Abstract
We investigated the moisturizing effect of the bath-additive containing cholesteryl isostearate (IS-CE), which is known to have a stimulating effect on sebum secretion, by evaluating the amount of amino acids released from the skin into bath water, skin surface conductance, and skin dryness. The water-holding properties of the stratum corneum in the forearm of 18 healthy male volunteers was experimentally abolished by treatment with acetone/ether. The release of amino acids into the bath water was suppressed by the bath additive, and depended on the increasing concentrations of IS-CE in the bath additive. In the forearm of 15 healthy male volunteers, the areas treated with acetone/ether were daily immersed for 10 minutes in bath water during the period of two days. A significant recovery effect of bathing with an IS-CE bath-additive on the experimentally-decreased conductance value was seen over that of plain-water bathing. In contrast, bathing with a bath additive without IS-CE did not show any significant increase in the conductance value. Six female volunteers who suffered from dry skin on their lower legs, daily immersed each leg for 20 minutes in bath water for 8 successive days. Bathing with a bath additive containing IS-CE significantly improved skin dryness as compared with that of plain-water bathing. These findings suggest that IS-CE prevents the release of amino acids from the acetone-ether-induced dry skin, resulting in an increase in the water-holding properties in dry skin.
