PCOS supplements: what the evidence actually shows.
Supplements are the most marketed corner of PCOS. A few have genuinely interesting data. None replace the basics, and most of the evidence is small, short and inconsistent. Here’s the sober version.
In the U.S., dietary supplements don’t need FDA approval for safety or effectiveness before they’re sold, as the FDA itself explains. Doses, purity and labelling vary. That doesn’t make every supplement useless — but it does mean the burden of proof should sit with the product, not with you.
The evidence at a glance
| Supplement | Proposed benefit | Evidence in PCOS |
|---|---|---|
| Myo-inositol / D-chiro-inositol | Insulin sensitivity, ovulation | Limited and inconclusive overall; some benefit for metabolic measures |
| Spearmint tea | Lower androgens, less hirsutism | One small 30-day RCT: lower free testosterone, no objective change in hair score |
| N-acetylcysteine (NAC) | Metabolic and reproductive markers | Meta-analyses show modest changes in glucose, cholesterol and testosterone; trials vary in quality |
| Vitamin D | Metabolic and reproductive outcomes | Correct deficiency if present; benefit beyond that is unclear |
| Omega-3 | Triglycerides, inflammation | Small studies; eating oily fish is a reasonable food-first approach |
| Berberine | Insulin sensitivity | Early data; significant drug-interaction potential; avoid in pregnancy |
Inositol
Inositol is the most-studied PCOS supplement. A systematic review that informed the 2023 guideline pooled 30 trials and concluded the evidence was “limited and inconclusive”: some benefit for certain metabolic measures, possible benefit from D-chiro-inositol for ovulation, and likely fewer gastrointestinal side effects than metformin. We cover doses, forms and the 40:1 ratio claim in detail in inositol for PCOS.
Spearmint tea
Spearmint has anti-androgen properties. In a randomised controlled trial of 42 women with PCOS and hirsutism, drinking spearmint tea twice a day for 30 days significantly reduced free and total testosterone and improved women’s own ratings of their hirsutism — but did not change the objective clinician-rated hair score. The author noted that 30 days is too short for hair-growth changes. It’s inexpensive and generally well tolerated as a tea, which is why many people try it. Treat it as a gentle add-on, not a substitute for treatments with stronger evidence. More in PCOS acne and hair.
N-acetylcysteine (NAC)
NAC is an antioxidant precursor. A 2023 meta-analysis of 11 trials (869 women) in Frontiers in Nutrition found NAC reduced fasting glucose compared with metformin or placebo and lowered total cholesterol compared with placebo. A separate meta-analysis of 18 studies in the British Journal of Nutrition found NAC reduced total testosterone and raised FSH, without significant changes in several other reproductive markers. Effects are modest and trial quality varies. Discuss with a clinician, particularly if you take other medications.
Vitamin D
Vitamin D deficiency is common, and many people with PCOS have low levels. Correcting a confirmed deficiency is sensible general health care. Whether extra vitamin D improves PCOS-specific outcomes in people who aren’t deficient is unclear. Ask for a level before taking high doses.
Omega-3, magnesium, chromium, cinnamon and others
Each has a handful of small PCOS studies with mixed results. None has strong enough evidence to recommend routinely. Food sources — oily fish, nuts, seeds, legumes, leafy greens — give you the nutrients without the uncertainty.
Berberine: proceed with caution
Berberine is often called “nature’s metformin”. Early studies suggest metabolic effects, but it affects how the liver processes many medications, causes gastrointestinal side effects, and should be avoided in pregnancy and breastfeeding. Don’t combine it with metformin or other glucose-lowering drugs without medical advice.
What to skip
- “Hormone balancing” blends with long ingredient lists and undisclosed doses.
- Detox teas and laxative-based “PCOS cleanses”.
- Anything promising to “cure” or “reverse” PCOS.
- Supplements recommended by someone who also sells them, without disclosing it. (For the record: The PCOS Companion sells no supplements and uses no affiliate links.)
Safety checklist before you start anything
- Told my clinician or pharmacist, including all medications I take
- Checked it’s safe if I’m pregnant, breastfeeding or trying to conceive
- Chose a product with third-party quality testing
- Picked one outcome to track for about three months
Making sense of supplement studies
When you see a headline claiming a supplement “lowers testosterone” or “restores ovulation”, a few questions help:
- How many people? Many PCOS supplement trials include fewer than 100 participants.
- How long? Thirty-day or eight-week studies can’t show effects on hair growth or long-term outcomes.
- Compared with what? A placebo-controlled trial is stronger than a before-and-after study.
- Which outcome? A change in a blood marker isn’t the same as a change in symptoms you notice.
- Who funded it? Manufacturer-funded studies aren’t automatically wrong, but independent replication matters.
We apply these questions throughout our editorial policy.
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Frequently asked questions
No supplement has strong evidence as a PCOS treatment. Inositol is the most studied, with limited and inconclusive evidence overall. Spearmint tea and NAC have small studies suggesting modest hormonal or metabolic effects. Foundations like diet, exercise and indicated medication matter more.
A small 30-day randomised trial found two cups a day lowered free and total testosterone and improved self-rated hirsutism, but didn’t change clinician-rated hair scores. It’s promising but limited evidence.
Meta-analyses suggest NAC may modestly improve fasting glucose and cholesterol and lower testosterone. Trials are small and vary in quality, so talk to your clinician before trying it.
If blood tests show you’re deficient, correcting it is sensible. Evidence that extra vitamin D improves PCOS outcomes in people who aren’t deficient is unclear.
Some supplements, such as folic acid, are recommended before conception. Others haven’t been studied for safety in pregnancy. Review everything you take with your clinician when trying to conceive.
Sources and further reading
- Fitz V, et al. Inositol for polycystic ovary syndrome: a systematic review and meta-analysis to inform the 2023 update of the International Evidence-based PCOS Guidelines. J Clin Endocrinol Metab. 2024;109(6):1630–1655. doi.org/10.1210/clinem/dgad762
- Grant P. Spearmint herbal tea has significant anti-androgen effects in polycystic ovarian syndrome. A randomized controlled trial. Phytother Res. 2010;24(2):186–188. doi.org/10.1002/ptr.2900
- Liu J, et al. The effects of N-acetylcysteine supplement on metabolic parameters in women with polycystic ovary syndrome: a systematic review and meta-analysis. Front Nutr. 2023;10:1209614. doi.org/10.3389/fnut.2023.1209614
- Shahveghar Asl Z, et al. The effects of N-acetylcysteine on ovulation and sex hormones profile in women with PCOS: a systematic review and meta-analysis. Br J Nutr. 2023;130(2):202–210. doi.org/10.1017/S0007114522003270
- Teede HJ, et al. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. J Clin Endocrinol Metab. 2023;108(10):2447–2469. doi.org/10.1210/clinem/dgad463
- U.S. Food and Drug Administration. Dietary Supplements. www.fda.gov/food/dietary-supplements
Medical disclaimer: this article is educational and is not medical advice. It can’t diagnose or treat any condition. Talk to your clinician before changing medication, supplements, diet or exercise. Read our full disclaimer.