Water diffusion rate depends on the number of layers of
compactum stratum corneum. The stratum corneum thus
constitutes a uniform, poorly permeable structure which is
the main barrier to water loss by diffusion.
In this study, the test cream with BL lysate did not show
any positive effect on the skin barrier recovery rate but it
appeared to strengthen the skin’s natural barrier. The
number of tape strippings necessary to reach TEWL ‡
15 g ⁄ cm2
⁄ h was statistically higher in the group treated for
2 months with the test cream than in the placebo group.
As previously mentioned, this property of BL extract on
skin barrier function is of particular interest with regard to
the improvement of skin sensitivity: increasing the protec-
tive role of stratum corneum against exogenous agents may
limitate their penetration through the skin and indirectly
protect nervous fibres from excessive external stimuli.
Moreover, enhancing skin barrier may be of importance
particularly in certain inflammatory diseases where barrier
function is impaired such as atopic dermatitis, dry skin or
in aging. Barrier function experiences a variety of tests on a
daily basis including environmental, chemical or physical
factors (UV radiation, pollution, hot and cold tempera-
tures, air-conditioning, low humidity level, etc.), psycho-
logical stress and ⁄ or dietary deficiencies. The accumulation
of these aggressions results in the appearance of barrier
defects which in term may lead to the appearance of skin
disorders as xerosis (47,59). This phenomenon is exacer-
bated with age when repair processes become slower and
less effective