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ING-032Ingredient Research Profile

Protein & Amino Acids

N-Acetyl Cysteine (NAC)

Also known as: N-Acetyl-L-Cysteine · NAC

●●○Moderate Evidence

A precursor to glutathione — the body's master antioxidant. Well studied for lung health, liver protection, and exercise-induced oxidative stress. One of the most versatile supplements.

Effective Dose

600–1800mg / day

per clinical evidence

Evidence Level

Moderate

Protein & Amino Acids

Mechanism

Glutathione precursor, antioxidant, mucolytic

primary action

Best For

Antioxidant support

Lung health, Liver protection, Recovery

This profile is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare professional before starting any supplementation, especially if you have pre-existing conditions or take medications.

What Is N-Acetyl Cysteine (NAC)?

NAC is an acetylated form of L-cysteine, the rate-limiting precursor to glutathione synthesis. Glutathione is the body's primary intracellular antioxidant and detoxification molecule. NAC has pharmaceutical applications (acetaminophen overdose treatment, mucolytic in respiratory conditions) and growing sports science evidence.

How It Works: The Science

NAC provides cysteine for glutathione synthesis (GSH = glutamate + cysteine + glycine). GSH neutralises reactive oxygen species (ROS), reduces disulphide bonds in mucus (mucolytic effect), and supports Phase II liver detoxification via conjugation reactions. NAC also directly scavenges certain ROS independently of glutathione.

Primary Mechanism

Glutathione precursor, antioxidant, mucolytic

Evidence-Based Benefits

Attenuates exercise-induced oxidative stress

moderate

Reid et al. (1994) — IV NAC improved limb fatigue; oral forms show similar oxidative markers reduction

Supports liver detoxification and protection

strong

Gold-standard treatment for acetaminophen overdose via glutathione replenishment

Improves respiratory function in chronic lung conditions

strong

Multiple RCTs in COPD — reduces exacerbations and improves lung function

May reduce performance decline during intensified training

moderate

Medved et al. (2004) — attenuated fatigue during prolonged cycling at high intensity

Dosage Guide

Effective Dose

600–1800mg / day

600–1800mg/day in divided doses. For antioxidant support: 600mg twice daily. For liver protection: 1200–1800mg/day. Take with food to reduce GI discomfort.

Safety Profile & Side Effects

Well tolerated at standard doses. High doses (>3g/day) may paradoxically blunt exercise adaptations — excessive antioxidant supplementation can impair ROS-mediated training signals. Avoid excessive doses during heavy training blocks.

Who Should (and Shouldn't) Take It

Best for

Antioxidant supportLung healthLiver protectionRecovery

Who it's for

Those with high oxidative load, smokers, individuals taking hepatotoxic medications, or those with respiratory conditions. Athletes should use moderate doses (600–1200mg/day) and avoid excessive antioxidant supplementation around training.

Frequently Asked Questions

What is the recommended dose of N-Acetyl Cysteine (NAC)?

600–1800mg/day in divided doses. For antioxidant support: 600mg twice daily. For liver protection: 1200–1800mg/day. Take with food to reduce GI discomfort.

Is N-Acetyl Cysteine (NAC) safe?

How does N-Acetyl Cysteine (NAC) work?

Who should take N-Acetyl Cysteine (NAC)?

Related Ingredients

Glutathione (Reduced / S-Acetyl)Alpha-Lipoic Acid (ALA)Vitamin C (Ascorbic Acid)

Medical Disclaimer

Ingredient profiles are for informational purposes only and do not constitute medical advice. Consult a qualified healthcare professional before starting any supplementation, especially if you have pre-existing conditions or take medications. Full disclaimer →