Fiber supplementation results in expanded proliferative zones in rat gastric mucosa.

The effects of three different fibers on gastric fundic mucosal morphometrics and cytokinetics were compared by feeding defined diets to 40 male Sprague-Dawley rats for 4 wk. Groups of 10 rats each were fed a fiber-free diet as a control or the same diet uniformly diluted with either 20% oat bran, 10% pectin, or 10% guar. Fiber supplementation expanded the zone of proliferating cells by 58% with the guar-supplemented diet (p less than 0.05), 101% with oat bran (p less than 0.05), and 150% with pectin (p less than 0.01) compared with controls. Expansion was due to a downward shift in proliferating cells towards the muscularis mucosa of the oat bran and pectin groups (p less than 0.01) while pectin also expanded the proliferative zone toward the mucosal surface (p less than 0.05). Because expanded proliferative zones have been shown to precede and accompany neoplastic transformation, these data suggest a potentially negative effect of dietary fiber on the gastric mucosa.