---
title: "L Cysteine — $33K/mo Amazon US Product Research (2026)"
canonical_url: "https://flapen.com/research/us/health-household/l-cysteine"
last_updated: "2026-08-12T16:01:37.306Z"
locale: en
meta:
description: "Amazon product research for l cysteine: $33K/mo market, demand, competition, pricing, reviews & the verdict. Know if it's worth selling — Flapen."
"og:description": "Amazon product research for l cysteine: $33K/mo market, demand, competition, pricing, reviews & the verdict. Know if it's worth selling — Flapen."
"og:title": "L Cysteine — $33K/mo Amazon US Product Research (2026)"
---
# **L Cysteine**
**Worth a look**
Shows low returns (0.0%), but a concentrated shelf (top 5 take 77% of clicks) keeps it on the watch list.
Market size 55Growth 22Conversion 91Competition 19Returns 100Price range 81Avg price 85Brand share 31Review moat 38Quality gap 33
**Returns**
**Incredible****0.0%**
return rate — above 5% kills the launch gate
**Conversion**
**Great****11.0%**
search→purchase rate — share of searches ending in a sale
**Avg price**
**Great****$19.16**
avg listing price — sweet spot $15–$100
**Price range**
**Great****$10.25–$36.60**
cheapest to priciest tracked listing — scored on the share inside $15–$100
**Market size**
**Good****$396K**
$396K/yr · 188K searches
**Review moat**
**Okay****2,732.69**
avg incumbent reviews — the moat a new listing must climb
**Quality gap**
**Okay****4.5★**
avg incumbent rating — lower means beatable quality
**Brand share**
**Okay****86%**
top-5 brand share — brands hold most of the demand
**Growth**
**Bad****-6.0%**
90-day search growth — must beat 0% to launch
**Competition**
**Bad****77%**
top-5 click share — a locked-up shelf
## **Is l cysteine profitable on Amazon?**
According to Flapen's Amazon United States niche tracking, l cysteine is a $396K/yr Amazon United States market (188K searches/yr). The top 5 brands hold 86% of demand. Verdict: Worth a look — 50/100.
Data updated Jul 25, 2026 · scored weekly · [~~How we score niches ~~](https://flapen.com/research/methodology)
## **l cysteine market size & sales**
Units sold, revenue, conversion and listing quality across the tracked shelf.
- **Units sold / yr**
- **15K–20K**
- avg 1,250–1,500/product
- **Revenue / yr**
- **$287K–$383K**
- units × avg price
- **Conversion rate**
- **11.0%**
- **Avg BSR**
- **#1,816**
- **Page quality**
- **0%**
- **Prime**
- **100%**
- **Sponsored**
- **69%**
- **Out of stock**
- **0.0%**
- **Avg brand age**
- **69 months**
- **Avg seller age**
- **178 days**
## **Competition: brands, sellers & click share**
The top 5 products capture 77% of clicks — a locked-up shelf that new listings rarely crack.
**Brands**
**9 **—flat
**Sellers**
**34**
**Top-5 brand share**
**86%**
Top 20: 100%
**Top-5 click share**
**77%**
Top 20: 100%
**Open market**
**8%**
- Nutricost39% - NOW Foods21% - Life Extension13% - Horbäach7% - Cheers6% - BulkSupplements6% - Open — no brand owns it (3 brands, 8%)
## **l cysteine demand & seasonality**
Weekly Amazon search volume, last 103 weeks — -6.0% search growth over the last 90 days.
5K3KSpike '24Spike '25Spike '26 seasonSepDecMarJunAugNovMarMay
No pronounced peak months · busiest ÷ quietest = 1.9×
[**Open Trend **](https://flapen.com/research/us/health-household/l-cysteine/trend)
## **Top l cysteine search terms shoppers use**
The exact queries shoppers type, with yearly volume, growth and conversion.
