NOW Foods L-Cysteine 500 mg with Vitamins B-6 & C – 100 Tablets
Product Overview & Quick Facts
NOW® L-Cysteine 500 mg is a pure amino acid supplement crafted to support healthy skin, strong hair, and resilient nails from the inside out. Each tablet provides pure free-form L-Cysteine fortified with synergistic cofactors Vitamin C and Vitamin B-6. Together, these nutrients supply the essential sulfur building blocks your body needs to construct tough structural proteins and produce glutathione, your cells' master natural antioxidant.
Quick Specs Snapshot
✓Active Form & Potency: 500 mg pure L-Cysteine (derived from 650 mg L-Cysteine Hydrochloride), plus 60 mg Vitamin C (67% Daily Value) and 10 mg Vitamin B-6 (588% Daily Value) per single-tablet serving.
✓Primary Cellular Target: Keratin protein matrix synthesis in hair follicles and nail beds, alongside liver and cellular glutathione production.
✓Supply & Value Math: 100 tablets deliver a full 100-day supply (over 3 months of daily support) for an affordable daily investment.
✓Formulation Purity: Non-GMO, vegetarian coating, and free from wheat, gluten, soy, milk, egg, fish, shellfish, tree nuts, and sesame.
Buyer's Guide & Form Comparison
Why This Specific Form Matters
L-Cysteine is a sulfur-bearing amino acid. In low-cost supplements, plain cysteine can oxidize and break down before your digestive tract can absorb it. NOW® uses stable L-Cysteine Hydrochloride (HCl) and pairs it directly with Vitamin C to protect the molecule from oxidation, while adding Vitamin B-6 to activate the enzyme systems that put cysteine to work building protein [1, 3].
Ideal For Shoppers Who:
✓Want to target brittle, peeling nails and thinning hair by supplying direct structural protein builders.
✓Prefer a complete 3-in-1 formula containing the essential vitamin cofactors (B-6 and C) rather than juggling multiple individual bottles.
✓Want an economical once-daily routine with a full 100-day supply from a family-owned brand with independent lab testing.
Consider Another Option If:
✗You have difficulty swallowing standard solid tablets and require a liquid, powder, or chewable format.
✗You are looking specifically for N-Acetyl Cysteine (NAC) for acute bronchial and respiratory mucus breakdown rather than keratin support.
✗You have an active stomach ulcer or severe acid sensitivity and must avoid acidic nutrient forms on an empty stomach.
Every order is backed by VitaNet®, LLC's unconditional 100% money-back guarantee (we even cover return shipping, even on opened bottles) so you can test this formula completely risk-free.
How L-Cysteine Works in the Body
To understand how L-Cysteine works, it helps to look at two core jobs your body performs every single day: assembling durable structural proteins and defending cells against oxidative stress.
1. Building Strong Keratin Bridges
Your hair, skin, and fingernails are built predominantly from a tough, fibrous protein called keratin. Cysteine makes up a large portion of the amino acids found in keratin because it carries a unique sulfur-hydrogen atom group known as a thiol group (−SH) [1]. When hair and nail cells mature, two neighboring cysteine molecules hook their sulfur atoms together, forming what biochemists call a disulfide bridge (−S−S−) [1]. Think of these bridges like steel crossbeams holding up a bridge: the more disulfide bonds your body forms, the stronger, firmer, and more split-resistant your fingernails and hair strands become [1].
2. Fueling Your Master Antioxidant: Glutathione
Every cell in your body needs protection from everyday wear and tear caused by sunlight, normal metabolism, and environmental elements. Cells defend themselves using a tripeptide molecule called glutathione [2]. Glutathione is made from three amino acids: glycine, glutamate, and cysteine. Cysteine is the rarest of the three in typical cellular pools, making it the limiting ingredient [2]. Supplying free-form L-Cysteine ensures your liver, skin cells, and immune system have the raw fuel required to produce fresh glutathione, promoting healthy cellular defense [2, 3].
3. The Critical Roles of Vitamin B-6 and Vitamin C
Amino acids do not work in isolation. Vitamin B-6 serves as an essential cofactor for transsulfuration enzymes, enabling your liver to transfer sulfur and synthesize new amino acid chains efficiently [3]. At the same time, Vitamin C acts as a natural antioxidant shield, maintaining cysteine in its reduced, bioavailable form so it travels safely through your system to reach hair follicles and nail beds [4].
Daily Use, Timing & Synergy Protocol
Optimal Timing & Meal Pairing
Take 1 tablet daily with a meal and a full glass of water (H2O). Because L-Cysteine Hydrochloride and Ascorbic Acid are naturally mild acids, taking this tablet with food buffers the stomach lining and activates digestive enzymes for optimal amino acid uptake across the intestinal wall.
Daily Schedule & Smart Synergies
Taking your tablet with breakfast or lunch is ideal because daytime metabolism actively directs circulating amino acids into growing tissues.
✓Nutrient Synergies: Pairs well with Biotin (Vitamin B-7), Zinc, and Collagen peptides to create a comprehensive nutritional foundation for connective tissue and keratin support.
✗Spacing Rules: If you take high-dose mineral supplements (such as iron or copper) or prescription thyroid medication, space this tablet at least 2 hours apart, as concentrated minerals and sulfur compounds can compete for absorption pathways.
Timeline of Expectations
Week 1: Systemic absorption begins; intracellular cysteine and cofactor pools are replenished, supporting daily antioxidant production [2].
Weeks 3–4: As new keratin protein matrixes form at the base of your nail beds, fingernails often begin to feel sturdier with less immediate peeling.
