What is “Sarcosine” and what is it used for?

Sarcosine is a natural amino acid derived from glycine , of which it is both an intermediate and a byproduct. It is produced from glycine by the enzyme glycine N-methyltransferase and converted back into glycine by sarcosine dehydrogenase. It also appears as a step in the metabolism of choline and methionine , two nutrients rich in methyl groups that are essential for many biochemical reactions. Rapidly degraded back into glycine, sarcosine indirectly contributes to the synthesis of key compounds such as glutathione , creatine , purines , and serine . In healthy adults, its average blood concentration is about 1.4 ± 0.6 μM. In cosmetics, it is often used in its free form or, more commonly, as acylated derivatives such as sodium lauroyl sarcosinate , an amphiphilic molecule used in cleansing products, hair care, and foaming gels.

In the laboratory, it can be obtained fromchloroacetic acid and methylamine, whereas on an industrial scale, it is produced via Strecker synthesis. This chemical method involves reacting three components: an aldehyde , which is an organic molecule containing a carbonyl group; cyanide, which serves as a source of nitrogen and carbon; and ammonia , which is also a source of nitrogen. These reactants first combine to form an intermediate compound called an α-aminonitrile, which is then converted (hydrolyzed) into an amino acid, such as sarcosine.

The sarcosine has attracted growing interest because of its potential regulatory effect on sebum production, which would make it a particularly relevant active ingredient for targeted scalp care. Sarcosine is a derivative of glycine and is involved in certain metabolic pathways related to amino acids and lipids. This is why some researchers and formulators have hypothesized that it could influence enzymes involved in lipid metabolism, such as 5α-reductase, through metabolic modulation or interaction with its cofactors.

Sebum, produced by the sebaceous glands, plays an essential role in protecting andhydrating the skin and scalp, but its excess can lead to imbalances that promote the onset of problems such as excessive shine, dandruff or inflammation. Sarcosine is thought to act by modulating the activity of certain key enzymes involved in lipid synthesis, in particular 5α-reductase-1, an enzyme known for catalyzing the conversion of testosterone into dihydrotestosterone (DHT). This active hormone is known to stimulate excessive sebum production under certain conditions. By inhibiting or regulating this enzyme, sarcosine would thus help reduce excessive sebum secretion, contributing to the restoration of optimal skin balance.

However, the scientific literature does not demonstrate a direct link between sarcosine and sebum regulation.

Indirectly, its potential sebum-regulating property could also lead to a prebiotic effect, illustrated by the concept of a "scalp microbiome reset", which involves restoring a healthy scalp microbiota through recolonization by six beneficial bacterial strains (Staphylococcus pasteuri, S. warneri, Streptococcus australis, Rothia aeria, Veillonella parvula, Actinomyces odontolyticus). Indeed, by reducing excess sebum, sarcosine could alter the cutaneous ecosystem and deprive lipophilic microorganisms such as Cutibacterium acnes of their main nutrient source. This would limit their proliferation and free up space for other commensal species, thereby promoting greater microbial diversity.

In short, sarcosine may act simultaneously on lipid homeostasis and on microbiome balance, creating a more stable, less inflammatory skin environment that supports the coexistence of beneficial strains.

However, studies are needed to confirm the role of sarcosine in regulating sebum production, as well as its effects on microbiome balance.

Sarcosine is also an interesting ingredient because it may helpenhance the penetration of active ingredients into the skin. In fact, a study published in the Journal of Controlled Release in 2013 investigated new transdermal penetration enhancers based on amino acids modified with hydrophobic chains via a labile ester bond. Among them, sarcosine (N-methylglycine) stands out because of its polar head group and its low capacity to form hydrogen bonds, which promotes its insertion into the lipids of the stratum corneum. This insertion disrupts lipid organization, increases membrane fluidity, and facilitates the passage of active substances through the skin. Tests showed an effectiveness comparable to or greater than some conventional penetration enhancers, with low toxicity and a reversible effect, making it an attractive candidate to improve the cutaneous delivery of drugs or cosmetic actives.

Regarding its safety profile, sarcosine and its derivatives have been the subject of several rigorous evaluations. The Cosmetic Ingredient Review (CIR) published a report in 2001 on acyl sarcosines and sarcosinates, concluding that these ingredients are safe for cosmetic use at typical concentrations: up to 5% in leave-on products and up to 12% in rinse-off products. No irritating, sensitizing, or mutagenic effects were detected in in vitro and in vivo tests according to the CIR Final Report. However, a warning is issued about the possible formation of N-nitrososarcosine, a potentially carcinogenic nitrosamine, if sarcosine is formulated together with nitrosating agents (such as nitrites). This risk is well known, strictly controlled by European regulations (Regulation (EC) No 1223/2009), and is avoided by formulators by excluding any nitrosamine precursor.

• LANIGAN R. S. Final report on the safety assessment of cocoyl sarcosine, lauroyl sarcosine, myristoyl sarcosine, oleoyl sarcosine, stearoyl sarcosine, sodium cocoyl sarcosinate, sodium lauroyl sarcosinate, sodium myristoyl sarcosinate, ammonium cocoyl sarcosinate, and ammonium lauroyl sarcosinate. International Journal of Toxicology (2001).

• KELLER D. & al. Investigation of the skin-sensitizing properties of 5 osmolytic prodrugs in a weight-of-evidence assessment, employing in silico, in vivo, and read-across analyses. International Journal of Toxicology (2012).

• VAVROVA K. & al. Amino acid derivatives as transdermal permeation enhancers. Journal of Controlled Release (2013).

• HELDRETH B. & al. Updated Safety Assessment of Fatty Acyl Sarcosines and Sarcosinate Salts as Used in Cosmetics. International Journal of Toxicology (2021).

• HUANG Z. & al. The impacts of sodium lauroyl sarcosinate in facial cleanser on the facial skin microbiome and lipidome. Journal of Cosmetic Dermatology (2024).