21st Century Daily Amino Acid, 120 Tablets supplement bottle
21st Century

Daily Amino Acid, 120 Tablets

What We Researched
12 active ingredients analyzed · 10 inactive ingredients decoded · 2 brand certifications checked · 3 retailers compared · Last updated: Mar 2026
68
Product Score Fair
76
Brand Score Fair

Product Analysis

Transparency Excellent

Supplement Facts

IngredientAmount% DV
Calcium (as Dicalcium Phosphate and Calcium Carbonate) 150 mg 12%
L-Histidine (as L-histidine HCl) 17 mg **
L-Isoleucine 63 mg **
L-Leucine 105 mg **
L-Lysine (as L-lysine HCl) 93 mg **
dl-Methionine 21 mg **
L-Cysteine (as L-cysteine HCl) 11 mg **
L-Phenylalanine 32 mg **
L-Tyrosine 31 mg **
L-Threonine 69 mg **
L-Valine 58 mg **
Bioavailability Excellent

Absorption Rating

  • Calcium (as Dicalcium Phosphate and Calcium Carbonate) Fair
  • L-Histidine (as L-histidine HCl) Good
  • L-Isoleucine Good
  • L-Leucine Good
  • L-Lysine (as L-lysine HCl) Good
  • dl-Methionine Good
  • L-Cysteine (as L-cysteine HCl) Good
  • L-Phenylalanine Good
  • L-Tyrosine Good
  • L-Threonine Good
  • L-Valine Good
Other Ingredients Good

Fillers & Additives

  • Whey
  • Cellulose
  • Stearic Acid
  • Croscarmellose Sodium
  • Magnesium Silicate
  • Magnesium Stearate
  • PEG Medium
  • Polysorbate Medium
  • Polyvinyl Alcohol
  • Silicon Dioxide
Efficacy Very Poor

Dosage Analysis

  • Calcium (as Dicalcium Phosphate and Calcium Carbonate) 150 mg Under-dosed
  • L-Histidine (as L-histidine HCl) 17 mg Under-dosed
  • L-Isoleucine 63 mg Effective
  • L-Leucine 105 mg Under-dosed
  • L-Lysine (as L-lysine HCl) 93 mg Under-dosed
  • dl-Methionine 21 mg Under-dosed
  • L-Cysteine (as L-cysteine HCl) 11 mg Under-dosed
  • L-Phenylalanine 32 mg Under-dosed
  • L-Tyrosine 31 mg Under-dosed
  • L-Valine 58 mg Under-dosed

Supplement Facts

Ingredient Amount % Daily Value
Calcium (as Dicalcium Phosphate and Calcium Carbonate) 150 mg 12%
Sodium 5 mg <1%
L-Histidine (as L-histidine HCl) 17 mg **
L-Isoleucine 63 mg **
L-Leucine 105 mg **
L-Lysine (as L-lysine HCl) 93 mg **
dl-Methionine 21 mg **
L-Cysteine (as L-cysteine HCl) 11 mg **
L-Phenylalanine 32 mg **
L-Tyrosine 31 mg **
L-Threonine 69 mg **
L-Valine 58 mg **

Other Ingredients

Inactive ingredients used in manufacturing. All rated for safety.

Whey Generally_safe

It is used as a filler or protein source.

Cellulose Safe

Provides bulk and structure in tablets and capsules.

Stearic Acid Safe

Helps ingredients flow smoothly through manufacturing equipment.

Croscarmellose Sodium Safe

Helps tablets break apart and dissolve quickly in the stomach.

Magnesium Silicate Generally_safe

It is used to improve powder flow and prevent clumping.

Magnesium Stearate Safe

Prevents ingredients from sticking to manufacturing equipment during tableting.

PEG Caution

It is used as a binder, coating, or emulsifier.

Polysorbate Generally_safe

It is used to help mix oil and water-based ingredients.

Polyvinyl Alcohol Generally_safe

It is used as a coating for tablets or capsules.

Silicon Dioxide Safe

Prevents clumping and ensures consistent dosing.

Price Comparison

Price History

Tracked across major retailers. Updated periodically.

$12$11$10$9$8 Mar 12 $9.99
iHerb

Prices shown at time of last check. Click a retailer to see current price. GoodSupp is not affiliated with any retailer.

Brand Trust Report
21st Century

Founded 1991 · Tempe, Arizona, United States · 231 products · 21stcenturyvitamins.com/

Certifications

2 certifications
Consumerlab Verified
Nsf Gmp Verified Source

Transparency

4 claims
Third Party Testing Claim — Claimed Source
Testing Lab Disclosure — Verified Source
In House Testing — Verified Source

Violation History

4 incidents
Prop 65 Lead2021-06-22Source
Recall Vitamin D3 5000 IU Tablets2021-05-19Source
Lawsuit False advertising of Glucosamine/Chondroitin supplements.2012Source
Prop 65 Lead2008-12-23Source
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Frequently Asked Questions
Is 21st Century Daily Amino Acid, 120 Tablets a good supplement?

21st Century Daily Amino Acid, 120 Tablets received a product quality score of 68/100 in GoodSupp's independent analysis, suggesting some areas that could be improved. The product contains 12 active ingredients Of the 10 inactive ingredients, 5 are rated safe and 1 are flagged for review. The manufacturer, 21st Century, holds a brand trust score of 76/100 with 2 verified certifications including Consumerlab, Nsf Gmp.

What are the ingredients in 21st Century Daily Amino Acid, 120 Tablets?

21st Century Daily Amino Acid, 120 Tablets contains 12 active ingredients: Calcium (as Dicalcium Phosphate and Calcium Carbonate) (150 mg), Sodium (5 mg), L-Histidine (as L-histidine HCl) (17 mg), L-Isoleucine (63 mg), L-Leucine (105 mg), L-Lysine (as L-lysine HCl) (93 mg), and 6 more. Each ingredient's dosage, form, and safety rating is analyzed independently in GoodSupp's full product breakdown.

Is 21st Century Daily Amino Acid, 120 Tablets safe to take?

21st Century Daily Amino Acid, 120 Tablets has been analyzed for ingredient safety across all its components. Of 10 inactive ingredients, 5 are rated safe. 1 ingredient is flagged for review: PEG. 'Caution' doesn't mean dangerous — it indicates the ingredient has some considerations worth being aware of, such as potential sensitivities or ongoing research. Always consult your healthcare provider before starting any new supplement, especially if you take medications or have underlying health conditions.

Is 21st Century a trustworthy supplement brand?

21st Century receives a brand trust score of 76/100 based on GoodSupp's independent analysis of certifications, regulatory history, and transparency practices. Founded in 1991 and headquartered in Tempe, Arizona, United States, the company offers 231 products in their lineup. They hold 2 verified certifications including Consumerlab, Nsf Gmp. Third-party certifications are independently verified and indicate the brand meets specific quality, purity, and manufacturing standards. Note: 21st Century has 4 historical regulatory incidents on record, which are factored into the trust score.

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Disclaimer: GoodSupp provides independent supplement quality analysis for informational purposes only. Scores are generated algorithmically based on ingredient profiles, brand certifications, and public records. This is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Product data is sourced from manufacturer labels and public databases. GoodSupp is not affiliated with any supplement brand.