If you’re looking to support your body’s glutathione production and antioxidant defenses, this provides the key building block. At one tablet, you're getting 500 mg of **L-Cysteine** — just below the 600 mg minimum used in clinical research. Following the label's suggestion of 1–3 tablets daily puts you at 500–1,500 mg, comfortably within the studied range for supporting liver health and antioxidant capacity.

You're also getting 60 mg of **Vitamin C** and 10 mg of **Vitamin B6**, both of which play supporting roles in cysteine metabolism and glutathione recycling. These are modest doses — well below their own clinical ranges — so think of them as functional co-factors rather than standalone contributors.

One thing worth knowing: if you're supplementing for glutathione support, most clinical research actually uses NAC (N-Acetyl-L-Cysteine), which is more stable and better studied. Free-form L-Cysteine is less researched as a standalone supplement, so the evidence base here is thinner than the dose alone might suggest.

BioStacks
NOW

L-Cysteine 500 mg

1 Tablet · 100 servings · $0.13/serving

iHerbAmazon

Best for

General Health

Ingredients (3)

Vitamin B6

40%

Dose

10 mg

Target

25–100 mg

Form

Premium

L-Cysteine Hydrochloride

83%

Dose

500 mg

Target

600–1800 mg

Form

Premium

Vitamin C

24%

Dose

60 mg

Target

250–2000 mg

Form

Budget

Other Ingredients (5)

Magnesium StearateLubricant

A salt of stearic acid used as a lubricant in tablet and capsule production

Silicon DioxideAnti-caking

Fine silica powder used to prevent clumping

Coating (unspecified)Coating

Generic tablet coating declaration where the label does not itemize the coating's components; modern aqueous film coatings are typically cellulose-based (HPMC) with a plasticizer

Citric AcidAcidulant

Natural acid derived from citrus fruits

Microcrystalline CelluloseBinder

Plant-derived cellulose used as a binder and filler in supplements

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Sources & Scoring

Nutrient data (RDA, UL, and safety thresholds) sourced from: NIH Office of Dietary Supplements and National Academies Dietary Reference Intakes (DRI).

This is not medical advice. Consult a healthcare provider before making changes to your supplement routine.

The score analyzes what's on the label: ingredient doses vs. clinical ranges, chemical forms, evidence levels, and known interactions. It does not verify label accuracy or test for contaminants — for that, look for third-party certifications like USP or NSF.

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