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Supplement ingredient

Inositol

myo-inositol

A sugar-like compound involved in insulin signaling. Myo-inositol is widely studied in polycystic ovary syndrome (PCOS).

Evidence: Moderate

Evidence by use: Moderate for PCOS-related markers; limited for other uses. Systematic reviews of randomized trials report improvements in metabolic markers and ovulation-related outcomes in women with PCOS, though trial designs and dose differ and quality varies.

At a glance

Typical studied dose

PCOS trials commonly use about 2-4 g per day of myo-inositol, often split into two doses.

Food sources

Animal sources

Small amounts in meat and milk.

Plant sources

Citrus, beans, nuts, whole grains, cantaloupe (as phytic acid / inositol).

Background and testing

This is not an essential nutrient, so there is no deficiency to diagnose.

Who tends to use it

Women with PCOS or insulin resistance under medical care.

How it is tested

No test for need. PCOS is diagnosed clinically with hormone and ultrasound evaluation.

Supplement forms

Common forms

Myo-inositol powder or capsules; D-chiro-inositol; combination products (often myo:D-chiro 40:1).

More effective

Myo-inositol, or a 40:1 myo/D-chiro combination at studied doses, under the guidance of a clinician managing PCOS.

Less effective

D-chiro-inositol alone at high doses (may worsen ovarian outcomes in some research); 'fertility' blends with unstated amounts.

Safety, interactions and halal notes

Safety and interactions

Generally well tolerated; side effects at higher doses include nausea, gas, diarrhea and headache. Long-term data are limited.

Who should avoid it or ask a clinician first

People who are pregnant, are planning pregnancy, or have bipolar disorder or diabetes should speak to a clinician first.

Halal note

Plant-derived, usually from corn or rice. Check capsules.

Frequently asked questions

Does inositol help PCOS?

Trials report benefits in some markers, but it should complement, not replace, medical care.

Sources

Inositol for polycystic ovary syndrome: a systematic review and meta-analysis (PubMed 35477841)

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This page is for education only and is not medical advice. These statements have not been evaluated by the Food and Drug Administration. Supplements are not intended to diagnose, treat, cure or prevent any disease. Talk to a qualified clinician before starting a supplement, especially if you are pregnant, breastfeeding, take medicine or have a medical condition. Daily needs are US reference intakes for adults 19-50.

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