About the Product
Marvelous Nutrition's NAC is an N-Acetyl L-Cysteine (NAC) supplement in capsules, the most effective cysteine precursor for the synthesis of glutathione — the primary intracellular antioxidant in the human body — with documented effects on liver protection, respiratory support, immune health, and neuroprotection. NAC is one of the supplements with the strongest clinical and pharmacological evidence base in sports nutrition and preventive medicine: it is the first-line antidote for paracetamol poisoning in a hospital setting, the reference mucolytic in chronic respiratory diseases, and one of the compounds with the most emerging evidence for brain health and cellular longevity. 60 capsules. Category: organic support and antioxidant.
Ingredients: N-Acetyl L-Cysteine + excipients (full composition to be confirmed on the packaging). Check packaging for dose per capsule and capsule type (HPMC or gelatin).
Benefits
What is NAC and why is it the most effective cysteine precursor for glutathione synthesis:
N-Acetyl L-Cysteine (NAC) is the acetylated form of the amino acid L-Cysteine, with significantly higher oral bioavailability than free L-Cysteine (which is oxidized to cystine in the gastrointestinal tract before absorption). NAC is absorbed intact and deacetylated intracellularly to L-Cysteine, which is the limiting amino acid in the synthesis of glutathione (GSH = L-Glutamate + L-Cysteine + Glycine, catalyzed by γ-glutamylcysteine synthetase and glutathione synthetase). Glutathione is the most abundant intracellular antioxidant in the human body, present in all cells at concentrations of 1 to 10 mM, with critical functions in neutralizing free radicals (ROS, RNS), detoxifying xenobiotics and drugs (via glutathione S-transferases in the liver), regenerating oxidized vitamins C and E, and maintaining intracellular redox status.
Hepatoprotection and detoxification: the mechanism of NAC as a paracetamol antidote:
The most well-documented clinical use of NAC is as an antidote for paracetamol (acetaminophen) poisoning — one of the most common drug intoxications worldwide. Paracetamol is metabolized in the liver by CYP2E1 into NAPQI (N-acetyl-p-benzoquinoneimine), a highly reactive and hepatotoxic metabolite that depletes hepatic GSH by being conjugated with glutathione for detoxification. When paracetamol is taken in overdose, NAPQI depletes hepatic GSH and covalently binds to hepatocyte proteins, causing massive hepatic necrosis. Intravenous (and oral) NAC is administered in a hospital setting to replenish hepatic GSH and prevent necrosis — the most definitive proof of the importance of hepatic GSH in drug detoxification and the effectiveness of NAC as a GSH precursor. For athletes who frequently use NSAIDs (ibuprofen, diclofenac) or paracetamol for post-workout muscle pain management, preventive supplementation with NAC is especially relevant for liver protection.
Antioxidant support for oxidative stress from intense exercise:
High-intensity exercise increases the production of reactive oxygen species (ROS) by 10 to 200 times above baseline values — free radicals produced in muscle mitochondria during oxidative phosphorylation and in neutrophils during the post-workout inflammatory response. This oxidative stress contributes to post-workout muscle damage (DOMS), muscle fatigue, and transient immune suppression after high-intensity exercise. NAC, by replenishing the glutathione pool depleted by exercise, reduces muscular oxidative stress and improves recovery capacity between training sessions. The clinical trial by Medved et al. (2004), published in the Journal of Applied Physiology, documented that intravenous NAC infusion during prolonged exercise increased resistance to muscle fatigue by 26% and improved the activity of sodium and potassium transporters in muscle membranes (which are inhibited by oxidative stress).
Respiratory support: NAC as a mucolytic and respiratory mucosal protector:
NAC has a long clinical history as a mucolytic — its ability to break the disulfide bonds of mucus glycoproteins, reducing viscosity and facilitating expectoration, is therapeutically exploited in chronic bronchitis, COPD, and cystic fibrosis. For athletes who train in environments with polluted air (urban areas, poorly ventilated gyms) or who are prone to repeated respiratory infections, NAC offers additional support for respiratory mucosal integrity and respiratory tract immune function. Studies by Lai (2014) and De Flora et al. (1997) documented that oral NAC supplementation (600 to 1200 mg/day) reduced the frequency and duration of flu episodes and respiratory infections in adults during winter, suggesting an immunomodulatory effect independent of antioxidant support.
Neuroprotection and brain health: brain glutathione and the role of NAC:
The brain is particularly vulnerable to oxidative stress — it has a high metabolic rate (consumes ~20% of the body's total O₂), high content of polyunsaturated fatty acids (substrates for lipid peroxidation), and relatively low concentrations of enzymatic antioxidants compared to the liver. Brain glutathione is critical for neuroprotection against oxidative stress and neurotoxicity. Oral NAC supplementation increases GSH levels in the brain (documented by magnetic resonance spectroscopy) and has documented effects in multiple neurological and psychiatric conditions — including depression, anxiety, addictions, Parkinson's disease, and Alzheimer's disease — in multiple clinical trials and meta-analyses. For athletes in intensive training with high physical and mental stress, support for brain GSH via NAC contributes to cognition, mood, and sleep quality.
Synergy with Calibration's Reduced L-Glutathione: dual coverage of the glutathione pathway:
As described in the Calibration section of Marvelous Nutrition (which also includes NAC + reduced L-Glutathione), NAC and reduced L-Glutathione cover two complementary links of the glutathione pathway: NAC is the precursor for de novo GSH synthesis (provides cysteine for endogenous synthesis), while reduced L-Glutathione directly provides GSH. For standalone use, NAC efficiently covers the de novo synthesis pathway, which is the primary physiological pathway for replenishing the GSH pool in tissues.
Uses
Recommended dose: Check packaging for recommended dose per capsule and number of capsules per day. The most clinically studied dose is 600mg of NAC per day (in 1 to 2 doses) for general antioxidant and hepatoprotective support, which can be increased to 1200 to 1800mg/day in situations of greater oxidative stress (illness, very intensive training) under professional supervision. Take with meals for better gastrointestinal tolerability. NAC has a characteristic sulfuric odor (typical of thiol compounds) — this is normal and does not indicate product deterioration.
