Supplements for Skin

Facial creams






Edited by Dr. Valeria Pacific, Surgeon Specialist in Dermatology and Venereology

"Sensitive skin", hyper-reactive, intolerant, all synonyms are now widely used to indicate a condition, more and more frequent, characterized by an abnormal reactivity of the skin to various environmental factors (1,2). Apart from the weather (sun, wind), dust, pollution and intense thermal stimuli (temperature changes, very cold or very hot temperatures), are mainly cosmetic, such as detergents, sunscreens and make-up products, the substances most commonly called into question. The regular use of cosmetics too aggressive or of poor quality, and with a high content of potentially irritating substances (emulsifiers, perfumes, preservatives, etc) can, in fact, alter the integrity of the physico-chemical barrier skin, predisposing the subject to phenomena irritation, even with substances not really irritating and well tolerated by most of the population (3).

Although historically considered to be a typical problem of the female sex, epidemiological studies conducted in the last decade, as well as highlighting an increasingly high incidence of the phenomenon (particularly in industrialized countries) have also shown an interest in increasing the male, probably in relation the growing popularity of cosmetic products for men (4).

Although it is a growing phenomenon, the "sensitive skin" still remains a difficult condition to define and document the clinical point of view. In most cases, the diagnosis is based on subjective symptoms of burning, itching and sense of dryness of the skin, in the absence of clinical signs obiettivabili on the skin. There are, however, some fairly typical elements which can be searched, such as poor elasticity and dryness of the skin, in addition to the strong tendency for desquamation (5).

The face is the area of ​​the body most commonly affected, probably in relation to the frequent, repeated use of cosmetics and make-up products. The skin of the face is also characterized by a stratum corneum thinner (and thus more permeable to substances) and, finally, by a higher density of vessels and nerve endings, which in part would justify the greater reactivity. The nasolabial furrows are the most sensitive areas of the face, followed by the cheeks, chin, forehead, upper lip and periocular regions (6).

The understanding of the pathogenic mechanisms underlying the sensitive skin, as well as the choice of dermo-cosmetic products suitable for the management of this type of problem can not be separated from a good knowledge of the structure of the skin and especially the combination of elements which we call " physico-chemical barrier skin."

One of the main functions of the skin is, in fact, to ensure a "barrier effect" against physical, chemical and microbial contamination from outside. In addition, the skin has the task of modulating the loss of water for transcutaneous perspiratio insensibilis (Trans Epidermal Water Loss, TEWL), ensuring adequate hydration of the superficial epithelial layers. The corneocytes of the horny layer, surrounded by a casing corneum protein (cornified envelope) and immersed in a matrix of interlamellar lipids, in a structure very similar to that of a brick wall (corneocytes) and cement (lipids), constitute the structural bases the skin barrier. The lamellar lipids, along with sebaceous lipids (secreted by the sebaceous glands), in aqueous media (resulting from sweating and perspiration) and cellular debris, contribute to the formation of the so often named "hydro-lipid film surface." Play therefore a key role in the formation and maintenance of the integrity of the barrier, helping to prevent the loss of water (Trans Epidermal Water Loss, TEWL) and the penetration of water-soluble material. The corneocytes also contain a fraction of a humectant substances of low molecular weight, the so-called Natural Moisturizing Factor (NMF) that, together with the components of the hydrolipidic film of the surface, contributes to the maintenance of skin barrier function. The TEWL, Trans Epidermal Water Loss, amount of water that migrates from the dermis and the epidermis through the stratum corneum to the external environment, is a sensitive indicator of the integrity of the skin barrier. Although the mechanisms underlying the "sensitive skin" are not entirely clear, increased permeability of the stratum corneum (the skin barrier and then) and an exaggerated response of the vascular component and nervous skin, appear responsible for the phenomenon. Some authors have suggested that the hyper reactive skin of patients with sensitive skin is due to a chronic inflammatory state in the dermis surface, triggered by the skin's immune system (7,8). In this context, psychosomatic factors (stress), would cause, in addition, the release of neurotransmitters (substance P, etc.) by the cutaneous free nerve endings, which in turn induce vasodilation and mast cell degranulation with the release of mediators of inflammation ( neurogenic inflammation) (9). By analyzing the pathogenetic basis of the "sensitive skin", it is impossible not to notice the similarities with other very common conditions, such as atopic dermatitis or acne rosacea, inflammatory diseases of the skin to chronic relapsing, also characterized by an altered skin barrier function and, giust'appunto, by a marked hyper-responsiveness of the skin to various stimuli. A history of atopy (atopic dermatitis, asthma, allergic rhinitis) is found in 50% of women with sensitive skin, which is about twice the prevalence of atopy in the general population (10). It is therefore important, before a diagnosis of "sensitive skin", exclude the presence of other dermatoses, which often require a proper pharmacological therapeutic management.

