Inositol is the most-studied supplement for PCOS, with strong evidence from randomised controlled trials.
What it is: Inositol is a naturally occurring compound that acts as a second messenger for insulin signalling. The two main forms studied in PCOS are myo-inositol (MI) and D-chiro-inositol (DCI).
What the research shows:
• Improves insulin sensitivity and lowers fasting insulin • Reduces testosterone levels • Improves ovulation rates in people with anovulatory PCOS • May improve egg quality in fertility treatments • Can reduce acne and hirsutism (though slowly — 3-6 months) • Generally well-tolerated with few side effects
The 40:1 ratio: Research suggests that myo-inositol and D-chiro-inositol in a 40:1 ratio mirrors the body's natural ratio and may be more effective than either alone. Most evidence-based supplements provide 4000mg MI + 100mg DCI daily.
Timeline: Most studies show improvements within 3-6 months. Some people notice changes in menstrual regularity within 1-3 months.
Important caveats: • 30-40% of people may see no significant improvement • It's not a replacement for prescribed medications in severe insulin resistance • Quality varies between brands since supplements aren't regulated like drugs • Generally considered safe during pregnancy (discuss with your doctor)
Inositol is a reasonable first-line supplement for PCOS, but it's not a guaranteed solution for everyone.