiro-inositol plasma ratio is able to restore ovulation in PCOS patients: comparison with other ratios. (Nordio M, 2019)PubMed
Related ingredients
Maca Root Powder
BotanicalA cruciferous root grown in the Peruvian Andes, dried and milled into a powder used in libido, energy, and hormone-balance formulas.
Typical: 1,500–3,000 mg
Vitamin B6 (Pyridoxine HCl)
VitaminPyridoxine hydrochloride is the standard, inexpensive, and highly stable form of vitamin B6 used in nearly all multivitamins and B-complex products.
Typical: 1.7–50 mg
Black Cohosh
BotanicalBlack cohosh is a North American herb whose root and rhizome have been studied for decades in women going through menopause.
Typical: 20–40 mg
Chasteberry (Vitex)
BotanicalChasteberry is the dried fruit of Vitex agnus-castus, a Mediterranean shrub with a long history in women's health.
Typical: 20–40 mg
St. John's Wort Extract
BotanicalAn extract of the flowering tops of Hypericum perforatum standardized to hypericin and often hyperforin, the most studied botanical for mood.
Typical: 600–900 mg