Disclosed is an oral preparation that is capable of enhancing skin barrier functions such as moisture retention by accelerating the synthesis of ceramide in the skin, and furthermore increases the level of collagen in the skin, prevents skin wrinkles and sagging by inhibiting the saccharification of collagen, and can be safely ingested. Specifically disclosed are a ceramide synthesis promoter, a collagen synthesis promoter, and a collagen saccharification inhibitor, which involve the oral ingestion of xylitol, that have an excellent ceramide synthesis promoting effect, collagen level increasing effect, and collagen saccharification inhibiting effect, and can be safely ingested.
