Appearance of Intact Molecules of Dietary Ceramides Prepared from Soy Sauce Lees and Rice Glucosylceramides in Mouse Plasma.

Although the beneficial effects of dietary sphingolipids have recently been reported, the mechanism of their intestinal absorption has yet to be fully elucidated. In this study, the absorption and metabolism of dietary ceramides and glucosylceramides were evaluated by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis in the plasma of mice after a single oral administration. Ceramide molecules prepared from soy sauce lees (mainly composed of phytosphingosine and its derivatives) were undetectable or minor compounds in the plasma of control mice but appeared 1-6 h after administration. Rice glucosylceramide (mainly composed of sphingadienine) was endogenously detected in mouse plasma and showed a tendency to increase 1-6 h after administration by LC-MS/MS analysis. In addition, the ceramide molecules, which are hydrolysates of dietary glucosylceramide, were significantly increased in the plasma after administration. These findings strongly suggest that dietary ceramides and glucosylceramides are partly absorbed as intact molecules or hydrolysates.