Time-course characteristics for the digestion of endogenous as well as exogenous protein in the small intestine: a case study with rats fed a [15N]-soy protein isolate

Abstract

A study was conducted to evaluate a net value of exogenous (dietary) protein nutrition in rats fed a [15N]-labeled soy protein isolate (SPI). Although [15N]-SPI-derived nitrogen reached a plateau 2 hr after feeding, it accounted for only a half of the total nitrogen in the small intestine. 15N was confirmed that was normally transported to liver, kidney, spleen, and brain. The present study reveals the large degree of participation of endogenous proteins in dietary SPI during small-intestinal digestion.