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L-Cysteine Powder

Source Naturals
4.3
★ ★ ★ ★ ★
(355 ratings)
Cysteine 900 mg
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Score83
A clearly disclosed 900 mg cysteine serving with excellent value, focused on one antioxidant pathway.
How scoring works
Quantity:3 Ounce(s) • (83 servings)
Goals:
Anti-Aging

Score 83

A clearly disclosed 900 mg cysteine serving with excellent value, focused on one antioxidant pathway.
How scoring works
$12.92($0.15 per serving)
Amazon
$ 15.02
Pure Formulas
$ 19.59
iHerb
$ 18.77
iHerb
$ 18.77
Vitacost
$ 12.92
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Analysis

The 900 mg serving supplies L-cysteine hydrochloride monohydrate in a powder. The hydrochloride form is a useful stability advantage.

L-cysteine can contribute to glutathione production, giving it a clear antioxidant-building-block role. It has less direct healthy-aging evidence than NAC and covers only one pathway.

The single-active design keeps the purpose clear and easy to assess. Flexible measuring is useful, although sulfurous taste and odor may reduce convenience.

Who is it for
  • Adults specifically seeking L-cysteine
  • Users wanting a focused antioxidant precursor
Best for
  • Glutathione-building-block support
  • Flexible powder dosing

Pros

  • Provides 900 mg of L-cysteine hydrochloride monohydrate
  • Uses a stable hydrochloride form
  • Powder format
  • Excellent value

Cons

  • Less directly studied for glutathione support than NAC
  • Covers only one antioxidant pathway
  • Sulfurous taste and odor may be noticeable

Nutrient quality

94 Highest impact

The hydrochloride form provides a stable cysteine source. The cysteine amount is substantial for targeted supplementation.

Ingredient transparency

85 Highest impact

Every listed active has an individual amount and no proprietary blend hides key doses. Daily directions and the complete inactive-ingredient list are not supplied.

Customer satisfaction

58 Moderate impact

The supplied average is mixed and the aggregate pool is limited. No specific feedback is provided to assess recurring complaints or whether experience matches the intended use.

Value for money

92 Highest impact

Serving cost is low for the disclosed active amount. The focused design avoids paying for unnecessary active ingredients.

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Goals

Anti-Aging
Anti-Aging
Impact
High effect
C Goal FitA- Strength of SupportC- CoverageA Formula Quality

L-cysteine supplies a direct building block for glutathione, an important cellular antioxidant. Evidence supports that biochemical role, but this form has less direct healthy-aging research than N-acetylcysteine and does not cover other major pathways.

The high, clearly disclosed single-ingredient amount makes the contribution easy to judge. The powder is streamlined, though the hydrochloride form and sulfurous taste may be less convenient for some users.

Study evidence
Cysteine Mixed 2 studies

Ingredients

IngredientAmount per serving
L-Cysteine (L-Cysteine Hydrochloride Monohydrate)
 900 mg
Gluten Free Adults 18–50 Dairy Free Sugar Free
Report overview
Cysteine (L-Cysteine Hydrochloride Monohydrate) · 900 mg OverallScore96
A- Active Ingredient Quality & BioavailabilityA+ Dose, Safety & Label TransparencyA+ Value

The stable L-cysteine hydrochloride monohydrate form provides a clearly disclosed, high-potency dose. A single-ingredient powder avoids unnecessary binders and allows flexible measuring, though its sulfurous taste and odor may be noticeable. The large amount delivered per serving makes it highly cost-efficient for cysteine supplementation.

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86 Performance

L-Cysteine 500 mg

California Gold Nutrition
Base L-cysteine is usable but less stable than a hydrochloride salt; its cysteine quality and focus provide a clearer option when the original already provides a substantial focused cysteine serving. The cysteine amount is substantial for targeted supplementation.
79 Performance

Vegan Hair Skin & Nails

NOW Solutions
Chelated minerals, structural amino acids, hyaluronic acid, and antioxidant vitamins form a coherent hair, skin, and nail formula with good serving value; it offers broader hair or nutrient support rather than a focused cysteine upgrade. High-dose biotin and horsetail without silica standardization are the main limitations; Biotin can distort thyroid, hormone, and cardiac blood tests, so use should be disclosed before laboratory work.
74 Performance

Hair Skin & Nails

Swanson
MSM, well-identified horsetail, cysteine, choline, and PABA form a coherent beauty-focused blend at a low serving cost; it offers broader hair or nutrient support rather than a focused cysteine upgrade. Modest cysteine, choline, and PABA amounts limit depth, while excellent review volume supports confidence in general satisfaction.
89 Budget

L-Cysteine 500 mg

NOW
The hydrochloride form provides a stable cysteine source; the lower serving cost improves economy when the original already provides a substantial focused cysteine serving. The cysteine amount is substantial for targeted supplementation.
90 Budget

L-Cysteine 500 mg

Solgar
The hydrochloride form provides a stable cysteine source; it is among the lowest-cost eligible options, although it is not cheaper than the original when the original already provides a substantial focused cysteine serving. The cysteine amount is substantial for targeted supplementation.
90 Budget

L-Cysteine 500 mg

Bluebonnet
The hydrochloride form provides a stable cysteine source; it is among the lowest-cost eligible options, although it is not cheaper than the original when the original already provides a substantial focused cysteine serving. The cysteine amount is substantial for targeted supplementation.
64 Value

Hair Volume

New Nordic
Biotin, apple procyanidins, zinc, copper, horsetail, cysteine, and methionine form a broad hair-focused blend; it serves a broader goal but does not clearly improve value over the original. Basic mineral forms and modest amino-acid amounts limit depth, while concentrated biotin can interfere with several laboratory tests.
64 Value

Ultimate Hair & Nail Formula

Bluebonnet
A broad nutrient blend uses several useful forms, but many hair-focused amino acids and botanicals are modest; it serves a broader goal but does not clearly improve value over the original. The combined vitamin A amount and long-term vitamin B6 exposure are concerns for routine daily use; Formula breadth offers some value, though several small additions dilute the focus.
58 Value

Cell Formula

Nature's Way
The broad antioxidant blend uses several good nutrient forms, but cysteine makes only a small contribution and some antioxidant amounts are aggressive; it serves a broader goal but does not clearly improve value over the original. The high beta-carotene amount creates a specific concern for current or former smokers.
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Sources

Published studies used for the product analysis and the top-ranked studies for each ingredient and goal.

  1. Association of dietary sulfur amino acid intake with mortality from diabetes and other causes.
    Dong Z; Gao X; Chinchilli VM; Sinha R; Muscat J; Winkels R; Richie JP · European journal of nutrition · 2022
    Cohort study15,083 participantsAnti-Aging forCysteine
  2. Supplementing Glycine and N-Acetylcysteine (GlyNAC) in Older Adults Improves Glutathione Deficiency, Oxidative Stress, Mitochondrial Dysfunction, Inflammation, Physical Function, and Aging Hallmarks: A Randomized Clinical Trial
    Premranjan Kumar, Chun Liu, James Suliburk, Jean W Hsu, Raja Muthupillai, Farook Jahoor, Charles G Minard, George E Taffet, Rajagopal V Sekhar · The journals of gerontology. Series A, Biological sciences and medical sciences · 2023
    Randomized trial36 participantsAnti-Aging forCysteine