What is NAC (N-acetyl-L-cysteine) and why is it supplemented?
You've heard of NAC, but what's really behind it? N-acetyl-cysteine is the stabilized form of L-cysteine. Stabilized means that an acetyl group protects the amino acid from oxidizing in the stomach. Without this protection, a large proportion is lost before your body can use it.
Once ingested, the ingredient is converted to L-cysteine. L-cysteine, in turn, is one of the three building blocks for glutathione, the most abundant tripeptide in your cells. This is why the acetylated form has become the preferred variant in supplementation.
N-acetyl cysteine or L-cysteine - what's the difference?
Both provide L-cysteine in the end. However, the way they get there differs significantly.
| Property | NAC | L-cysteine |
| Stability | High (acetylated, oxidation-resistant) | Low (reacts quickly with oxygen) |
| Bioavailability | High | Limited |
| Supplement form | Standard in capsules and tablets | Rarely as a single supplement |
| Glutathione precursor | Yes (via L-cysteine) | Yes (directly) |
The pure form forms disulphide bridges on contact with oxygen. This sounds like a chemistry textbook, but it simply means that part of the ingredient is lost before it reaches the intestine.
The acetylated variant avoids this problem. The protective group keeps the molecule stable until it is absorbed. Only then is it converted and is available for glutathione synthesis.
Who is NAC suitable for as a supplement?
You train 4-5 times a week and notice that recovery takes longer than before. Intensive training uses up sulphur-containing amino acids faster than most nutrition plans provide. L-cysteine is one of the three building blocks for glutathione, and it is this pool that depletes first during high-intensity exercise. These high-dose capsules provide 500 mg of the stabilized precursor per capsule. Two on training days, one on rest days. You control it yourself.
You build up a stack and don't want to leave the glutathione base to chance. In biohacker circles, the GlyNAC stack (N-acetyl cysteine + glycine) is one of the most recommended combinations. Long-term users value the compound as an integral part of their daily routine. With 120 capsules per can, you have four months' supply without having to reorder.
The first thing you do with every supplement is read the list of ingredients. Then you won't have to search for long: N-acetyl-L-cysteine, capsule shell made from HPMC. That's it. No magnesium stearate, no fillers, no small print. Vegan, laboratory-tested, made in Germany.
How are the capsules taken?
One capsule contains 500 mg N-acetyl-L-cysteine. The recommended daily intake is 1 to 2 capsules.
Many products on the market only provide 250 or 300 mg per capsule. With 500 mg of high-dose N-acetyl cysteine per capsule, you need fewer capsules per day and retain full control over your dosage. One capsule or two, you decide. Depending on what the rest of your stack looks like.
Best taken between meals with plenty of water. The capsule size is compact. No gagging, no dissolving necessary.
Quality and production
GN Laboratories produces in Germany. Specifically, this means: production according to German food standards, independent laboratory tests for purity and content, documented batch traceability.
The capsule shell consists of hydroxypropyl methylcellulose (HPMC), is completely vegan and free from gelatine. When it comes to the ingredients, what's on the label is what's inside. No fillers, no hidden additives.
Each can contains 120 capsules, individually sealed to maintain product quality. One capsule a day lasts four months. With two capsules you have a two-month supply, at a unit price of less than 20 cents. Short delivery time within Germany, reviews can be found further down the page.
