Glyceryl stearate is an ester compound comprising mainly of stearic acid and glycerol. Other constituents include potassium, 2-stearoylglycerol, 3-stearoyl-sn-glycerol, and 1-stearoyl-sn-glycerol. The compound is a mixture of palmitic acids and mono-, di-, and triglycerides of stearic acid. This compound is commonly used in different cosmetic products as an emulsifying agent. Glyceryl stearate is insoluble in water. It is soluble in benzene, ethanol, and ether. The compound has a sweet taste and is hygroscopic and odorless. Some of the widely used names for this compound are glyceryl stearate SE and glyceryl monostearate SE. (Fluhr et al., 2008; Health)
- Mechanism of Action
Emollient properties of glyceryl stearate are attributed to glycerol, which is a fast-penetrating emollient. The topical application of this compound forms a protective barrier over the skin. This regulates transdermal water loss and maintains hydration of the skin. Retained moisture nourishes the skin and makes it appear soft and smooth. (Bárány et al., 2000; Salvio Neto & Matos, 2011)
- Natural and Synthetic Occurrence of Glyceryl Stearate
Glyceryl stearate is present in fatty food and is also produced in the body by the breakdown of fats catalyzed by the enzyme – pancreatic lipase. Glyceryl stearate is used as an emulsifying agent in cosmetic products and as a food additive in food products. This compound serves as an emulsifying, anti-caking, preservative, and thickening agent in several edible products. It is responsible for smoothening the texture of whipped cream and ice cream. In cosmetic products, this compound serves as an emulsifying agent in solvents, oils, and waxes. It makes the texture of these products more smooth, creamy, and luxurious.
In the pharmaceutical industry, the hygroscopic agents are coated by glyceryl stearate. The compound is also a control release agent and solidifier in pharmaceuticals. Glyceryl stearate is a resin lubricant. It is used in deodorants, hair care products, antiperspirants, sprayable emulsions, creams, lotions, sun care products, facial make-up products, self-tanning products, and baby care products. The compound stabilizes these products and improves their working efficiency. It balances the pH of the products and prevents them from becoming excessively acidic or alkaline. Glyceryl stearate is approved by the US Food and Drug Administration as a GRAS. (Health)
- Skin Benefits of Glyceryl Stearate
- Antioxidant Properties of Glyceryl Stearate
The antioxidant properties of glyceryl stearate are attributed to its activity against the enzymes – cyclooxygenase 2 and phospholipase A2. Reduced activity of these enzymes leads to a concomitant reduction in the production of inflammatory mediators, free radicals, and reactive oxygen species. Functioning as a cyclooxygenase 2 inhibitor and phospholipase A2 inhibitor, glyceryl stearate protects the skin from oxidative damage. The compound also improves the efficacy of other compounds in skin care formulations to protect the skin, alleviate the severity of the damage, and improve the overall appearance of the skin. [NIH]
- Skin Moisturization and Glyceryl Stearate
Glycerol or glycerin is a key component of glyceryl stearate which is known for nourishing the skin, improving hydration, and enhancing the skin appearance and texture. Environmental conditions such as the winter season can dry out the skin. Failure of the stratum corneum to retain the levels of moisture may also lead to dryness of the skin. Skin dryness may also manifest as tightness, pain, or itching of the skin.
Skin dryness is accompanied by reduced levels of water content in the stratum corneum of the skin. The normal water content is 15% to 25% at the surface of the skin and approximately 40% at the border of the stratum corneum and strum granulosum. Scaling of the skin surface becomes prominent when the water content of the stratum corneum falls below 10%.
Hydration of the stratum corneum is determined by epidermal water permeability, the ability of the stratum corneum to retain water, and the rate at which the water is lost from the surface of the skin. Hydration is also determined by the spatial arrangement of corneocytes, composition and arrangement of extracellular lipids, and the presence of hygroscopic compounds in the stratum corneum of the skin.
The humectant property of glycerol makes it an effective ingredient in emollients. Humectancy or hygroscopy of glycerol helps it attract and retain water as it diffuses into the stratum corneum of the skin. Glycerol does not disrupt the lamellar structure of the lipid bilayer of the skin while achieving a hydrating effect on the skin. Bulking property of glycerol in the corneocytes and between corneocytes is known to promote the barrier properties of the skin. The stratum corneum has greater water-holding capacity in the presence of glycerol, thus, leading to effective moisturization and hydration of the skin. (Fluhr et al., 2008)
- Skin Barrier and Glyceryl Stearate
Intact skin is important for protecting against environmental stressors including ultraviolet radiation, chemical, mechanical, and thermal agents. The interaction of corneocytes with intercellular bilamellar lipids and optimal organization of the components of the stratum corneum contribute to the maintenance and integrity of the skin barrier. The optimal barrier function is attained by maintaining a balance between the solid and liquid lamellar phases.
