|Year : 2015 | Volume
| Issue : 4 | Page : 193-197
Cleansers: To use or not to
Samipa S Mukherjee1, BS Chandrashekar2, Rohini P Gaikwad3
1 Department of Paediatric Dermatology, Bangalore Medical College and Research Institute, Bengaluru, Karnataka, India
2 Department of Dermatology, Cutis Academy of Cutaneous Sciences, Vijayanagar, Bengaluru, Karnataka, India
3 Department of Dermatology, Maharashtra Institute of Medical Education and Research, Talegaon (D), Pune, Maharashtra, India
|Date of Web Publication||24-Sep-2015|
Samipa S Mukherjee
Department of Paediatric Dermatology, Bangalore Medical College and Research Institute, Vijayanagar, Bengaluru, Karnataka
Source of Support: None, Conflict of Interest: None
Cleansers are agents responsible of cleansing the skin to get rid of the dust, dirt, sebum, and dead cells accumulated as a part of normal desquamation process. Cleanser technology has come a long way from the traditional soaps and detergents to the more modernized liquid cleansing agents and syndets. They have thereby helped in reducing the side-effect potentials of cleansers and improved the beneficial effects. Addition of newer molecules helps in maintaining the skin barrier integrity and moisture on the skin. However, although the bright side of cleansers shines there is a gray zone of controversies regarding its usage. Discrepancy between the claims and evidences herewith make it imperative to consider the pros and cons. This article aims at summarizing the points in favor and against the usage of cleansers.
Keywords: Cleansers, controversies, natural moisturizing factors, stratum corneum, surface lipids, technology
|How to cite this article:|
Mukherjee SS, Chandrashekar B S, Gaikwad RP. Cleansers: To use or not to
. Indian J Paediatr Dermatol 2015;16:193-7
| Introduction|| |
Cleansers are classically defined as agents formulated to remove dirt, sweat, sebum, oil and desquamated cells from the skin. Therefore besides their cleansing properties they also impart a feeling of freshness and improves well-being. As basic hygiene practices improve, expand, and continue to undergo a change globally, the frequency of bathing ∕ skin cleansing continues to increase: Cultural practices are moving from basic hygiene toward more cosmetic refreshment. Daily showering for 2-3 times a day is not an uncommon practice leading to an increased use of cleansers. However, the interaction of cleansers with the stratum corneum (SC) and surface lipids can have multiple deleterious effects. Although there are no widely-accepted methodical specifications with which to objectify cleansing effectiveness and skin compatibility of occupational skin cleansing products, a thorough understanding of the fundamentals of cleanser impact on the skin and how to select the most appropriate cleanser to preserve skin health is imperative. Minimizing skin damage caused by cleansers is the first step, followed by delivering moisturizing benefits to the skin.
| Interaction of skin and cleanser|| |
The skin serves a critical function of barrier between the external environment and internal milieu. It is now widely understood that the SC is a biochemically active layer in which key processes take place. , The barrier function of the SC is also important in minimizing entry and permeation of molecules, including water molecules, into the skin from the external environment. , It is well understood that hydration of the SC is required not only for maintaining the esthetic properties of skin (moisturization, softness, smoothness, lack of flaking, etc.), but also for the critical processes (lipid biosynthesis, desquamation, and natural moisturizing factor [NMF] production) that take place within these nonliving, yet biochemically active, layers of the skin.
The SC is commonly described as a "bricks and mortar" structure in which the keratin-filled corneocytes are the "bricks," which exist within a lipid-rich phase (composed primarily of ceramide, fatty acids, and cholesterol) or the "mortar."  SC lipids are primarily nonpolar and functionally distinct from a conventional phospholipid bilayer; the SC water permeability is approximately three orders of magnitude lower than for a plasma membrane. The SC lipids are generated during keratinocyte differentiation. Phospholipids, glucosylceramide, sphingomyelin, and cholesterol are intracellularly packaged into lamellar bodies and then secreted into the extracellular domain of the SC.  A detailed research into the composition of the SC lipids has revealed ceramides, free fatty acids, and cholesterol to be the important constituents. , Cleansers and surfactants interact with this lipid layer on the skin and may have deleterious effects. The extent of damage depends on several properties of the cleanser, skin, and environmental conditions. The generation of ceramides, cholesterol, and fatty acids from lipid precursors is critical in maintaining barrier integrity and for the preservation of the relative proportion of SC lipids. Lipid synthesis is up-regulated in response to damage-induced dryness to maintain effective skin barrier.