Months 2–3+: Because a fingernail takes roughly 4 to 6 months to grow out completely and hair grows at roughly half an inch per month, the cumulative benefits of stronger disulfide bonding become visibly apparent in smoother, more resilient nails and healthy-looking hair texture [1].
Physical Profile, Ingredients & NOW Quality Standards
Tablet Appearance & Natural Sensory Notes
NOW® L-Cysteine comes as a solid, oblong tablet with a smooth vegetarian coating. When you first open the bottle, you may notice a light, characteristic mineral or sulfur aroma. This is completely natural: sulfur is the active element within cysteine that provides its biological benefits. The vegetarian coating ensures the tablet has no unpleasant taste and slides down smoothly with water.
Other Ingredients Demystified
•Microcrystalline Cellulose: Natural plant fiber that gives the tablet structure and consistency.
•Silicon Dioxide: A naturally occurring mineral compound that keeps powders flowing evenly so every tablet delivers an exact dose.
•Magnesium Stearate (vegetable source): A plant-based lubricant that prevents ingredients from sticking to equipment during pressing.
•Vegetarian Coating: A clean plant blend [hypromellose (plant cellulose), stearic acid, sunflower lecithin, triethyl citrate, and sunflower oil] that creates an easy-to-swallow barrier without animal gelatin.
•Citric Acid: A natural fruit-derived acid that helps protect the active ingredients and maintain freshness.
NOW® Manufacturing & In-House Lab Testing
NOW Foods conducts comprehensive in-house testing using ISO/IEC 17025 accredited laboratories. Their quality control process screens every incoming batch using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to confirm heavy metals (lead, arsenic, cadmium, and mercury) meet strict safety thresholds that often exceed standard commercial guidelines. They also verify amino acid identity and purity through High-Performance Liquid Chromatography (HPLC) and Fourier-Transform Infrared Spectroscopy (FTIR), while testing for microbiological purity (yeasts, molds, and bacteria) in a certified cGMP facility. The bottle itself is crafted from 100% Post-Consumer Recycled (PCR) resin to help minimize plastic waste.
Supplement Facts & Retailer Verification
Supplement Facts
Serving Size: 1 Tablet • Servings Per Container: 100
Description
Amount Per Serving
% Daily Value
Vitamin C (as Ascorbic Acid)
60 mg
67%
Vitamin B-6 (as Pyridoxine HCl)
10 mg
588%
L-Cysteine (from 650 mg L-Cysteine HCl)
500 mg
†
† Daily Value not established.
Allergen Notice: Not manufactured with wheat, gluten, soy, milk, egg, fish, shellfish, tree nut, or sesame ingredients. Produced in a GMP facility that processes other ingredients containing these allergens. Natural color variation may occur in this product. Store in a cool, dry place after opening.
Curator's Quality Note • VitaNet®, LLC
Since 1995, VitaNet®, LLC has curated genuine, science-backed nutritional formulas. With over 31 years of independent retail experience, we partner with reputable manufacturers like NOW Foods—family-owned since 1968—whose in-house testing laboratories verify identity, potency, and purity. Every purchase is backed by our full 100% money-back guarantee, including return postage.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Frequently Asked Questions
1. What is the difference between L-Cysteine and N-Acetyl Cysteine (NAC)?
L-Cysteine is the natural free-form amino acid that your body directly incorporates into keratin protein chains to strengthen hair, skin, and fingernails. N-Acetyl Cysteine (NAC) is an acetylated form primarily used to break up thick respiratory mucus and support acute liver detoxification pathways. For daily cosmetic structural support of hair and nails, free-form L-Cysteine is the direct physiological building block.
2. Why does the bottle have a slight sulfur smell?
A light sulfur aroma is completely normal and confirms the presence of active, genuine L-Cysteine. Cysteine is one of only two sulfur-containing amino acids in human biology. The sulfur atom is the exact element responsible for creating the disulfide bonds that make keratin proteins tough and durable.
3. Can I crush or split this tablet if I have trouble swallowing?
Yes. The tablet can be split with a pill cutter or crushed and mixed into applesauce or yogurt. However, because L-Cysteine and Vitamin C have a naturally tart and sulfuric taste, the smooth vegetarian coating was specifically added to make swallowing the whole tablet comfortable and neutral in taste.
4. Why are Vitamin B-6 and Vitamin C added to this formula?
Vitamin B-6 acts as an essential enzymatic helper for transsulfuration pathways, ensuring your cells can metabolize and integrate cysteine into new proteins. Vitamin C acts as an antioxidant protector, preventing cysteine from prematurely oxidizing in the digestive tract so that it reaches your tissues in active form.
5. Will taking this tablet break an intermittent fast?
While a single tablet contains negligible calories, free amino acids can stimulate nutrient-sensing pathways in the body. Furthermore, taking L-Cysteine on an empty stomach during a fast may cause mild digestive discomfort. It is best taken with your first meal of the day when you break your fast.
Scientific References
Robbins, C. R. (2012). Chemical and Physical Behavior of Human Hair (5th ed.). Springer-Verlag. [Disulfide cross-linking in keratin architecture].
Lu, S. C. (2013). Glutathione synthesis. Biochimica et Biophysica Acta (BBA) - General Subjects, 1830(5), 3143-3153. PMID: 22995213.
Stipanuk, M. H. (2004). Sulfur amino acid metabolism: pathways for production and removal of S-adenosylmethionine and S-adenosylhomocysteine, cysteine, and homocysteine. Current Opinion in Clinical Nutrition and Metabolic Care, 7(1), 63-71. PMID: 14710168.
Paulsen, C. E., & Carroll, K. S. (2013). Cysteine-mediated redox signaling: the chemistry of oxidation and the methods to study it. Chemical Reviews, 113(7), 4633-4679. PMID: 23495610.
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