6.3Poor
A fully disclosed EAA powder with 5 g of all nine essential amino acids and 2 g of leucine per scoop, sweetened with stevia, at about $1.67 a serving.
3rd-party testedcGMP
5 videos Shop$1.67/serving
NAC 600 mg Capsules with Selenium
600 mg of NAC plus 25 mcg of selenium per capsule for about $0.44 a day; well made and plainly labeled, but NAC's benefits for healthy adults are modest.
7.0
Mixed
Nutrition Reviews score
Weighted across efficacy, quality, value, experience & transparency. See breakdown
- Form
- Capsule
- Serving
- 1 Capsule
- Servings
- 100
- Per serving
- $0.22
cGMP facilityKosherHalal
Gluten-freeDairy-freeSoy-freeNon-GMO
Check price on AmazonBuy from the brand$21.99
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Last reviewed October 26, 2026 by the Nutrition Reviews Editorial Team · How we review
Our verdict
NOW's NAC is a well-priced, plainly labeled way to take the 1,200 mg daily dose used in most research, from a manufacturer with accredited in-house testing. The catch is NAC itself: evidence for noticeable benefits in healthy people is thin, and its legal status rests on FDA enforcement discretion rather than a final rule. It is a sensible choice if you and your clinician want to try NAC, as long as you count the selenium.
Best for
- Adults who want a plain, fully disclosed NAC at the commonly studied 1,200 mg daily dose
- Budget-minded shoppers comparing NAC brands
- People who prefer NAC from a manufacturer with accredited in-house labs
Skip it if
- People taking nitroglycerin or living with asthma, unless their clinician approves
- Anyone already taking a high-dose selenium supplement
- Pregnant or nursing people without medical advice
How it scored
Our five-factor score out of 10. Factors are weighted by how much they matter to the outcome you’re paying for. Methodology
7.0
Mixedout of 10
- Efficacy30%5.8
Key ingredients at clinically studied doses, and how strong the evidence is.
- Quality & Purity25%7.5
Third-party testing and certifications, manufacturing standards, contaminant testing, recall history.
- Value20%7.6
Cost per effective serving compared with category peers.
- Experience15%7.4
Taste, mixability, texture and tolerability from aggregated buyer and creator feedback.
- Transparency10%8.0
Full label disclosure (no proprietary blends), available COAs, honest marketing.
Our review
NOW's NAC 600 mg provides 600 mg of N-acetyl cysteine and 25 mcg of selenium (as L-selenomethionine) per capsule, with a suggested dose of one capsule twice daily. That is 1,200 mg of NAC and 50 mcg of selenium a day, about 91% of the selenium Daily Value and well under the 400 mcg adult upper limit. Older bottles and some listings still mention 50 mcg of molybdenum, which NOW's current label no longer includes.
NAC has an unusual legal history. FDA approved it as a drug in 1963, and in 2020 warning letters it said that made NAC ineligible as a supplement; Amazon pulled NAC products in 2021. In August 2022, FDA issued final guidance saying it would not act against otherwise lawful NAC supplements while it weighs a rule to allow them, and Amazon resumed sales. As of October 2026 no rule has been proposed.
The body uses NAC to make glutathione, a key antioxidant, but only about 6 to 10% of an oral dose reaches the blood. In a 2018 trial, this same 1,200 mg daily dose improved exercise performance only in people who started with low glutathione, and a 2017 meta-analysis found no clear performance benefit. Most other trials tested NAC as a drug in people with medical conditions; its hospital use for acetaminophen overdose is a drug use, not a supplement claim. Common complaints are a sulfur smell, harmless speckling in the capsules and stomach upset. At NOW's list price of $21.99 for 100 capsules, the label dose costs about $0.44 a day, and NOW tests its products in its own accredited labs.
What’s inside
| Key ingredient | Per serving | Why it matters |
|---|---|---|
| N-Acetyl Cysteine (NAC) A glutathione precursor; two capsules (1,200 mg) match the daily dose in a 2018 trial that helped only people with low glutathione, and oral absorption is about 6 to 10%. | 600 mg | A glutathione precursor; two capsules (1,200 mg) match the daily dose in a 2018 trial that helped only people with low glutathione, and oral absorption is about 6 to 10%. |
| Selenium (as L-selenomethionine) Two capsules supply 50 mcg, close to the 55 mcg RDA and far below the 400 mcg adult upper limit; count other selenium sources. | 25 mcg (45% DV) | Two capsules supply 50 mcg, close to the 55 mcg RDA and far below the 400 mcg adult upper limit; count other selenium sources. |
Supplement Facts
Serving Size 1 Capsule
Servings Per Container 100
Amount Per Serving% Daily Value
Selenium (elemental) (from L-Selenomethionine) 25 mcg45%
N-Acetyl Cysteine (NAC) 600 mg†
* Percent Daily Values are based on a 2,000 calorie diet. † Daily Value not established.
