DIGESTIBILITY AND BULKING EFFECT OF ISPAGHULA HUSKS IN HEALTHY HUMANS

The digestibility of ispaghula, a mucilage from Plantago ovata compose d mainly of arabinoxylans, and its faecal bulking effect were studied in seven healthy volunteers who ingested a low fibre controlled diet p lus either placebo or 18 g/day of ispaghula for two 15 day periods. Wh ole gut transit time and gas excretion in breath and flatus were not d ifferent during the periods of ispaghula and placebo ingestion. Faecal wet and dry weights rose significantly, however, during ispaghula ing estion. Faecal short chain fatty acid concentrations and the molar pro portions of propionic and acetic acids also increased. Most of the isp aghula had reached the caecum four hours after ingestion in an intact highly polymerised form. During ispaghula ingestion, the increase in t he faecal output of neutral sugars was accounted for by the faecal exc retion of arabinose and xylose in an intact highly polymerised form; t he apparent digestibilities of these sugars were 24 (11) and 53% (6) r espectively (mean (SEM)). In conclusion, ispaghula is more resistant t o fermentation than previously reported in humans, and its bulking eff ect largely results from intact material.