The Best Amino Acid Nutritional Supplements
We compared three top-rated amino acid supplements based on owner ratings, expert reviews, and price. Nutricost NAC emerges as the top pick for its quality and value.
Updated
The bottom line
Nutricost N-Acetyl L-Cysteine (NAC) Capsules are our top pick for an amino acid supplement, offering 600mg of high-quality NAC per capsule at $15.95 for 180 capsules. Owners rate it 9.2/10 from 14,733 ratings, citing benefits for allergies and liver health. The closest alternative is NOW Supplements NAC, priced at $21.85 for 250 capsules, but it includes selenium, which may not be necessary for all users. Sports Research L-Theanine, at $19.95 for 60 softgels, is a strong contender for relaxation and focus but is not a direct substitute for NAC.
Nutricost N-Acetyl L-Cysteine (NAC) Capsules $15.95
Best value and quality NAC supplement
Nutricost NAC offers 600mg of NAC per capsule, 180 capsules per bottle, and is vegan, non-GMO, and gluten-free. It is third-party tested and highly rated by owners for allergy and liver health benefits. The tradeoff is that it does not include additional ingredients like selenium.
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NOW Supplements NAC $21.85
High-quality NAC with added selenium
NOW Supplements NAC contains 600mg of NAC and selenium per capsule, with 250 capsules per bottle. It is non-GMO, gluten-free, and GMP certified. Owners rate it 9.2/10 from 21,248 ratings. The tradeoff is the higher price and inclusion of selenium, which may not be needed by all users.
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Sports Research L-Theanine 200mg $19.95
Best for relaxation and focus
Sports Research L-Theanine offers 200mg of L-Theanine per softgel, formulated with patented Suntheanine. It is made with organic coconut oil and is non-GMO, gluten-free, and soy-free. Owners rate it 9.2/10 from 15,479 ratings for its calming and focusing effects. The tradeoff is that it is not a direct substitute for NAC.
Check price on AmazonThe field, ranked
- Nutricost N-Acetyl L-Cysteine (NAC) Capsules Best value and quality NAC supplement 9.0/10 $15.95 Amazon
- NOW Supplements NAC High-quality NAC with added selenium 8.0/10 $21.85 Amazon
- Sports Research L-Theanine 200mg Best for relaxation and focus 8.0/10 $19.95 Amazon
Who should buy which
Nutricost NAC is best for those looking for a high-quality, affordable NAC supplement. NOW Supplements NAC is a good choice for those who want the added benefits of selenium. Sports Research L-Theanine is for those seeking relaxation and focus without the jitters of caffeine.
Owner complaints
A few owners of NOW Supplements NAC reported side effects like memory issues, but these were not common. Sports Research L-Theanine had one report of sleep issues, but this was an outlier.
Also-rans
None of the products earned a pick role, but all are strong contenders in their respective categories. Nutricost and NOW are top choices for NAC, while Sports Research is notable for L-Theanine.