Roughage revisited - The effect on intestinal function of inert plastic particles of different sizes and shape

The mechanisms by which dietary fiber exerts its laxative action are not fu lly understood. Finely grinding wheat bran reduces its effect.. Inert plast ic particles are equipotent tea bran if they consist of flakes or sliced tu bing. It is not known whether altering the size or shape of inert particles alters their effect on intestinal function. In a randomized crossover stud y, 18 volunteers swallowed 24 g/day of plastic as branlike flakes or as sma ll granules for 10-12 days with a two-week washout period between intervent ions. Whole-gut transit time (WGTT), orocecal transit time (OCTT), defecati on frequency, stool form, stool water content, stool pH, and dietary intake were assessed. The plastic flakes caused a 24% (P < 0.001) reduction in WG TT and a 19% (P = 0.002) fall in OCTT. Resultant and appropriate changes in stool form, interdefecatory intervals (IDI), and stool weight were seen. T he small granules did not cause any significant change in WGTT or OCTT, alt hough IDI did decrease and stool output and stool form score increased. The stimulant effect of solid particles in the intestinal lumen upon transit t ime is influenced by the morphology of the particles.