16 Aesthetic Dermatology S KIN & ALLERGY N EWS • December 2008

C OSMECEUTICAL C RITIQUE Barrier Repair Products

old atmospheric temperatures lead lipid precursors integrate into ceramide Other frequently used occlusive ingre- ,” Baton Roca, Fla.:CRC to lower humidity. In such condi- biosynthetic pathways in the epidermis, dients include beeswax, dimethicone, Press, 2000, p. 217). The high-glycerin Ctions, water is more likely to evap- augmenting SC ceramide levels and thus grapeseed oil, lanolin, paraffin, propylene products were found to be superior to all orate from the skin, particularly in indi- ameliorating barrier integrity. glycol, soybean oil, and (“Atlas of the other products tested because they viduals with an impaired skin barrier. Cosmetic Dermatology,” New York: rapidly restored dry skin to normal hy- With the arrival of winter, a discussion of Cholesterol Churchill Livingstone, 2000, p. 83). dration levels and helped prevent a return the importance of the skin barrier and Most cholesterol is synthesized from ac- Significantly, occlusives are effective only to dryness for a longer period than the oth- how to repair it is appropriate. Notably, etate in cells such as the keratinocytes, al- when they coat the skin; upon removal, er formulations, even those containing cosmeceutical barrier repair products have though basal cells can also absorb choles- TEWL returns to its previous level. Oc- petrolatum. Of note, glycerin is included an important role to play. terol from the circulation. Cholesterol clusives are typically combined with in the new Vaseline Intensive Rescue Mois- production increases when humectant ingredients in moisturizers. ture Locking and Dove lotion. The Skin Barrier the epidermal barrier is im- In 2004, investigators performing a ran- Several important functions paired (“Skin Barrier.” New domized, double-blind, controlled trial ob- Climatic and Endogenous Changes are served by the skin barri- York: Taylor and Francis, served that mineral oil and extra-virgin co- Cold, low humidity, aging-related changes er: preventing transepider- 2006, pp. 33-42). conut oil were as efficacious and safe as in hormone levels, and even cholesterol- mal water loss (TEWL), Both peroxisome prolifer- moisturizers in treating mild to moderate lowering statin drugs can contribute sig- shielding the skin from aller- ator–activated receptors and xerosis in 34 patients, with both groups nificantly to dry skin. Therefore, products gens and irritants, and pro- retinoid X receptors play a demonstrating enhanced surface lipid lev- used last year or even last month might tecting against infections. role in transporting choles- els and skin hydration (Dermatitis not be ideal today. This defensive role depends terol across keratinocyte cell 2004;15:109-16). When patients plan to travel from a largely on corneocyte func- membranes by augmenting Natural oils. Given the increasing pop- warm-weather climate to colder areas dur- tion and the surrounding ex- expression of ABCA1, a ularity of natural and organic ingredients, ing the winter, I remind them that the skin BY LESLIE S. tracellular matrix (J. Invest. BAUMANN, M.D. membrane transporter that essential oils of botanic origin are now fre- needs 3 days to acclimate and marshal its Dermatol. 2005;125:183-200). regulates cholesterol flow quently used in moisturizing products or defensive capacity against cold tempera- The cornified cell enve- (“Fitzpatrick’s Dermatology as moisturizing agents themselves. Some tures. I also suggest that they moisturize lope that encases the corneocyte is a 10- in General Medicine,” 7th ed., New York: of the more effective include sunflower on airplanes, where air is very dry, and nm–wide, insoluble layer composed of McGraw-Hill, 2007, pp. 386-7). , evening primrose oil, olive oil, plan to moisturize more frequently in various highly crossed proteins, particu- and oil. cold-weather environments. larly loricrin, the principal component, Fatty Acids Natural oils contain fatty acids that play Specifically, I recommend what I con- and involucrin, desmoplakin, and Free fatty acids and fatty acids in the skin key roles in maintaining the skin barrier. sider to be the best barrier repair mois- periplakin (J. Cell Sci. 2001;114:3069-70). are bound in , glycosylce- Linoleic acid, an omega-6 fatty acid, is pre- turizers: the Dove Proage product line, The envelope structure is formed via cross- ramides, ceramides, and phospholipids. sent in sunflower, , evening prim- AtoPalm MLE Face Cream, Moisture- linking by the calcium (Ca2+)-dependent The free fatty acids in the SC are mainly rose, and jojoba oils. Besides its role as a Worx by DermWorx Inc., and Kinerase Ul- transglutaminase-1 (TG-1) enzyme. straight chained (“Skin Barrier.” New component of structural lipids necessary tra Rich Night Repair cream. For the body, The water barrier function of the skin York, Taylor and Francis, 2006, pp. 33-42). for barrier integrity, linoleic acid is used by I recommend TriCeram Ceramide Dom- is largely attributed to the lipids in the ex- Essential fatty acids such as linoleic acid the body to produce J-linolenic acid, a inant Barrier Repair, Dove Proage Beauty tracellular matrix that surrounds the cor- can be obtained only through the diet or polyunsaturated essential cis-fatty acid im- Body Lotion, Vaseline Intensive Rescue neocytes (Adv. Lipid Res. 1991;24:1-26). topical application. portant in prostaglandin synthesis and, Moisture Locking Lotion, Cetaphil Mois- (Of note, TEWL is considered insensible Currently, it is thought that no single lipid thus, the inflammatory process. turizing