The short answer
Magnesium plays a role in insulin signalling, and magnesium deficiency is more common in people with insulin-resistant PCOS. Studies show magnesium supplementation may improve fasting insulin and mood, but dosage should be discussed with a healthcare provider—typical therapeutic ranges studied are 250–400 mg/day, and excess supplementation can cause adverse effects.
The evidence for magnesium in PCOS
A 2019 randomised controlled trial found that 250 mg of magnesium daily for 8 weeks significantly reduced fasting insulin, total testosterone, and hirsutism score compared to placebo. Magnesium also supports sleep and may reduce anxiety, both commonly affected in PCOS. Evidence is promising but not conclusive enough to replace first-line treatment.
Food sources and supplementation
Dietary magnesium is found in dark leafy greens (spinach, kale), pumpkin seeds, legumes, whole grains, and dark chocolate. If supplementing, magnesium glycinate and magnesium citrate are better absorbed than magnesium oxide. Always consult a healthcare provider before supplementing, especially if you take medications, as magnesium can interact with some drugs.
Quick follow-up questions
Is magnesium safe to take every day for PCOS?
Dietary magnesium from food is safe for most people. Supplemental magnesium is generally well-tolerated at amounts up to the tolerable upper intake level (350 mg/day from supplements in adults) but should be reviewed by a doctor, especially if kidney function is a concern.