Skip to content
Nutrition Reviews

Head to head · Amino Acids (BCAA & EAA)

NOW Foods NAC 600 mg Capsules with Selenium vs Xtend Original BCAA Powder

NOW Foods scores higher overall (7.0 vs 6.7 out of 10), mainly on efficacy, value and transparency. Xtend still leads on quality & purity and experience.

Updated October 2026 from our full reviews · How we score

Higher score
Front of the NOW NAC 600 mg bottle, 100 capsules, with selenium
NOW FoodsNAC 600 mg Capsules with Selenium
7.0
Mixed

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.

Check price on AmazonBuy from the brand$21.99

We may earn a commission when you buy through these links — it never affects our scores. How we make money

Read the full review
Front of Xtend Original BCAA, Blue Raspberry Ice, 30-serving tub
XtendOriginal BCAA Powder
6.7
Mixed

A best-selling BCAA drink: 7 g BCAAs, glutamine and electrolytes with zero sugar, but BCAAs add little if you already eat enough protein.

Check price on AmazonBuy from the brand

We may earn a commission when you buy through these links — it never affects our scores. How we make money

Read the full review

We may earn a commission when you buy through these links — it never affects our scores. How we make money

The short answer

Choose NOW Foods if…

  • 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
  • You care most about efficacy, value, transparency

Choose Xtend if…

  • A flavored, zero-sugar drink to sip during training
  • People who like the taste and want some electrolytes
  • Athletes who want an NSF Contents Certified amino drink
  • You care most about quality & purity, experience

Key differences

Biggest scoring gap
Value: NOW Foods 7.6, Xtend 6.0. This factor covers cost per effective serving compared with category peers.
Independent testing
Only Xtend carries NSF Contents Certified; NOW Foods has no independent certification we could verify. NSF Contents Certified: NSF confirms the product contains what the label says and no harmful levels of contaminants.
Formula
Of the key ingredients in our reviews, only Xtend lists leucine and sodium.
Format
NOW Foods: capsule, 100 servings per container; Xtend: powder, 30 servings per container.
Dietary labels
Only NOW Foods is labeled gluten-free, dairy-free, soy-free and non-GMO. Only Xtend is labeled sugar-free.

Side by side

NAC 600 mg Capsules with SeleniumOriginal BCAA Powder
Our score7.0 / 106.7 / 10
Efficacy (30%)5.84.8
Quality & Purity (25%)7.58.4
Value (20%)7.66.0
Experience (15%)7.48.2
Transparency (10%)8.07.0
FormCapsulePowder
Serving1 Capsule100 servings per container1 scoop (13.5 g)30 servings per container
Price per serving$0.22See retailer
Testing & certifications
cGMP facilityKosherHalal
NSF Contents Certified
DietaryGluten-free, Dairy-free, Soy-free, Non-GMOSugar-free
Key ingredients
  • N-Acetyl Cysteine (NAC)600 mg
  • Selenium (as L-selenomethionine)25 mcg (45% DV)
  • L-Leucine3,500 mg
  • L-Isoleucine and L-Valine1,750 mg each
  • L-Glutamine2,500 mg
  • Sodium and potassium220 mg / 170 mg
Flavors—8 (Blue Raspberry Ice, Watermelon Explosion, Glacial Grape…)
Creator video reviews34

Pros and cons

NAC 600 mg Capsules with Selenium

  • 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
  • Evidence for noticeable benefits in healthy adults is limited
  • Sulfur smell and capsule speckling are common, and some users report stomach upset
All 8 pros and cons

Original BCAA Powder

  • Fully disclosed label: 7 g BCAAs (2:1:1) plus 2.5 g glutamine
  • Zero sugar and zero calories per serving
  • 220 mg sodium and 170 mg potassium for training hydration
  • BCAAs alone lack the other essential amino acids needed to build muscle
  • Adds little for people who already meet daily protein needs
All 9 pros and cons

Our verdict: NOW Foods vs Xtend

NOW Foods is the stronger product overall, 7.0 to 6.7 in our scoring, ahead on efficacy, value and transparency. Each full review shows the evidence, testing and buyer feedback behind these scores.

Full NAC 600 mg Capsules with Selenium review Full Original BCAA Powder review

What creators say

Questions people ask

Is NOW Foods better than Xtend?
In our scoring, NOW Foods NAC 600 mg Capsules with Selenium rates higher overall (7.0 vs 6.7 out of 10). NOW Foods leads on efficacy, value and transparency; Xtend leads on quality & purity and experience. Scores weigh efficacy, quality, value, experience and transparency.
Are NOW Foods and Xtend third-party tested?
NOW Foods has no independent certification we could verify; Xtend carries NSF Contents Certified.
Who should choose NOW Foods over Xtend?
Our reviews suggest NOW Foods is 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 and people who prefer NAC from a manufacturer with accredited in-house labs, while Xtend is best for a flavored, zero-sugar drink to sip during training, people who like the taste and want some electrolytes and athletes who want an NSF Contents Certified amino drink.
What is the difference between NOW Foods and Xtend?
Only Xtend carries NSF Contents Certified; NOW Foods has no independent certification we could verify. NSF Contents Certified: NSF confirms the product contains what the label says and no harmful levels of contaminants. Of the key ingredients in our reviews, only Xtend lists leucine and sodium. NOW Foods: capsule, 100 servings per container; Xtend: powder, 30 servings per container.

More amino acids (bcaa & eaa) comparisons

EAA Powder vs Essential AMIN.O. Energy

PerfectAmino Tablets vs EAA Powder

NAC 600 mg Capsules with Selenium vs EAA Powder

PerfectAmino Tablets vs Essential AMIN.O. Energy

NAC 600 mg Capsules with Selenium vs Essential AMIN.O. Energy

PerfectAmino Tablets vs NAC 600 mg Capsules with Selenium

See all amino acids (bcaa & eaa), ranked