- **l cysteine**52K/yr-10.8%10.2% conv. - **l-cysteine**40K/yr-11.5%10.0% conv. - **cysteine**24K/yr+12.9%4.2% conv. - **l cysteine supplement**19K/yr-17.2%9.1% conv. - **l-cysteine supplement**10K/yr-14.4%8.9% conv. - **cystine**8K/yr+32.9%2.3% conv. - **cysteine supplement**12K/yr+21.5%6.7% conv. - **lcysteine**7K/yr-22.6%8.0% conv. - **cisteina**3K/yr+335.4%1.9% conv. - **l cystine**5K/yr-19.5%7.8% conv. [**All search terms **](https://flapen.com/research/us/health-household/l-cysteine/search-terms)
## **Top l cysteine products & what they sell for**
Every tracked product — its share of the shelf, its review moat, and what it sells for.
Each bubble is one product — market share against review moat; bubble size tracks estimated sales, color grades how beatable the incumbent looks.
0%10%$40K20%$79K30%$119K40%$158K101001K10K100K Reviews — right = deep review moatMarket share (90d) ≈ est. sales
Beatable (≤4.3★) Contested Strong incumbent (>4.7★)
All 13 tracked products in this niche — three views at once, no toggling.
### **Top sellers**
by 90-day click share
[1**Nutricost L-Cysteine 1000mg 120 Capsules 60 Servings Gluten-Free**Nutricost**$14.77**4.6★163 rev](https://www.amazon.com/dp/B0DRM6MP1D) [2**Now Supplements L-Cysteine 500 mg 90 Veg Capsules - Healthy Skin Hair and Nails* with Vitamin C**NOW Foods**$12.36**4.7★99 rev](https://www.amazon.com/dp/B0F1944NW5) [3**Life Extension N-Acetyl-L-Cysteine (NAC) Immune Respiratory Liver Health NAC 600 mg Potent antioxidant Support Free-radicals Easy to Absorb 60 Capsules**Life Extension**$10.25**4.6★7,821 rev](https://www.amazon.com/dp/B008ML8D4O) [4**Horbach L-Cysteine 1000mg | 100 Powder Capsules**Horbäach**$13.46**4.4★958 rev](https://www.amazon.com/dp/B07N7QYMSS) [5**Nutricost N-Acetyl L-Cysteine (NAC) 600mg 180 Capsules**Nutricost**$15.75**4.6★14,257 rev](https://www.amazon.com/dp/B01CUQFKW4)
**~~View all top sellers →~~**
### **Newest**
by launch date
[**Now Supplements L-Cysteine 500 mg 90 Veg Capsules - Healthy Skin Hair and Nails* with Vitamin C**NOW Foods**$12.36**99 rev1y ago](https://www.amazon.com/dp/B0F1944NW5) [**Nutricost L-Cysteine 1000mg 120 Capsules 60 Servings Gluten-Free**Nutricost**$14.77**163 rev1y ago](https://www.amazon.com/dp/B0DRM6MP1D) [**NaturaLife Labs N-Acetyl-L-Cysteine (NAC) 1600 mg 100 Capsules - Vegan Non-GMO & Gluten-Free**NaturaLife Labs**$15.68**754 rev2y ago](https://www.amazon.com/dp/B0CW8QXQD7) [**BulkSupplements.com NAC 1000 mg Capsules - N-Acetyle Cysteine 1000mg NAC Supplement NAC1000mg - NAC Capsules Gluten Free - 2 Capsules per Serving 180-Day Supply 360 Capsules**BulkSupplements**$20.65**1,055 rev3y ago](https://www.amazon.com/dp/B0CCX27QHY) [**Cheers Restore | Supplement with DHM + L-Cysteine | Feel Better After Drinking & Support Your Liver | 12 Doses | Dihydromyricetin Cysteine Milk Thistle Prickly Pear B-Vitamins Ginger**Cheers**$34.11**635 rev5y ago](https://www.amazon.com/dp/B099MNTRZW)
**~~View all new products →~~**
### **Trending**
90-day click momentum
