Absorption and Metabolism of γ-Oryzanol, a Characteristic Functional Ingredient in Rice Bran.

γ-Oryzanol (OZ), a functional substance found in rice bran, consists of multiple molecular species. In both in vitro and in vivo studies, the researches exploring the various function of rice bran OZ have been conducted for a long time, and it has become clear that OZ has a lot of pharmaceutical activities. It is assumed that each type of OZ molecular species may have different effects. In contrast, the profile behaviour of OZ inside the body has not been fully understood. This article reviews the previous studies about the digestion, absorption, metabolism, and effects of rice bran OZ and also introduces the new method to evaluate the OZ metabolic fate by using high-performance liquid chromatography (HPLC) combined with tandem mass-spectrometry (MS/MS) which has higher selectivity and sensitivity.