2010 年 7 巻 5 号 p. 50-54
The lipid matrix in the stratum corneum is important to the barrier function of mammalian skin. Ceramides are main components of intercellular lipids in the stratum corneum and play an essential role in skin barrier function. Moreover, recent investigations have demonstrated improvement in skin barrier properties after oral intake of ceramides of plant origin in mice and healthy adults. However, beneficial effects on skin barrier function by oral intake of ceramides other than those of plant origin have not been reported.
It is known that acetic acid bacteria accumulate intracellular ceramides. Therefore, we examined the dietary effect of ceramide-containing acetic acid bacteria on skin barrier function. Studied were 3 groups, each comprised of 20 healthy adults with awareness of dry skin. The control group was given a placebo, the low acetic acid bacteria group [low-dose group] was given 55.6 mg dry acetic acid bacteria containing 400 μg ceramide, and the high acetic acid bacteria group [high-dose group] was administered 111.1 mg dry acetic acid bacteria containing 800 μg ceramide per day for 8 weeks. Transepidermal water loss (TEWL) and stratum corneum hydration (SCH) were measured as indexes of skin barrier function on the cheek, upper inner arm and back of the neck of all study subjects. The most marked effect was on the cheek, the area most exposed. On the cheek, the TEWL value increased significantly on week 4 after starting administration in the control group, but remained at the baseline level in both the low-dose and high-dose groups. In both the low-dose and high-dose groups, TEWL values decreased significantly on week 6. The SCH value increased significantly after 6 weeks administration in the control group, whereas in both the low-dose and high-dose groups the SCH value increased significantly after just 4 weeks of intake. This increase occurred within a shorter period than in the control group. These results suggest that oral intake of ceramide-containing acetic acid bacteria effects to maintain skin barrier function in healthy adults with awareness of dry skin.