In the absence of a standardized and validated therapy for the management of the phenomenon of "sensitive skin", a correct dermo-cosmetics plays a fundamental role in the control and improve the various aspects of this phenomenon. The increasing demand from the market of products for sensitive skin, induced, therefore, the most important cosmetic companies to invest resources in the creation of cleansers, moisturizers, deodorants and make-up products specifically formulated to protect the skin and meet the needs of this most delicate slice of the population.

Finding your way but in front of the wide range of products on the market? What features should have a cosmetic to be used with confidence to this category of persons?First, a cosmetic ideal, regardless of the function that is called to play, must not impair the physiology of the skin and the integrity of the barrier.

Let's start by cleansing, act of daily hygiene performed several times a day. A cleansing too aggressive, such as that based on surfactants, especially anionic or cationic (most irritating), may cause damage to the lipid structure (delipidizzante action on the skin barrier) and protein of the stratum corneum, with increased skin permeability to factors potentially irritating, decreased ability to defend against chemical and biological attacks and, most importantly, increased trans-epidermal water passage (TEWL) and reduction in skin hydration. The use of a classic alkaline soap (pH 10.2) twice daily is able to reduce the thickness of the stratum corneum, further increasing skin reactivity (11). The cleaner is ideal, however, he manages to effectively remove dirt, grease and environmental pollutants, while respecting the lipid and protein barrier. In patients with "sensitive skin" are definitely the most suitable products with low irritancy, low foaming, and able to make substances (moisturizing and emollient) useful for maintaining ideal conditions. The syndet, both solid and liquid detergent systems obtained without the process of saponification (soap-non-soap) and come with a weakly acidic or physiological pH (5.5 and 7), close to that of the skin, are more respectful of physiology skin. The syndet liquids, in particular, are still less irritating, since in such formulations may be used in lower concentration mixtures of surfactants. The addition of substances eudermic protective action or moisturizer, such as vegetable oils (sunflower oil and soybean oil), humectants (glycerol), ceramides and cholesterol, allowing in part to neutralize the action of surfactants delipidizzante, mitigating the TEWL and reducing skin dryness.

Another category of detergents that is a specific indication in patients with "sensitive skin" is that of detergents affinity (oil and milk, detergents) that does not require the use of surfactants, have a simplistic and destructive impact on skin barrier much lower . Although they may not even be removed with water, rinsing should, however, complete the cleansing, to prevent other substances, necessary to the formulation (emulsifiers, preservatives, etc), may remain on the skin by providing a phenomena irritation or allergy.

The use of water without detergent, a habit common among sufferers of "sensitive skin", in an attempt to reduce the degree of skin reactivity, it provides no benefit. Water alone, in fact, as a single phase, it is not readily absorbed by the skin and may, on the contrary, have an effect on delipidizzante skin barrier (12).

