Science
Mechanism of Action
N-acyl sarcosinates, exemplified by Sodium Lauroyl Sarcosinate, function as amphiphilic molecules, featuring a hydrophobic fatty chain and a hydrophilic carboxylate group. This unique structure allows them to efficiently bind to both oil-based impurities and water-based substances, facilitating their removal from skin surfaces. Beyond its gentle cleansing action and ability to improve hair's body and sheen, this ingredient has been observed to enhance the dermal penetration of other active compounds in a formulation.
Research
Clinical Evidence
Medium confidence2-5%
Key findings
- 01 Clinical studies involving concentrations between 2% and 5% demonstrated that the ingredient is non-irritating and non-sensitizing to human skin.
- 02 The CIR Expert Panel found leave-on products containing up to 5% to be safe, which was the highest concentration tested for irritation and sensitization.
- 03 A study examining the use of a facial cleanser containing this ingredient (concentration unspecified) over 3 weeks showed a significant reduction in the alpha diversity of the prokaryotic microbial community and alterations in the skin's lipidome, including increased phosphatidylglycerol and phosphatidylcholine, and decreased ceramides. A reduction in porphyrin levels was also noted.
- 04 Patch testing in a predisposed patient with recurrent hand dermatitis showed positive reactions at lower concentrations (0.1%, 0.5%, and 1% aqueous solutions), indicating a potential for individual sensitivity.
Transparency
Dusting Analysis
The Formula
Formulation
Stability
Sodium Lauroyl Sarcosinate demonstrates stability across a broad pH spectrum, from slightly acidic to moderately alkaline conditions. For optimal final product stability, formulations should generally maintain a pH above 6. Its aqueous solutions typically present a pH in the range of 7.5–8.5. Interestingly, at a more acidic pH (4.5–5.5), it exhibits thickening properties.
Synergies
- Can enhance the penetration of other active ingredients through the skin.
Conflicts
- Should not be combined with ingredients capable of forming N-nitroso compounds, due to the potential for sarcosine to nitrosate into N-nitrososarcosine, a known animal carcinogen.
- Requires careful consideration when formulated with ingredients whose safety relies on minimal dermal absorption, given its ability to enhance skin penetration.
Safety
Safety Profile
The CIR Expert Panel concluded N-acyl sarcosines and sarcosinates are safe for rinse-off products up to 15% and for leave-on products up to 5%, the highest concentrations tested in clinical irritation and sensitization studies. However, formulation should avoid ingredients that could lead to N-nitroso compound formation due to the risk of N-nitrososarcosine. While generally non-irritating, a specific case of recurrent hand dermatitis showed sensitivity at 0.1-1%, suggesting a risk for predisposed individuals. Data for products likely to be inhaled are insufficient to support safety.
Your Skin
Skin Compatibility
Our Assessment
Verdict
Sodium Sarcosinate is a valuable mild cleansing and foaming agent, generally well-tolerated at effective concentrations for most skin types, though careful formulation is required to avoid N-nitroso compound formation and to consider its impact on the skin microbiome and lipid barrier.
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