28 SKIN MICROBIOME
dimension to skin care formulations where every active material that comes into contact with the skin needs to be considered for its hydrating properties and impact on the skin microbiome. A development that demands a greater level of evaluation and interpretation. So how does the new xylitol bioactive
perform in this context? And what does it mean for formulators and brand owners?
Supported by science Xylitol is known to boost skin hydration and already used in a variety of skincare products,6 such as moisturisers, body lotions and face creams. It is also well established in many oral care applications,7
thanks to its ability to act
as a bacteriostatic, inhibiting the growth of a specific microorganism - Streptococcus mutans - in the oral mucosa. However, it has yet to gain the same level of
attention and traction as other active materials commonly used in the personal care sector. New research, as discussed below, aims to provide data-driven evidence to support xylitol’s moisturising and microbiome-boosting benefits and strengthen its proposition for skin care.
Hydrated and healthy Studies suggest that the skin-hydrating effect of xylitol may be the result of two complementary mechanisms.8
It works to improve the
composition and organisation of the lipidic layer of the stratum granulosum, i.e. the thin layer of cells just below the stratum corneum. It also acts as a humectant to attract and retain water in the stratum corneum. The benefits of these two modes of action
are demonstrated by a recent clinical study.9 Conducted on 43 female volunteers aged between 30 and 60 years, it found that a single, topical application of a 4% Genencare XL – hereafter referred to as xylitol - significantly boosted skin moisturisation levels over a 8-hour period. Capacitance measurements taken using a corneometer show an improvement of nearly
* Tx-T0 xylitol significant versus placebo, p<0.05, n=43 ** Xylitol moisturisation effect, % difference versus placebo
8 7 6 5 4 3 2 1
0 -1
Skin dryness
S. aureus takes over S. epidermidis
Skin barrier damage
Dysbiosis
Figure 3: Skin dryness and the microbiome are interconnected
19% in those treated with the 4% xylitol gel, compared to placebo control (Figure 4). These results support the notion that the
improvement of epidermal barrier homeostasis following topical application of xylitol is due to an increased lipid fluidity in the uppermost layer of the stratum granulosum. This enables accelerated release of lipid from the stratum granulosum, thereby improving the lamellar structure and accelerating epidermal permeability barrier recovery.
Microbiome-minded skin care One in three probiotic supplements produced around the world is supplied by IFF.10
Our
understanding of the gut microbiome undoubtedly helps shape developments in skin health. With this deep microbiome expertise, we help the personal care industry advance their technical understanding of how xylitol impacts skin microbiome colonisation and diversity.
Gel Genencare XL 4% ■ Gel Placebo ■
+18.9%** *
+15.8%** *
+17.9%** *
+12.5%** *
0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0
T1 hour T2 hour T4 hour T8 hour Source: IFF’s Health & Biosciences, Personal Care, 2022
Figure 4: Skin moisturisation levels measured on inner forearms of 43 volunteers over an eight-hour period improves in the presence of xylitol
PERSONAL CARE September 2022 Control In the same study, researchers carried
out two experiments to explore the extent to which xylitol supports the diversity of the skin microbiome.9
Given that microbiome methodologies have yet to be standardised11 , an
internally developed in-vitro biofilm formation technique was used to grow two specific bacterial strains that are known to colonise the surface of the skin: ■ Staphylococcus epidermidis (S. epidermidis) - one of the most abundant commensal bacterium colonising human skin, studies suggest it induces a protective response that prevents the invasion of foreign pathogens.12 ■ S. aureus - a commonly identified commensal bacterium and opportunistic pathogen, it is known to be a leading cause of skin and soft tissue infections. Each strain was grown separately in culture media in the presence of xylitol (at 2%, 4%
S.Aureus ■ * Statistically significant difference to control S. Epidermidis ■
*
*
* * * *
Genencare XL 2%
Genencare XL 4%
Genencare XL 6% Source: IFF’s Health & Biosciences, Personal Care, 2022
Figure 5: Biofilm formation of S. epidermidis and S. aureus shows xylitol supports colonization of S. epidermidis
www.personalcaremagazine.com
Electrical capacitance (A.U)
Absorbance measurement (nm)
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