Effect of regular sauna on epidermal barrier function and stratum corneum water-holding capacity in vivo in humans: a controlled study.

During the last few years, sauna has become the epitome of wellness. Besides studies in general medicine evaluating the health benefit of sauna, e.g. on the cardiovascular system, no systematic study regarding skin physiology has been published. The present exploratory study was intended to analyse the effect of regular Finnish sauna on skin physiology. The effect of regular sauna bathing was assessed with non-invasive instruments: stratum corneum water-holding capacity, skin redness, transepidermal water loss and surface skin pH were analysed in 41 healthy volunteers, aged 20-49 years, in a group with regular sauna exposure compared to a control group with no regular sauna exposure. A more stable epidermal barrier function, an increase in stratum corneum hydration, a faster recovery of both elevated water loss and skin pH after exposure to 2 x 15 min sauna at 80 degrees C could be demonstrated in volunteers with regular sauna. Heart beat rate and ionic concentration in sweat as well as epidermal blood perfusion showed a training effect under regular sauna. A decrease in casual skin sebum content on the skin surface of the forehead was observed in these volunteers. The present data suggest a protective effect of regular sauna on skin physiology, especially surface pH and stratum corneum water-holding capacity.

Placebo-controlled, double-blind, randomized, prospective study of a glycerol-based emollient on eczematous skin in atopic dermatitis: biophysical and clinical evaluation.

BACKGROUND/AIMS: Atopic dermatitis (AD) is a frequent, chronic inflammatory disease influenced by local, immunological, genetic and environmental factors. Important symptoms of AD are dry skin, intense pruritus and impaired epidermal barrier function. The therapeutic management of AD is difficult and needs individualized concepts. Moisturizing creams and emollients are useful and important treatment adjuncts for the daily skin care of patients with dry and inflamed skin, e.g. AD. Glycerol is known to increase stratum corneum (SC) hydration, improve epidermal barrier function and decrease clinical signs of inflammation. However, no controlled study on the efficacy of glycerol on barrier function and SC hydration in AD has been published. In the present study, a topical 20% glycerol preparation was compared with its vehicle in patients with AD. The aim of the present study was to evaluate the effect of a single emollient ingredient in AD within the full frame of a phase III drug study. METHODS: 24 patients with AD were treated for 4 weeks twice daily with a glycerol-based emollient in a randomized, double-blind study. Transepidermal water loss, skin capacitance, erythema and skin surface pH were assessed with biophysical, non-invasive instruments. The SCORAD and a local severity score were evaluated. After a wash-out period of 2 weeks, these parameters were assessed in order to quantify the sustained effect of this treatment. RESULTS: SC hydration was significantly improved, and epidermal barrier function was restored under treatment with glycerol-containing cream compared to the glycerol-free placebo. No significant differences were detectable for erythema values, SCORAD and local severity between the glycerol-containing cream and placebo. However, an improvement over time was detectable in the assessed parameters in both groups indicating the importance of emollient treatment in AD. CONCLUSIONS: Glycerol-based emollients have a positive influence on the skin of patients with AD. They enhance the SC hydration. Furthermore, it was possible to evaluate skin care products with a protocol design for efficacy studies of fully registered drugs in a placebo-controlled study.