N-Acetyl Cysteine is the acetylated form of the amino acid L-cysteine. This chemical modification allows the molecule to resist gastric breakdown and be efficiently absorbed by the digestive tract before being used by the body to synthesise glutathione. This tripeptide, made of glutamate, cysteine and glycine, is present in every cell of the human body and plays a central role in neutralising free radicals, supporting liver detoxification, and maintaining the body’s natural defences.

NAC acts on several fronts in the body. First, it provides the substrate needed for glutathione synthesis, strengthening the body’s antioxidant and detoxifying capacity. Second, NAC has its own direct antioxidant properties thanks to its thiol (sulphur) group, capable of neutralising certain free radicals independently of glutathione. Third, NAC has a long history of use as a mucolytic agent, capable of thinning bronchial secretions by breaking the disulphide bonds of mucoproteins. These mechanisms make NAC a supplement with varied applications: liver support, protection against oxidative stress, respiratory comfort, and maintenance of natural defences. The 1,000 mg dose offered by Now Foods matches the dosages most commonly used in scientific studies on NAC supplementation.

The liver is the central detoxification organ in the human body. Liver glutathione is one of the main tools the liver uses to accomplish this task. NAC supplementation, by supporting glutathione production, helps maintain the liver’s detoxifying capacity — particularly relevant for people living in urban environments exposed to multiple environmental stressors. NAC has been used for decades in hospital settings as a reference antidote in certain liver emergencies, which reflects its particular affinity for the liver. As a food supplement, it is used at more moderate doses as part of a preventive approach to liver support.

The recommended dose is 1 tablet per day, taken with a meal and a large glass of water. Taking it with food improves absorption and reduces the risk of gastric discomfort. To optimise glutathione production, it can be useful to combine NAC with vitamin C, which works in synergy to recycle oxidised glutathione back to its active reduced form. A course of one to three months is generally recommended, renewable as needed; the 120-tablet format allows a full four-month course without interruption.

Not recommended for pregnant or breastfeeding women without medical advice. People on medication should consult their healthcare professional before starting NAC supplementation.

What is the difference between NAC and glutathione supplements?

NAC is a precursor of glutathione — the body uses it to make its own glutathione. Direct glutathione supplements are an alternative option, but their oral bioavailability is debated, as glutathione can be partially broken down in the digestive system. NAC works around this by providing the cysteine needed for the body to produce glutathione itself.

Can NAC be taken long-term?

NAC can be taken over extended periods as part of a general wellbeing approach. One-to-three-month courses are common and can be renewed after a break of a few weeks. The 120-tablet Now Foods format is specifically designed to allow long courses without needing to restock.

Where can I buy NAC N-Acetyl Cysteine Now Foods in Paris?

NAC 1000 mg, 120 tablets, by Now Foods is available at Herba Barona, our specialist supplement shop in the 12th arrondissement of Paris. Personalised advice in-store and delivery available.

Herba Barona is an independent specialist supplement shop in the heart of Paris — established in 2006. What you order is genuinely on our shelves: we ship from our own stock, with no dropshipping and no long waits.

Visit us at 10 rue Théophile Roussel, Paris 12 — or use Click & Collect and pick up your order in-store. We also deliver across France and Europe. Friendly, expert advice in English from our team.

Where is the shop?

Herba Barona is at 10 rue Théophile Roussel, 75012 Paris — a two-minute walk from Ledru-Rollin (line 8), close to Bastille. Open Tuesday to Saturday, 9:30 am–6:30 pm.

Can I order online or collect in store?

Yes. We ship across France and Europe under the same conditions as our French store, or choose Click & Collect to pick up your order for free at our Paris shop.