Cream, and CeraVe Moisturizing water loss through the skin, which differs alone mediates barrier function, and that Humectants. These water-soluble sub- Cream. from active perspiration.) This lipid mix- normal levels of ceramides, cholesterol, stances with high water absorption ca- Regardless of the climatic conditions, ture is composed of approximately 50% and fatty acids, in the correct ratio, are cru- pacity can attract water from the atmos- for patients with dry skin, I always caution ceramides, 25% cholesterol, and 15% fat- cial for maintaining barrier integrity. phere (if atmospheric humidity exceeds against using foaming cleansers, bubble ty acids (J. Lipid Res. 2007;48:2531-46). Interestingly, Man et al. evaluated barri- 80%) and from the underlying epidermis. baths, and bar soap, which denude the epi- Changes in any of these three components er recovery by altering the barrier with ace- Application of a humectant results in a dermis of lipids. Rather, I suggest a cleans- of the extracellular matrix can lead to a tone, then applying ceramides or fatty acids slight swelling of the stratum corneum, ing oil such as Shu Uemura or Laura disruption in skin barrier function. alone, or a combination of ceramides and yielding the perception of smoother skin Mercier cleansing oils. CeraVe, Dove, fatty acids, and found that normal barrier with fewer wrinkles. In low-humidity con- Aveeno, and Cetaphil are appropriate Ceramides recovery was achieved only with the appli- ditions, humectants may actually take wa- cleansers for moderately dry skin, and Ceramides constitute 40% of the lipids in cation of all three extracellular matrix com- ter from the deeper epidermis and dermis, cold creams, such as Ponds and Noxema, the human stratum corneum (SC) (J. In- ponents—ceramides, fatty acids, and cho- resulting in increased skin dryness (J. Biol. are well suited for very dry skin. For non- vest. Dermatol. 1987;88:2S-6S), but they lesterol (Arch. Dermatol. 1993;129:728-38). Chem. 2002;277:46,616-21), so these in- facial dry and sensitive skin not prone to are not present in significant amounts in gredients work better when combined body acne, a suitable product is Grandma the stratum granulosum or basal layer. Skin Barrier Repair with occlusive ingredients. Minnie’s Oil’s Well Nurturing Do-It-Oil Consequently, terminal differentiation is Occlusives. Occlusive ingredients, which The most frequently used humectants (patients with a tendency to get acne likely an important factor in ceramide are oily compounds often used in cos- include glycerin, sorbitol, sodium should be advised to avoid this product or synthesis. The basic structure of ce- metics because of their capacity to dissolve hyaluronate, urea, propylene glycol, D-hy- any other than contains ). ramides consists of a fatty acid covalently fats, coat the SC and inhibit TEWL. Oc- droxy acids, and sugars, with glycerin es- Finally, I remind patients that the skin bound to a sphingoid base. clusives also impart an emollient effect. pecially important because it displays both and skin barrier can be repaired through In a study conducted by Unilever, ce- Petrolatum and mineral oil are two of humectant and occlusive qualities. diet and dietary supplementation. Specif- ramide levels were shown to increase in the best occlusive ingredients available. Glycerin. Glycerin (glycerol) exhibits hy- ically, omega-3 fatty acids, borage seed oil, keratinocytes after the exogenous applica- Used as a skin care product since 1872 and groscopic characteristics closely resembling and evening primrose oil may strengthen tion of sphingoid precursors (specifically considered one of the optimal moisturiz- those of natural moisturizing factor (J. Soc. the skin barrier and ameliorate dryness tetra-acetyl phytosphingosine or TAPS) (J. ing agents, petrolatum displays a water va- Cosmet. Chem. 1976;27:65). This allows and itching. ■ Invest. Dermatol. 1996;106:871). In anoth- por loss resistance 170 times that of olive the stratum corneum to retain high water er study by Unilever, TAPS, combined oil and is well known for being noncome- content even in an arid environment. DR. BAUMANN is director of cosmetic with the fatty acids 1% linoleic acid and 1% dogenic (Dermatologica 1971;142:89-92; J. Recently, glycerol was shown to play an dermatology at the University of Miami. She juniperic acid, also increased ceramide lev- Am. Acad. Dermatol. 1989;20:272-7). By important role in skin hydration, insofar as has received funding for clinical grants from els (J. Invest. Dermatol. 1996;106:918). In virtue of its long-standing status as the glycerol levels were shown to be associat- Allergan Inc., Avon Products Inc., Galderma the latter study, researchers found that bar- most effective occlusive moisturizing ed with stratum corneum hydration levels Laboratories, Medicis Pharmaceuticals rier integrity was improved in patients agent, petrolatum is typically thought of (J. Invest. Dermatol. 2005;125:288-93). Corp., Stiefel Laboratories, and Unilever treated with TAPS, and the improvement as the accepted standard to which other Previously, two high-glycerin moistur- PLC. To respond to this column, or to suggest was even greater when TAPS was com- occlusive ingredients are measured (“Dry izers were compared with 16 other popu- topics for future columns, write to Dr. bined with linoleic and juniperic acids. Skin and Moisturizers,” Boca Raton, lar moisturizers in 394 patients with se- Baumann at our editorial offices via e-mail These findings imply that topically applied Fla.:CRC Press, 2000, p. 251). verely dry skin (“Dry Skin and at [email protected].