If Pure Encapsulations is the connoisseur's pick, NOW NAC is the sensible one almost everyone should actually buy. You get 250 capsules of 600 mg NAC for around $25 — roughly $0.10 a dose and an 8-plus-month supply — backed by NOW's in-house, UL-audited testing lab, which is genuinely one of the most transparent quality operations in supplements. The added selenium and molybdenum are pitched as sulfur-metabolism cofactors, and while the amounts are trivial, they don't hurt. This is the editor's default: clinical dose, credible testing, unbeatable cost per capsule.
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Read the complete NAC (N-Acetylcysteine) guide →Plain 600 mg NAC veg capsule with no absorption enhancement. The 25 mcg selenium + 25 mcg molybdenum are token cofactors, not a bioavailability upgrade — but the base NAC is well-absorbed standard material.
NOW's in-house UL-audited lab is among the most transparent in the category, publishing extensive testing data. Not a per-product NSF Certified for Sport seal, but more visibility than most.
600 mg/capsule fits the 600-1200 mg/day studied window. One or two daily reaches the range cleanly.
Standard NAC tolerability; typical sulfur note. The 25 mcg selenium is trivial but worth remembering if you also take a multivitamin and eat Brazil nuts — selenium is cumulative.
~$0.10/capsule and 250 caps per bottle make this the standout cost-per-dose winner among trustworthy brands — an 8+ month supply at one per day.
“Selenium and molybdenum meaningfully boost NAC's sulfur metabolism”
At 25 mcg each these are token amounts included as marketing cofactors; there's no clinical evidence that adding trace selenium/molybdenum to 600 mg NAC changes glutathione or liver outcomes.
“One of the most transparent testing labs in the supplement category”
NOW operates a widely respected in-house, UL-audited analytical lab and publicly shares testing methodology and results, exceeding the transparency of most competitors here.
“Best cost per dose among trustworthy NAC brands”
At ~$0.10/capsule for a 250-count bottle from a credibly tested brand, no other pick on this list matches the cost per clinical dose.
Don't buy this for the cofactors — 25 mcg selenium is a fraction of a day's intake and clinically inert here. Do note that selenium stacks across your multivitamin and diet, so it's a reason to track, not to celebrate.
Cheap NAC is easy; cheap NAC from a lab that actually publishes its testing is not. NOW is the unusual case where the value pick is also a quality pick.
NOW NAC is what we'd hand a friend who asked 'which NAC should I get?' Clinical dose, credible testing, and a cost per dose nothing else on this list beats. Ignore the selenium marketing, remember it counts toward your daily selenium, and you have the best all-round value pick here.
Check NOW Foods on AmazonStep up to hypoallergenic practitioner-grade sourcing if excipient purity matters more than price.
See it on the list →Even cheaper per bottle if you want a bare single-ingredient formula and don't need NOW's lab transparency.
See it on the list →Landmark trial establishing oral NAC's proven clinical role in acetaminophen toxicity, the strongest evidence base for the molecule.
Large RCT showing oral NAC did not reduce COPD decline overall — a key example of oral NAC's mixed real-world efficacy versus its reputation.
