Myo-Inositol and PCOS: Why the 40:1 Ratio Matters
By Abhi Wadhwa, Co-founder, EX1
The inositol ratio studied for PCOS is 40:1. Here is what the trials studied, the doses they used, and how to read an inositol label.
Inositol is a sugar-like compound the body uses for cell signalling. In women's health two forms matter: myo-inositol and D-chiro-inositol. Research in women with PCOS has focused on a specific 40:1 ratio of these two forms, which mirrors the ratio found naturally in the body.
What the 40:1 ratio means
Inositol products vary in whether and how much D-chiro-inositol they include. The 40:1 ratio of myo-inositol to D-chiro-inositol is the ratio found in blood plasma and serum, and the one commonly used in studies. A true 40:1 product delivers a full myo-inositol dose with a smaller, precisely matched amount of D-chiro-inositol.
In women with PCOS, trials have commonly used around 2 grams of myo-inositol twice a day, roughly 4 grams daily, usually in the 40:1 ratio with D-chiro-inositol. When reading a label, what matters is that the ratio and the per-serving dose are both stated plainly, rather than a smaller amount left unspecified.
What research has examined
In women with PCOS, research has examined menstrual regularity and ovulation. A meta-analysis in BJOG reported that inositol improved ovulation and the frequency of menstrual cycles versus placebo, and a network meta-analysis in Reproductive Health found a myo-inositol and D-chiro-inositol combination improved menstrual recovery. Inositol is generally well tolerated.
This is an active and encouraging area, but it is not a substitute for diagnosis and care from a doctor. PCOS is a condition that should be managed with professional guidance, and any supplement is a complement to that care, not a replacement for it.
Frequently asked
What is the best ratio of inositol for PCOS? Much of the research uses a 40:1 ratio of myo-inositol to D-chiro-inositol, the ratio the body holds naturally.
How much myo-inositol do the studies use? In women with PCOS, trials have commonly used around 2 grams twice a day, roughly 4 grams daily.
Is inositol safe? It is generally well tolerated. Discuss any supplement with your doctor, especially during pregnancy or while trying to conceive.
The EX1 take. EX1 Inositol for PCOS is built on the 40:1 ratio studied in PCOS research, delivering 3 grams of myo-inositol with 75 mg of D-chiro-inositol per serving of three tablets. It is formulated for women managing PCOS, with folate, which contributes to normal homocysteine metabolism, and chromium, which contributes to normal macronutrient metabolism. The studied ratio. The dose printed plainly. Nothing hidden.