The deleterious effects of skin cleansers happen through compromised skin barrier or inherent irritant nature of alkali used in its production. Skin cleansing with a surfactant (detergent) containing products is associated with irritation, dryness, erythema, and post wash skin tightness. ,,,
In the earlier times, cleanser induced lipid damage was not given the due significance as most of the studies focused on cleanser induced irritation on the skin.
| Surfactant and stratum corneum interaction|| |
The cleanser surfactants bind to the SC proteins and cause transient swelling of cells along with hyperhydration. This subsides post wash and deswelling occurs leading to drying stresses on the SC. , Swelling of SC cells can also facilitate the penetration of surfactants, as well as other cleanser ingredients, into deeper layers, possibly leading to a biochemical response such as irritation and itch. Studies on the interaction of cleansers with SC proteins have shown that the tendency of surfactants to cause protein denaturation/damage is related to the charge density of protein-bound, micelle-like surfactant aggregates.  This explains the following well-known order for the irritation potential of surfactants, namely, anionic surfactants > amphoteric surfactants > nonionic surfactants. Among anionic surfactants, the tendency to bind to proteins varies as follows: Sodium lauryl sulfate or sodium laurate > monoalkyl phosphate > sodium cocoyl isethionate (SCI). 
| Surfactant and stratum corneum lipids interaction|| |
Cleanser surfactant molecules form self-aggregated spherical or globular nanostructures (termed micelles) in solutions above a certain concentration, referred to as the critical micelle concentration (CMC). Most cleansing compositions are well above the CMC and under these conditions even a brief (<1 min) direct exposure of skin to surfactants can result in the removal of SC lipids.  Below the levels of CMC, the surfactant can weaken the lipid bilayer and thereby impair the barrier function. Studies have shown that there is no detectable loss of ceramides from the skin on usage of cleansers or soaps, however in contrast about 8% of the free fatty acids were removed, indicating that free fatty acids are liable to damage due to surfactant usage.  The observation that fatty acids are released at a much higher rate suggests that fatty acids are highly extractable during cleansing and that other lipids are being released only as part of the normal exfoliation process.
| Surfactant and natural moisturizing factor interaction|| |
Cleansing results in leaching of water-soluble NMF components from the skin, decreasing the skin's ability to hold moisture, and contributing to post-wash dryness. NMF is derived from proteolytic cleavage of filaggrin, which has natural moisture retaining properties. In conditions of low relative humidity, NMF synthesis is up-regulated deep within the SC to increase the water-binding capacity of the skin, promoting water retention and restoration of appropriate hydration levels.
The Role of pH
The role of pH in inducing skin damage has been studied and still remains a matter of debate. Soap-based cleansers are alkaline in nature while the pH of most syndets (synthetic surfactant-based cleansers) is close to neutral or slightly acidic. Variations in irritation potential among alkaline soaps and neutral pH syndets can arise from inherent structural and charge-density differences, direct effects of pH on the SC, and/or indirect effects of pH on the solution chemistry of charged head groups. Ananthapadmanabhan et al. showed that SC swelling, and lipid rigidity is a function of pH in the absence of cleanser surfactants.  However, Takagi et al. in their study concluded that the long-term continuous use of a soap-based cleanser does not affect the pH-maintaining mechanism of human skin which is in contrast to the earlier quoted opinion. 
Clinical Manifestations of Surfactant Damage
Strategies for Minimizing Skin Damage
- After wash tightness: This phenomenon is directly related to the deswelling of SC cells that happen post wash due to water evaporation. The hyperhydration in the initial phase of surfactant interaction with SC coupled with lower equilibrium hydration levels creates a higher than normal rate of evaporation, and thus, a differential stress in the upper layers of skin, leading to after wash tightness
- Skin dryness, scaling, and roughness. This phenomenon is attributed to the loss of free fatty acids from the skin surface. Other factors such as low humidity and cold temperatures can aggravate the condition. An increased transepidermal water loss also seems to play a role in increasing dryness
- Skin irritation: This can occur due to the inherent irritant properties of alkalis in soaps. Erythema and itching are inflammatory responses to penetration of the skin by a foreign substance like a surfactant.
The quest for an ideal cleanser still continues. Several improvements have been made in the cleanser technology to minimize the damage caused by the surfactants and impart a moisturizing effect to the skin. Cleanser technology has evolved from the soaps to syndets to cleansing lotions to shower gels with moisturizing lipids and emollients. Historically, formulations of skin cleansers included alkyl carboxylate surfactants, commonly referred to as soap. ,, Significant understanding of the deleterious effects of soap on the skin has demonstrated the need for milder cleansing alternatives. The introduction of syndet bars, with mild alkyl isethionate as the synthetic surfactant in the early 1950s, gave a revolutionary breakthrough to the soap industry. Subsequent improvement was made by the addition of moisturizing components to the liquid cleansers, which helped in sealing superficial cracks, increasing the water retention capacity of the skin and improving the humectant properties as well. It has been shown that mild syndet bars with fatty acids do deposit about 1-2 μg cm −2 of fatty acid during wash conditions. Interestingly, similar levels of fatty acids are removed by the cleanser after a single wash.  Soaps cause significant perturbation of the lipid layer as compared to syndets thus increasing the after wash effects on the skin.
