抄録
Malabsorption of protein-bound vitamin B_<12> (B_<12>) is often observed in elderly people with an inability to digest food, because most of B_<12> in raw foods is tightly bound to proteins and the protein-bound B_<12> is not easily assimilated. In this study, we examined whether cooking and processing of ordinary Japanese foods which are used as the source of B_<12> affect the absorption efficiency of B_<12> from the foods. Namely the absorption efficiency of B_<12> was evaluated by the amount of free B_<12> released from protein-bound B_<12> in foods in the in vitro digestion test. The content of free B_<12> in foods after the in vitro digestion varied depending on the conditions of cooking and processing. However, there were some foods in which the amount of free B_<12> in the digestion test exceeded the saturated amount of B_<12> (ca. 2μg) capable to bind to the intrinsic factor secreted from the stomach in a single meal. These were raw and boiled mackerel, chicken liver, skipjack extract broth and dried skipjack soup stock. Therefore, it was suggested that taking these foods well in ordinary meal could result in protection against B_<12> deficiency due to malabsorption of protein-bound B_<12> in elderly people.
