Disclosure: We earn commissions on purchases made through our links. This never influences our scores. Editorial policy
NOW Foods vs Life Extension NAC (2026)
Disclosure: We earn commissions on purchases made through our links. This never influences our scores. Editorial policy
The Verdict
Life Extension edges NOW Foods on our rubric (86 vs 84 on our 0-100 execution score), but NOW Foods is the better value at about $0.18 per dose versus Life Extension's $0.42. NOW Foods adds selenium and molybdenum as glutathione cofactors; Life Extension carries its LE Certified testing. In our view, if you want the lowest cost per 600mg dose, NOW Foods wins clearly; if you prefer Life Extension's testing program and straightforward formula, the small premium is reasonable. Both deliver the standard 600mg NAC dose.
NAC 600 mg, 250 Veg Capsules
NOW Foods
N-Acetyl-L-Cysteine (NAC) 600 mg, 60 Capsules
Life Extension
Head-to-Head Comparison
| Category | NAC 600 mg, 250 Veg Capsules NOW Foods | N-Acetyl-L-Cysteine (NAC) 600 mg, 60 Capsules Life Extension |
|---|---|---|
| Brand Score | 84/100 | 86/100Winner |
| Dosing & Form | 25/25Winner | 25/25 |
| Purity | 13/25 | 19/25Winner |
| Value | 23/25Winner | 19/25 |
| Transparency | 23/25Winner | 23/25 |
| Cost/Day | $0.18Winner | $0.42 |
| Dose/Serving | 600mg | 600mg |
| Form | N-acetyl cysteine capsule with selenium and molybdenum | N-acetyl-L-cysteine capsule |
| Third-Party Tested | No | ✓ Yes |
| Proprietary Blend | No | No |
Why This Comparison Matters
NOW Foods and Life Extension both make a 600mg N-acetyl cysteine at a value price - the standard NAC dose used in much of the research. NOW Foods pairs its NAC with selenium and molybdenum (cofactors for glutathione production); Life Extension keeps it straightforward with its own certified testing. This is a clean value NAC matchup between two trusted brands.
NAC is a single, well-defined compound, so the decision is about dose accuracy, testing, and cost per capsule rather than formulation nuance.
We scored both on evidence, quality, cost per dose, and transparency.
Detailed Score Breakdown
NAC 600 mg, 250 Veg Capsules
NOW Foods
600mg per capsule with added selenium (25mcg) and molybdenum (50mcg) as cofactors
GMP certified facility, NPA A-rated, but no independent third-party purity certification (USP, NSF, or ConsumerLab)
$0.18/day at 1,200mg (2 capsules) - outstanding value from a reputable brand
Full label disclosure with all ingredients, forms, and amounts clearly listed
Excellent value at $0.18/day with added trace mineral cofactors. Large 250-count bottle. Lacks independent third-party testing, but NOW Foods has a strong manufacturing reputation.
N-Acetyl-L-Cysteine (NAC) 600 mg, 60 Capsules
Life Extension
Standard 600mg clinical dose per capsule
Non-GMO LE Certified with in-house and contract lab testing, but lacks major independent certifications (USP, NSF)
$0.42/day at 1,200mg (2 capsules) - mid-range pricing
Full label disclosure, clean formulation, form clearly specified
Solid mid-range option from a brand with a strong research focus. Smaller 60-count bottle means you will reorder more frequently.
How We Compared These Products
Every product in our database is scored on four equally-weighted pillars: dosing accuracy and form quality, purity verification (third-party testing), cost per clinically effective dose (not cost per pill), and label transparency. Each pillar is worth 25 points for a total of 100.
Cost per effective dose is calculated using the clinically studied dose from published research, not the manufacturer's suggested serving. If a product requires multiple servings to reach the dose used in clinical trials, that cost is reflected in the value score.
For a full explanation of our scoring methodology, see our methodology page. Prices were last checked on the dates listed for each product and may have changed.
More N-Acetyl Cysteine (NAC) Comparisons
We earn commissions on purchases made through our links. This never influences our scores or recommendations. See our editorial policy.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. Dietary supplements are not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare professional before starting any supplement regimen.