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N-ACETYL CYSTEINE: A Natural Insulin-Sensitizer for PCOS?

N-ACETYL CYSTEINE: A Natural Insulin-Sensitizer for PCOS?

New research shows women with PCOS who have insulin resistance may benefit from taking the nutritional supplement N-Acetyl Cysteine, also known as NAC.

NAC is both an antioxidant and amino acid (building blocks of protein). Specifially, NAC is a derivative of the amino acid L-cysteine, an essential precursor used by the body to produce glutathione. Glutathione is an extremely important and powerful antioxidant produced by the body to help protect against free radical damage, and is a critical factor in supporting a healthy immune system. NAC is widely sold in Europe as a treatment for the common cold and it has other numerous uses from being a treatment for bronchitis to removing heavy metals and environmental pollutants from the body. NAC has also been found to reduce inflammation, heart disease and most recently, insulin.


Only a handful of studies have examined the benefits of NAC in women with PCOS. The most recent study, published in the European Journal of Obstetrics, Gynecology and Reproductive Biology compared the effects of NAC and metformin on insulin levels. In this prospective trial, 100 women with PCOS were divided to receive metformin (500mg three times daily) or NAC (600mg three times daily) for 24 weeks. The results: Both treatments resulted in a significant decrease in body mass index, hirsutism, fasting insulin, free testosterone and menstrual irregularity, and both treatments had equal effectiveness. Furthermore, NAC led to a significant decrease in both total cholesterol and low-density lipoprotein levels, whereas metformin only led to a decrease in total cholesterol level.

This research supports findings published in the Journal of Fertility and Sterility in 2002 where researchers reported significant improvement in insulin levels among women with PCOS who took 1.6-3g/day of NAC and who had elevated insulin levels before the start of study. Women also showed improvements in testosterone, cholesterol and TG levels.

In regards to fertility, when NAC and clomid was compared with metformin and clomid, the metformin-clomid group had more ovulation and a better chance at achieving pregnancy among women with PCOS.

Side Effects

Overall, NAC is well tolerated but can cause gastrointestinal adverse effects including nausea, abdominal pain, vomiting, constipation, and diarrhea, particularly when used in high doses. The therapeutic dosage of NAC to improve insulin levels based on the published studies is 1.6-3 grams/day. If you are overweight, you may benefit from the higher end of the dose range. Fulghesu et al found that obese patients with PCOS did not respond to doses under 3 grams/day. You should not exceed 7grams/daily. As with any nutrition supplement, it is important to discuss use with your physician before taking.

Bottom line: NAC has been shown to improve menstrual regularity but has not been shown to help improve fertility in women with PCOS. NAC may help improve insulin resistance in women with PCOS who have high insulin levels and could be used with metformin or if metformin isn't an option. NAC also seems to have a favorable effect of lowering cholesterol, TG and testosterone. Long-term studies with NAC are needed. It would be interesting to determine the effects of taking NAC in combination with metformin or other supplements proven to improve to improve insulin in women with PCOS.

We want to hear from you: What has been your experience with NAC?

Fulghesu AM, Ciampelli M, Muzj G, Belosi C, Selvaggi L, Ayala GF, Lanzone A. N-acetyl-cysteine treatment improves insulin sensitivity in women with polycystic ovary syndrome. Fertil Steril. 2002 Jun;77(6):1128-35.

Abu Hashim H, Anwar K, El-Fatah RA. N-acetyl cysteine plus clomiphene citrate versus metformin and clomiphene citrate in treatment of clomiphene-resistant polycystic ovary syndrome: a randomized controlled trial. J Womens Health (Larchmt). 2010 Nov;19(11):2043-8. Epub 2010 Oct 12.

Oner G, Muderris II. Clinical, endocrine and metabolic effects of metformin vs N-acetyl-cysteine in women with polycystic ovary syndrome. Eur J Obstet Gynecol Reprod Biol. 2011 Aug 8.


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I have been using 600 mg NAC twice a day for about a month now. I have had some astounding results. My facial hair growth which was increasing steadily and spreading down towards my neck has almost stopped. I alternate between Puritan's Pride and GNC brands and find Puritan's Pride to be slightly more effective. If I miss a dose, I have immense sugar and carb cravings which tells me that the NAC really does help lower insulin levels thereby banishing those cravings.

I am now looking to add Chromium and ALA to my regimen.

Previous to this, I have used fasting as a means to restore my period, but subsequent bouts of overeating have resulted in gaining back the 40 lbs that I lost and now I am back to my PCOS state. But I am confident that soon I'll be back on track with my health.

For those with hirsutism... please try NAC.

Posted by: Sophie | June 4, 2012, 2:20 am

I have PCOS, and have been on Metformin for about 16 years now. I had very few periods as a young woman (about once a year) and low fertility, and treated with hormones to get pregnant in my early 30's. (Got twins!). Yet, it took my sister who is a gynecologist to point out that I probably had PCOS, and sure enough. That's when I went on Metformin for my heart health. About two years ago I started taking green coffee bean extract. It worked so well that I could cut my Metformin dose in half.

When I excitedly told my endocrinologist about it she was completely uninterested in my comments about the green coffee bean extract, and thought instead it was all diet related. I tried to tell her that my diet had not changed, but she would not listen.

I just found out about N-acetylcysteine and am eager to try that as well.

Be well, all of you. There are ways to get better, and sometimes we have to do research on our own to find some answers...

And thank you to the researcher who try to help!

Posted by: Monika Andersson | November 21, 2015, 2:20 pm

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