Glycerol prevents the transition from liquid to solid phases of the bilamellar lipids. Glycerol maintains the fluidity of the bilamellar layer of the stratum corneum. Glycerol-induced stabilization of the skin barrier does not only reduced the transepidermal water loss but also improves different skin conditions such as atopic dermatitis. Restoration of the skin barrier is also associated with increased secretion of the lamellar bodies. These effects cause the stratum corneum to demonstrate improvement in the biosynthetic functions. Therefore, glycerol is an essential element in the homeostasis of the epidermal barrier. (Fluhr et al., 2008)
- Desquamation of the Skin and Glyceryl Stearate
Desmosomes are essential elements involved in the interaction between keratinocytes. In healthy and normal skin, the production and degradation of desmosomes shall be well-regulated and balanced. Different internal and external factors including humidity and calcium ion gradient are responsible for regulating the production and degradation of desmosomes. These desmosomes play an important role in the cohesion within the stratum corneum. Weaker cohesive forces in the stratum corneum leading to desquamation or shedding of corneocytes. Enzymes that regulate desquamation are kallikrein 5 and kallikrein 7. The optimal function of these enzymes is regulated by the hydration of the stratum corneum. (Fluhr et al., 2008)
Glycerol in the glyceryl stearate enhances the degradation of desmosomes by promoting the activity of kallikrein 7. Increased activity of degradation enzymes is related to the increased water content of the stratum corneum, caused by the administration of glycerol. Glycerol-based pharmacological formulations enhance the appearance and function of the skin in individuals suffering from xerosis. (Fluhr et al., 2008)
- Anti-irritant Effect of Glyceryl Stearate
Anti-irritant agents are co-administered with irritant substances to improve their tolerance and relieve the irritant properties. Glycerol is applied with surfactant SLS to reduce its irritant effects, ability to penetrate the stratum corneum and prevent SLS from disrupting the epidermal barrier. It also reduces skin damage and improves skin hydration. Glycerol is an effective anti-irritant agent in alleviating the effects of different irritant agents.
Glycerol also enhances the penetration of other pharmacological formulations into the skin. Glycerol promotes normal proliferation of the epidermal cells and facilitates the process of wound healing. Glycerol has antimicrobial properties and it also protects against ultraviolet radiation. (Fluhr et al., 2008)
- Safety Profile of Glyceryl Stearate
Glyceryl stearate along with other related compounds was assessed for their safety in a study conducted in 2007. Glyceryl stearate is a relatively safe compound that does not have any significant side effects. The compound does not elicit phototoxicity, skin irritation, reproductive and developmental toxicity, tumor production, carcinogenicity, and genotoxicity. Some of the rare side effects of glyceryl stearate include rashes, thirst, nausea, itching, bloating, headaches, and dizziness. Individuals with sensitive skin and women who are pregnant shall use topical glyceryl stearate after consulting with a physician. Prior to the use of formulations containing glyceryl stearate, a skin test shall be performed to assess for skin irritation and sensitization. (“Amended final report on the safety assessment of glyceryl dilaurate, glyceryl diarachidate, glyceryl dibehenate, glyceryl dierucate, glyceryl dihydroxystearate, glyceryl diisopalmitate, glyceryl diisostearate, glyceryl dilinoleate, glyceryl dimyristate, glyceryl dioleate, glyceryl diricinoleate, glyceryl dipalmitate, glyceryl dipalmitoleate, glyceryl distearate, glyceryl palmitate lactate, glyceryl stearate citrate, glyceryl stearate lactate, and glyceryl stearate succinate,” 2007; Bárány et al., 2000; Salvio Neto & Matos, 2011)
- Emulsifier Complex and LipidTAC Products
LipidTAC offers a wide range of products suitable for every skin type. The products nourish and restore the imbalances in the skin, improving the overall appearance of the skin. The LipidTAC emulsifier complex is derived from natural sources and does not contain any ethoxylated ingredients. The complex is a self-emulsifier for oil-in-water emulsions. The acyl lactylates of the emulsifier complex are responsible for conditioning skin and hair. The lactic and acyl component of fatty acids react together to produce anionic lactylates. The two constituents are natural moisturizing factors (NMF) present in the skin. Lactylates are excellent conditioners, enhancers, and stabilizers. The emulsification system is balanced and complete and is used in creams and lotions to provide a conditioned and soft feel to the skin. Raw materials used for the production of emulsifier complex are GMO-free. Glyceryl stearate, sodium stearoyl lactylates, and Cetearyl alcohol are the key constituents of the LipidTAC emulsifier complex. The initial two compounds are also added to edible formulations, however, Cetearyl alcohol is not food grade, hence, used in cosmetics only.
Amended final report on the safety assessment of glyceryl dilaurate, glyceryl diarachidate, glyceryl dibehenate, glyceryl dierucate, glyceryl dihydroxystearate, glyceryl diisopalmitate, glyceryl diisostearate, glyceryl dilinoleate, glyceryl dimyristate, glyceryl dioleate, glyceryl diricinoleate, glyceryl dipalmitate, glyceryl dipalmitoleate, glyceryl distearate, glyceryl palmitate lactate, glyceryl stearate citrate, glyceryl stearate lactate, and glyceryl stearate succinate. (2007). Int J Toxicol, 26 Suppl 3, 1-30. https://doi.org/10.1080/10915810701663143
Bárány, E., Lindberg, M., & Lodén, M. (2000). Unexpected skin barrier influence from nonionic emulsifiers. Int J Pharm, 195(1-2), 189-195. https://doi.org/10.1016/s0378-5173(99)00388-9
Fluhr, J. W., Darlenski, R., & Surber, C. (2008). Glycerol and the skin: holistic approach to its origin and functions. Br J Dermatol, 159(1), 23-34. https://doi.org/10.1111/j.1365-2133.2008.08643.x
Health, N. I. o. Glyceryl Monostearate. https://drugs.ncats.io/drug/230OU9XXE4
Salvio Neto, H., & Matos, J. d. R. (2011). Compatibility and decomposition kinetics studies of prednicarbate alone and associated with glyceryl stearate. Journal of thermal analysis and calorimetry, 103(1), 393-399.