L Cysteine
Worth a lookShows low returns (0.0%), but a concentrated shelf (top 5 take 77% of clicks) keeps it on the watch list.
Returns
Incredible0.0%return rate — above 5% kills the launch gate
Conversion
Great11.0%search→purchase rate — share of searches ending in a sale
Avg price
Great$19.16avg listing price — sweet spot $15–$100
Price range
Great$10.25–$36.60cheapest to priciest tracked listing — scored on the share inside $15–$100
Market size
Good$396K$396K/yr · 188K searches
Review moat
Okay2,732.69avg incumbent reviews — the moat a new listing must climb
Quality gap
Okay4.5★avg incumbent rating — lower means beatable quality
Brand share
Okay86%top-5 brand share — brands hold most of the demand
Growth
Bad-6.0%90-day search growth — must beat 0% to launch
Competition
Bad77%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
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.No pronounced peak months · busiest ÷ quietest = 1.9×
Top l cysteine search terms shoppers use
The exact queries shoppers type, with yearly volume, growth and conversion.- l cysteine52K/yr
- l-cysteine40K/yr
- cysteine24K/yr
- l cysteine supplement19K/yr
- l-cysteine supplement10K/yr
- cystine8K/yr
- cysteine supplement12K/yr
- lcysteine7K/yr
- cisteina3K/yr
- l cystine5K/yr
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.
All 13 tracked products in this niche — three views at once, no toggling.
Top sellers
by 90-day click share
Nutricost L-Cysteine 1000mg 120 Capsules 60 Servings Gluten-Free
Nutricost$14.774.6★163 rev
Now Supplements L-Cysteine 500 mg 90 Veg Capsules - Healthy Skin Hair and Nails* with Vitamin C
NOW Foods$12.364.7★99 rev
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$10.254.6★7,821 rev
Horbach L-Cysteine 1000mg | 100 Powder Capsules
Horbäach$13.464.4★958 rev
Nutricost N-Acetyl L-Cysteine (NAC) 600mg 180 Capsules
Nutricost$15.754.6★14,257 rev
Newest
by launch dateNow Supplements L-Cysteine 500 mg 90 Veg Capsules - Healthy Skin Hair and Nails* with Vitamin C
NOW Foods$12.3699 rev
Nutricost L-Cysteine 1000mg 120 Capsules 60 Servings Gluten-Free
Nutricost$14.77163 rev
NaturaLife Labs N-Acetyl-L-Cysteine (NAC) 1600 mg 100 Capsules - Vegan Non-GMO & Gluten-Free
NaturaLife Labs$15.68754 rev
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$20.651,055 rev
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$34.11635 rev
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$29.324.6★
Now Supplements L-Cysteine 500 mg 90 Veg Capsules - Healthy Skin Hair and Nails* with Vitamin C
NOW Foods$12.364.7★
BulkSupplements.com L-Cysteine HCl Powder - NAC Supplement Amino Acid Supplement - Gluten Free 500mg per Serving 250g (8.8 oz) (Pack of 1)
BulkSupplements$16.934.3★
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$20.654.5★
Nutricost L-Cysteine 1000mg 120 Capsules 60 Servings Gluten-Free
Nutricost$14.774.6★
What reviews say buyers love and hate about l cysteine
What buyers praise and complain about, mined from review topics.What buyers love
“The quality is always consistent”
“They are affordable”
“Appears to be effective”
“As advertised”
“Good Supplement”
“Great liver supplement”
“I sleep better”
“I like this dosage”
“my 11 year-old has no problem swallowing it”
“This has easily been the most helpful supplement I've ever taken”
What buyers complain about
“strong plastic smell”
“Not effective”
“Has side effects”
“make it harder for me to sleep”
“One dose of this product made me sick”
“terrible stomach upset”
“The taste is not good”
“Bad quality control”
“Super tiny bottle”
“A bit expensive”
Top return reasons
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.