Silk has historically been synonymous with luxury and beauty. The exquisite fabric, renowned for its sensual feel, has enrobed queens such as Cleopatra and Himiko of third century Japan. Silk trading along the Silk Route has helped bring world cultures together for thousands of years. Even today, natural silk remains the undisputed “queen of textiles.” While silk remains a treasured textile in clothing and beyond, new attention is being focused on the utility of silk extracts in skin care product formulation. Silk extracts in skin care are now linked to better skin esthetics and health.
Silk extract, prepared from the cocoon of the silk caterpillar (Bombyx mori), consists primarily of two proteins, fibroin and sericin. In textiles, fibroin is spun into silk thread and sericin is discarded. In skin care, both silk proteins provide benefits, and sericin is currently the most widely utilized. Silk extraction and preparation techniques are paramount in determining net benefits to the skin care consumer from silk proteins.
Today, silk extracts are used cosmetically to create an active topical nano-matrix promoting moisturization, sebum absorption and skin tightening. Bio-active proteins and peptides present in silk extract increase cellular activity of epidermal cells and growth rates of collagen producing dermal fibroblasts.
Studies have also shown that silk extract aids in wound healing for skin cells and non-cellular skin components. Silk proteins also demonstrate potent antioxidant, UVB photo protective and anti-tyrosinase melanin inhibitive effects that help promote a brighter, protected and less inflamed complexion. While the skin care benefits are abundant, the three most beneficial effects of silk extracts in skin care include cellular and dermal matrix regeneration, moisturization with cosmeceutical delivery and skin brightening with UVB protection.
Cellular and dermal matrix regeneration
In recent Chinese and Japanese research studies, silk proteins have been shown to increase growth and survival of human dermal fibroblasts (collagen producing cells) by up to 250 percent compared to control groups. Similarly, studies have shown measurable increases in epidermal thickness with the application of silk extract. In America, human wound healing studies have found that silk biomaterial wound dressings increase wound healing rates, re-epithelialization (wound coverage by epidermis), dermis growth and collagen synthesis.
The body of scientific evidence supporting silk extract’s role in improving skin’s cellular regeneration is large and growing. Bioactive peptides appear to be responsible for some of these beneficial effects while the ability of silk to form a tightly adherent microenvironment-controlling nanofilm may also play a role. Regardless of the mechanism, improved dermal fibroblast survival and growth from silk extract correlates with better dermal function, as shown in wound healing studies. This is important because improved dermal function has the potential to enhance skin thickness and elasticity.
In these studies, silk extract formulations were left on the skin for prolonged periods. Accordingly, skin moisturizers and sleep masks may offer the best emulation of these findings.
Moisturization with cosmeceutical delivery
A recent skin hydration study of 47 renal patients with dry, itchy skin found that adding silk extract to a moisturizing cream base greatly improved skin hydration relative to base cream alone. While moisturization is important and this study represents a positive finding, there is more to the story. Silk extract provides an improved delivery of cosmeceutical actives. Studied under the microscope, silk extract particles resemble a micro-sponge.
When silk extract is placed on the skin with other ingredients mixed in, the active agents leech out of the silk over time — and toxins from the skin leech in. Active compounds within the silk powder matrix are slowly absorbed into the skin while the silk slowly absorbs things that can be detrimental to the skin such as sebum and keratinaceous debris.
Moisturizers and sleep masks are the traditional ways silk is used to deliver moisture and active compounds to the skin. In addition, innovative silkbased spa-focused facial masks are an increasingly popular new way to obtain these benefits swiftly.
Skin brightening with UVB protection
A hospital study of more than 40 patients applying a moisturizer with and without silk extract demonstrated significant reductions of skin pigmentation levels in both the arms and legs. The findings were both clinically and statistically significant. The potency of silk extract anti-tyrosinase brightening activity, however, has been found to be variable, in large part depending on the finer aspects of silk extraction technique and initial silk quality.
Silk extract promotes brightness while at the same time offering broad anti-inflammatory properties that, in laboratory studies, are comparable to aspirin-like compounds. In addition to calming skin brightening, silk extract has been shown in studies to greatly reduce the risk of two common American problems — UVB-induced skin damage and tumor development.
The dawn of silk skin care has arrived, albeit in a soft and gentle way. While it hasn’t yet hit mainstream buzz, the cosmetics industry has taken notice. Formulas with silk extract offer truly unique benefits. With skin regeneration, cosmeceutical ingredient delivery, skin protection and brightening, there is a lot to love with silk!
