Physiological Pharmaceutics

154 Physiological PharmaceuticsFigure 7.3 The effect of age on transit thriugh the colonthat in women (83±11 g. day -1 mean±se) and could be explained entirely by differences intransit. The increase in stool weight with fibre was significantly related to dose withapproximately 1 g of non-starch polysaccharides (the main component of dietary fibre)increasing stool weight by 5 g per day. Smaller increases in stool weight were seen in females,persons with initially low stool weights and small people. Faecal pH was lower in men thanin women and was related to methane production. Methane producers had higher faecal pHthan non-producers (7.06 compared to 6.65), lower stool weight (93±12 g. day -1 comparedto 156 ±13 g. day -1 ) and slower transit times (84.6±11.7 h compared to 48.6±6.6 h). Thesestudies show that, when on similar diets, women have much lower stool weights and slowertransit times than men. Children appear to have similar colonic transit times to adults,although colonic transit is significantly delayed in the elderly (Figure 7.3).The effect of stress on gastrointestinal transit remains controversial. Colonic motilitycan be increased by emotional stress 35 . It is generally recognized that abdominal painincreases and bowel function becomes irregular in patients with the irritable bowelsyndrome in periods of emotional stress, and that the symptoms often improve as theanxiety diminishes.Although exercise is often recommended as therapy for constipation, the relationshipbetween gastrointestinal transit and exercise is unclear 36 . Certainly immobility leads toconstipation, but increased exercise above the norm appears to have no effect. However, onestudy reported that moderate exercise decreases whole gut transit time from a mean of 51hours to 37 hours when riding and 34 hours when jogging 37 .The effect of dietWhole bowel transit time is generally between 24 and 36 hours in healthy individuals, butvalues ranging from 0.4 to 5 days have been reported in the literature 38 39 . Transit through