FERMENTATION AND SUBSEQUENT DISPOSITION OF C-14-LABELED PLANT-CELL WALL MATERIAL IN THE RAT

A C-14-labelled plant cell wall preparation (C-14-PCW) produced from spinach (Spinacia oleracea L.) cell culture exhibits uniform labelling of the major polysaccharide groups (%): pectins 53, hemicellulose 13, cellulose 21, starch 3. This C-14-PCW preparation has been used in rat studies as a marker for plant cell wall metabolism. Metabolism of the C-14-PCW occurred largely over the first 24 h. This was due to fermentation in the caecum. The pectic fraction of the plant cell walls was degraded completely in the rat gastrointestinal tract, but some [C-14]cellulose was still detected after 24 h in the colon. Of the C-14, 22 % was recovered in the host liver, adipose tissue and skin, 26 % excreted as (CO2)-C-14 and up to 18 % was excreted in the faeces. There was no urinary excretion of C-14. In vitro fermentation using a caecal inoculum showed reduced (CO2)-C-14 production, 12 % compared with 26 % in the intact rat. C-14-PCW is a useful marker to investigate the fate of plant cell wall materials in the gastrointestinal tract. These studies show both bacterial fermentation of the C-14-PCW and host metabolism of the C-14-labelled fermentation products.