What is NAC?
NAC, short for N-acetyl-cysteine, is a supplement made from the amino acid cysteine, which you get naturally from protein-rich foods like poultry, eggs, and beans. Its biggest role is helping the body make glutathione, one of the most powerful antioxidants your cells use to fight stress, balance hormones, and repair tissue. Think of glutathione as your body’s cleanup crew, clearing away cellular “sparks” that can cause inflammation and throw your hormones off rhythm.
NAC has been used in hospitals for decades to protect the liver and clear mucus in the lungs. More recently, researchers have been exploring how its antioxidant and hormone-supporting qualities may benefit women’s reproductive health.
NAC for Menstrual Health
Your cycle runs on a delicate balance of hormones. Too much oxidative stress can disrupt that balance, leading to pain, irregular bleeding, or fertility struggles. Studies show NAC can help:
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In women with endometriosis, NAC was linked to less menstrual pain, smaller cysts, and higher chances of pregnancy.
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In women with fibroids, NAC reduced the size of growths that often cause heavy or unpredictable periods.
For women dealing with these conditions, NAC may help the cycle run more smoothly.
NAC and Healthy Ovulation
Ovulation happens when an egg is released.NAC has been shown to:
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Lower excess testosterone
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Improve insulin sensitivity
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Support healthier follicle development
In clinical trials, women with PCOS who took NAC along with fertility medications had better ovulation and pregnancy rates than with medication alone. Think of NAC as a teammate that helps the body respond more effectively.
Beyond the Cycle: Long-Term Women’s Health
NAC’s benefits don’t stop at periods or ovulation. Research suggests it may:
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Improve blood sugar, cholesterol, and insulin resistance, all important for women with PCOS, and overall women’s wellness for better cycle health.
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Support egg quality during fertility treatments by protecting the mitochondria, the “power plants” of cells.
Together, these findings point to NAC as a supplement that may not only improve reproductive health but also support overall metabolic wellbeing.
What We Still Don’t Know
Most research on NAC has been done in women with conditions like PCOS, endometriosis, or fibroids. Evidence is limited for women with completely regular cycles. Long-term safety studies are still missing, and dosages vary widely across trials. While some used 600 mg three times a day, others tested about 1,800 mg over a few days in the cycle. Very high doses in animal studies even showed fertility problems, so NAC should always be taken under the guidance of a healthcare professional, especially if you are pregnant or using hormone-based medications.
Top Reasons Women Consider NAC
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Cycle support: May ease pain, heavy bleeding, or irregular cycles linked to PCOS, endometriosis, or fibroids.
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Fertility teammate: Can improve ovulation and pregnancy outcomes in PCOS when combined with standard treatments.
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Metabolic support: Helps with insulin resistance, blood sugar, and cholesterol.
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Not a cure-all: Won’t guarantee perfectly regular cycles in women without cycle issues.
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Doctor partnership: Best used with medical guidance to find the right dose and timing.
Long-game potential: Antioxidant protection may help keep the reproductive system healthy over time.
Resources:
Polycystic Ovary Syndrome and Hormones – Meta-analysis showing NAC lowered testosterone and raised FSH in PCOS 【Cambridge University Press, British Journal of Nutrition】 link
NAC with Fertility Medications – Randomized controlled trial of NAC as an add-on to Letrozole for PCOS 【Annals of the New York Academy of Sciences via LWW】 link
Endometriosis Study – NAC reduced pain, cyst size, and improved pregnancy rates 【International Journal of Environmental Research and Public Health (MDPI)】 link
Fibroid Trial – NAC lowered fibroid volume by ~25% compared to placebo 【PubMed, International Journal of Gynecology and Obstetrics】 link
Metabolic Health in PCOS – Systematic review showing improvements in glucose, insulin resistance, and lipids 【Frontiers in Nutrition】 link
Egg Quality in IVF/ICSI – NAC improved glutathione and mitochondrial DNA in granulosa cells 【Frontiers in Medicine】 link