The skin is sensitive to the definition generally dry or very dry. For this reason, the choice of a good moisturizing formulation to be used immediately after cleansing, plays a key role in restoring the integrity of the stratum corneum (restructuring of the barrier), improve skin hydration and prevent exacerbation of symptoms. The formulations moisturizers are, in general, the result of the combination of agents, emollients, humectants and occlusive. Products enriched with moisturizing substances can accelerate the repair process of the stratum corneum (lipids: cholesterol, fatty acids, ceramides, pseudoceramidi), seem to be particularly indicated in those with sensitive skin, reducing its susceptibility to irritation phenomena. Moisturizers are often added to formulations capillary-protective substances (vitamin C, bioflavonoids) and with a mild anti-inflammatory action (glycyrrhetinic acid, zinc oxide, etc.). Pleasant, evanescent and easy to apply, cream, emulsion oil-in-water or water-in-oil, is undoubtedly the most suitable formulation in subjects with sensitive skin.

As for detergents, when you choose any other dermo-cosmetic product intended for a person with "sensitive skin", it is important to pay particular attention to the content of potentially irritating substances or allergens such as fragrances, preservatives, heavy metals and, above all, emulsifiers. The latter, in fact, are predominantly cationic surfactants and anionic surfactants, highly irritating, the content of which, albeit necessary, should be as low as possible.

Regarding the photoprotection and the use of sunscreens, in subjects with "sensitive skin" would be appropriate to prioritize based formulations physical filters (oxides of zinc, titanium, magnesium carbonate, talc and kaolin). These are photostable and non-irritating, nor allergenic, unlike chemical filters which, penetrating through the stratum corneum, can meet or photodegradation, predisposing to allergic or irritative phenomena. Despite the good safety profile, the use of physical filters, however, is limited by their poor pleasantness cosmetics. Alternatively, they may, therefore, be used new formulations, processed through technologies that allow to increase the protective efficacy towards UV rays, while maintaining a low level of chemical filters.
 

Bibliography

  1. Spring G, E. Berardesca Sensitive skin: mechanisms and diagnosis. Int J Cosmet Sci 2005 Feb; 27 (1) :1-10
  2. And Berardesca, Farage M, Maibach H. Sensitive skin: an overview. Int J Cosmet Sci 2013 Feb, 35 (1) :2-8
  3. Saint-Martory C, Roguedas-Contios AM, Sibaud V, et al. Sensitive skin is not limited to the face. Br J Dermatol 2008; 158: 130-133
  4. Farage MA. How do perceptions of sensitive skin differ at different anatomical sites? An epidemiological study. Clin Exp Dermatol 2009; 38:521-530
  5. Seidenari S, M Francomano, Mantovani L. Baseline biophysical parameters in subjects with sensitive skin. Contact Dermatitis 1998; 38: 311-315
  6. Chew A and H. Maibach Sensitive skin. In: Dry Skin and Moisturizers: Chemistry and Function. (Loden M and H Maibach eds), pp. 429-440. CRC Press, Boca Raton 2000
  7. Berardesca E, Cespa M, Farinelli N, et al. In vivo transcutaneous penetration of nicotinates and sensitive skin. Contact Dermatitis 1991; 25:35-38
  8. Yamasaki K and RL Gallo. The molecular pathology of rosacea. J Dermatol Sci 2009; 55:77-81
  9. Kumagai M, Nagano M, Suzuki H, et al. Effects of stress on memory by fear conditioning nerve-mast cell circuit in skin. J Dermatol 2011; 38:553-561
  10. Willis CM, Shaw S, De Lacharriere O, et al. Sensitive skin: an epidemiological study. Br J Dermatol 2001, 145 (2) :258-263
  11. White MI, Jenkinson DM, Lloyd DH. The effect of washing on the thickness of the stratum corneum in normal and atopic individuals. Br J Dermatol 1987; 116 (4) :525-530
  12. Cheong WK. Gentle cleansing and moisturizing for patients with atopic dermatitis and sensitive skin. Am J Dermatol 2009 (10 Suppl) :13-17 
 

Supplements for Skin


Facial creams