Other ingredients: Hypromellose (cellulose capsule), Stearic Acid (vegetable source), Citric Acid and Microcrystalline Cellulose.
Not manufactured with wheat, gluten, soy, milk, egg, fish, shellfish, tree nut or sesame ingredients. Produced in a GMP facility that processes other ingredients containing these allergens.
Testing & quality
NOW says its in-house laboratories are ISO/IEC accredited and that its manufacturing holds a third-party GMP certification (Intertek badge on product pages); some products carry Informed Sport, but its C-1000 has no USP or NSF certification.
Goals it supports
Creator video reviews
Independent creators reviewing NAC 600 mg Capsules with Selenium on YouTube.
2 positive1 mixed0 critical
Pros & cons
What we like
- 600 mg of NAC per capsule, matching doses used in research when taken twice daily
- Simple, fully disclosed label: NAC plus 25 mcg of selenium and no proprietary blend
- NOW tests products in ISO 17025-accredited in-house labs and holds third-party GMP certification
- About $0.44 a day at list price, and often less on sale
Watch-outs
- Evidence for noticeable benefits in healthy adults is limited
- Sulfur smell and capsule speckling are common, and some users report stomach upset
- No independent product certification such as NSF or USP
- The formula changed: molybdenum was dropped, but some listings still mention it
Questions buyers ask
Is NAC still allowed to be sold as a dietary supplement?
Yes, for now. FDA says NAC is technically excluded from the supplement definition because it was approved as a drug in 1963, a position it stated in 2020 warning letters. In August 2022 it issued final guidance saying it would not act against otherwise lawful NAC supplements while it considers a rule to allow them. As of October 2026 no rule had been proposed.
How much selenium does this add, and is that safe?
Each capsule has 25 mcg of selenium, so the label dose of two capsules adds 50 mcg a day. The adult RDA is 55 mcg and the upper limit is 400 mcg, so this is safe for most adults on its own. If you also take a multivitamin or a separate selenium supplement, add them up, because long-term excess can cause garlic breath, brittle nails and hair loss.
Why do the capsules smell or have dark specks?
NAC contains sulfur, so a sulfur or rotten-egg odor when you open the bottle is normal and common to most NAC products. NOW says natural color variation and speckling can appear when the powder is exposed to air and do not affect quality. Keeping the freshness packet in the bottle and the lid tightly closed helps limit both.
Sources we checked (20)
- 1.nowfoods.com/products/supplements/nac-600-mg-capsules
- 2.nowfoods.com/sites/default/files/2025-08/0085_v12_Right.png
- 3.nowfoods.com/sites/default/files/2025-08/0085_v12_Left.png
- 4.nowfoods.com/quality-safety
- 5.nowfoods.com/about-now/legacy-family-employee-ownership
- 6.amazon.com/dp/B000MGWFWI
- 7.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warnin
- 8.fda.gov/food/hfp-constituent-updates/fda-issues-response-two-citizen-petition
- 9.fda.gov/food/hfp-constituent-updates/fda-releases-final-guidance-enforcement-
- 10.federalregister.gov/documents/2022/08/02/2022-16499/policy-regarding-n-acetyl-l-cysteine-
- 11.supplysidesj.com/regulatory/amazon-resumes-sales-nac-supplements
- 12.supplysidesj.com/supplement-regulations/amazon-confirms-plans-on-removing-nac-suppleme
- 13.ods.od.nih.gov/factsheets/Selenium-HealthProfessional/
- 14.mskcc.org/cancer-care/integrative-medicine/herbs/n-acetylcysteine
- 15.pubmed.ncbi.nlm.nih.gov/3803419/
- 16.pubmed.ncbi.nlm.nih.gov/2029805/
- 17.pubmed.ncbi.nlm.nih.gov/29233792/
- 18.pubmed.ncbi.nlm.nih.gov/28102488/
- 19.youtube.com/watch?v=RWSG_GJ7oU8
- 20.api.fda.gov/food/enforcement.json?search=recalling_firm:%22NOW+Health+Group%22
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