[**Cheers Protect | Daily Liver Supplement for Drinkers with L-Cysteine + DHM | Increase Glutathione Levels | 30 Doses | Cysteine Dihydromyricetin Milk Thistle Prickly Pear B-Vitamins Ginger**Cheers**$29.32**4.6★**▲ 43%**](https://www.amazon.com/dp/B07VQKWCYJ) [**Now Supplements L-Cysteine 500 mg 90 Veg Capsules - Healthy Skin Hair and Nails* with Vitamin C**NOW Foods**$12.36**4.7★**▲ 38%**](https://www.amazon.com/dp/B0F1944NW5) [**BulkSupplements.com L-Cysteine HCl Powder - NAC Supplement Amino Acid Supplement - Gluten Free 500mg per Serving 250g (8.8 oz) (Pack of 1)**BulkSupplements**$16.93**4.3★**▲ 20%**](https://www.amazon.com/dp/B00IYT1ZTY) [**BulkSupplements.com NAC 1000 mg Capsules - N-Acetyle Cysteine 1000mg NAC Supplement NAC1000mg - NAC Capsules Gluten Free - 2 Capsules per Serving 180-Day Supply 360 Capsules**BulkSupplements**$20.65**4.5★**— 10%**](https://www.amazon.com/dp/B0CCX27QHY) [**Nutricost L-Cysteine 1000mg 120 Capsules 60 Servings Gluten-Free**Nutricost**$14.77**4.6★**— 8%**](https://www.amazon.com/dp/B0DRM6MP1D)
**~~View all trending →~~**
## **What reviews say buyers love and hate about l cysteine**
What buyers praise and complain about, mined from review topics.
### **What buyers love **
**Quality-Overall**18%
*“The quality is always consistent”*
**Value For Money**10%
*“They are affordable”*
**Efficiency**9%
*“Appears to be effective”*
**Advertised Vs Actual Product**8%
*“As advertised”*
**Vitamin**6%
*“Good Supplement”*
**Regulates Digestion**3%
*“Great liver supplement”*
**Sleep Quality**3%
*“I sleep better”*
**Dosage**3%
*“I like this dosage”*
**Ease Of Chewing/Swallowing**2%
*“my 11 year-old has no problem swallowing it”*
**Nutritional Content**2%
*“This has easily been the most helpful supplement I've ever taken”*
### **What buyers complain about **
**Smell**17%
*“strong plastic smell”*
**Functionality-Overall**9%
*“Not effective”*
**Side Effects**8%
*“Has side effects”*
**Sleep Quality**7%
*“make it harder for me to sleep”*
**Dosage**6%
*“One dose of this product made me sick”*
**Acid Regulator/Stomach Ache Relief**6%
*“terrible stomach upset”*
**Taste-Overall**4%
*“The taste is not good”*
**Quality-Overall**3%
*“Bad quality control”*
**Size-Overall**3%
*“Super tiny bottle”*
**Value For Money**3%
*“A bit expensive”*
### **Top return reasons **
**Advertised Vs Actual Product**30%
**Functionality-Overall**20%
**Dosage**10%
**Side Effects**10%
**Value For Money**10%
**Acid Regulator/Stomach Ache Relief**10%
**Regulates Digestion**10%
## **Common l cysteine questions**
- **Is l cysteine profitable to sell on Amazon United States?**
- The niche generates $396K/yr across 13 tracked products. 90-day search growth is -6.0%. Flapen's verdict: Worth a look (50/100).
- **How competitive is the l cysteine niche?**
- 9 brands and 34 sellers compete. The top 5 products take 77% of clicks and top 5 brands hold 86% of demand.
- **What do buyers complain about in l cysteine?**
- Top complaints mined from reviews: Smell, Functionality-Overall, Side Effects. The return rate is 0.0%.
- **When does demand for l cysteine peak?**
- Demand is steady year-round — the busiest month runs 1.9× the quietest.
- **What does it cost to enter the l cysteine niche?**
- Listings span $10.25–$36.60; the average listing price is $19.16 (sweet spot $15–$100). The average incumbent carries 2,733 reviews — the moat a new listing must climb.
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