Liquid cleansers were introduced in 1990s, which are now a combination of anionic and amphoteric surfactant mixtures to enhance mildness. The concept of deposition of emollients and moisturizers were borrowed from the conditioners used after shampooing of hair to render softness to hair. Liquid cleansers can be designed to deposit beneficial lipids such as cholesterol and fatty acids during the wash. A novel surfactant system, the directly esterified fatty isethionate (DEFI) surfactant system in the body wash has been introduced which is pre-saturated with stearic acid to minimize lipid extraction from the SC and enhance the mildness properties of the surfactant.  The role of stearic acid present in the DEFI surfactant system in cleansers is to minimize lipid damage and replenish fatty acids in the SC. The other newer products in the market include the addition of ceramides, moisturizing oils, oatmeal extracts to improve the efficacy while reducing the side effects. The use of certain triglyceride oils can enhance ceramide synthesis within the SC as shown by Conti et al. can be an effective way to build an efficient and healthy barrier. 
Cleansers have come a long way from just being agents, which help in the removal of dirt, sweat, and sebum to agents, which impart moisturizing benefits to the skin. Having said this, they do not escape from having their own downside. Controversies still exist in their usage.
Controversies in Cleanser Usage
Having discussed earlier that the mildest of cleanser does cause lipid disruption in the skin barrier by washing off the free fatty acids and cholesterol the claim that they are safe and do not damage the skin is false. It is however of note that with the advent of newer variants of cleansers the aim is to cleanse the skin and restore the integrity of skin barrier. The cleanser properties can be further enhanced by the usage of DEFI based surfactant system. The protein swelling/denaturation tendency of some of the key cleanser surfactants, measured in terms of their collagen swelling potential, reflects the irritation potential.
studies have shown that water is the mildest cleanser, and a regular bath is enough to rinse away the dust that settles on the skin. Water does not cause any lipid barrier dissolution and disruption. However, it has been argued that water alone may not be sufficient to clear the oil, sebum, and grease on the skin. Lipid dissolution tendency of various surfactants, as indicated by their ability to dissolve stearic acid and cholesterol: Alkyl polyglucoside > sodium dodecyl (lauryl) sulfate > cocamidopropyl betaine > SCI followed by water. Thereby it can be safely argued that daily usage of soaps and syndets for cleansing and bathing may not be necessary except for esthetic reasons, the limitation being environmental conditions and personal hygiene habits.
Takagi et al. showed that the long-term continuous use of a soap-based cleanser does not affect the pH-maintaining mechanism of the human skin.  It is also interesting to note that reversal of skin pH occurs within 3-6 h post the usage of any cleansing agent. Hence, the claim that soap with skin friendly pH is beneficial poses a significant dilemma with the above evidences. Having said that it is imperative to note that a cleanser with a skin friendly pH definitely has lesser side effects however this fact should not be exaggerated.
The cost-benefit ratio
Bathing with regular water followed by moisturizing using coconut oil or liquid paraffin helps in preventing dryness and costs significantly less as compared to that of cleanser usage, which is important in our country.
Standardization of components and finished products: Terhaer et al. in their article have concluded there are no commonly accepted criteria to classify products in view of cleansing effectiveness and skin compatibility.  Generally accepted criteria and test methods are needed for the evaluation of hand cleansers in order to provide the possibility of transparency and comparability.
Guidelines and recommendations
The recommendations by the European Academy have quoted a RCT stating that washing with water alone may have a more drying effect on the skin.  However, we must not forget Indian guidelines are lacking, the temperature and environment conditions prevailing here are different and cost-benefit ratio needs to be borne in mind.
| Conclusion|| |
Cleansers no longer just impart cleansing benefits but also deliver other functions of moisturizing the skin and maintaining its integrity. Opportunities to deliver other benefits from cleansers need to be explored. The development of an ideal cleanser continues to remain a challenge. However, the wisdom lies in not using cleansers and syndets as a blanket regime for all dermatology conditions but weighing the pros and cons before prescribing them. To conclude, cleansers do not succeed in getting a clean sweep in dermatology instead they give us a food for thought!
Financial Support and Sponsorship
Conflicts of Interest
There are no conflicts of interest.
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