Long-term moisturising may harm skin barrier function
Scientists from Sweden tested two different moisturising products and found that they had opposing effects on the skin barrier.
The first moisturiser that the team referred to as the complex cream was made up of 20 per cent lipids, 5 per cent urea, and 1.3 per cent emulsifiers, in addition to water and other ingredients.
The second moisturiser, referred to as the hydrocarbon cream, had had a higher lipid level (40 per cent), no urea and a lower level of emulsifiers (0.4 per cent).
The double blind randomised trial involved 20 healthy volunteers who applied either the complex or the hydrocarbon cream to one forearm and one buttock, leaving the other free of treatment to use as a control.
Moisturisers can damage barrier function
After 7 weeks the TEWL (trans epidermal water loss) and the skin’s reaction to the irritant sodium lauryl sulphate SLS was measured.
In addition, the study also looked at how the creams affected the mRNA expression of certain epidermal genes.
Long term application of the complex cream decreased the TEWL and the skin’s susceptibility to SLS, according to the study findings; however the hydrocarbon cream had the opposite effect, increasing TEWL and susceptibility to SLS.
The researchers suggest that the effect of the hydrocarbon cream may be due to the lipids in the cream interfering with the intercellular lipids in the skin and affecting their barrier function.
Such changes may be seen as an impairment of the skin barrier, initiating a recovery process within the skin which might be seen as changes in gene expression, suggested the scientists.
Indeed, long term application of the hydrocarbon cream increased the mRNA expression of a number of genes involved in the assembly, differentiation and desquamation of the stratum corneum including IVL, TGM1, KLK7 and KLK5.
Products tailored to skin’s needs
The study concludes that moisturizers are able to modify skin barrier function and the mRNA expression of certain epidermal genes.
As these effects are dependent on the composition of the moisturiser the scientists suggest moisturisers should be tailored in accordance to the barrier requirement of each dry skin disorder.
Source: Archives of Dermatological ResearchDOI 10.1007/s00403-008-0906-6Long-term treatment with moisturizers affects the mRNA levels of genes involved in keratinocyte differentiation and desquamationIzabela Buraczewska, Berit Berne, Magnus Lindberg, Marie Lodén, Hans Törma