💊 What it does
N-Acetyl Cysteine (NAC) is a derivative of the amino acid cysteine and the primary precursor to glutathione — the body's most important endogenous antioxidant. Glutathione neutralises free radicals, detoxifies harmful compounds in the liver, and is critical for immune function. NAC has a long pharmaceutical history as a treatment for paracetamol (acetaminophen) overdose and as a mucolytic (mucus thinner) in respiratory conditions. Supplement research has explored applications in mental health (OCD, bipolar disorder, addiction), respiratory health, liver protection, fertility (male factor infertility), and polycystic ovary syndrome (PCOS).
👤 Who needs it
People with high oxidative stress — chronic illness, heavy exercise, pollution exposure, alcohol consumption. Those with respiratory conditions (chronic bronchitis, COPD). Men with fertility issues — evidence supports NAC for improving sperm quality. Women with PCOS. People with OCD or bipolar disorder as an adjunct to conventional treatment (emerging evidence). Anyone wanting to support liver health. Note: healthy people with good dietary cysteine intake produce adequate glutathione without supplementation.
🥦 Food sources first
Cysteine (NAC precursor) is found in: sunflower seeds, tofu, lentils, oats, broccoli, red peppers, onions, garlic. Sulphur-containing vegetables (garlic, onions, leeks, cruciferous vegetables) support glutathione production through multiple pathways. Selenium is a cofactor for glutathione peroxidase — ensure adequate selenium alongside.
🗓 When to supplement
When oxidative stress is high and specific indications exist. For respiratory conditions with excess mucus. For male fertility support. As liver protection in heavy alcohol users. Not needed by healthy people with varied diets.
🏷 Best form to look for
Standard NAC (N-acetyl-L-cysteine) in capsule or tablet form. 600 mg twice daily is a common protocol. Effervescent NAC has slightly better absorption. Avoid NAC supplements in tablet form that have yellowed (oxidation degrades potency).
⏰ When to take it
Take on an empty stomach for best absorption, or with a small snack if GI upset occurs. Twice daily dosing is more effective than once daily for maintaining glutathione levels.